2001 C70 2.0T - Won't stay running unless MAF unplugged

[Tommytom]

It seems that I have to try to fix these issues myself. I took car to local mechanic (fair volvo experience I assume), he eliminated air leaks that were present in the system - I had problems starting car when cold (RPM hunting, after gasing it for awhile it stabilized), also seemed to be slow as for these 163HP - two vacuum lines lose and one going straight to the air (one from intake manifold bubble). He said I must get my ETM fixed - no error code stored, though. He said there is a sticker on ETM, maybe someone installed XeMODeX alike already... Before I decide to get that done anyway, I want to make sure it can cure my baby.

After I took car from him (still hot) it was running really nice, next day in the morning it simply failed to start and showed two codes:
P1238
P0171

I tried to hold it running by pressing throttle (as I used to do before) but it failed to work. I cleaned MAF, still the same. I decided to unplug it completely and surprisingly it starts fine. Maybe not fine, but at least I can drive it. Seems to be in limp mode now, ETS light is on along with CEL, however no stalling or RPM hunting. After I start it it goes up to 1400 RPM to stabilize around 950-1000 seconds later.

What do you guys think? Should I fix my ETM in the first place or try to knock out my error codes first? Thanks!

My suspects:

• MAF, I cleaned it using CRC MAF Cleaner. From what I remember values were rather fine on idle. Can't verify it know because it won't start when it's plugged in
• O2 Sensor
• Air leak? I think he at least eliminated all of those, however I plan to run dummy smoke test to see if anything comes up.
• Dirty fuel filter/fuel pump issues?

I'm not a native speaker, hopefully you can understand this gibberish

[Ozark Lee]

P1238 is a turbo control valve code. A bad TCV will not cause the car to not run, it will just run poorly at speed. Is your ETS light on?

What you describe sounds like a bad MAF sensor but a bad MAF and a bad throttle module can kinda do the same thing. All ETMs have a sticker. Some are white, some are yellow, and I'm not sure what Xemodex puts on in the way of a sticker. If it is a stock white sticker it is trouble although it may more may not be your problem at this point. A bad ETM is good about lighting up the ETS light at even the slightest detected problem.

A bad MAF can also cause the P0171 that you have.

If you don't have the ETS light lit then I would be inclined to swap the MAF sensor but it would be nice to get VIDA readings to find out more before you start throwing parts at it. The rub there is that shops can charge you darn near what a MAF sensor costs just to get a VIDA/DICE scan. A standard P code reader doesn't tell you about the ETM performance but VIDA will.

...Lee

[Tommytom]

I agree P1239 will not cause my car not to run. My ETS light is on now, lighted right after I unplugged MAF sensor.

Unfortunately I've got white sticker on my ETM. My mechanic tested ETM using VIDA and it passed the test sucessfully. He also mention there is additional sticker, probably someone already tried? to fix it. I'll try to swap MAF with a friend of mine (C70 with the same engine) tomorrow to see if that helps. I'll also verify if all the vaccum lines are connected correctly.

Thanks for the reply!

[precopster]

My money is definitely on the MAF on this one. A bad ETM won't cause unrelated codes. The car is reporting correctly. Before changing MAF disconnect battery for 30 minutes so engine ECU has baseline settings.

[xHeart]

Dirty fuel filter/...?

It wouldn't hurt if it hasn't been replaced since 2001.