I have a 95, 850GLT, non turbo wagon. I've been fighting with a CEL since I bought the car. I keep getting misfire codes, mainly for cylinders 4 and 5. I started with a complete tune up, cap, rotor, wires, air filter, fuel filter, and even replaced the coil. All are VOLVO parts. It still misfired! Then I got a couple of new codes, that the O2 sensors were not working or not present. They have been replaced with BOSCH parts for the front and rear sensors. Still misfires! I bought an OBDII scanner to see what was going on. It tells me there is an open loop fault, and my MAF reading is 0.00 at all times! Oh yeah, I've also already changed the thermostat, cleaned the throttle body, serviced the EGR, ( cleaned out the totally clogged port in the intake), swapped the injector order, found a vac leak at the tree and replaced the missing o-ring! It STILL misfires! I even went as far as getting ahold of another (used) pressure regulator for the injector rail, and another EGR control to try, and still, I have the misfire on cyl 4, and cyl 5. On the highway, the car seems FINE! At idle in park, it runs a bit rough, but in gear, as you come to a complete stop, the engine runs rough! it has never stalled on me though. I even reset the ECU by disconnecting the battery for over an hour! I really need to get this CEL off soI can pass Massachusetts State Emissions! Thanks in advance for any and all your help!

 

I'm not going to be much help cause I have the same problem with my 97 850 R. Only difference is my misfire is on cylinder 1. Have you had a compression test? My compression is low on that cylinder, but not so low that it should cause the intermittent misfiring. Mine runs great then it will start to miss, if I push on the gas it smooths right out and takes off like nothing is wrong. Luckily I don't have inspections in Ohio.

 

Hi,

Sorry about the problem, I hate rough idle problems myself. BTW, I am a graduate of The Winchendon School (About 20 minutes westof Fitchburg/Leominster).

A couple of people have had a similar problem lately, and one person even went as far as testing everything with state-of-the-art Snap-on digital scope and he still had misfire at Bank-1, and the O2 sensor kept acting up on him, though it was Bosch OEM sensor.

The first two things that come to my mindare thefollowing:

1. Fault in the MAF (MAP?)sensor, wiring or connections. With battery disconnected, clean connectors with electrical contact cleaner. If it was the turbo engine, the problem is common: http://volvospeed.com/Repair/maf_secure.php Also, with the engine at idle, try to wiggle the wire or connector or the sensor to see it the engine responds or throws a code.

2. Vacuum leak (there are hoses & elbows that are well-known to deteriorate due to age and cause some engine performance problems).

http://volvospeed.com/maintenance.shtml

I have some questions I'd like to know about:

1. When you say Volvo parts, are they parts you bought from a dealer? The following is the OEM, and I would double-check to make sure that the dealer didn't sell you non-OEM parts:

1. Spark plugs: Genuine Volvo (should have Volvo stamps on the insulator portion), made in England.
2. Plug & coil wires: Bougicord, made in France.
3. Distributor cap & rotor: Bosch, the cap is German but the rotor may be made in Spain.
4. Air Filter: MANN, made in Germany or Argentina.
5. Fuel Filter: Bosch, made in Germany.
6. O2 Sensor: Bosch, made in Germany: http://volvospeed.com/Repair/o2sensor1.php

I would recommend that you use FCP Groton in CT to save $$$ on OEM parts, unless you did buy the parts from them: http://www.fcpgroton.com/volvo.htm#850. Since you're closer, it would only take 2-3 days for shipping after placing an order.

>They have been replaced with BOSCH parts for the front and rear sensors.
As far as I know, there should be only one O2 sensor for non-turbo engine (B5254S).

I would also try dumping a larger bottle of Techron fuel system cleaner into a half-full tank and drive until near empty. Removing the injectors to have them cleaned may help a bit, but I kind of doubt it.

Also, make sure the connections for the throttle switch is secure. See attached pic but note that I'll delete the pic tomorrow so be sure to save it in your PC.

I hope this is of some use.


JPN

P.S: After the battery has been disconnected, make sure to let the ECU re-learn idle. To do this, turn off ALL electrical devices, start the engine and let it idle for 5-10 minutes. During this period, do not turn on anything that uses power, not even parking lights and stay off of the brake pedals, as this keeps the rear brake lights on.

 

Well everyone, I FINALLY found my problem! I kept putting off doing a compression test, HOPING that I'd find the problem! I did the test, and Cyl 4 was ZERO !! Cyl 5 was lower than 1, 2, and 3. So today, I started replacing the cylinder head! I'm SO glad I'm only an hours drive to FCP in Groton CT ! They have saved me a TON of money in parts! Sure enough, when I got the old head off, 1 valve in cyl 4 had a chunk out of it, and there was a slight hang up on one of the valves on cly 5 ! I got REALLY LUCKY, bought a complete, used engine from the local salvage yard for $150.00!! When I pulled the head, I was in AWE of the condition of the "doner" engine! It's SPOTLESS, and to top it odd, it looks like it had a recent VALVE JOB !! Now to my question...
The coolant pipe set that fastenes to the back ( firewall side ) of the head, is there a gasket or "O" ring there? The head set came with nothing, and I didn't see anything when I pulled it off ! Should I put some silicone sealer on the flange before bolting it up, or what? Thanks in advance for any and ALL HELP !! I can't wait to see what it drives like running on ALL 5 cylinders! LOL

Warren 95 850 GLT wagon 20 valve, 217,000 and still going!!

 

>Well everyone, I FINALLY found my problem! I kept putting off doing a compression test, HOPING that I'd find the problem! I did the test, and Cyl 4 was ZERO !! Cyl 5 was lower than 1, 2, and 3. So today, I started replacing the cylinder head! I'm SO glad I'm only an hours drive to FCP in Groton CT !

Great! You're so lucky that you can actually go to FCP Groton, I envy you.

As to the coolant line, I do not have an accurate info or engine breakdown illustration, so wait till others jump in. But you could probably visually determine to see if connections use gasket/O-ring. Gaskets are most often used between flat mating surfaces, and O-rings are usually used where lines/tubings have "sleeve".

Anyway, glad to hear you're on your way to rejuvenating your 850. Well done!

Cheers,


JPN

 

FCP is now one of my FAVORITE places to shop! LOL Next time I go, I'll take some pix for you! Now if I can lower the NOX .3 more, it'll pass inpection! LOL I did see some carbon built up on the top of the pistons, even though I did the SEA FOAM treatment once! I think I'll try it again...the first time, i couldn't see my neighbors house for almost 10 minutes! Anyway, Ireally appreciate ALL the feedback, and help I've gotten so far ! Have an AWESOME DAY!

Warren

 

Hello again Warren,

I just replied to your other post.

Next time, I would try Techron fuel system cleaner (the larger bottle) into a half tank, then again in a full tank.

I wish I were back in the States; if I had to visit FCP Groton now, I would have to fly over a large body of water & terrain.

Good day to you too. I hope you can pass the emissions inspection next time.


JPN