2006 XC90 V8 stalling & misfiring

aholt · Post by **aholt** » 16 Jul 2015, 11:42

Hi all,

I posted a thread about 9 months ago about a car I had just purchased. I am still fighting with the car, and wanted to update the information and hopefully gain some new insight.

The car is still misfiring, it seems to do it in extreme temperatures only. I stopped checking codes basically all spring because of it being a very busy time, but we didn't have any instances of flashing CEL and the "slow down or shift up" message. It started happening again as the weather heated up to the 90s+. The car also stalled immediately after starting a handful of times since I've owned it, my husband thinks he didn't turn it long enough, I don't recall having that issue when I started it.

Two weeks ago, I took it to have the AC lines replaced as they were leaking. They also recharged the AC. Since that happened, it stalls out any time the AC is on and I am idling. At stop lights, immediately after starting, etc. The only time it seems to be fine idling with AC, is when I start it up in the morning for the first time. They said the voltage is dropping to 9v when it stalls.

Car needed a new catalytic converter when I bought it, I had one installed yesterday. Really worried about ruining the new one since we still can't figure out why it is misfiring.

Since owning the car I have:
changed spark plugs (not OEM, planning to swap soon)
replaced bank 2 oxygen sensors (as a first step with the CAT code)
replaced fuel pressure sensor
changed air filter
changed fuel filter
cleaned MAF
cleaned throttle body (didn't replace gasket, planning to do that today)
replaced the battery that was bad (was the original)
replaced(?) ground wiring (the mechanic told me they did this)

the grounds being cleaned/replaced/whatever seemed to help the random flashing CEL, it started only misfiring right after a stall. Yesterday when I picked it up from the shop, it had been sitting in the blazing heat (inside thermometer read over 100 degrees) as I accelerated and pulled from the shop, it did a full misfire with flashing, it also stalled at least 2 times. I can't remember if the light turned off on it's own and came back, but on my way home, I had the codes checked at an auto part store, it was a misfire in 6 of 8 cylinders, 1 and 5 were okay. Usually it's all cylinders. Today while on a test drive, the CEL came on, but no flashing. I had the codes pulled and it was in 4 cylinders.

The only other code I've had more than once is the crankshaft position sensor (p0336), when the shop brought it in for the AC they found that code, it has come back about 2 or 3 times in the last 2 weeks. The shop said they swapped the sensor and didn't see a change in performance.

Sorry for the novel, I am at my wits end and just need this car to be safe to drive my kids in! Any input is appreciated.

aholt · Post by **aholt** » 16 Jul 2015, 15:14

a quick update

I ran a test run, at about 8 miles after resetting light, the car stalled with the AC on at a light, but immediately picked itself back up. As I made the turn, it started flashing CEL and so I pulled over and stopped. When I started it back up, the code was gone. I drove it to the place I had been earlier in the day & he pulled the codes, misfire in 7 cylinders, crankshaft position sensor, AND A FREAKING P0430 CAT CODE. I hoped to never see that code again. Please tell me that since yesterday I didn't already burn up a new cat, this makes me feel like the $1000 repair I did yesterday was for nothing.

Post by **Vovo_merz** » 17 Jul 2015, 09:08

Hi there, I highly doubt that you can burn a cat that fast, and would like to suggest replacing the MAF sensor and the thermostat also add some injector cleaner to fuel.
but the best option will be to find someone with Vida Dice or take it to the (stealer) as you might be putting in money chasing the problem and it could be something simple and fairly cheap ( been there already)

Good Luck

aholt · Post by **aholt** » 17 Jul 2015, 10:49

Vovo_merz wrote:Hi there, I highly doubt that you can burn a cat that fast, and would like to suggest replacing the MAF sensor and the thermostat also add some injector cleaner to fuel.
but the best option will be to find someone with Vida Dice or take it to the (stealer) as you might be putting in money chasing the problem and it could be something simple and fairly cheap ( been there already)

Good Luck

I appreciate you taking the time to weigh in!

I have tried testing the MAF by unplugging it and seeing if the issue stays the same. When it's unplugged the car stalls out immediately, my understanding would mean the MAF sensor wasn't bad, but maybe I misunderstood. The car is back at the shop because after the catalytic converter replacement I was having hot air blowing on my feet while driving, lots of engine compartment noise & vibration through passenger cabin. I forgot to mention in my original post that I also had the battery and alternator tested, the battery was determined to be bad, so I replaced, the alternator tested fine except for having high (.6) ripple. I am thinking I might just need to put in a new alternator and cross my fingers.

aholt · Post by **aholt** » 19 Jul 2015, 11:17

any other ideas?? please help, it's been 9 months & i don't feel safe driving the car! i told my mechanic that when i had the battery and alternator tested months ago, it read a high ripple (.6) and he says in his gut he doesn't think it's the alternator, I don't know want to push a 800+ repair to have it not do anything. is there any chance that the ripple reading could have been a false reading because the battery was so low?

mika · Post by **mika** » 22 Jul 2015, 09:44

The maf needs to be unplugged before the car is on, not unplugged once it is on.

Obviously something is off and it is bankrupting you. Looks like a lot has been replaced. Have you tried simple stuff like pulling the ECU computer and reseating it? What about disconnecting the battery cables and trying to start the car to clear the computer? These are all things you should be able to do by yourself, buy a simple metric socket set from walmart or harbor freight and start digging in!

Which part of the US is this car located in BTW?

aholt · Post by **aholt** » 22 Jul 2015, 13:12

I had a mobile mechanic come over because I am sick of not seeing what is being done. He plugged in his big Pegisys computer and I saw all the codes that have been stored.
Past Codes:

BCM:
C0045-01 Brake Pressure Sensor B - General Electric Failure
U0428-29 Invalid Data Received from Steering Angle Sensor Module
U0126-00 Lost Communication with Steering Angle Sensor Module
U0001-00 High Speed Can Communication Bus
U0114-00 Lost Communication with DEM
U0401-64 Invalid Data Received from ECM

TCM:
P0744-00 Torque Converter Clutch Solenoid Circut Intermittent

Read Codes:
CEM:
1A52 Communication with DDM
DF17 No Diagnostic Code Description Available
E000 Communication with Control Module Faulty
1A64 Communication with AOC Module

DIM:
0001 Mileage Manipulated

Also, the P0430 was there, misfires (as usual). He cleared the codes and one of the times the car was started and idling the CEL came straight back on, we checked and it was P0336. He went from thinking the battery was bad (it showed only 6v after the big computer was left plugged in), then thinking alternator because the voltage was jumping from 14.40 down to 14.20ish in one jump. He said going down by .2 or .3 is okay but not that high of jumps. Then after the sensor code came up he thought it was that. He is getting an OEM sensor and installing tomorrow. Any direction or opinions from here?

aholt · Post by **aholt** » 22 Jul 2015, 13:18

mika wrote:The maf needs to be unplugged before the car is on, not unplugged once it is on.

Obviously something is off and it is bankrupting you. Looks like a lot has been replaced. Have you tried simple stuff like pulling the ECU computer and reseating it? What about disconnecting the battery cables and trying to start the car to clear the computer? These are all things you should be able to do by yourself, buy a simple metric socket set from walmart or harbor freight and start digging in!

Which part of the US is this car located in BTW?

I just wrote another update, but we have tried undoing the battery cables, and almost everything on the list we've done ourselves. The biggest thing is where to go next I guess for this issue. Do we just go for the big alternator repair and hope it helps? Pretty expensive gamble. We already did that with the cat and the code is still showing up.

The car is now in Utah, but it was purchased in Seattle, WA and driven to Utah. If I remember, before Seattle it was in Texas.

aholt · Post by **aholt** » 05 Aug 2015, 16:00

Long overdue update on the issue:

Volvo spark plugs from the dealer and an OEM crankshaft position sensor has solved my misfire and stalling. I have not had those issues again since it was repaired 2 weeks ago (although I was out of town for a lot of it, but the issue was extremely consistent & easy to replicate). What we are experiencing now, is still having the P0430 code. We have put in a new cat, and changed o2 sensors about 9 months ago. I found out today that my old mechanic used Walker brand for the o2 sensors. Considering an OEM crankshaft position sensor worked when an aftermarket didn't, is it possible that this is also caused by non OEM sensors?? Or is it possible that the cat I put in is bad? What tests would I do to test the cat is working properly?

Thanks for your continued help.

robrike · Post by **robrike** » 08 Nov 2015, 07:29

I would certainly try Volvo sensors and see if the codes for cat come back then if they do see about having cat swapped out under warranty. Shouldn't fail in 1 year.