'87 3.2 No start, spark, fuel or tach

PeteBrown · 10-08-2014, 10:11 AM

My '87 Carrera 3.2 ran great one day and then would not start the next time I tried it about a week later.

I have swapped out the DME relay a couple times with two new ones I have, replaced all fuses and checked the grounds. The engine turns over but there is no spark and I don't smell any fuel. The DME relay does not click, the ICV does not vibrate and the tach does not move when turning over.

Before I pull the DME, I need to check the CHT and TDC sensors - how do I check them? Do I check them via an Ohm reader connected to the DME cord or at the sensor? I need a little help here with the electronics.

Thanks,
Pete

The cap'n · 10-08-2014, 10:22 AM

If the relay doesn't click, especially with multiple relays, I'd look at power and grounds for that before I went any farther. Have you jumpered the socket to test it?

The Cap'n

rick-l · 10-08-2014, 10:26 AM

A temperature sensor would not inhibit spark.

I'd see if the idle air control vibrates and then check the reference and speed sensors. 280-11 of the Bentley (480 of the pdf that floats around) or 960 +/- 10% between pins 1 and 2 and open 1 to 3.

PeteBrown · 10-08-2014, 10:59 AM

How do you jump the socket?

The ICV does not vibrate. How do you check the reference and speed sensors?

The cap'n · 10-08-2014, 11:52 AM

Look at the wiring diagram. "30" is battery power, "87" and it's variants are usually the outputs. There's a schematic on the case of the relay. I don't have either a wiring diagram or a relay here, but I suggest you try jumping "30" and "87" and see if you power up things that need to be powered up ... Google should be your friend!

The Cap'n

scarceller · scarceller's Garage

If the ICV is not vibrating, with key in run, then DME is not powered up or for some reason has not started running program code. Don't bother checking sensors they are not the issue here as they will not stop the DME from booting.

Here's my suggested test at the relay with key in RUN and the relay plugged into the harness:
- do you have power on pin 30? this is always HOT main power feed from battery
- do you have power on pin 86? this gets power with key in RUN or Start, it picks the relay
- do you have power on pin 87? when relay picks 87 is switch closed with 30

Test in that order, with key in run. Bottom line is that all 3 of those must have 12vdc with key in RUN

Report back.

We will start with those tests first, but the alarm system is also involved here and if the alarm is tripped the DME will not switch on. We won't assume the alarm is tripped yet, let's do the above three tests first.

PeteBrown · 10-31-2014, 11:25 AM

It turns out my ECU was DOA and the cause for my '87's no start issue. Sal Carceller was able to walk me through a few tests to determine what was or was not receiving power and it was the DME itself. I sent it off to Sal and he repaired it quickly and now my car is back on the road. Thanks Sal for all your help.

scarceller · scarceller's Garage

Pete,

For the record your DME failure was a road vibration failure from years of road vibration it caused damage to the Digital circuit board. I'd never seen your particular failure before so it's a new one for me but made perfect sense after I found it.

Thanks for the feedback

Quote:

Originally Posted by PeteBrown

It turns out my ECU was DOA and the cause for my '87's no start issue. Sal Carceller was able to walk me through a few tests to determine what was or was not receiving power and it was the DME itself. I sent it off to Sal and he repaired it quickly and now my car is back on the road. Thanks Sal for all your help.