Pulling hair out! '99 S80 Rough Idle, Limp, NO CODES!

BavarianFanatic · Post by **BavarianFanatic** » 09 Jul 2010, 17:35

I'm a noob to Volvos but not complicated cars. My primary experience is with BMWs. I did a search but I'm not finding anything specific. I'm trying to help out my neighbor with his '99 S80 2.9.

Initially he was experiencing surging and stumbling which I immediately flagged as a potential ETM problem after a little bit of Googling. By the time he got the car to me it wouldn't even idle. It would surge, bounce a bit and stall. Once it cooled it would idle very poorly but not rev past about 2k. I pulled the ETM and found a significant amount of build-up of varnish and a very sticky throttle plate. I cleaned it all up but the sticky plate persisted. It seemed to have a bad bearing or some other internal issue that the return spring couldn't overcome. I reinstalled it to see if the cleaning would have any effect and it actually did clean up the idle quite a bit. But the stumbling and lack of revs persisted.

I picked up a used but known good ETM from another '99 S80 2.9 in hopes that would be the quick fix. Well it wasn't. It DOES idle quite a bit better when cold and also revs much smoother with less "gaps", but it's still not right. It also worsens as it warms up. The thing that's killing me through all of this is that it's not throwing any codes whatsoever and there's no MIL. I'm completely in the dark here. Is there something I'm missing? Is there anything else aside from the always popular ETM that would cause this? I'm assuming it's stuck in limp mode since it won't rev past 2,000 RPM. Curiously time spent with the battery disconnected has zero impact either. Whatever the problem is, it's impact is instantaneous.

Any and all help and/or suggestions enthusiastically accepted!

jbrown122 · Post by **jbrown122** » 09 Jul 2010, 17:39

When installing a new ETM, the car NEEDS! programming from Volvo.
Try putting the old throttle back in, then and try cleaning/replacing the MAF.
Make sure the ETM gasket isnt stuck up in the manifold, and make sure the ETM label is facing the radiator fan.

537playing · Post by **537playing** » 09 Jul 2010, 17:47

I would bet that your MAF is causing the stumbling!

BavarianFanatic · Post by **BavarianFanatic** » 09 Jul 2010, 20:07

The ETM was from an identical model so it shouldn't need to be aligned like a new one would. The alignment is required for new since the same throttle is used in multiple applications. It's definitely installed correctly and the gasket is fine.

I pulled the MAF while the car was running and it died as I expected. Readings from the MAF are as I'd expect. But here's where it gets weird...

It's REALLY acting like it's missing at idle/low revs. The plugs are apparently new so logic tells me to start checking into the coils. I pulled the coil plugs one at a time to see if I could identify one that didn't affect the idle. To my amazement I'm able to pull FOUR coil plugs with zero effect on the idle - one at a time cylinders 1 through 4. Also to my amazement pulling the coils didn't trigger an MIL or any codes. I'm beginning to wonder if the PCM has an issue.

Onrust · Post by **Onrust** » 11 Jul 2010, 11:31

BavarianFanatic wrote:The ETM was from an identical model so it shouldn't need to be aligned like a new one would. The alignment is required for new since the same throttle is used in multiple applications. It's definitely installed correctly and the gasket is fine.

Not sure what you are saying, but a new/other ETM ALWAYS needs to be programmed at a Volvo workshop.

jbrown122 · Post by **jbrown122** » 11 Jul 2010, 19:24

Not sure what you are saying, but a new/other ETM ALWAYS needs to be programmed at a Volvo workshop.

Exactly what I was thinking.

Post by **boosted5cyl** » 13 Jul 2010, 07:29

Interesting one aright. As other's have pointed out, each ETM is uniquely coded and needs to be "married" to the ECU before it will work correctly, this is different to a calibration or adaptation. Of course this needs to be done at a dealer

.

If its only idling on two cylinders though it would be more than rough, it should be shaking like a mofo. Im not sure where you can start with this one. Pull the individual coils and plugs out, see if you get a spark when the car is running. This isnt a guarantee that its sparking under compression of course, but it will give you an idea. Have you swapped the coil on say 6 and 1 to see if 1 starts firing? Personally, I pull the injector connectors to test the cylinders, rather than coil wires, even though the wire going in are LT. HT seems to have an affinity for me! In my experience misfires at idle dont always throw OBD codes...Does the check engine light come on when you start the ignition (just making sure it works!!!)

I guess you could reseat the ECU. Its possible its failed, but very, very rare and again, a replacement (new or used) needs to be "married". This is one thing that sucks about P2 cars, im surprised you dont have to go to a dealer (or use a VADIS) to change a freakin lightbulb.

jonathanS70 · Post by **jonathanS70** » 10 Feb 2011, 18:39

I am having the same issue with my 1999 s70 GLT, i had the ETM update at the dealer, I cleaned the ETM and put a new seal on it. I changed the plugs (old ones were black with carbon). Car runs well, but when I get to a light and spot short the rpms dive uner 500 then hold 900. Sometimes the rpms will slightly fluctuate 100 to 200 RPMS. No codes!! I hate throwing parts at the problem!! Almost seems like a vacuum leaK? Have you found anything?