Rough Idle issues. No Codes

[It Broke Again]

Hi,

Three days ago my '99 S80 T6 with 98,000klm (60000 miles) developed a intermitent idle hunting problem when started. A couple of blips of the throttle and it would normally settle down and idles around 650rpm.

I hooked up my scangauge II and found no codes set. As it is a white label etm I became suspicious so I removed, cleaned, replaced gasket and reinstalled it and the problem was still there.

I took it for a 15 minute drive in peak traffic with the scangauge connected with the TPS, Loop, Revs and volts on the display hoping to notice something that may confirm the cause. Three things I noticed,, firstly was that when I came to a stop and it was in open loop the idle problem started again until the loop closed. The second was the voltage never exceeded 13.5v. Thirdly the TPS varied between 0 & 5% while in the idle position. It stalled completely once during the drive while stopping. When I got home I re-read the codes and again there was no codes set.

So I am a little stumped, is it the beginning of the Etm, O2 sensors or accelerator pedal failing or something else?

Regards

[537playing]

Sounds like your ETM is failing. You can try to clean it up first, but if that doesn't work, then you need to replace this ETM. Search this and other forums for symptons of a failing ETM.

[MoVolvos]

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This should be helpful

Volvo Rough Idle Problems (ETM issues) - how to fix


Blessings,
BKM
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[It Broke Again]

Hi,

I was having the car scanned in a shop yesterday with their fancy machine and they found no codes, but they did notice the TPS was not registering as expected during high revs. A few minutes later all accelerator functions went dead.

The car would start and run at 300 revs but no pedal pressing made any difference. I spent around 1 hour of waiting, restarting, waiting, restarting until the car started properly and I was able to make it back home. (with some two footed driving) When I got home I rescanned with my scangauge and also had no codes.

I ordered an ETM from Xemodex last night, I hope that this will solve the problem, however I have a suspicion that it may not be the complete solution. I will wait and see.

Cheers

[mikealder]

Do you have the ability to data log from the OBD-II port with your scanner and save to something like a csv file? if so set it recording just the throttle position and the pedal position, compare the results on the PC once its gone wrong as it could be either item at fault, my money would be on the ETM as they are crap but the throttle pedal position transmitter can also fail leading to intermittant/ loss of throttle control - Mike

[It Broke Again]

Do you have the ability to data log from the OBD-II port with your scanner and save to something like a csv file? if so set it recording just the throttle position and the pedal position, compare the results on the PC once its gone wrong as it could be either item at fault, my money would be on the ETM as they are crap but the throttle pedal position transmitter can also fail leading to intermittant/ loss of throttle control - Mike

My scanner doesn't record at all, it just shows "live" info. I have also come to your conclusion, blame the most obvious with the poorest history but also expect that something else may be contributing. They wouldn't sell accelerator pedals at FCP or EEuro if they didn't need too.

cheers