I am in the process of converting my Rover 3.5 L to FI. I have build a megasquirt ECU V2.2 system a few years ago. I am not sure how to start with the installation. Should I first try the 14CUX original Rover system to see it the engine runs fine or immediately run with the Megasquirt system ?
Anybody experienced with the megasquirt set-up ? need some help.
Werner
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Hi Werner,
There are so many geniuses here when it comes to this but when they schooled me, I learned that the 14CUX system is self-adapting and runs all on its own. The MS system allows you to fine tune your Fuel Injection and the newer MS systems will run sequential injection and ignition management for a more advanced ignition system. You can rid of the antique distributor.
Cheers,
NCtim
Hi Werner,
If the ultimate goal is to run the megasquirt then I would start with it.
The time spent setting up the Rover injection and then replacing it,
Would be better spent tuning the megasquirt.
If you are really concerned about your engine build, fire it up on a carb first to break it in and then mount the fuel injection.
Once you get comfortable with the megasquirt you will wonder why you were worried about it at all.
Down load a couple of the tuning programs and play around with them offline.
One I use is "Tuner Studio", which is one of the easier programs to use. And it offers a self tuning option that is really usefull
But I find that I use "Mega Tune" more often as it makes more sense to the old school me.
Cheers
Fred
Hi Fred,
I've been reading all the MS and Mega Tune manuals and I have a headache now. I truly know now that you guys are geniuses if this is simple stuff to accomplish for you all.
Cheers,
NCtim
Fred,
The only reason I am worried about the engine rebuild is the proload on the rockers. The deck is shaved by 0.030 but ran well with the carb.before the rebuild. Now I want to make sure that the preload is right. I need some info on this so I'll start a new tread or find the "How to" in older forums.
I think I start with the older version of MS V2.2 with distributor and switch over to MS 3 later so I can get rid of the dizzy and have 8 individual coils or 2 banks of 4.
Werner
Werner, this might be the preload thread you're looking for: http://forum.britishv8.org/read.php?6,8887
Please post lots of photos and notes as you come along with your EFI installation! I hope to follow in your footsteps soon. My scheme is to use the Rover intake manifold, but custom fab a plenum top that will aim a throttle body straight back toward my existing cowl-mounted air filter... and since there's no room to package a hot-wire sensor in that space, I'm planning on using Megasquirt. If I had room to package a hot wire sensor, I'd just stick with the Rover control system. I'm not convinced Megasquirt is necessarily better in the end, and I'm not looking forward to the tuning phase of Megasquirt installation development.
Curtis,
I'll give you all the info with pictures I have so far.
I do not look forward to upload and fine tune the megasquirt files either but maybe with some help from friends that have done it before it might not be all that bad. I am planning on starting with the MS1 version first and when the engine runs fine I will upgrade to MS3 so I can get rid of the dizzy. Glad to see that there is lots of interest for the MS system.
BTW, how do you like my powder coating . It has the color and texture from the Ferrari valve covers. Not easy to do but for our first time it looked pretty good.
We are working on a banner.
Need to find some help with the replacement of the door sills. Hope to find it in the forums.
Werner
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Nice valve covers, Werner!
If our Megasquirt enthusiasts will indulge me, I have a couple quick questions:
1) am I correct to assume that Megasquirt is equally happy with just about any OEM throttle position sensor? (If not, what should one look for in a throttle position sensor?)
2) given that the 14CUX-generation Rover throttle butterflies measured 65mm in diameter and were sized for the 3.9L engines, if you were considering using an entirely different throttle body assembly on a 3.5L Buick/Rover V8 what diameter throttle body would you look for?
Rover integrated plenum cover and throttle body assembly:
(http://www.britishv8.org/Articles/Images-V15-1/Rover-EFI-K.jpg)
The megasquirt will work with just about any TPS. But it must be a linear type sensor for best results. Some TPS are sloped, and while usable, they make tuning harder.
Sensors for some vehicles such as BMW, Volvo,VW etc won't work as they are actually idle and WOT switches and not a true position sensor.
Port type EFI really doesn't care what size the throttle body is. Technically you can't go too big. The consideration is more about throttle control and charge tuning. An oversized opening causes the throttle to be very hard to modulate. Many manufacturers use a progressive opening linkage just to allow a larger throttle body to be driven smoothly. Such as the later Land Rover v8's. That's why the first 1/2 of the throttle feels so dead. Interestingly most OEMs with electronic throttle control exaggerate the throttle control to make a small motor feel bigger.
You also lose any tuning advantage that a well sized throttle body would have given you towards a ram air effect.
For a mildy built 3.5 the 65mm throttle valve should be more than enough.
An easy way to find out would be to measure manifold vacuum at WOT and maximum torque.
Cheers
Fred
Hiya
Hope this isn't classed as me spamming - although I do run a small company specialising in Megasquirt and Rover V8s in particular, the linky below will help you a lot - irrespective of if you buy anytghing from me !
I would suggest EDIS vs Direct Coil Drivers, MS1 and also that you use a Hotwire Injector system vs the Flapper one.
Look at www.megasquirt-v8.co.uk
If I can help just ask, but as others have said it will transform the engine, I run twin MSQs (Programs" 1 x for max power (and fuel !) and another as a "Economy" Map for just driving about, you can swap between them either via loading via a laptop or build the ecu right and have a dashboard switch :O)
MS1 will do all you need and then some, use latest version MS1 V3.57, MS3 is frankly for what you engine is far too OTT and expensive, you'll gain 1/32 of F all :O). Use MS1 get it running then spend the saving on a rolling road session with someone who knows not just about tunning but who is also familair with tunuing MS. You can do the fuel side yourself, the spark is the trickier one to sort. If you get stuck let me know and I can send you a suitable spark table
Never forget the engine you have there is basically a 50s Buick engine, simple and MS3 is just not going to give you any gains over a well set up MS1
Hope this helps
Nige
I have a question maybe you could answer. I have a FAST efi throttle body. It's basically a 4 bbl carb body with 4 injectors in it if you're not familiar with it. It's going to go on a ford cologne V6. I have a dual plane manifold. With the carb when cruising, the primaries feed only the longer intake runners but under more throttle the secondaries open up and the short runners get fed at the same time. With MS2, should I try to set it up like a progressive carb, with only the 1st bank of injectors working, then under more throttle have the secondaries open and the second bank of injectors kick in? Or should I set it up like up double pumper and have all 4 opening with all 4 injectors working. I would also like 2 maps, one for performance, 1 for economy.
You'll need an IAC valve, MS-I might have some limitations there, and that is something to be very particular about. Just a solenoid valve can work, but basically if you want to run EDIS you can't do IAC.
The simpler MS systems are good, and inexpensive, so they make a lot of sense. But it's really all in what you want out of the system. The engine may be 50s technology but that is not so far removed from today. It's still pistons running up and down, and everything else is peripheral and can be updated. You've seen the build details on my Buick 340 for instance. It's a '67 engine but is fitted with neoprene seals, crank trigger, port injectors, etc. Ultimately individual egt's and COP, and then there is the transmission control. MS-1 is hopelessly inadequate for that task, but MS-3 is not. There is however a new board on the scene, called the Qorivva:
http://blogs.freescale.com/2011/06/07/calling-all-petrolheads-configurable-aftermarket-ecus-for-sale/
I know very little about it at this point but it seems interesting. One thing I like very much is the sealed case and connector.
On the throttle body, you get some progressive action by the way you connect the linkage. On mine I'll be using a bellcrank to double that action for smooth off idle performance. A small car with a big engine does not need much throttle most of the time.
On the dual injectors, most of those are set up with some overlap so that the secondaries begin to come in before the primaries saturate.
Jim
I am thinking that what you call IAC is what I know as "Extra Air Valve" or of the Rover V8s the "Stepper Motor" in which case you are correct in that MS1 will not control the 4 wire RR Stepper motor. However, MS1 will control the simpler and more relaible Bosch 2 wire Air Valve, and offer the ability to program it in terms of the "Autochoke" as to how much to lift the RPM to on cold start ups, and then lower the rpm bit by bit down to "Off" at another set RPM at a set temperature when reached. It will also control the tickover and give a rock solid one via closed loop settings
I actually don't like the RR stepper motor, they are reknowned for sticking, and being a PITA !
Control of a gearbox linking to the Engine ECU then yes MS3, but for engine control MS1 is more than enough, I have customers using highly tuned and rather exotic Rover V8s, dyno'd and set up spot on, a MS2 or MS3 would stuggle to give "More" BHP & Torque.
Too many people think that £s more = must be better, and to some degree that is true, but MS1 is a whole load easier to get to grips with and set up and get good than MS2 and 3 which are a huge step up in complexity. A spot on MS1 will and does often beat MS2s, I have lost count on how many poor MS2 set ups I have seen over the years !.
Ms2 basically gives a Bigger tune table than a MS1, will run a Steeper Motor, and allows the owner to rewrite and tweak the code it is written in, other than that MS1 will do everything MS2 does.
I have a lot of customers who have started with MS1 with the intention of going MS2 and never have, also people who have tried starting on MS3 and given up with a non runner. MS3 is superbly designed but you do have to know what you are doing to build and tune up the unit, more so than with say MS1.
Viva L Difference !
One thing is for sure, MS in any config set up properly knocks spots of "Lucas Prince of Darkness"
I even ended up selling these for those who wnated a coffe table talking point :
:O)
Nige
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Here is a link to a handy dandy chart that shows the different features of the various versions of Mega-Squirt.
http://ms3efi.com/feature-xref.html
I'm a big believer in using MS3! Its faster, smarter and you can do more with it. Even if you don't use all of the features of MS3, the fuel tuning down to one tenth of a percent can make a big difference when tuning low load drivability conditions ie.city driving.
When I was running MS2 there were times when 1% of fuel trim was either to rich or lean. With 1/10 % of adjustment, it makes it easier to tune for both fuel mileage and power!
1/10% fuel adjustment also makes auto-tune work much better as well! There much less "hunting/surging" during the auto-tune phase of setting up your VE table, due to the faster processor and finer adjustments. This is important for first time users.
Even though it is more complex then MS1/MS2, MS3 combined with Tuner Studio is actually easier to use for a "car guy" like myself.
I like to compare the various versions of Mega-Squirt to a PC computer. You can have a PC that was designed a couple of years ago, or you can have one that was designed 10 years ago! Both will work, but which one would you rather have?!!
Bill
Mac?
That business about the air valve... how are you going to get different steps and different flow volumes from a solenoid air valve? Isn't it going to be either open or shut? If you could step it down... well, wasn't that what the stepper motor was designed to do?
I actually prefer the Ford IAC which is PWM controlled and needs only 2 wires. I like the configuration and mounting better too.
Jim
In all the commotion, we almost forgot to welcome a new member to the forum.
Glad to have you here, Nigel!
Re: Megasquirt vs 14CUX
Posted by: Moderator
Date: April 24, 2012 04:09PM
Mac?
Sure! :-)
I have been using Tuner Studio on my mac some, but using Parallels and running it through windows. It will run on the Mac, but i have not worked out the connections there yet..
Yes,
Welcome Nigel! I suspect that I'll have loads of questions for you. Also, thanks for the link. On the MS version 1, I didn't think this system could control sequential spark, only wasted spark technology. Am I incorrect?
Cheers,
NCtim
MS1 is Wasted spark, not sequential.
As I said in my email to you yes MS3 is very very nice, but OTT for any Rover V8, some here use MS2 on TVRs etc for track days, but I have a customer with a MS1 power tweaked TVR and he outperforms so many "High Spec" Others - mainly due to it being set up spot on via Megaalogviwer / tuner studio AND a healthy time with a Rolling road to get spark map spot on. MS1 is easier to work with if complexity is not an attraction for you.
The Bosch 2 wire Air Valve I use is a PWM unit, hence "Tunable"
You can put stockings, high heels and lipstick on a Pig - but its still a pig
If others think MS3 is the answer to a Rover V8 then fine for them, the final result is only as good as the set up and tuning, I have even helped with a V12 1959s Meteor Tank - now on MS1 !
I have also (as I had to for my current own project, had to make VR sensor brackets and Trigger wheels for the 4.0 unit (as my 5.2 has this as a front end on it :O( I don't like th factory units as they are in the bellhousing, and do fail - particularly with what I do with them :LOL:
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The VR Bracket has slots to allow adjustment to the timing, and also to get the correct Air Gap,
I think this proved to be a solidworks and Prototype nightmare to get spot on :O)
Hope this is of interest
Nige
Thanks again, Nigel. This is all good info.
Cheers,
NCtim
Very nice sensor mount. There is a large market for those and the matching trigger wheel, especially if it will fit all of the Rovers, 215's, 300's, 340's, 350's and Buick V6's. In which case it may also work on the big block Buicks. (Can it be used with the stock mechanical fuel pump in place?) I think your development efforts could pay off nicely. The nicest design I've built so far bolts to the fuel pump boss and won't work if a mechanical pump is needed.
I'm with Bill on this one, the ability to independently tailor fuel and spark to each cylinder and set up auto-tune to let the controller optimize each one as opposed to batch fire of both fuel and spark with a one-size fits all approach has big potential payoffs. You let the MS3 vehicle spend the same time on the dyno as that MS1 and I think you'll see the difference.
But it isn't all about the Hp figures, driveability, or even economy and there can be no doubt that added complexity can take you into the realm of diminishing returns. For some, such as Bill and myself, the individual cylinder tuning is needed. Both of us run superchargers on one-of-a-kind custom intake manifolds. Without the uber budget to endlessly develop and test it is highly unlikely that you can get perfectly even intake distribution with such a design on the first prototype no matter how good you are. So while the MS1 will work, it may be very far from optimal. This is not an issue that the average builder has to deal with, but even so, the unequal length headers we are stuck with means uneven cylinder conditions, and any uneven cylinder condition is fertile ground for individual tuning.
In regards to your IAC solution, that sounds quite creative but the issue I ran into with MS1 was an inability to both control idle air and provide a timing advance output (SAW signal) for the EDIS. Even with the 2 wire Ford PWM IAC I wasn't able to run both. The best I was ever able to do was to use a solenoid for fast idle and even then (going from memory here) I think it was an either/or situation where I could have EDIS advance OR fast idle but not both. I do remember feeling very frustrated with this limitation which I considered short sighted, and it led in short order to an upgrade to the first MS-II beta daughterboard, and then the newer (current) MS-II configuration. (anybody want to buy a beta1 MS-II?) If you have solved this dilemma I applaud your accomplishment, and wish I'd known about it 8 or 9 years ago. Even now I would like to know more of the details.
So all I'm saying is that it's a real good idea to make sure you have a clear upgrade path, and if you might need the higher features it is cheaper in the long run to provide for it at the beginning rather than later. The v3.57 MS board is a good piece. The MS-II or MS-III cards plug right in for ease of upgrade and there is an MSX expander for more inputs and outputs (need the bigger enclosure), plus the GPIO which uses a separate enclosure and can serve many functions including transmission controller. Most of us go more complex because of a need. I don't know very many people who want to go more complex simply for the sake of complexity. OTOH, I DO know people who will go high tech for bragging rights, and that is a legitimate excuse.
Jim
I agree, The MS3 is a great solution for what you are doing, as you are pushing the options of what you can do waaay
over standard. The problem is that for some MS is just a "Small Part" of their hobby, and more than often <sigh> they haven't got a ****ing clue when it comes to ECUs tuning, making a wiring loom, etc etc. I have had emails saying ....
"Like the sound of your MS1 system - can you do me one with the correct plug for my Lucas harness" <WTF ?>
"Will this run my x y z enghine without major modifications"
"Can you build me a wiring loom and get it switched completely to Megasquirt if I bring it over 1 afternnon and wait ?" <you'll have a Kin long wait Matey .....
And the best email yet
" I am not exactly sure which engine I have, but am interested in your kit, can you advise on what else I need other than your ful kit" <please just go away pleassse ....>
So, faced with this, a MS3 would baffle them. Actually on rethinking what I have typed the MS1 would baffle them. In fact its possible if you shuffled their left and right shoes around it woulod puzzle them, thankfully I don't get that many of the "I am a Muppet" Clan, though some do make me blink at the monitor ....
Most peps I deal with have some knowledge of most things, but are only "Good" at a few. Some can Tig weld "Unobtainium" with ease, but not build a ECU to save their lives, some can wire but not weld, some can't weld wire or do much else, but, with detailed instructions and some support want to have a go, I try to cover all.
I did have a "Proper Job" after I found out that this well paid "Proper Job" was likely to end up with me in a box underground quite shortly I was luckily "Let Go" and wondered what to do, I had friends literlaly begging me to megasquirt their trucks, and after a while I thought "What if I could make a complete kit that even some of the muppets could actually follow with ease and megasquirt their V8s ?"
I love my V8s, I do get involved with other engines (aparrently there are oter engines out there than V8s) and I love what I do
I tinker, make up brackets and solutions to problems, I am amazingly getting known in the UK as a guy to buy stuff from becuase I will help when stuck, the winner than near beat me was the "Chap" who said he couldn't get his engine to run. after WEEKS of calls I ended up at his 4x4 racer and tried to find the fault. As an autoelectrician by trade the install was perfect, a beautifull job.....
After 6 hours I was stumped, NOTHING and I mean NOTHING mad it run, I checked everything - several times - you know the I have looked in here once but I will just lok again in desperation that the f up fairy may have visited and swapped it sinmce I looked last time sort of look at ....
I sat in the corner on a tarpalin and drank a coffee, I was uncomforatble, lifted up the tarp to see what I was sitting on, its was a 300 TDi LR engine - Whats this for I asked ?
"That mate was the old F engine which I F wished I havd never F removed for the F Poxy F V8 and your bl**dy megasquirt........"
And tell me, what exactly is the fuel in the Tank"
:O)
Prob sorted
MS3, please ........................ :O)
With my Kits of MS1 the majority of customers are "LR Challenge" Motors, V8s and water don't mix, as I am sure many here will know.......heres why I love MS ....
http://www.youtube.com/watch?v=GP29tqQcgMY
Then the TVR Boys found me, there old Lucarse ECU are dying, some want MS2, many go MS1, easy to help
MS3 ius superb, no Q, its just the "Main Market" I operate in has peeps with little / no / none skill :O) and all plead proverty
and many just wnat a simple relaible foolproof <cough> system that they can sort out and get to grips with
Supplying them with MS3 would see the remainder of what hair I have fall out and the Will to Live prob slip away from me ....
Hence my Love of MS1
MS2 I think is more / was / a stop gap for MS3. Ms3 is a world apart from MS1, and I still think there is a market for all.
ALL MSs are a vast jump in terms of qulaity relaiblity and user freiendlyness vs Lucarse prince of Darkness stuff, if ever you wnat a shock, unwrap a Lucas V8 Harness and "Admire" and gasp at the "Quality" especioally around the joins ......
Not sure what the prob was with PWM etc but I have no probs with it working with everything else...Odd
But then again so am I :O) ...........
Nige
Case in point, Mopar Gen 3 hemi, you can use Mega 3 to run everything, try to limp along, bound and gaged with the factory set-up or spend thou$ands, with some aftermarket sharks. A few folks cave in to anti-tech sentiment and spring big buck$ for carb and distributor adaptions. This would be a thoughrougly well engineered engine, fed and controlled, from the dark ages. IMHO, why bother with a modern design at all ? Cheers, roverman.
I am glad I started this post. I didn't realized there was such an interest in FI and MS. There will be much more questions asked in the future about this .
Thanks Nigel for the info. Where exactly is Costa del South in the UK ?
I'll be coming to the UK next year for 6 weeks so I might make some time to visit if work schedule allows.
I'll be working at Sizewell. Got in touch with RPI but had complaints about the way they treat customers.( Never got the VAT back for parts imported in the USA).
I am going to stick with MS1 for a while.
Werner
RPI ....Oh yes I tried dealing with them a couple of times
Spoke to one of the guys - Chris - a Legend in his own mind, Like Adolph Hitler - but without the charm
I couldn't believe the attitude and unhelpfulness sprouted down the phone at me.
Dealt with John Eales (JED) instead - and gave him my money for top servic and support :O)
Nige
QuoteI actually prefer the Ford IAC which is PWM controlled and needs only 2 wires. I like the configuration and mounting better too.
Jim, I'm curious to know which Ford throttle body / IAC you're thinking of?
I've looked hard at some of the Mustang throttle bodies - there must be a dozen companies making aftermarket versions and some of them are appealing - but I'm leaning toward a Chevy 4.3L V6 (72mm) throttle body because I think its form factor might work a lot better for my installation. It's only 56mm thick (flange to flange). Chevy mounted it as a downdraft, but I'd mount it vertically with the throttle linkage on driver side. (I prefer a linkage to a cable, and its design appears to suit that better than most.) Its IAC is tucked-in pretty neatly to the body, side by side and about the same size as the TPS, both on passenger side.
Anyone have a comment about using the GM 4-wire IAC with MS2 or MS3?
Here's what I don't understand about the Chevy throttle body: they put a "diffuser" on the back of the throttle plate that blocks a lot of airflow, particularly at low throttle openings. Even at wide open throttle the diffuser probably blocks 25% of airflow! Aftermarket throttle plates are available without diffusers... although removing the diffuser is as easy as grinding off two rivet heads. The diffuser is in addition to a "nautilus" shaped cable connection - so why did they do both?
(by the way... the diffuser is shown here in a video about how to remove it: http://www.youtube.com/watch?v=Gy0_ecIof7M )
Curtis
The GM 4 wire IAC works well with MS2/3. For the most difficult part for me was tuning the IAC for my application. Since there is no position sensor in most IAC motors, they are controlled by steps or voltage applied for a certain amount of time. (step size). Since some IAC motors can react more quickly then others, its up to the tuner to set the step size and other values based on how the idle speed responds during warm up.
Normally the default settings in MS are pretty close, then it just requires some tweaking.
In MS2 your options are warm up only. In this case you set the idle speed with the throttle stop screw and the IAC is used as a fast idle device for cold starts/warm up. Once the engine is warmed up the IAC pintle is fully extended or closed.
With MS3 you can have either "warm up" or "closed loop" idle control. With closed loop idle control, the throttle stop screw is adjusted to a "minimum" idle speed which is slower then what your "target idle" speed would be. Then MS3 extends or retracts the IAC pintle based on desired idle rpm/engine load.
Most all newer vehicles are closed loop idle controlled.
Link to MS3 idle control page http://www.msextra.com/doc/ms3/Idle_Control.html#SECTION00055000000000000000
Currently I'm still running my IAC set up as warm up only, with the same settings as I had while the car was using MS2. I haven't tried using the closed loop IAC feature in MS3 yet. Its one of those back burner projects that I may play around with in the future when I have the time. I would think that the GM 4 wire IAC should work for closed loop as well, since GM does it!
The diffuser is there to direct air flow in relation to how the EGR gases are distributed within the stock GM Vortec intake plenum. It also allows GM to make one throttle body for the different engine displacements. The 4.3L has a larger diffuser then the 5.7L.
I have seen the diffusers fall off before. We had a truck in a couple of weeks ago that the diffuser came loose and was getting caught in an intake valve, the motor didn't like that so much!
I removed the diffuser on mine by drilling out the rivits and installing solid rivits (instead of pop rivits) in the holes. I'm not a big fan of cutting the diffuser, since there is still a chance that the left over piece could still come loose.
Bill
This is a great topic!!! Thanks for posting Werner.
I have the 14CUX system and I can't seem to get the car to run well at low RPM (engine misses between 1000-2000 rpm) or get the (new NGK) oxygen sensors to go into closed loop (the two are probably related. Wiring checked out okay). It might be because I am running a fairly agressive cam and have it set at 104 degrees. So I am curious to know if the MS might be the solution to my EFI woes...
Very helpful comments, Bill. Thank you!
I think I might leave the throttle plate's diffuser in place through initial development, on the theory that a 4.3L (72mm) throttle body is probably larger than ideal for my 3.5L engine anyhow. Last night I mocked-up a plenum design, and today I visited my local machine shop and got them started on machining a custom plenum base. The proposed plenum top is extremely simple in form... still not sure if it will be carbon fiber, aluminum, or satin black powder-coated mild steel. As designed, the whole plenum will be so narrow that Rover's steel fuel rail will be removable without disturbing the plenum top or throttle body. I might end up fitting an extrusion-based fuel rail, but my initial plan is to simply rework the two ends of the one-piece tubular rail.
So here's my next question:
For MS2/MS3, how helpful is it to fit an adjustable fuel pressure regulator? Is an OEM style regulator more robust? Is there much real utility to having a gauge, or will I only need one for initial development? (Aesthetically, I'd prefer to keep things simple and monochromatic...)
The main disadvantage of the Rover fuel rail is that due to the injector angle it is a pain to install. This can be fixed by replacing the big bend with a braided hose though. If you are using the Rover lower Intake, keeping the trumpets is probably a good idea sin e they tune the runners.
If someone comes up with a particularly good fpr I would like to know the details. I've been using Ford but they are not that easy to add to a custom rail. I tried an adjustable but went back to stock for simplicity and ease of replacement. I feel it is better to use a standard rail pressure and match injector size and pulse width to the engine. Fpr's generally are a band aid for systems that aren't adjustable.
A gage is handy for tuning or troubleshooting but otherwise is a potential leak. Rail pressure rarely changes once the system is stable.
A midrange surge is an extremely common problem in modified OEM systems. Frequently it cannot be cured using the stock controller, even if there is axway to tune it, and it doesn't seem like anyone wants to discuss it. I got rid of it on my car only when I ditched the Ford controller, which with a tweecer add on was very tunable if you only had access to Ford's secret files. With MS-II it worked just fine.
Jim
I would agree with Jim on this. Generally its best to use a stock pressure regulator if the horsepower levels are close to stock levels and the stock injectors are being used. ECMs have a useful range of pulse width control. If the injector is to large then the pulse width becomes to narrow and the engine becomes difficult to tune at idle and low rpm cruise. If the injector is to small the pulse width can be maxed out at WOT and cause a lean condition.
Adjustable fuel pressure regulators can be handy if the engine is highly tuned/modified and there is not a suitable sized injector avilable for the horsepower levels.
An adjustable fuel pressure regulator allows the tuner to move the "pulse width window" up or down slightly by changing the fuel pressure. Often times simply changing the pressure by 5-10 psi will be enough to bring the pulse widths into the ideal range for the ECU. Once the ideal pressure is found, normally it is left alone since changing the fuel pressure will change your entire tuning requirements.
There are calculators on the MegaSquirt web site and these will get you close for injector sizing. However you won't know where your pulse widths are until the engine is up and running/tuned. If the engine's horsepower was over/under estimated, or the horsepower level has been increased/detuned, then an adjustable regulator may be an option instead of buying 8 new injectors. (been there done that)!
The main thing is you want to stay in the fuel pump's ideal working range which is usually 30 to 60psi for most pumps. If the pressure has to be adjusted out of this range in order to bring the pulse widths in line, then the best option is to change to a different flow rate injector.
An advantage MS3 has over MS2 is the finer fuel table resolution .1% compared to 1%, this can be helpful when tuning for very short pulse widths. With the finer resolution I've noticed that the MS3 is a little easier to tune at idle and low load (city driving) conditions. For a car driven on the race track, it won't make a huge difference. For a street car, driven in the city that has larger injectors and other mods MS3 and an adjustable regulator are probably worth while investments.
Bill
I copied the following from the MS manual that explains the effect of pulse width at low load/idle.
QuoteIdle Pulse Width
You have to select your injectors based on the maximum horsepower your engine can produce to prevent the engine from running lean at wide open throttle. But why not just pick the biggest ones you can find?
The answer has to do with idle and cruise pulse widths. If you use very large injectors, your idle pulse widths get very short. This can drastically reduce the mixture ratio control that you have during idle and cruise situations, and lead to very poor driveability and seemingly strange tuning behaviour.
To illustrate, suppose you have established that your engine produces the lowest MAP reading at an idle pulse widths of 1.2 milliseconds, and your opening time is 1.0 milliseconds (considered the 'standard opening time'). Recall that MegaSquirt can only change fuel by 0.1 milliseconds at a time.
And also recall that MegaSquirt assumes NO fuel is injected during opening (which is close to true, since the injectors remain closed until the coils charge, then they snap open at the end of the opening time). Now if the net effect of the enrichments change by 2%, the pulse widths don't change at all. Even if they change by 49%, nothing changes. But once they change by 50%, the pulse widths suddenly changes to 1.3 seconds.
So the next leaner possibility is 1.1 seconds, and the next richer is 1.3 seconds. However 1.3 milliseconds is not 1.3/1.2x100% = 8.3% richer, instead it is (1.3-1.0)/(1.2-1.0) = 50% richer! The mixture becomes very, very rich, and the engine runs poorly.
To confuse your tuning efforts further, it may be that you are already near a threshold, so that a small change in one parameter makes a very big change in the air/fuel ratio in one direction, but no difference at all in the other direction!
But doesn't the EGO correct? Actually, it can't. Even if you set the step size to 1%, nothing happens until the 50% (i.e. 1.3 milliseconds) threshold is reached. That is, the step size only takes effect once the 0.1 threshold of PW is reached. And if the number of ignition events between steps is large, the engine may stumble and die before it recovers and leans out. So in fact you may be better to set the O2 step high (50%), and the number of ignition events low (say 2) so that the average over just a few injections is correct. It is a band-aid approach, however, and likely to induce ignition related problems.
Obviously the converse is true if the engine goes lean. It has to go at least (1.1-1.0/(1.2-1.0)=50% lean before anything happens. If does go lean, it may back fire and die before it gets a chance to become richer.
You might think you can get around this by decreasing the injector opening time (to get a larger "adjustable time") and increasing the VE (or req_fuel), but that doesn't work because the 'ideal' injection time is still 1.2 seconds, and the permissible step is still 0.1msec, regardless of the way you add the components of the pulse width up.
And making matters worse is the fact that many high-performance engines will want even lower pulse widths at cruise than at idle, compounding the tuning problems and introducing more driveability issues. A system with a very short pulse widths like this will be difficult to tune. It will appear not to respond at all to enrichments over a certain range of a parameter (say IAT), then suddenly it will seem to change so drastically that you seem to require an entire new set tuning values.
Now even if your engines idles perfectly at a very low pulse widths, changing load, speed, and other variable (EGO, IAT, etc.) will demand slightly different air/fuel ratios. However, none of them are likely to need exactly the +50% you have to choose from!
This is why several aftermarket ECU manufacturers recommend an idle pulse widths of not lower than 1.7 milliseconds. If yours is lower than this, you need to address it before you will be able to tune your engine for all operating conditions. Ultimately the best solutions are appropriately sized injectors or staged injectors.Quote
Very good reference Bill. I see someone has been working on the manual. Could you post a link please?
Jim
You guys are so incredibly helpful. Thank you!
Since I have two Rover fuel pressure regulators, I guess I'll try to make that style work. I like the price!
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Now I've turned attention is on what should probably be even simpler... the intake air temperature sensor (IAT).
Q1: for a normally aspirated engine, is there any reason to prefer mounting the IAT either before or after the throttle body? (My intuition is that upstream of the throttle body is cleaner, especially if PCV is ported in nearby. Downstream may be warmer.)
Q2: should I try to arrange it so the airstream flows over the IAT sensor, or is it fine if the sensor is just in near proximity?
Q3: do you expect there's any significant performance to be gained by putting a phenolic spacer between the lower manifold and the plenum in an effort to reduce intake air temperature? (Some of the UK performance shops sell spacers for this purpose. I could make my own if it truly makes sense, but I'm skeptical.)
Jim
Sure! Link to main menu for MegaSquirt manuals http://www.msextra.com/doc/index.html
When searching through the manuals/links, I've found that most of the basic information such as injector sizing, fuel, ignition tuning, etc can be found in the MS1 manuals.
Then for more specific features or advanced topics, the information can be found in the MS2 and MS3 sections.
Curtis
I've found that locating the IAT sensor as far away from the throttle plate as possible works best. The issue is with heat soaking the sensor on re-starts.
For example I had the IAT located fairly close to the throttle body and when I would shut the engine off for 20 minutes or so. Then do a re-start the engine would run lean for a short time until the sensor cooled down to ambient temperature. When I would check the data the IAT could be reading 115*F when the ambient temp was only 70*F.
In theory the in rushing air should cool the sensor down right away. If I started the car and headed out on the highway right away, the sensor would indeed cool to ambient quickly. However if I started the car and was just doing stop and go driving, the sensor would take much longer to equalize to ambient temperature. At the lower RPMs/throttle openings there isn't as much air flow across the sensor to cool it.
I ended up moving the sensor to the air inlet at the cowl. In this location the sensor dosn't get as hot during a hot soak condition and the sensor responds to ambient temps much more quickly.
There are correction tables in MS3 to help compensate for heat soaked sensor as well. I've played around with the settings some and they can make a difference. Ultimately I found experimenting with different IAT locations gave me the best results though. Depending on your air intake set-up, usually its pretty easy to move around the IAT sensor!
It is best to have the sensor directly in the air stream.
Not sure how effective the spacers are. I would think that they could help somewhat, as a lot of the OEMs are now going to plastic intake manifolds in order to reduce air intake temps.
Bill
Interesting. Sort of makes me wonder if a location in front of the radiator and not in the intake at all might not work well.
Jim
For those who draw they're air intake forward of the radiator and behind the grill, I would think that it work quite well.
The main thing is to locate the IAT sensor in a position where it can measure true incoming air temps. So for installations that have no cold air intake set-up, that most likely would mean locating it the air stream near the air filter.
There are also MAT (IAT) correction tables in MS2 and MS3. So for example once the engine is tuned you find that the engine runs slightly rich in the morning and maybe a little leaner mid-day when the ambient temp is hotter. You can use the correction table to automactically adjust the VE table up or down as the ambient temperature changes.
MS3 takes this one step further by offering both the correction table and an additional setting (MAT correction value) that allows you to change the percentage to which the physics of gas law is followed.
The method I use to tell if I need to use correction table is to first get the VE table, ignition timing table, etc tuned so that the engine runs well. Then drive car on a cold morning with auto-tune on and in the "hard or very hard" setting. Then check to see if auto-tune wants to change most of the bins richer or leaner. (It's easy to tell because the numbers will be either blue or red) Then leave the VE as is (don't allow Auto tune to change the VE table). Next drive the car with auto-tune on during a hot temperature day. If auto-tune wants to correct the VE in the opposite direction as the cold morning drive, then I'll use the MAT correction table.
Normally its best to do this test several times, to account for changing weather conditions etc. Also its best to start out with a small amount of correction and work your way to higher correction values if needed.
The goal is to get to the point where auto-tune wants to change as few VE bins as possible whether the ambient temp is hot or cold.
http://www.msextra.com/doc/ms2extra/MS2-Extra_Conversion.htm#matcor
Bill
Very good tip Bill. That is something I haven't tried yet, but I will now that you have explained it.
I will consider mounting the IAT just behind the grille. That will eliminate more wires up to the Enderlie style scoop/TB. Both should be at the same temperature as both are at the leading edge of the car in terms of airflow.
Jim