Message: "Try slow down or shift up"

Faust · Post by **Faust** » 10 Sep 2016, 16:51

Well, some progress of a sort. I pulled the cover today and found one burned coil, I replaced that with a known good one and all of the Auto-lite plugs with Bosch. Started and ran perfectly, for about two miles. Then back to all of the symptoms noted above. Tomorrow, when it is cool, I'll pull the cover and check the situation. I am expecting to find another bad coil. When I complained at the stealers, one of the service reps suggested that they could have loaded updated software. She was quickly hushed up and sent away so they could proceed with blaming the tow guy. The software issue had occurred to me. Is it possible that could be producing the symptoms ( and burning coils?).

An aside, when I stop the car, and restart after a few minutes, the "try slow down" message and the blinking CEL disappear. They reappear in a few minutes as performance degrades. The misfire which is also apparent at idle also temporarily disappears.-

Faust · Post by **Faust** » 10 Sep 2016, 18:37

The coil I referred to as "burned" had cracked its case and leaked black stuff I assumed to be some form of insulation.

Post by **abscate** » 10 Sep 2016, 21:08

Software won't burn coils. Test the voltage to the coils to make sure you aren't getting too much. Unlikely.

Pull plugs and inspect. Any history there?? Are they 13 years old??

Faust · Post by **Faust** » 11 Sep 2016, 04:37

Not familiar with "modern" ignition systems. Judging by wire size, I assume that the coils should be receiving 12V +/-. .

When checking the coils yesterday, I pulled all of the plugs (Autolite, probably not original) and replaced them with four electrode Bosch. Color of all the plugs was an acceptable light brown; except for the plug associated with the bad coil, which was a darker brown.

I doubt I will be "lucky" enough to find an obviously burned out coil. being Sunday, I will probably take it to Autozone and see if they can pull a code on misfires.

Faust · Post by **Faust** » 11 Sep 2016, 07:52

I seem to have achieved a solution. Taking advantage of the cool of the morning, I checked the cylinder (#2) where I had replaced the burned out coil with a "known good one". By pulling the lead, I determined that the "known good one" wasn't firing. I replaced that with another from my handful of coils and idle improved. Idle was still a little ragged, do I pulled the leads on other coils looking for a change. I determined that cylinder #5 was also not firing. I replaced that coil, and all now seems well, pending a longer drive to test it further. I suppose that when I found the visibly burned up coil, I leapt to the conclusion that was my whole problem. Not thinking that one bad cylinder would not result in the power loss I was experiencing.

Exactly why two coils should fail while the car sat without operation for want of a key is probably a story for which the world is not yet prepared. I certainly does seem to destroy the dealers assertion that "the tow guy did it".

Thanks to all who have volunteered suggestions.

Post by **abscate** » 12 Sep 2016, 01:02

Faust..the coils on these cars get constant 12vdc, and are fired by the ECU grounding each coil at the right time.

Given that ECUs never fail, it's basically checking the supply voltage, and then ground wire and the 10 mm M6 bolt is tight ( important as it's the high tension ground)

Diagrams and resistance measurements are in the VRD and also in my 1999 T5 maintenance log

Search 'ME7 coil resistance'

From the P80'forum ( last year, 1999, uses coil on plug with ME7)

https://www.matthewsvolvosite.com/forums ... il#p325109

Message: "Try slow down or shift up"

Re: Message: "Try slow down or shift up"