Misfire No Codes 2006 XC90 2.5t

LOutlaw1 · Post by **LOutlaw1** » 22 May 2023, 15:05

So, just a little context/background info. March 2023 bought my first Volvo as a second vehicle. 2006 XC90 2.5t. Fell in love with it immediately but it needed a lot of love. It would stall and idle terribly.

Got to work right away. PCV service and ETB cleaning fixed the stalling and rough idle. Fuel filter, oil change, new Bosch plugs, new Volvo/Bosch coil on plugs, sunroof drain repair, new carpet, air filter, new inter cooler hoses, both oxygen sensors, repaired abs pump motor just to list the majority of items.

Now to the present moment. I’ve been driving the car for the last ~2000 miles. It still had a slight stutter when idling and driving around 45mph. After scratching my head and looking at different parameters in VIDA I found multiple misfires and mostly on cylinder three. Screen shot attached. Also the number of misfires in the screenshot is over a five minute period of time.

Note: Fuel pressure has been checked with a gauge on fuel rail. Live pressure and leak down pressure is reading within spec. Initial key turn is 60psi and after 30 seconds of running it comes down to 43-44psi.

Swapped coils around and nothing changed. I’m going to do a compression test. If it tests fine I’m leaning towards injectors or vacuum leak since it’s affecting all cylinders. So far I’ve discovered no vacuum leaks which is what I checked initially when servicing PCV.

Anyone have any other ideas? Thanks in advance.

Post by **ggleavitt** » 22 May 2023, 18:22

I kinda want to ask what other codes you have, see if there's something else causing a fuss. Battery original or anything close to new?

Coil pack or injector connectors or grounds maybe? You have 2 wires each per coil and 2 wires per injector, 1 wire each going to the ECM and 1 wire to a common ground attachment point inside the wire looms (separate looms for injector and coil pack, join at rear of motor I think). It can't hurt to pull all of the connectors and check for corrosion or broken wires or anything obvious that could cause an electrical fault, especially as rate (RPM) of pulse increases. This is a 5 cylinder so Bosch ECM that sits upright in the frame on the passenger side, might not be worth pulling the unit to check for corrosion if the vehicle never experienced water that high. For sure check all the grounds on the fenders though, they're probably all fine but now you know they're fine. Could try swapping injector from cylinder 3 push comes to shove.

Sure others will have some ideas, you're already on the right track in my opinion.

Edit- add injector sentence, battery reference

LOutlaw1 · Post by **LOutlaw1** » 22 May 2023, 19:16

Has brand new Volvo battery. All grounds look good. No corrosion that I can find so far. Ran out of daylight. Haven’t ohm’d the injectors yet but that isn’t always accurate. At work now so I’ll check some more items in the next day or so. Still need to also check compression tomorrow.

Only codes I’m throwing in VIDA is BCM-0109 and SAS-000E which is from the steering angle sensor. That was my next thing to tackle after getting this misfire issue taken care of.

Also if there’s an issue with the ECM would I get some kind of communications fault/error?

LOutlaw1 · Post by **LOutlaw1** » 23 May 2023, 06:36

!!Update!! :: Now that it’s daylight… I proceeded to do the compression test and all cylinders were almost perfectly equal. Within 2psi of each other. However I found the issue with the misfire. I pulled back some of the insulated tubing on the wire harness for the COPs and VVT solenoids. There were cracks in the colored wire insulators and some of them were rubbing against each other. Had I not actually removed the tubing I wouldn’t have caught this issue. Now to get all the items to repair. I’ll update when repair is complete to see if that gets rid of the misfiring.

LOutlaw1 · Post by **LOutlaw1** » 23 May 2023, 19:16

Ran out of daylight again and will test in the morning. I managed to repair the harness and it seems to have helped but I won’t know for sure until after test drive and with ViDA plugged in. Attached are photos of the repair to the COP and VVT harness.

LOutlaw1 · Post by **LOutlaw1** » 30 Jun 2023, 21:03

Haven’t touched the car in a couple weeks waiting on parts. (Radiator, thermostat, coolant hoses,etc) Radiator has a crack in it. As far as misfire goes I’ve narrowed it down to the VVT hub exhaust side. When I change it I will update if it solves the misfire.

bumperplates · Post by **bumperplates** » 05 Jul 2024, 22:34

Did you solve your misfires in the end?