v6 bad misfire

[mrmom9822443@gmail.com]

I am completing a chevy 3.4 EFI, RWD  in my TR 250 (was graveyard bound). Found a complete non running motor in salvage yard and decided to rebuild it. Ordered a Master kit, had machine shop rebuild heads and machine block. I got it installed, wired it up with a complete 'plug and play' loom I purchased. Fired it up and it ran OK but idled too fast. As I atempted to remedy the situation it started misfiring and fowling plugs.  It seems to be getting too much fuel. I have reset valves (read that suggested 1.5 turns is too much so I backed off to 3/4 turn), checked cam /crank timing allignment, checked fuel pressure, and checked for vacume leak.
 
Can't think of anything else to try. The company I bought the harness and reprogrammed computer has tried to assist and claims they have never had a problem with their system. I'm not very computer / electronic literate but found it simple to hook up the EFI. Maybe I should have stayed in the dark ages (carburator).

This is my first forum and thought maybe someone may have helpful idea (or a carb. dist. set up).

[Charles]

sounds to me like you have lots of unmanaged air.

Is it gas or oil on the plugs?

Do you have all of the sensors installed and wired correctly?

Before starting the shotgun process please do some checking of what should be, double check ever thing.

I am running 3.4L V6 EFI, have 24000 miles since 6/2014.

The sensors you will need are, 3X crank, 24Xcrank, cam, IAT, TPS, MAP, ?

You might take a look at easyautodiagnostics.com or troubleshootmyvehicle.com

happy hunting

charles

[mrmom9822443@gmail.com]

Thanks, Gas on plugs. I'll check out sights.

[Charles]

I missed the temperature sensors, there are two (2). One is for the temperature gauge the other is for the engine management, they, I think, are different. Hard to get them confused, they have different connectors.

The biggest areas for vacuum leaks are the upper and lower intakes gaskets, crankcase ventilation check the valve on the valve cover, MAP.

Forgot to mention, very important, GROUNDS, zero reference points. There a lots of ground leads that need to be connected to the stud on the front of the engine. Just about every one of the sensors have ground.

I also missed the two (2) O2 sensors, one for each side.

Opps, another one IAC

happy hunting

charles

[DiDueColpi]

Daniel,

Do you still have the OBD connector on your harness?
If so, plug in a scanner and see what the ECU is seeing.
Tons of info available off of that little plug.

Cheers
Fred

[mrmom9822443@gmail.com]

Thank you for all your suggestions. I am currently investigating a possible valve train issue.I ordered a stock grind on the cam from
Mabbco (master engine rebuild kit) and was looking at invoice and noticed warning not to pre oil the lifters- which I had done. Technition at Mabbco said they might not be allowing valves to close and might need to replace lifters and cam. He suggested a compression check and I found consistent 125 on every cylender. Found that it should be around 175 to 190. I know I installed rings correctly. I'm waiting for Tech to get back with me so I thought I might see if there were any thoughts or experiences out there.

Thank you again, Dan

[BMC]

Interesting. Are you sure the camshaft was set/timed correctly? Everything is suspect on an engine problem, nothing should be overlooked.