Misfire #3

Samus850 · Post by **Samus850** » 27 Aug 2021, 21:18

My 5cyl xc90 has had an intermittent misfire on cylinder #3 for about 3 years now. It occurs on acceleration at highway speeds and usually only when it is warmed up. I have replaced the spark plugs, then the coils, and recently the injectors but problem persists. The recurring fault code is misfire on cylinder number 3.
My thoughts of the remaining possibilities are #1: poor sealing of the piston rings is allowing oil into the chamber ( although it does not use oil), or #2: the ECU is defective.
The car is generally used for in town driving and the problem does not occur and is forgotten, but any hwy trips and the misfire makes accelerating or passing a nerve racking adventure.
Suggestions or advise greatly appreciated.

pbierre · Post by **pbierre** » 27 Aug 2021, 23:53

Have you carefully inspected the coil-pack harness wires? You're looking for cracks in the wire jacketing and corrosion spots on bare copper. The coil pack requires a strong, steady current -- that's why the wiring is 12 gauge.

When you pulled out the spark plugs, did #3 look any different?

Are you smelling unburned gas in the exhaust? Oil smoke?

Post by **RickHaleParker** » 28 Aug 2021, 00:05

Check for Air leaks around the #3 intake port. Could be a leaking intake gasket at #3. A shot of either around #3 intake might detect it.

Do a Compression Test. Compression problems that may cause a misfire on one cylinder only: Burnt exhaust valve, bent intake or exhaust valve, or leaky head gasket.

When a head starts warping #3 is the first to go. Because it is in the center of the bow ( Point of maximum deflection ).

Samus850 · Post by **Samus850** » 28 Aug 2021, 15:33

Thanks for those tips! I have used carb/choke cleaner to spray around the intake manifold with no change. (I forgot to mention that originally)
The spark plugs did not appear any different from each other, I was expecting originally to find a cracked insulator. I will recheck the injector and coil wiring first chance I get and if no fault found I will complete the compression test and report back.

BenS60 · Post by **BenS60** » 28 Aug 2021, 15:47

Hi,
Does anyone know if I can swap the engine from my 2004 S60 2.5t B5254T with a 2003 Volvo v70 2.4T B2544T?
It looks practically the same with dual overhead cams. Will the wiring harness work from the S60 or will I have to grab it from the V70?
Will i need to flash the ECU or will it be compatible without flashing?
If anyone knows.
Thanks

Post by **RickHaleParker** » 28 Aug 2021, 20:53

BenS60 wrote: ↑28 Aug 2021, 15:47

Double check your spelling. You appear to be contradicting yourself.
2004 or 2006 S60 2.5T ?

BenS60 · Post by **BenS60** » 29 Aug 2021, 01:09

RickHaleParker wrote: ↑28 Aug 2021, 20:53
BenS60 wrote: ↑28 Aug 2021, 15:47
Double check your spelling. You appear to be contradicting yourself.
2004 or 2006 S60 2.5T ?

Hey Rick
I have a 2004 S60 2.5t. I have a spare engine from a 2003 v70 2.4t .
Is the 2.4T compatible with the S60?

Samus850 · Post by **Samus850** » 26 Sep 2021, 17:50

Hello, I wanted to give an update on the misfire problem. We had to make a spontaneous trip of about 1600 miles and the problem continued the whole way and even slightly worse, but when I slightly let off the throttle to a cruising speed it was smooth and problem free. I did not bring my code reader and all the while assumed it was the same issue it had been for the past few years but when I got home and scanned it and it came up with (sorry I forgot the code) but for the fuel pump controller mounted behind the inner fender liner at the right rear wheel. I grabbed a used one from my local pickandpull and voila! The hesitation and bucking problem were gone.
I’d love to post a photo but it’s a Bosch #0580001002.
I hope this helps someone out and must say thank you to those who offered their advice.

Post by **RickHaleParker** » 26 Sep 2021, 21:07

Probably something marginal on #3. Like weak fuel injector, air leak ... ect.

Post by **abscate** » 07 Oct 2021, 23:51

Samus850 wrote: ↑26 Sep 2021, 17:50 Hello, I wanted to give an update on the misfire problem. We had to make a spontaneous trip of about 1600 miles and the problem continued the whole way and even slightly worse, but when I slightly let off the throttle to a cruising speed it was smooth and problem free. I did not bring my code reader and all the while assumed it was the same issue it had been for the past few years but when I got home and scanned it and it came up with (sorry I forgot the code) but for the fuel pump controller mounted behind the inner fender liner at the right rear wheel. I grabbed a used one from my local pickandpull and voila! The hesitation and bucking problem were gone.
I’d love to post a photo but it’s a Bosch #0580001002.
I hope this helps someone out and must say thank you to those who offered their advice.

Interesting that a fuel problem would isolate to a cylinder.