Hello everyone! I'm really hoping someone here can help me! I have a 95 850 wagon, non turco, that keeps giving me various misfire codes! it ALWAYS starts with the code 543. Here's what's been done, so far:
complete tune up, cap rotor, wires, plugs, air filter & flame trap

cleaned the egr passage

2 new o2 sensors

new IAC

new exhaust from the cat back

timing belt was done just before I purchsed it, about 3,000 miles ago

cleaned the throttle body

run injector cleaner through 4 tanks of fuel

And it STILL idles rough ! It's smooth and has plenty of poser on the highway. sometimes when I start it, it seems like a mild explosion when it first fires.. not a back fire, but like too much fuel ?? I did get a code for " running at maximum enrichment" once ! I'm totally baffled by this car, I love it, but it's getting annoying to see that "check engine" light on all the time! Oh yeah, sometimes the light is on steady, and other times, it flashes! What's up with that?

Thanks in advance for ALL your help!

Warren

 

Hi Warren,

Greetings from Yokohama, Japan.

It seems like your 850 recently has had an ideal tune up. BTW, did you replace the fuel filter with Bosch?

It may be due to a faulty ignition module, ECU, etc... Or the injectors may need to be physically cleaned but at this point there's no telling. 850's fuel system is sometimes fickle, especially now that the car is getting old, many people have had trouble with fuel pump & pump relay. Run the engine at night and see if the ignition coil is arcing. If it is, it's time for a new coil.

Double-check on the ignition wire connections to make sure they are tight. Also, at fuel injectors, disconnect the electrical connector and clean the inside with electrical contact cleaner, connect & disconnect several times. Also, try retrieving codes from the engine & transmission modules. Clear the codes and see if it resolves the problem. If not, you could make the ECU re-learn idle by disconnecting the battery for 15 minutes, re-connect it and idle the engine for 10 minutes with all electrical devices turned off.

Wait others jump in, someone else may have better solutions than I do.

Good luck,


JPN

P.S: Can you provide us with the info on parts you installed for tune-up? Did you use OEM parts?

 

All but the o2 sensors were OEM Volvo original parts! So why does the "check engine" light sometimes stay on steady, and other times flash?? I'm leaving for Florida in the AM, but when I get back, I plan on changing the fuel filter...it was supposed to have been done befor i bought the car, but who knows?? LOL Thanks again for ALL and ANY suggestions!
Warren

 

>So why does the "check engine" light sometimes stay on steady, and other times flash??
It is called "Volvo Technology"[8D].

BTW, it's too late at this point, but Volvos don't like non-OEM O2 sensors.

Have a safe trip,


JPN

 

I had the same problem with our 850 non turbo. Turned out to be the coil pack. Enough juice to start it and once up to speed keep it running well, but it had an under power miss.

 

Hmmm... I've never had a problem using a bosch O2 sensor in place of the OEM! I just replaced the fuel filter, reset the codes, and reset the computer, and STILL I get misfire codes! Always starting with 543 ! I've sprayed 2 cans of carb cleaner on every vac line under the hood, and nothing! Cleaned the EGR passage, yes it was pretty well plugged up, and checke the EGR control... hasn't helped! I did replace the coil, just in case, but that had no effect either! Could I have something in the injector rail blocking injectors, or could 4 out of 5 be clogged? The car does have 214,000 miles on it!!?? Thanks again for ALL your input and help!
Warren

 

Hi Warren,

I apologise if my replies areannoying you, I have absolutely no intention to bother you, only trying to help you with what I know.

Bosch is the OEM for Volvo O2 sensors, as far as I know thereforeI assume they're fine.

It is highly unlikey that 4 out of 5 injectors are clogged.

I re-read the previous replies, went back to the code chart and 5-4-3, I believe, is misfire in at least one cylinder, right? Here are my next suggestions:

Please specify what brand of ignition wires have been installed. If you have a service manual, such as Haynes, try testing the wires with digital multimeter for correct Ω readings if you have one.

Also, please specify what kind of spark plugs have been installed. Bosch Platinum +2 (two ground electrodes) seem to be causing trouble for some people, though I myself never had problem with them. Remove each spark plug andcheck for their condition; this will pretty much tell you what is happening inside each cylinder. If they appear ok, try cleaning the threads on the plugs with wire brush (brass would be the safest)and reinstall them. I'll copy & paste what I wrote in one of the pined threads:

COPY:
*Note on Spark Plugs:
Bosch Platinum +2 seems to have poor reputation, though I myself never had trouble with them. However, Bosch Platinum +4 and NGK Iridium seem to have excellent reputation. For turbo (B5234T), Champion RC7GYC is specified, whereas Bosch FR6DC/Champion RC9YC is specified for non-turbo (B5254S?). The easiest way is to buy genuine Volvo; Turbo $32 (approx)/NA $13 (approx).

Platinum plugs are pre-gapped andre-gapping is generally unnecessary. If re-gapped, the center electrode may be damaged. Never drop a plug onto the floor/ground. Platinum plugs do not require cleaning, as they are designed to self-clean, and are generally good for 60,000 miles/100,000kms. Upon installation, apply anti-seize compound on top few threads (closer to the hex), hand-tighten (extension bar may be used) until tight, then tighten an additional 1/4 turn for gasket-type or 1/8-1/16 turn for non-gasket type, or use a torque wrench to specified torque. Refer to service manual for specific procedure for your engine. Replace plugs only when the engine is cold.

Some selections at FCP Groton:
http://www.fcpgroton.com/volvo850tuneup.htm

END OF COPY

I have a feeling that there's something in the ignition system, but other people may have different opinions. I know this is troublesome, but I would re-check everything in the ignition system, and if they are ok, then I can onlysuggest that you visit a Volvo dealer and have them run a diagnosis.

I wish you the best,


JPN