ROW Flash, and Now Car Is Undrivable!

[Dave80GTSi]

Guys – Many thanks to each and every one of you who have added your thoughts to this puzzle. I very much appreciate them all, and they’ve given me a number of issues to ponder. Thankfully I do have the unique circumstance here of not needing to rush into this, giving me ample time to do some research and homework.

Pouring thru my Bentley manual, page by page last evening, I finally stumbled across a pretty obscure paragraph, reproduced below:

“On ME 7.2 ( … which is mine) and ME 7.8 cars, the engine control module (ECM) software performs a learning and adaptation routine for the throttle unit if:

- The power supply to the ECM is interrupted (Me: Yup!)

- The ECM plugs were disconnected (Me: Yup!)

- A new ECM is installed (Me: Well, maybe sorta?)

- The throttle unit is replaced (Me: Nope!)

- The ECM is programmed (Me: Yup!)”


So, no question whatsoever that the throttle needs to be recalibrated. [One can perhaps wonder how, if a person were to unplug their battery for months at a time for winter storage purposes, that scenario might fit to the above five (5) bullet points – maybe ticking the box for Point 1?]

But in any case, the Bentley manual then goes on to paraphrase the contents of the TSB info that I posted earlier on in this thread, with the stern admonition (among others) that the min / max temperature guidelines which are noted in the TSB “MUST” be observed. And since my first couple of attempts to recalibrate the throttle did not abide by these temperature guidelines (at that time, who knew?), I am certainly not prepared to admit defeat, nor to cast any sort of blame.

So, while I do remain quite a bit surprised that their temperature window seems to be so strict as to make or break the success of this entire operation, nevertheless it all does appear to come together so to make some sort of logical sense. And so I will set to the warm-the-engine-up-first prelude that I noted earlier, for my third recalibration attempt to be done this coming weekend.

Since I’ve publicly come along this far, out here in the open on this forum, I will most certainly post updates - if for no other reason than to perhaps help out the next soul who might someday follow in these footsteps.

Sincere thanks once again to all - DM

[Dave80GTSi]

A week has now passed.

Garage temperature in the high 30’s F. Start car, let it idle. Seems fine. Goose the throttle every now and then, and it obediently revs like it should. Monitoring the coolant temps with my Autel real-time display.

After maybe 3 or 4 minutes, once the coolant temp reaches about 100 degrees F, the throttle ‘goosing’ starts to create the stumble, same as the previous time a week ago. Best way that I can describe it would be as if this were a carb car, and the accelerator pump jets are way too rich – the engine stumbles and will not rev.

Continue to let engine idle for maybe another 20 minutes. Idles just fine, but whenever the throttle is poked, the engine stumbles and is non-responsive, same old deal. Continue to let the engine idle until the coolant temp reaches a steady 180 degrees F, and then shut off the car.

Let the car sit for maybe 5 minutes, so to let the engine temps warm up the inlet air passages thoroughly. Turn on the key to calibrate the throttle – about 30 seconds into this, I hear some new sounds coming from the engine – sounds like a step motor tuning on and off a couple of times Then silence. After 90 seconds, shut off key, let sit for 2 more minutes. Then start the car.

No change, exact same symptoms as about a week ago – the engine simply will not run above maybe 2000 rpm. Just on the off chance, I try to drive the car around the block, but no go. I can do nothing but idle the car back home in second gear, and the car is again parked.

At this point in time, I cannot see anything that I have done incorrectly in order to re-calibrate the throttle. I hare followed the various instructions to the letter.

The only conclusion that I can now reach is that the ECU is buggered, and a friendly discussion with ECU Doctors will accordingly be done on Monday.

Thanks - DM

[Gilles]

Dave, many years ago I had the exact same symptoms with my car (Fiat X1/9) but it had a Bosh FI and the problem ended being the connector that goes to the throttle body and then a second time on an Alfa Romeo and ended being the connector to the ECU