erratic idle, sometimes

landyacht33 · Post by **landyacht33** » 29 Dec 2010, 17:07

hi all
96 volvo 850 turbo wagon
Alright here is the problem. my wagon is giving and intermittent, erratic idle and is giving me around 10 mpg. i found a crack in the hose on the driver side vacuum hose on the intake manifold as well as a crack in the hose on the bottom of the throttle body so fixed those with no avail. while sitting the car smells a little more sulfur like than plain rich. i changed my plugs which were built up with carbon and i also removed my idle air control and cleaned it well and also removed and cleaned my throttle position sensor. it will run fairly smooth, then i detect a slight miss, then goes to 400rpm bucking idle then back to smooth all while sitting at a light for 2 minutes. i check for codes everytime i drive it just to see if its throwing a code and always 0 codes. any ideas would be great
thanks
Adam T

Post by **Ozark Lee** » 31 Dec 2010, 15:18

Without any codes this is a tough one to solve. Obviously something is wrong and everything in your symptom description points to a vacuum leak but that normally throws a CEL every time.

If it would finally throw a CEL and you could post the number back we might be able to help.

We aren't ignoring your posts but we just don't have enough information to post an intelligent response.

...Lee

landyacht33 · Post by **landyacht33** » 31 Dec 2010, 16:31

i agree! i took it to the dealer and they claimed they couldnt find anything wrong with it. i drove it around some again today and it is idling terrible but only at a stop. i got it to even idle around 200 rpm and the lights went dim but couldnt get it to actually stall. DRATS!
still no codes and i dont want to throw money at parts. can a bad cat cause all this? the car smells a little more sulfur like then just the typical rich and it doesnt smoke a whole bunch. ??????
jerk wagon!
HAPPY NEW YEAR!

850doin150 · Post by **850doin150** » 31 Dec 2010, 22:42

I have the same exact problem. Except mine is throwing the service light!
So maybe it will help solve yours. I gotta go to autozone n see what the code is and repost.
Same smell also!

landyacht33 · Post by **landyacht33** » 01 Jan 2011, 08:09

the service light is just a reminder for service and not a signal of a problem. i have a few ideas such as coolant temp sensor and fuel pressure regulator. ill let you know as well when i figure this out.

Post by **shiloh51933** » 20 Feb 2011, 08:51

landyacht33 wrote:the service light is just a reminder for service and not a signal of a problem. i have a few ideas such as coolant temp sensor and fuel pressure regulator. ill let you know as well when i figure this out.

Did you ever figure this problem out? I have the same problem with the idle bouncing up and down in park.neutral when I rev idle. My service light goes on when I first start her and stays on extra longer than other lights. I just installed new MAF, temp sensor, plugs, wires, cap/rotor, oil/filter. It feels like a fuel problem to me; fuel injectors are good, fuel pump is good, new fuel filter. I was thinking fuel pressure regulator myself and seeing you mention it in your thread has me leaning towards that. There are no loose or missing vacuum hoses and what I noticed is this starts to happen after she starts to warm up near operating temperature. Appreciate any info on what you did.

Post by **jblackburn** » 20 Feb 2011, 09:19

The service light means nothing. It was put there to remind you to bring your car into the dealer for service. Ignore it, put a piece of tape over it, or remove it.

This is a long shot towards the erratic idle, BUT

Switch your O2 sensors and connectors. The front one probably won't reach the rear connection, but that is OK - just leave it unplugged, but put the sensor in place so it doesn't sound like a B52.

With the rear sensor up front, does the car run any better once it warms up? The sensors work off an oscillating pattern, and when one goes bad, it can do exactly that with the idle.

Post by **shiloh51933** » 20 Feb 2011, 09:40

jblackburn wrote:The service light means nothing. It was put there to remind you to bring your car into the dealer for service. Ignore it, put a piece of tape over it, or remove it.

This is a long shot towards the erratic idle, BUT

Switch your O2 sensors and connectors. The front one probably won't reach the rear connection, but that is OK - just leave it unplugged, but put the sensor in place so it doesn't sound like a B52.

With the rear sensor up front, does the car run any better once it warms up? The sensors work off an oscillating pattern, and when one goes bad, it can do exactly that with the idle.

Yes the service light is annoying, lol...I guess your thinking that the front one is on the way out. This sucks cause this is all happening at once...the MAF had to be replaced cause she wouldn't start without it and I'm not the type to ride around without the MAF or an O2 sensor unplugged(I see hacks do it all the time round here). Good look on the response my dude.

Post by **jblackburn** » 20 Feb 2011, 09:56

Give it a shot - you don't want to throw $100 at a part you don't need. The rear one doesn't do anything but monitor the efficiency of the catalytic converter, so you will throw a code but it won't do anything in the meantime.

Pcar · Post by **Pcar** » 20 Feb 2011, 20:13

Hey guys, I have the exact same problem and it's driving me to drink ! 1999 xc70 /w 150k . Replaced plugs cleaned MAF and about to clean throttle body. I'll be watching to see if we can work this out.