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Official Engine Stalling Thread

Help, Advice and DIY Tutorials on Volvo's extremely popular car line -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, including 850 R, 850 T-5R, 850 T-5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

This topic is in the MVS Volvo Repair Database » Secondary Air Injection System Diagram

Another 'me too'

Post by Guest »

Different guest here :)

My mother in law has a 94 850 with 132K miles. For the last 3-4 months she has been complaining of the car stalling under various conditions. She took it to a couple of 'knowledgable' mechanics but they could find nothing nor could they reproduce the issue. Classic.

We visited this past weekend for 3 days. I spent 2 days before that researching the issue on the web. I can tell you there are hundrends of reports of this happening to the 93-96 850 from all over the world!! From what I have seen the vast majority has between 99K - 150K when this happens.

Her stallings occured under different conditions and lately they were becoming frequent. The car would stop on decelaration to a traffic light. While accelerating on the freeway. While making a funky, off-camber left turn and sitting idle on traffic. Prety much all the stalling issues reported.

So, having only 2-3 days I tried most of the remedies that have been proposed here and on other forums & sites. Here's what I found and what I did:

- changed the Fuel Pump Relay (103) in the fuse box. Was getting a bit too hot for my liking (electronics engineer) and the contacts did not look that great either.

- replaced the fuel filter since she bought the car used and there were no records of this having been done before. Although the filter was not the original (did not have the undercoating) it looked like it was it's time when it was removed.

- Removed & replaced the entire Flame Trap assembly (flame trap, O-ring & holder). <$10 from the dealer and quite easy to do . Although the flame trap on the car wasn't in such a bad shape, the holder was very badly covered and covered with gue & carbon deposits. Stange.

- Removed and thouroughly cleaned the Throttle Body & housing. Now that, was a job. A little tricky to take the TB out mostly because of the vacum hoses running on that plastic elbow housing on top of the TB. Removed the 4x 10mm screws on TOP of the TB to make my life easier. Not as daunting as most would imagine but do take your time. The TB was covered handsomely with carbon deposits. Do I call it heavy? not really for a car with 132K. I removed the TB since it was so much easier to clean out plus, it allowed me to also clean the intake & the EGC hole which WAS quite clogged. Nicely 2-hour job.

- Since I was there, I removed and checked the flexible hose from the air filter to the TB. I was surprised to find that that was coated with oil? fuel? not exactly sure but definitely not to my liking. This was even worse on the plastic casing that was connecting this hose to the TB (which houses the flame trap). I guess if all that junk would go to the flame trap, it is logical to assume they would also coat the housing and hoses but the condition of the flame trap to the rest of the assembly was day and night. Maybe the previous owner replaced the flame trap not too long ago but did nothing to the housing? A little odd since she's had the car ~ 4 years now.

Overall, being a weekend warrior/mechanic I found all the info I needed on various sites including this with some excellent diagrams and photos. For those intimidated, I had never touched another Volvo before and I did all this in about 5 hours taking my good time plus I changed oil, flushed the brakes and a few other things like that. With the Fuel Relay & the Fuel Filter, cost was $129.75 in parts from the local Volvo dealership.

Now, the car is running much nicer and stronger. There are still a couple of things I would have liked to have time to check but if this keeps on coming, I will next time I visit. For one, the ECU is reporting a mixture too lean/ too heavy which I thought would go away after the work. It didn't. I'm guessing the O2 sensor needs a good cleaning or even replacement (there is an excellent page on the net about cleaning and reusing it).

Also, there is a strange -to me- noise when the car key is in position 2 or 3 from the engine bay. Sounds like and electrical humming and it is fairly loud and noticable with the hood open but not at all when it is closed. I narrowed it down to the area where the pulley & TB/ Idle Air Motor is housed. That WAS there before and is still there now. Since I have never worked on Volvos and the 850 before, does anyone know what the heck that is and if it should be there? Did not sound like it was coming from the ignition cap which is housed outside the black box covering the TB/Pulley/Idle Air motor.



Post by Guest »

Should have also mentioned in the above that she had a brand new battery put in just a week ago and that you will need a TB Gasket from the dealer (<$10).

Also, when removing the plastic elbow on top of the TB with all the vacuum hoses, I only had to remove the bottom one of the front and the top at the rear :)

Guest orig

Post by Guest orig »

Day 10, ITS BACK!!!

Thanks for that TB report other Guest. Looks like I'll have to take the TB off afterall as you did because in the afternoon of Day 9, yesterday, the deceleration stalling was back (car hasn't shut off yet but the shudder is building to that again I'm sure).

Question, that hole you mention,

Quote: "The TB was covered handsomely with carbon deposits. Do I call it heavy? not really for a car with 132K. I removed the TB since it was so much easier to clean out plus, it allowed me to also clean the intake & the EGC hole which WAS quite clogged. Nicely 2-hour job."

is that in the outboard side of the TB? that is, can I get to it through the plastic elbow side? I noticed some kind of hole in the lower half of the cylinder and tried to clean that when I did the outboard "quickie" TB cleaning but maybe I didn't clean it well enough.

I'd like to try cleaning that better again before the trip to the dealer for the TB gasket and having to remove the TB completely from the engine and replacing the FT assembly while I have everything apart again. Althogh White Turbo did seem to say that evn the Mechanical TBs fail after 100K miles and I have about 125K on the '94 850.

Anyway if I do this and still have problems, it's so long Volvo, so stay tuned if anyone wants to buy an older 850. What started out as a decent vehicle has turned into a money pit, but in fairness most cars do with age but from my experience, the Japanesese money pit seems to be the shallowest (exceptions I'm sure). "Oh, what a feeling..."


Post by Andrew »

Sorry to hear your stalling is back. For now, my mother-in-law loves me although I am not exactly sure if this is a good thing or not :P

Now, on to your question. I actually mispelled it, I meant EGR (Exhaust Gas Recirculation). There is a very good write up on this with good photos URL here.

The whole write up might be a little confusing at first but basically, all he is describing is the complete removal of the TB plus the pulley & idle air motor. The intake (housing behind TB) is where that EGR hole is located. It is about 1/2" wide I'd say and it was quite nasty. Cleaning this up properly is not the easiest task because of the angle but any cleaning you can do on it, it'll help.

The TB I worked on had actually 2 little holes on the front face to correspond to the 2 vacuum lines connected underneath. If you only saw one, you might want to check closer as there should be a second there too.

Finally, I know it sounds like more work, but removing the TB is quite easy. 4 hex screws (10mm I believe) and it's undone. Remove the plastic elbow on top of the TB first to make your life easier. It only has one screw holding it in place, on it's left. You could also take the 3 screws that hold the pulley & Idle Air motor out too to make it even easier. I removed them all together without disconnecting each separately and had no issues with that or putting it back together.

Only thing, do be a bit gentle with the thin vacuum hoses as they do get brittle with age and easy to break.

Hope this helps. After a complete cleanup, you should see some improvement in the power of the car. Have you changed the Fuel Pump relay (under the fuse box)? A lot of people have had success replacing that. I did all the work together mostly because I did not have time to eliminate causes plus, it was a nice maintenance for the car. $130 for all the parts (incl TB gasket) is a small price to pay if it fixes the problem.

Good luck.


Guest orig

Post by Guest orig »

Andrew, thanks for the follow-up post. Will tackle this this weekend.

Question, do you think I can get away with re-using the TB gasket and if not, did you use gasket sealer on the new one or do you just put the replacement one on "dry"? What kind of surface prep?

Saves me from taking off early to run to the dealer since their parts department is conveniently (for them at least) closed on Satutdays. I assume you can't get this part anywhere else?


Post by Andrew »

Depends on how old it is, but I kinda doubt you could reuse the TB gasket. My guess is it would tear and fall apart on you as you try to get it off so, you will need another one.

There are a bunch of sites sponsoring this site as well as VolvoSpeed.com that have OEM parts; they should carry this I would expect. I had to go to the dealer because of the limited time I had to do this.

One thing you could try is, call your local Volvo dealer's Part Department, order and pay (via CC) for the TB gasket and request that they leave it with the dealership's cashier or receptionist. That way, you can pick it up after hours or over the weekend :) Most dealers I have dealt with have been happy to do that but obviously, it is up to your local dealer to be helpfull or not.

Surface prep depends on the condition of the TB. The one I worked on, the surfaces were in very good condition and after a little elbow grease & carb cleaner, it was shinning like new. If that's the case, a little sealant or if you don't have one handy, a little vaseline ;) will do the trick nicely. If on a pinch, I have used *a little* oil for sealing minor gaskets but YMMV. Dry would be a last resort for me and would require a little more tightening of the screws. If the TB contact area has imperfections or gook you cannot take out, try a little buffing with a drill/dremel but obviously use a light buffer. You really don't want to take any part of the surface off as sealing would become really hard.

Good luck.

PS: Day 5 now of my mother in law calling to thank me for the work and praising on how well the car runs. She's getting 2.3mpg better fuel consumption too. She has said before that at times, it would go up to 2 weeks before stalling so, I'll get excited after it makes it through week 3.

Guest orig

Post by Guest orig »

Thanks again Andrew. I'll pop on over to the dealer this afternoon and pick up the TB gasket and a FT assembly (been riding without a FT now for about 12 days). Iffy weather predicted so may or may not get it done by Monday, but then there is always Monday off. Just found out my job is being elimnated, so a day off may help the "mental health". ;)

Guest again

Post by Guest again »

*Sigh* We had a stand-up mtg. late Friday to find out the higher ups don't really know what is going on but to keep working hard until our office is closed. Let me ponder that one... Could of skipped it as it turned out.

Anyway, I didn't get to the dealer in time due to unusually heavy traffic, hello Mr. Murphy!, so I settled on the "quickie" clean again that is, just cleaning the outboard side of the TB accessed after removing the black hard-plastic elbow that also houses the FT assembly. Sure enough, the car is running OK again this moring, but since the last partial cleaning of this type only lasted about 9 days, I'm sure it (the deceleration stalling) will be back.

Question, why do you think that cleaning works temporarily at all but fails rather quickly? Is it those 2 little holes that are temp. unclogged allowing better circulation to the 2 vacuum lines that appear to be connected there? Actually I don't even know if the "holes" do go all the way thru the cylinder as I didn't try to poke a pin or what-have-you thru the tiny holes, 1 bigger that the other, but instead sprayed the h*ll out of them with bolt lube and wiped dry. The black flexible hose from the elbow to the Air Filter also had another split in it so I duck-taped it some more, does that play a role? Odd...

Any theories?


Post by redjewel »

Me, too. I was having problems with my "94 850 cutting out and then wouldn't restart right away. I had the fuel pump and fuel filter changed. That was not it so then we changed the fuel relay and it hasn't done it since. Also, I'd like to ad that I took my Volvo to the dealership to have the recall checked for the fuel tank and they said there were no defects. It hasn't been 3 days of having my car back and now it is gushing fuel out which there was no problem with it till I took it to the dealership. Now that is messed up.

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Post by 95autoturbo »

If you are getting all the lights I would strongly suggest to clean and tighten all of your connections to your battery-It is amazing how sensitive the electrical system is in these volvos especially with the automatic eletronic transmissions!

Just ordered me a pnp switch from autozone $49 bucks!

They also have obII to check your codes!

another trick is

1. turn your key to position 2 (car not started)

2. disconect your battery cables

3. touch your cables together for a solid 30sec (this step is done without being attached to the battery ofcourse)

4. connect the cables back to the battery nice and tight!

5. do not start car, take key out, then go-(meaning only start it when you are ready to drive) that should clear all your loose connection false codes so that you can get a good reading!

6. Good luck!
Last edited by 95autoturbo on 17 May 2005, 15:50, edited 1 time in total.
yes......It is an 850!

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