94 850 Turbo rough constant idle and misfiring

[Volvofan94]

Good Evening MVS,

After the most recent cold spell passed over my area (about two weeks ago), the Turbo hasn't been the idling the same. It sounds like the engine is misfiring on one or more cylinders by listening to the engine at idle and car in park. The car shakes at idle as well. But anyway, I checked the codes at the computer and received two codes: 543 and 455. After doing some research and installing a new set of Bougicord Spark plug wires, Volvo sparkplugs, OEM distributor and rotor, the problem exists and has since gotten worse. Now when I check the codes at the computer error codes: 543, 455, 542, 545, and 555 are displayed.

Here are some things I've observed:
1. The problem appears after the car has warmed up (temp needle at 3 o'clock position). If the engine is cold it seems to run normally. Once the temperature gauge rises off the cold mark things start to get worse...
2. No smoke comes out of the tailpipe (I'm hoping this rules out the possibility of a burnt valve in cylinder 5).
3. Generally the idle is constant @ ~900 RPM.
4. In normal driving everything appears well.

Things I have done to hopefully fix the issue:
1. Brand new OEM plugs, wires, distributor cap, and rotor.
2. Replaced all old vacuum hoses.
3. Going to replace the ECT this weekend

Possible ideas on what to check/do next:
1. Replace ECT
2. Verify I have the spark plug wires connected properly at the distributor (pretty sure I do as it idles smoother when cold, but doesn't hurt to double-check!).
3. Perform a compression test in cylinder 5.

CEL Code reference:
543 Misfire at least one cylinder
455 Misfire cylinder 5
542 Misfire more than one cylinder
545 Misfire at least one cylinder, three way cat damage
555 Misfire cylinder 5, three way cat damage

I appreciate any thoughts or suggestions.

Thank you everyone!

-volvofan94

[1998v70xcbill]

swap fuel injector with other cylinder

[rspi]

[rspi]

[Volvofan94]

Thanks everyone for the replies (and rspi for the videos)!

Tomorrow I'll take a look at my fuel injector in cylinder 5. Not sure if this helps confirms its the injector or not, but when the engine is running the number 5 fuel injector does have a vacuum leak like hissing sound. The fuel rail is pushed down securely and the other 4 fuel injectors sound fine. I've looked around the Idle Air Controller valve area, but didn't feel any air leaking from the vacuum lines.

Any thoughts on the sound it's making?

-volvofan94

[Volvofan94]

Quick update...

Yesterday and today I tried to replace/check a few more items on this problem, but had no success. Everything I checked in the engine seems to be ok, but here is the list I did yesterday and today with the results.

1. Replaced my ECT
2. Swapped the cylinder 5 fuel injector to a different cylinder - no difference still receiving the 543 and 455 error code.
3. Checked compression on cylinder 5 - looked good at 130lbs.
4. Checked for spark as per rspi's video. The coil is providing good spark.
5. Tested the Fuel injector wire - reading 13.6 Volts with the engine running (11 volts engine off)

Another thought, could I have a stuck valve or lifter in cylinder 5?

-volvofan94

[Volvofan94]

Quick update #2...

Ordered a new MAF sensor and it should be here this weekend. After doing research and testing on various engine components (EVAP, IAC, Fuel Injectors, Camshaft Position Sensor, vacuum lines, etc) it looks like a faulty MAF could be to blame. The car doesn't give me a CEL for the MAF sensor, but I checked the others and each is looking good and within spec. The MAF sensor was pulling additional voltage with ignition OFF and that was out of spec; I figured it best be replaced.

But in the meantime, I've been driving the car. Trying to flush the old gas out of the fuel tank before filling up again with Premium Fuel. I have a habit of putting 87 and the ethanol blended fuel into my car, which I hear is not good for the Volvo turbo engines. I was able to add some Seafoam and luckily it smoothed out the idle. After driving the car at 4000 rpm for a few minutes seemed to have taken care of the misfire codes.

I'll provide an update when I have the MAF installed...wish me luck!

One more question, I can't seem to pull codes from the A-6 port. Anyone know why?

Thank you guys; very much appreciated!
-volvofan94

[abscate]

I chased my turbo rough running last year for several weeks and found bad induction - torn intercooler hose and loose clamp. I also thought I had bad fuel and bad injectors - if pulling the plug on the MAF helps out, it is pointing to bad air hoses somewhere.

[Volvofan94]

Yeah, I did unplug the MAF sensor, but the idle speed increased by 500 RPM...this was after I drove the car that day and the idle speed was already at 1500 RPM in park. I thought by unplugging the MAF sensor the idle should return to normal if it's a MAF problem because the IAC and something else takes over to control the idle speed. Could be wrong...

Luckily my new MAF and fuel injector relay arrive today and I'll get them installed and can post back the results. Fingers crossed it works!

But good thought on checking the induction hoses. I will check for air leaks on those this morning as well.

-volvofan94

[Volvofan94]

Well some good/bad news...

Good news is the new MAF and Fuel Relay seemed to have fixed the issue before resetting the codes. But the bad news is when I went to reset the CEL codes the problem returned. The car now idles really low in gear (500 RPM). Took it for a test drive and it felt like the engine stopped when I was coasting because the brake pedal was really firm like the brake booster wasn't working. Unfortunately I didn't get too far before going back to the garage.

I looked at all the induction hoses per abscate's recommendation and didn't find a leaking area. All vacuum lines have been replaced as well.

Tomorrow I'll try to unplug the battery to reset the ECU. I don't think it will do much, but I'm starting to run out of ideas on what could be causing the problem.

-volvofan94