High RPM misfire

mx6gt1 · #1 01-19-2014, 08:09 PM

Hi
I have recently bought a 2005 X5 3.0i. When I bought it, it was smoking so i changed the cvv and all hoses. I have also replaced a bad DISA vavle, the O2 sensor, valve cover gasket, and battery. It finally runs great EXCEPT when it revs up to ~5500 rpm. The engine light comes on and it starts running rough, especially at lower RPM. Sounds like its running on 5 cylinders. Turn it off and start it and it runs fine again. The only code I get is misfire on cylinder 5. I tried changing the plugs around, then the coils, and it still misfires on cylinder 5. I did a compression test on 5 and 4 and they both came in at 150psi. I'm not sure what they should be at.

There is a bit of oil on the spark plug threads, but i figure it only has about 20km on it since the CVV was changed, so its probably remnants.

Any help is appreciated.

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upallnight · #2 01-19-2014, 08:41 PM

Could be a bad injector since you already checked the coil, plug, and compression and they were all good. The oil on the spark plug thread would indicates that you need to do a VCG.

xplayer007 · #3 01-19-2014, 09:15 PM

You may want to check your catalytic converter. I had a problem with misfires for about 2 years went through coil packs, spark plugs, valve cover gaskets. Changed out cats and problem solved.

mx6gt1 · #4 01-19-2014, 09:34 PM

Wouldnt injectors throw another code?
Are there 02 sensors after tha cats in these? Or can the cats be replaced with test pipes?

upallnight · #5 01-20-2014, 12:35 AM

What other code will an injector throw??? The cylinder has a misfire and that is the code that was thrown. When you have a misfire, the computer sometime shut off the injector to prevent unburnt fuel from entering the cat and destroying the cat. With the injector off the misfire is more pronounce since the cylinder is dead.

Shutting off the engine reset the computer but the misfire may still be there. Once a certain number of misfires have occurred according to the computer it throw up a code and shut off the injector.

You can bring your car to a place that can clean all the injectors or you can replace the injector to cylinder No.5. However if you remove the fuel rail and pull out some of the other injectors, replace the rubber o-rings at the tip of the injectors.

mx6gt1 · #6 01-28-2014, 02:22 PM

Ok. So I replaced Fuel Injector #5 and all the top O-rings (my seal kit came with the wrong size O-rings for the bottom). The new injector looked quite different than the others but the important dimensions were right and it fit just fine. I started it back up and it had a permanent misfire on cylinder 5, even at idle. I tried switching the new injector to cylinder 4. Now its back to running fine until it gets above 5500 RPM. Then it goes into a limp mode which I can fix by clearing the codes. Only now I get misfire on cylinders 4 and 5. I have checked and the re is definitely no fuel leaking form the O-rings.

ExpensiveTaste · #7 01-28-2014, 02:57 PM

Hook up INPA and look at the cylinder balance at idle. Does it also misfire revving to 5500 RPMs in neutral (no load)? Is there a chance you dropped some gasket material into the intake manifold while replacing the DISA and there's gasket material blocking the airflow in the number 5 port?

mx6gt1 · #8 01-28-2014, 04:33 PM

Anyone know if that software works with a Bluetooth OBD Adapter? That's all I have, using the torque app. I also have a fuel system failure.

mx6gt1 · #9 01-28-2014, 04:34 PM

it also has a misfire at 5500rpm in neutral

upallnight · #10 01-28-2014, 04:48 PM

I have used a bluetooth adapter with Torque on my X and it works. Look like you are not able to go into close loop so the engine is just using a predetermine fuel map. Could be the reason why you have the misfire since the 02 sensor is not correcting the mixture base on the actual engine conditions.

Are the 02 sensor the original or have they been changed?

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