sudden jerking/hesitation ??

volvocare · Post by **volvocare** » 29 Apr 2005, 19:11

I own a 96 volvo 850 glt. I've been getting odd hesitations lately when getting close to idle (stoping at red lights - stop and go). The problem seems ok when over 1500 RPM. It's on and off. It might not do it for 2 weeks or so, then, it's there again.

No codes come up? Would it be the start of a fuel pump failure? The car has about 130000 miles. Or would it be the O2 sensors? I've also heard of dirty throtle body's doing this at times and camshaft sensors.

Any ideas?

White850Turbo · Post by **White850Turbo** » 29 Apr 2005, 21:00

The most likely cause is a dirty throttle body or a dirty idle air control valve. Both very easy fixes.

Guest · Post by **Guest** » 02 May 2005, 07:37

I just wanted to let WhiteTurbo know that cleaning the Throttle Body (ETM) appears to have worked for now on the '94 850. No stalls during deceleration into stops today on the way to work. (See "Official Stalling" Sticky Thread at top of thread index). It was cooler this morning though so I won't really know until the warmer ride home this afternoon. Crosses fingers for stress-free rides to work again. One strange side effect, the battery appears to be stronger now. Could be the slightly higher idle speed now.

I decided not to take the TB off the engine due to having to possibly replace the engine side mounting gasket which I didn't have so I only cleaned it from the flexible hose side after taking the hose/plastic hose elbow off. I used a gasoline soaked rag since it seems to be metal and also a can of rusty bolt lubricant because I have that small straw that comes with the can sometimes mounted to it to direct spray right to the flap (butterfly valve?) hinge area spots on each side. Let it air out a long time before I reassembeld everything. It was crusty looking with that brownish varnish build-up. The plastic hose elow had al kinds of oil laying in it but I didn't want to use gas on that cleaning so I just tried to clean up with dry paper towel.

I also tried to clean out the Flame Trap while I had the hard plastic flexible hose elbow off which I heard may affect this stalling problem but even more importantly will prevent oil pressure build-up in the engine if it gets too clogged (I was having oil seemingly disappear, it didn't seem to be burning but I was filling the level a lot more) . Thing is though, the FT was so old and crusty that the Flame Trap AND the FT housing it was in crumbled apart at the bottom. Since I didn't have a Flame Trap I just put the assembly back together after dry towel cleaning it up WITHOUT the Flame Trap. I was going to run it a week to see if it was OK and then replace it (FT, housing and rubber O-Ring next weekend. The connection is shaky since I only have the top "nob" holding the asembly together since the bottom "nob" is gone. I probably should have electrical taped it for now to beef up the seating.

Is this a bad idea to run W/O the Flame Trap? Will it cause permanant damage to the engine? I thought I read a guy who was a former volvo mechanic saying although there is no official guidance on this, he felt you could probably get away with not replacing it.

WT, Thanks again for your help and what do you think of the FT issue?

Guest · Post by **Guest** » 04 May 2005, 14:42

vc,

Just in case you haven't seen this yet:

https://www.matthewsvolvosite.com/chat/p ... 4&start=15

The recommended solution for the deceleration stalling problem has seemed to work for me so far (3 days).

volvocare · Post by **volvocare** » 08 May 2005, 04:29

Well, got it fixed. Spark plug wires and cleaned the distributor cap/rotor. At the same time, I cleaned the throttle body intake.

It did the job. One mention...the wires were not that old...one year old, purchased thru FCP groton (I am surprised the did not last longer)...They were bougicord's. This time, I went with a more expensive paid, hope the do the job better.

Paul "volvocare"

J_Guynn · Post by **J_Guynn** » 08 May 2005, 07:02

volvocare wrote:Well, got it fixed. Spark plug wires and cleaned the distributor cap/rotor. At the same time, I cleaned the throttle body intake.

It did the job. One mention...the wires were not that old...one year old, purchased thru FCP groton (I am surprised the did not last longer)...They were bougicord's. This time, I went with a more expensive paid, hope the do the job better.

Paul "volvocare"

Did you ohm out the wires before replacing them? Since you "changed" more than one thing at the same time how do you know which fixed your problem? Unless you could see damage on the wires I wouldn't be so quick to replace them.

volvo85094 · Post by **volvo85094** » 30 Aug 2005, 07:20

I cleaned my throttle body but no change. Now my 850 won't start.

Guest · Post by **Guest** » 30 Aug 2005, 09:09

volvo85094 wrote:I cleaned my throttle body but no change. Now my 850 won't start.

From my experience, that should have nothing to do with your latest problem but just in case, go back and make sure you put everything back together right. Did you disconnect anything electrical or mechanical vaccuum lines, etc. during your removal/cleaning that you may have forgoten to reconnect or maybe you inadvertently disconnected something else or tore a stray line?