Yet another misfire thread - Cylinder 3 - No compression

[TisMe]

Double post, oops.

[TisMe]

Have you removed and looked at the number 3 spark plug after running with the coil disconnect, fuel injector connected for cylinder 3? If it's dry I'm it may indicate the ECM is shutting down the fuel injector for that cylinder. Not sure what's going on when you disconnect the fuel injector for cylinder 3 and lose power and get a code for cylinder 2. What's the actual code you get for cylinder 2?

I forgot to point out this valuable detail! I did not notice whether the plug was wet, but when I pulled it, it has all kinds of black carbon combined with the smell of fuel. Pulling the others during the compression test, they all look normal. No carbon, no smell. Next drive, I'll try to take the time to pull the plug and check whether it's wet.

The code is ECM-2330. Just pulled it. My memory was incorrect, it's referencing cylinder 3 and 4. #3 makes sense, as that's the plug I pull. The inference to #4 is what weirds me out. However with this quick mile-long test drive just now, my power was fairly decent, so perhaps the #4 reference is just a false flag.

For some reason online resources just say "Injector 3 Signal missing", yet the OBD reader reference both injectors. I'd suspect anyone inquisitive enough could replicate this in their own P2 Volvo

In a case like this, which doesn't make sense, I would point an infrared thermometer at the each of the cylinder exhausts outlets to see which cylinders still seem to be firing and contributing power and which are dead.

I'll dig up my thermometer, thanks! This would likely answer whether #4 is losing its power alongside the #3 injector plug removed.

[abscate]

Remember there is no sensor connected to each cylinder detecting misfires. The ECU measures acceleration after each power stroke and determines which cylinder it is by cam/crank sensor.

If it’s running rough, it will get fooled and report spurious cylinder errors

[TisMe]

It's nearing that time...

This may be an awkward question, but does anyone have any opinions on non-OEM intake/exhaust valves? Considering the possible repercussions of low-grade parts, I'm not trying to throw cheaper materials into my engine, but trying to find the company that Volvo sources to print their stamp on the box. Or perhaps the company that has a reputation you can't deny. This appears to be information that's not easily discoverable through searches.

I'm sure this won't be my last enquiry

[abscate]

For a turbo you need to use the Volvo spec sodium filled exhaust valve. You will only need two exhaust valves, $50-60 each

Inter valve , CRP, TRW all fine for intakes. About $15 each

[TisMe]

Neat, thanks for that! Starting to think you've experienced this yourself

I was leaning toward Victor Reinz for my stem job, but looks like Corteco makes them as well. Even CRP. All the trusted brands, interestingly enough. Wondering if they're all equal, or if any of them dropped the ball for such a sensitive area.

I'm suspicious leaky rubber may have... stemmed... the valve implosion, but I won't get ahead of myself with wishful thinking.

[RickHaleParker]

If you rotate the engine until #3 is on the compression stroke. Then pump smoke into the cylinder through the spark plug hole. You could also attach a Air hose to the compression tester deep well extension and see if the cylinder will hold pressure. If a valve is burnt you will get flow out of the intake or exhaust.

Firing order 1-2-4-5-3. Bring #5 to the top of the compression stroke using a compression gauge . Place a rod in #3 and continue to rotate the engine until the rod peaks. #3 is is on top of it's compression stroke.

[erikv11]

Neat, thanks for that! Starting to think you've experienced this yourself

I was leaning toward Victor Reinz for my stem job, but looks like Corteco makes them as well. Even CRP. All the trusted brands, interestingly enough. Wondering if they're all equal, or if any of them dropped the ball for such a sensitive area.

I'm suspicious leaky rubber may have... stemmed... the valve implosion, but I won't get ahead of myself with wishful thinking.

For me: always replace the valve stem seals when the head is off and only buy them from Volvo. It's not clear who makes them AFAIK, and not worth guessing. The aftermarket ones are a known problem. You don't want them leaking again. https://parts.volvocarslisle.com/p/Volv ... 72424.html

[abscate]

Volvo only for the stem seals, x2

There is a part number for the set of 20 which will save you $40 from the individual price.

[erikv11]

Part number 272424, it's in my post already.

Currently 20% off at Volvo of Lisle where blue box parts are already usually cheap, see link above.