Bad idling on '93 850

Post by **MadeInJapan** » 17 May 2006, 07:41

Run your fingers around the little rubber elbows on the small lines....main ones are around the sides of the intake manifold (on each side). These are the ones that crack most often...you'll feel they are brittle or are cracking. You can also start your car up and spray some carb cleaner in these areas. If there's a crack or break in the lines your car will surge when you spray the stuff, as the vacuum will pull the flamable fluid into the engine to burn. It won't hurt anything and will give you some info that can help you diagnose a vacuum leak issue.

About the MAF...it is a sensor that is sticking up from the airbox....on the top of the pipe that goes to the turbo, or if you don't have a turbo, to the Throttle. Sometimes these go bad and cause similar behavior as you've described, but usually this one will throw a code. If you disconnect the MAF sensor and your car idles okay, this could be the cause. Also, the connector on this gets loose and there's an easy fix for that....you might see if this isn't if first (diagram and how-to provided below):
http://www.volvospeed.com/Repair/maf_secure.php

Dunoyer · Post by **Dunoyer** » 04 Jun 2006, 20:20

akitawagon wrote: try a new or certified used TPS first; it's a lot cheaper. Also, check your vacuum lines and MAF (mass airflow sensor) as Matthew suggested.

You may not get an error code until the TPS finally fails or becomes less than marginal. I didn't get the code for the TPS until the "idle hunting" got really bad.

Where do you recommend I go to get a TPS. Volvo dealer parts are always so expensive.

Post by **MadeInJapan** » 04 Jun 2006, 21:07

You might try www.erievovo.com Call them if you don't see anything listed on their site.

a799608 · Post by **a799608** » 05 Jun 2006, 19:09

any update. did you solve the problem? my 98 s70 is doing similar things and am curious as to what worked for you.

Dunoyer · Post by **Dunoyer** » 06 Jun 2006, 20:26

a799608 wrote:any update. did you solve the problem? my 98 s70 is doing similar things and am curious as to what worked for you.

Is this an epidemic? Are these cars poorly designed? I had this trouble way back when the car was still under warranty in 1997. They replaced the cam position sensor and the air slide valve. The problem re-emerged in 2003, and a mechanic replaced the Cam position sensor again in response to a diagnostic code but that didn't fix it. Another mechanic replaced the air slide valve and cleaned the circuit connections to all the sensors which report back to the control unit. That worked for a while, then the symptoms came back. So my status is this: I've got some electrical gremlins somewhere in my car, no one really knows where so they try things to see it they work. So far, the things that have been tried have worked in the short term but not the long term. So it is completely baffling the most competent mechanics. I'm thinking now of replacing the throttle position sensor as a diagnostic repair. These diagnostic repairs SUCK! Because they cost a lot without any guarantees of success. Another suggestion is to replace the control unit or the wiring harness, either one of these repairs would run into the thousands and there are no guarantees I wouldn't be idle hunting all over again, at which point I would then trade the car in to the dealer for a fraction of the money I spent trying to diagnose the problem. I can only explain this with poor engineering, I mean, this whole time, I'm getting few diagnostic codes from the on-board computer, or any check engine lights. It's very frustrating, because otherwise, this car seems built to last, but how fun is it to drive a car that idles like shit. I morn the days of simple carburetors. Now there are f***ing circuits everywhere and no chance to troubleshoot. Semiconductors will do us in....

Jean

l33tDad · Post by **l33tDad** » 07 Jun 2006, 08:11

Dunoyer wrote:
akitawagon wrote: try a new or certified used TPS first; it's a lot cheaper. Also, check your vacuum lines and MAF (mass airflow sensor) as Matthew suggested.

You may not get an error code until the TPS finally fails or becomes less than marginal. I didn't get the code for the TPS until the "idle hunting" got really bad.
Where do you recommend I go to get a TPS. Volvo dealer parts are always so expensive.

http://www.eeuroparts.com/productdetail ... &code=5933
$48.73 new

l33tDad · Post by **l33tDad** » 07 Jun 2006, 08:19

Have a side question. My '93 is just starting to do this, but with a twist. It only really does the idle hunting when the engine is cold. When it warms up, it's a ton better. Oh, it does it at the car wash too.. Yea, I know that's odd, but when I took it to the laser wash where the car stands still and all the "stuff" goes around the car, it started idling funky again. Now, I did notice another potential issue when this happened at the car wash: the temprature gauge fluctuated almost in unison with the bad idle. Also, sometimes the gauge doesn't register anything and I realized that the car seems to run a little rough when that happens. The question I have is can a faulty coolant temperature sender cause bad idle? If so, where is it located? eEuroparts has it for $25, so it may be worth a shot to see if it helps.

Dunoyer · Post by **Dunoyer** » 07 Jun 2006, 08:46

So these cars have bad idle disease! Is it only on the standard transmissions?

coustyj · Post by **coustyj** » 07 Jun 2006, 09:37

I have a standard - manual - transmission and have never experienced this type of "disease" as it was put. I have 114k and no major problems. Just kept up with routine maintenance whe it was needed per manual

Post by **akitawagon** » 07 Jun 2006, 15:24

My 93 850 is an automatic. Our cars are getting older and the components are now at that replacement time if they haven't been changed in a while or aren't normal maintenance items.

In my case with the "idle hunting", replacing the O2 sensor and throttle position sensor (TPS) fixed the problem. Your car might be a combination of separate things that need fixing also. Give the TPS replacement a try.

Be glad you don't have a 1999 to 2001 Volvo that has the ETM issue (electronic throttle module). Now that's an expensive design problem that's finally been "sort of" addressed by Volvo.

l33t Dad, if you temp gauge on your dash is not registering or registering correctly, you may need to replace the thermostat. Mattew has a nice write up for this.