Throttle position and rough idle volvo v70 2.4t 2001

[Ajappinen]

Hello, my throttle position seems to jump between 10.6% and 12.2% accordig to my obd reader. The idle is also unstable jumping between 640rpm and 700rpm. Can the hard idle be caused by throttle body problem? What is the normal throttle position value and how much should it change at idle?

[scot850]

It can also be caused by leaking air or vacuum lines. Easiest way to check for leaks in the system is to use a smoke machine.

However, being an 01 is should have the same style of ETM as the 99-00 P80's. At his age it is amazing it is running at all. Have you tried cleaning the ETM?

Neil.

[Vova585]

Agree with scot850.
You don't want it to be throttle body. Car works the hardest in idling mode and ecu has to work hard to ballance the idle. Things that can explain your symptoms(not limited to) vaccum leak, worn engine mechanical parts, worn/dirty injectors, worn/misreporting o2 sensors dirty/broken maf....
So I would probably: replace air filter, check/clean maf, put some injector cleaner into tank...if you are more mechanically inclined- replae spark plugs, clean throttle body, look if your intercooler is not full of oil, check pcv system(basically glove test), listen for vaccuum leaks..if you are even more advanced- smoke test. Compression test. Remove and test injectors, look at inputs from temp, baro, maf, o2 sensors.

[Ajappinen]

It can also be caused by leaking air or vacuum lines. Easiest way to check for leaks in the system is to use a smoke machine.

However, being an 01 is should have the same style of ETM as the 99-00 P80's. At his age it is amazing it is running at all. Have you tried cleaning the ETM?

Neil.

Agree with scot850.
You don't want it to be throttle body. Car works the hardest in idling mode and ecu has to work hard to ballance the idle. Things that can explain your symptoms(not limited to) vaccum leak, worn engine mechanical parts, worn/dirty injectors, worn/misreporting o2 sensors dirty/broken maf....
So I would probably: replace air filter, check/clean maf, put some injector cleaner into tank...if you are more mechanically inclined- replae spark plugs, clean throttle body, look if your intercooler is not full of oil, check pcv system(basically glove test), listen for vaccuum leaks..if you are even more advanced- smoke test. Compression test. Remove and test injectors, look at inputs from temp, baro, maf, o2 sensors.

Spark plugs and coils are new so i dont think they are the problem. Most of the vacuum lines are old so perhaps they could leak but i tested it with diy smoke machine (a beekeepers smoker) on maybe a bit too windy day and i did not notice any big leaks. I have also not cleaned the ETM since it is hard to get to and apparently easy to break.

O2 sensor data seems good but i have an fairly new MAF that i changed maybe a year ago and i tested to disconnect it at idle and it caused the engine to shut down, even though i have done it before and the car has stayed running so that is a new thing.

Car has an performance air filter now but the symptoms were same with the oem one. And it passed the glove test very well.

I could try cleaning the injectors since they propably have never been cleaned and look into the intercooler.

[scot850]

What brand of MAF did you fit? These cars can be finicky on some brands.

ETM's on a turbo engine is a bit of a pain to access. I usually pull the engine cooling fan to give better access. Having not removed the ETM version on a P2 chassis Volvo I am not sure on best way to remove. Can you take and post a picture of the side view of the radiator and the front of the engine so I can see how it is laid out?

The ETM's are not too easy to break. Again I am not sure on how the harness to it is laid out. On a P80 with that style of ETM, the hardest part is to separate the harness connector. The later (late 02) on with a throttle body I don't like as it has the flimsiest connector I have ever come across that is about 100% likely to break.

Only thing to watch on both versions is to not flood them with throttle body cleaner as it can get into the actuators, Dampen a cloth with the TB cleaner or use dampened cotton buds. If you are careful removing the gasket can usually go again.

Neil.