High idle on cold start Topic is solved

Zappas dad · Post by **Zappas dad** » 18 Mar 2017, 13:53

Hi everyone, I am new to the site and find myself quite excited to be a part of such a diverse gathering of Volvo enthusiasts, and to have so many resources available!
So...with regard to the subject at hand, my 95' 850 turbo wagon (the green hornet) recently developed a high idle upon cold starts, immediately revving to right around 3000 r's. The car is throwing O 2 sensor codes. Does anyone know if that would be the cause of my problem? Thank you.

Post by **theWIFES_S70** » 18 Mar 2017, 14:16

Hey Zappas dad, good to have you here! Looking forward on getting to know the green hornet! You'll find that some of our sages on here can diagnose even the most stubborn of occurrences with nary a few details. I haven't read about a problem like this occurring. I hope we can get it sorted out! 3000 is pretty high. Our car only hits that on the highway...

You'll probably get requests for some of the following information:

- How many miles do you have on the clock? (If you're over a 150,000 it's definitely time to swap out those 02 sensors.)
- Does the idle eventually even out? (Or is your car idling at 3000 once the car has reached operating temperature?)
- Power OK?
- Is the operating temperature normal? (Is it taking the usual time to reach normal operating temperature?)
- Cap, rotor, plugs, wires... All VOLVO parts? Fairly new?
- Air Filter and MAF ok?
- How's your throttle cable? Is it a rusted, sticky mess?

Post by **Clemens** » 18 Mar 2017, 16:24

For starters I would try to find a used O2 sensor at a junk yard and swap that. You can also clean the idle control valve (very easy to do).

Post by **erikv11** » 18 Mar 2017, 17:48

What they said ^^^.

Start with cleaning the IAC, that only costs a couple bucks (for crab cleaner) and a few minutes. Remove IAC, put on eye and hand protection, spray carb cleaner into IAC, shake it around vigorously until you hear the valve inside clunking back and forth, dump out the carb cleaner. Repeat if necessary. Let it dry then put it back in.

Lots of things can cause an O2 code, including intake problems and vacuum leaks. I'd poke around before swapping the O2 sensor, unless you can get one real cheap and have some time to do it. It must be a Bosch part to work properly.

Zappas dad · Post by **Zappas dad** » 18 Mar 2017, 18:14

Thank you all very much for the input! In response to the questions raised by ' the wife's S70 ' a little over a hundred and eight thousand miles, the idle does even out after about a minute, and it only happens when it's cold, like early in the morning...the power is fine, pulls hard surprises all who have experienced full boost pulls from say 60-120 mph. Operating temp is normal, time to operating temp is normal. Cap, rotor, plugs, wires (ipd) coil (msd) air filter and MAF are new. Just replaced all vacuum lines while rebuilding and reinstalling turbo. Have not however checked the idle air control valve. Throttle cable is fine.

Post by **erikv11** » 18 Mar 2017, 18:45

Oh, sounds like your car is well taken care of! Is it a Bosch MAF? You can try unplugging the MAF, but I doubt that is the problem.

Since the O2 sensor code is already throwing, how about just unplug the front O2 and see if that makes any difference? I've never tried that, but I don't think unplugging it causes high idle.