Could this be an ECU problem?

[alniki]

Got an intermittent engine stalling problem and traced it up to a 'no spark' condition. My wrench said it may be caused by intermittent disconnection in the electric circuits.

Acceleration was fine, no hiccup or flat spot and no abnormal fuel smell but usually one or two minutes before the engine went out I noticed the engine response and output was less than ideal. At least on two occasions the engine went out after marked road undulation, maybe just a coincidence.

The crank sensors should be fine as I have replaced both a couple years ago. The ECU was serviced less than 1000 miles ago in another garage but I was not told what went wrong except that a part inside was replaced with a used good one. Could this be an uncured ECU problem or failure of the replaced part?

Thanks for looking and appreciate any advice!

[DRACO A5OG]

To be certain you need another to compare to but I am thinking it may be your reference sensor, have your wrench test both speed and reference sensors.

Bentley shows what the OHMs should be.

[alniki]

Hi, long time no see
Both sensors were replaced by myself not many miles ago so I guess they should be fine. And if I remember it right only the speed reference sensor would cause engine stalling while the other causes no starting.

[DRACO A5OG]

Oh hey Brother!

When you installed it, did you at all twist it in? I hope not, that will kill the sensor.

If you can borrow some a 3.2 DME that will eliminate that as a suspect.

Jim

[DRACO A5OG]

Also check your plugs, cap and rotor and ground points

[alniki]

Don't remember twisting the sensors in, they were not very difficult to install once you got under the car. I replaced the CHT as well.

Grounding is a suspect, too.

Actually am thinking of sending the ECU to Steve Wong for a service and new chip.

[Chuck.H]

Sounds like the classic problem of cracked solder joints in the DME. Open it up and inspect the ones that stand up from the board, as they put a lot of strain on the solder joint.

Search the archives, there is lots written on this.

Hope this helps,
Chuck.H
'89 TurboLookTarga, 327k miles

[ischmitz]

The answer is yes. The DME can fail intermittently as others said because of poor solder and cracked joints. Best to get a loaner and check if the problem goes away. Depending on how good you are with electronics you could fix this yourself.

[Vincent Hill]

"after marked road undulation" ?? I did not understand what this meant after reading your thread??

[dshepp806]

I wouldn't "guess the sensors are OK", at all.. Best check them, again....then, head to other areas,....you have to know NOW that they're operationally OK..

BEST!

Doyle

[alniki]

Thanks guys! I'll check the DME and sensors!
With "marked road undulation" I mean the road runs up and down in a very short distance.

[DRACO A5OG]

Originally Posted by alniki

Actually am thinking of sending the ECU to Steve Wong for a service and new chip.

+1, send to Steve

Also check your dizzy, have your wrench remove, note position, check for slop, laterally and axial.

Mine had both in slop and it caused a miss fire between 2-3K RPMs.

Due to the axial slop, my internal snap in bearings were shot, there are no replacement parts for this. I purchased a known good used one. It spun with some resistance and did not slop up or down (laterally). Good news is if you only have lateral play then you can ad some SS shims/washers to take out the play. Make sure it is properly lubed.


Click Pic

Jim

[alniki]

Thanks mate! I did lube the dizzy myself but have not pulled it out for inspection lately. Think it a good idea to check even it's not related to stalling.

Sounds like when there are no longer any good used dizzy available our toys have to rest in peace