1996 Volvo 850 Rough Idle - Cylinder 2 Misfire

svandeu · Post by **svandeu** » 27 Oct 2009, 19:31

Hello everyone, this is my first post, I've been looking over the forum here for quite some time though.

My Volvo 850 has recently taken a turn for the worse and idles terribly when I start it up, and runs rough when I drive it. Using an ODBII scanner, I get codes that I am having Sensor Bank problems as well as misfires on Cylinder 2 and sometimes Cylinder 1 (I've cleared the codes a few times and the Cylinder 1 code does not always appear.)

I've recently replaced and tested the spark plugs, wires, distributor cap and rotor.

Any other ideas? It's driving me crazy!

FCPEURO · Post by **FCPEURO** » 28 Oct 2009, 09:17

What kind of plugs are you using?

Post by **jblackburn** » 28 Oct 2009, 09:37

I've recently replaced and tested the spark plugs, wires, distributor cap and rotor

Are you sure you re-connected all the lines snugly to the airbox after this? After I finally sorted out my new wires on the distributor this weekend and got all the cylinders firing at the right time (oops), I forgot to reconnect the pipe to my turbo, and as soon as I touched the gas pedal, it coughed and died.

svandeu · Post by **svandeu** » 28 Oct 2009, 15:34

I was using Denso Iridium plugs in it. They worked great for the 2 months the plugs were in before this current problem. They were wearing normally, save for the one in Cylinder 2, which was blackened from not firing correctly (if at all).

I cleaned off the plug and put it back in to see if things would work better (not figuring that they would) and things were the same.

I bought some Champion Copper plugs (as a quick fix) from a local auto parts store to see if the plugs were the problem. They weren't. The Champions are still in the car at the moment.

jablackburn, I assume you mean the vacuum lines? If so, I double checked them as well. I had a problem a few years ago with one of them cracking from age and causing rough running.

Craigd2599 · Post by **Craigd2599** » 28 Oct 2009, 15:41

Take the denso iridiums and throw them at the guy who sold them to you. Iridium, platinum, stupidium...all garbage. Basic copper core are the only things that work in our cars, bro. You can buy the OEM's from the dealer, they are pre gapped. Your gap setting should be .27

svandeu · Post by **svandeu** » 28 Oct 2009, 16:40

Craigd2599 wrote:Take the denso iridiums and throw them at the guy who sold them to you. Iridium, platinum, stupidium...all garbage. Basic copper core are the only things that work in our cars, bro. You can buy the OEM's from the dealer, they are pre gapped. Your gap setting should be .27

So I've gathered from reading on here!

Still doesn't fix the current issue though . . .

Post by **jtp** » 28 Oct 2009, 21:32

my denso iridium's are working fine after I gapped them. Just be careful when you gap them cuz they break easy. That said, it's easier to go stock and I'll switch back soon.

svandeu wrote:I get codes that I am having Sensor Bank problems

What's the code? Rich, lean, sensor unresponsive?

svandeu · Post by **svandeu** » 29 Oct 2009, 09:32

So I took the car to my local mechanic and his resident Volvo and VW expert looked at it and diagnosed the problem as having low compression in Cylinder 2. Car needs a valve job and a head gasket replacement.

Job was quoted at 1,400, but I can save about $200 by buying my own head gasket instead of him buying one.

Thoughts?

Craigd2599 · Post by **Craigd2599** » 31 Oct 2009, 08:31

I would try a seafoam treatment first. My personal preference is GM Top Engine Cleaner but Seafoam works well too. You dump 1/3 to 1/2 of the can into the crankcase. You pour the rest into a bowl or a small plastic tub. Run a vacuum line from one of the ports on the vacuum tree on the manifold and slowly suck the Seafoam from the bowl into the engine. You have to work the throttle with one hand and control the suction with the other. DO NOT let it take very much at a time or you run the risk of hydraulicking a cylinder. Low compression may be nothing more than carbon build up and a stuck ring. Let the car suck this liquid until maybe 1/4 of the contents remains. Then let it take the last bit and let it kill the engine. Leave it sit for about 10 minutes then start it up. You need to do this outside, not in your garage because the smoke is unbelievable. Start the car and take her up and down the road accelerating at full throttle to about 30 MPH until the smoke clears completely. You will need to do a plug change and oil change. The crud clings to the spark plugs. You will see an incredible difference. This might be all it take. Seafoam runs about $10 and GM Top Engine Cleaner is about $15. I like GM better and you get more in the bottle but either way it's good. I hope this works and you don't have to pop for the head work

brooks · Post by **brooks** » 31 Oct 2009, 10:51

Craigd2599 wrote:Take the denso iridiums and throw them at the guy who sold them to you. Iridium, platinum, stupidium...all garbage. Basic copper core are the only things that work in our cars, bro. You can buy the OEM's from the dealer, they are pre gapped. Your gap setting should be .27

My Volvo OEM plugs were Denso Iridium plugs. I googled the part number on the plugs to see if they could be found cheaper in the future. Turns out the Volvo 5 pack is actually a good deal for those plugs.