14 replies to this topic

[Il Bastardo]

These problems have plagued our 1994 850 Estate for over a year. The car has spent 4 weeks with a local Volvo wizard to no avail but he did manage to find $834. worth of unrelated stuff to fix, then off it went to the Volvo dealer who did even less, so only asked for $653.
The real frustration lies in that the problems are intermittant. No trouble codes come up when it is hooked up for diagnosis and not surprisingly the car never acts up when it's in the shop.
As a matter of fact most of the time, 80% let's say, and some days 100% of the time she performs flawlessly. That's under all types of situations too. Stop and go etc.
So here's what''s going on, maybe you all can help solve this:

Starts hard or not at all.
Won't start, then after a 15-60 minute rest is just fine and starts instantly
Will self accelerate, while idling to as much as 3000 rpm, then quiets down.
Will self accelerate while being driven, foot off the gas pedal, you can feel the pedal moving away
Will not respond to the accelerator when depressed.
Accelerator will not allow itself to be depressed, feels jams in other words
but isn't, then corrects itself
Occassionally it will belch black smoke after one of these episodes.
Stalls in traffic when braking, restarts then stalls again when braking. I can get past this by putting tranny in N, braking with left foot with right foot on the gas.

Edited by Il Bastardo, 26 March 2006 - 11:15 PM.

[Mesoam]

if the pedal travels by itself that is the cruise control, check the module under the battery tray

if it revs by itself it is getting the necessary air to rev that high (the throttle plate is opening) which once again could be related to the cruise...hypothesizing here, possibly a defective module is allowing the cruise to come on even in neutral...again hypothesizing

could also be the Idle Air Motor allowing too much air??

honestly you will have to slowly but surely start eliminating suspected problems...

start with a tune up & stage 0, this includes all vacuum lines, cleaning of the EGR, servicing the PCV (must remove the manifold)

[Il Bastardo]

if the pedal travels by itself that is the cruise control, check the module under the battery tray

if it revs by itself it is getting the necessary air to rev that high (the throttle plate is opening) which once again could be related to the cruise...hypothesizing here, possibly a defective module is allowing the cruise to come on even in neutral...again hypothesizing

could also be the Idle Air Motor allowing too much air??

honestly you will have to slowly but surely start eliminating suspected problems...

start with a tune up & stage 0, this includes all vacuum lines, cleaning of the EGR, servicing the PCV (must remove the manifold)

[font=Century Gothic]Thanks for responding, although you may be sorry. No good deed and all.
What am I checking for in the cruise control? Where would the defective module be? Aggh! where is the Idle air motor, I don't know what 1/2 this stuff is, my Haynes manual might have some answers but I'm really in for it, I can see that. Tune up, spark plugs, wires what else would you suggest and by the way what is "stage 0". It did pass it's Connecticut emissions test just the other day with flying colors. My car is a '67 122s Estate, I can fix that.

[Milo]

I had similar problems (although none of the pedal problems) with my 960. I never did find out what was wrong with it before I sold it, however the more information I read the more I think that the intake manifold gasket, or the throttle body gasket were leaking air into the system. Removing the throttle body and cleaning it, and replacing the gasket was the first major fix I ever did to my 850 and it went smoothly. Before that I had taken wheels off and thats about it. While it is off you will likely have had to remove the Idle motor in the process so clean that. This is a really good place to learn about your car and how to fix it. Be patient, 850's are surprisingly resilient cars and if you don't fix it today the world will not end.

http://www.volvospeed.com/Repair/egr.php

check this for pulling the throttle body. I highly recommend a ratcheting 10mm box wrench to remove the TB. I also recommend RTV Ultra Copper to create the seal, and brakleen to clean both the TB and the Idle Motor.

http://www.volvospeed.com/Repair/airpump1.php

check this for pulling the airpump if it is a Non turbo car.

Milo

[Il Bastardo]

Thanks to Milo and S.J.,

Have already checked the mats and all valve stem caps and they are A OKAY. That took a lot out of me but now I can move on to the ashtrays and roof rack.

I don't know what I'd do without you guys, no really. I don't want to get all misty here but I do appreciate the leads. Thanks. IL

[ziddey]

There's a bunch of things to check out. Also, it would REALLY help if you could itemize what the dealers charged you. For the amount of money, they must have done quite a bit of things and it'd help us be able to better suggest things further to look for.

But definitely, just unplug the cruise module and pull off one of the rubber hoses (vacuum lines). By pulling the line, it won't be able to pull down the gas pedal anymore.

It doesn't make sense that you'll sometimes get a stuck pedal. That seems to be unrelated to the cruise control. So it could be your throttle cable getting stuck.

But definitely, check the throttle body. Take it apart and clean it. Could be the idle air motor (nonturbo right?!). EGR is also possible, as is the tps sensor even! So many things. Please reply with what's already been done!

[TG850T5R]

My Brother had the same problem / symptoms on his car (not a Volvo).

The car will stall for no reason, acceletare and all the other stuff that you are describing..... No one can figure out what the problem was and it drove us crazy until we met this really really experienced 60 year old mechanic.... He was able to diagnose the problem under 3 min....

In our case it was the A/C regulator that was all messed up and trying to conrol the cars idle speed..... The symptoms would occur even when the A/C was off..... I don't know how the A/C regulators work on Volvos but you might wanna check it out to be sure......

[ziddey]

My Brother had the same problem / symptoms on his car (not a Volvo).

The car will stall for no reason, acceletare and all the other stuff that you are describing..... No one can figure out what the problem was and it drove us crazy until we met this really really experienced 60 year old mechanic.... He was able to diagnose the problem under 3 min....

In our case it was the A/C regulator that was all messed up and trying to conrol the cars idle speed..... The symptoms would occur even when the A/C was off..... I don't know how the A/C regulators work on Volvos but you might wanna check it out to be sure......

hmm that's interesting. it'd probably be the last thing i'd suspect though since i've never heard of that with the 850's. what car was that? it makes sense! to the OP, could you check all your codes and maybe you have one for something wrong with ac?

[TG850T5R]

hmm that's interesting. it'd probably be the last thing i'd suspect though since i've never heard of that with the 850's. what car was that? it makes sense! to the OP, could you check all your codes and maybe you have one for something wrong with ac?

We were living in Europe at the time and the car was a 1996 Rover 400 (which is a twin of Acura Integra GSR in the US). No one including the dealer and bunch of other mechanics were able to diagnose the problem. The dealer wanted to put in a brand new ECU for $3K which we said no to..... But this old guy was literally able to diagnose the problem without even driving the car... We just told him about the symptoms and he fix the car for $100. I am a big believer that if you are dealing with a true proffesional -they don't need to drive the car or take it apart to see what the problem is....

[Il Bastardo]

For Mesoam: I would accept your offer of help in a heart beat. My place or yours?
For Ziddey: the repairs so far as documented on the invoices and that seem relavent are:
90,000 mile factory maintenance ( at the dealership)
Spark Plug Kit
Engine air filter
carb cleaner
trans solenoids (2 replaced). As stated above they couldn't detect anything else to do except regular maintenance
For Milo, AlvinL & TG850T5R Thanks Again

[RAzOR]

My 2cents.

1. Go to www.alldatadiy.com and pay $25 for an annual subscription. This allows you access to ALL of the service manuals on-line, diagnostic codes and procedures, and service bulletins that may identify your problem right away.

2. Your car is a 95 so it has a diagnostic block in the front right corner of the engine bay. Using AllData code procedures you can interrogate the ECU for codes. This is tremendously helpful and really easy once you do it a few times.

3. Unplug the cruise control plug from under the battery tray. The curise control is THE ONLY thing that can move your pedal. It sounds like a rouge cruise control. Unplugging it will kill it. To further ensure its off, look under the dash near the gas pedal. You will see a black actuator attached to the gas pedal arm. Detach the actuator from the pedal just in the case the actuator is getting vacuum.

These cars are really pretty easy to access once you figure out the paths to the parts. AllData will have the step by step with pictures. You will able to do it from memory after the first time.

Tools to buy for yourself are a set of Metric Spinners 5mm-13mm and sockets from, say Sears. Also get a set of Torx drivers (like screw drivers). Lastly, get a decent set of thin, rubber palmed work gloves. It goes without saying that you have screwdrivers and pliars.

4. Warm and Idle the engine and squeeze every rubber hose between the turbo and the intercooler. If one is broken, the idle will jump when you hit it. It take all of five minutes to do a thorough job. Don't forget the lower one. You will need to jack the car up in front and remove the lower cover (two screws on the ends and clips along the middle) to really access the lower hose.

5. Check to see that the duct/hose from the air filter/MAF has not come loose on the turbo down low. It is also possible that the PCV has come out of its spot on this same duct. This caused rapid, intermittent idle rise and rough idle on my 94 turbo since the PCV was sometimes in and sometimes not. Since it is downstream of the MAF, it confused the ECU. The access looks nasty, but it isn't. Look up replacing the PCV valve in AllData and they'll show you the tricks to make access easy (removing the entire air filter assembly for one) and how to get at the one hose clamp that removes the lower end of the duct off the turbo.

Again, once you dive in and get to know these cars, they are very good to work with.

Edited by RAzOR, 28 March 2006 - 07:16 PM.

[Il Bastardo]

Thanks to RAzOR as well. Burbank was the last home of my 122 Wagon before coming East.

[T5BRICK]

the black smoke and stalls could be your MAF(i think some folks call it an AMM or MAS). it's real easy to replace.

when mine was going out i would get random surges on the freeway and it would stall at stop signs and stoplights. i would also get black smoke like you are.

i could be off, but it's just a thought.