Tachometer problem 3500 LX9 V6 1980 MGB

[dukesplace]

Hi Folks,

My engine is a KillerB installation - 2006 3500 LX9 122730 ECM OBD1. The tach wire comes from the ICM under the coil pack. The wire shows 3 volts at idle and 8-9 volts when revved. I have installed a new VDO Electric Tach p/n 333-160. Its not working. I've talked with the VDO tech guys and they are trying to figure it out.

I installed a  Sunpro Tach Signal Booster CP7561 To boost the signal - no help.

What are you guys that have ECM's using for a tach?

Thanks,
Tim
timringland@hotmail.com

[Scott Costanzo]

Tim, I'm using a stock tach with an updated circuit board in it. I've found it to be very close to what the ECM thinks the engine is turning throughout the rpm range.

-- Scott

[dukesplace]

Thanks Scott,

Where did you get the updated circuit board for the stock tach?

[Scott Costanzo]

Tim,
I got it from here:

http://members.shaw.ca/tsmit/tachmod/tachmod0.

I've had it for over 10 yrs now so it was cheaper when I got it. I think we're running similar ECMs and ignition systems. I would think your VDO tach would work with DIS.

-- Scott

[DiDueColpi]

Hi Tim,
Are you using the white  tach. wire from terminal "E" on the ICM?
You might have to program your tach for alternator sensing as I think the ICM output is in 1 pulse per rev.
Just turn switch # 1 off and see if you get a response.

[dukesplace]

Hi Fred,
Yes I am using the whte wire from the ICM. On my ICM the white wire is coming from terminal  C. Terminal E has purple/white - reference high to the ECM, Terminal F black/red reference low to ECM.

On the tach - with dip switch #1 in the off position - what position are the other two in?

Thanks, Tim