Rough idol and stalling on 2001 V70 2.4L Turbo

[ProblemV70]

Our 2001 V70 2.4L Turbo has been finicky over probably the past 7 years. It would struggle to start if not driven daily, especially after it rained. Once the car was up and running, the rest of the day our V70 would be fine. The car has been to the Volvo mechanic many times over the years searching for the problem. Unfortunately this week, things became a little different. It will start up without a problem but then have a rough idol, bouncing the RPMs from about 700-1500, and then finally dropping down and stalling out. If I apply gas, I can rev up the engine for a bit. But then no matter what I do, the car will stall out.

I have tried to read through a lot of the posts with similar problems and watched some videos from the internet. I have changed out the fuel pump relay which was located above the pedals and in position CMI 12. That was a little confusing as the parts stores and search engines were trying to give me a different part than the one I took off my car. I ended up buying the new relay from the Volvo dealer, so I hope that I got the correct one. It did look like the old relay. It is a black rectangular 5-pin relay with three pins in a horizontal row and then two larger pins in a vertical line.

I also changed the Mass Air Flow sensor. I also bought it new from the dealer to ensure I had the correct part -- spending more by doing that. The dealer gave me the Bosch part #0280218088. The one I took off the car was a Bosch #0280218108. I questioned the dealer parts personnel about this, and they showed me that their computer showed these parts as the same with just different numbers. So I installed the one from the dealer.

It seemed to be better, just a little rough on the idle. One of the videos I watched said that the MAF would need to reset after cleaning but to take it for a short drive so it would reset. I figured replacing was similar so I went for a short drive. Initially the car was driving fine, but would stall out at a stop sign or a slow turn, and I would have to restart the car. It ended up barely responding to gas and had to be restarted multiple times to be limped the two blocks home.

We have a Schwaben scanner. Prior to changing the mass air flow sensor we did not have any codes. Now after driving it with the new relay and sensor, we have these codes:
Electronic Control Module ECM-1 300 Mass air flow sensor: Flow too low
ECM-2 400 Fuel pump relay; signal too low
ECM-6 806 turbocharger control system flow fault; flow too high
Central electronic module CEM-3 A01 fuel pump; signal missing

What should I do now? Does the fuel pump need to be replaced? Did I get the wrong Mass Air Flow sensor?

Thank you for your help. The car only has about 155k miles. So I don't want to let it go just yet. In the past when it was running, it ran well. We use 93 gas and add Lucas gas treatment every third or fourth fill-up. The only other recent issue (maybe about two months ago) is that the fuel gauge is stuck on full until we get down to almost 3/4 tank.

[dikidera]

Firstly, if only by the codes, I'd say you have a vacuum leak somewhere because of the low air flow but your turbo is flowing more?. Also your CEM and ECM are complaining about the fuel pump relay, or could be old codes. Clear them and see if they come back.

The rough start...I can think of a few things. When was the fuel filter last changed? How about a measure of the pump's pressure. Secondly, and I am not sure if our cars have them, but fuel pump check valve, this valve prevents fuel from going back the way it came in, but like I said, I am not sure if our cars have these. If the fuel rail is somehow losing the fuel, and maybe filling with air instead, I can see how it would start roughly. Or maybe a leaky injector flooding a cylinder.

[ProblemV70]

Thanks for the reply. I did clear the codes prior, but I will try it again today. I also read online that I should disconnect the battery for at least 15min after installing the MAF sensor, so I will also try that.

I'll try to search for a vacuum leak. That might be out of my limited skill set. I will also see if our foxwell scanner will be able to get any live data if the car will keep running long enough.

I'm not sure when the fuel filter was changed. My husband used to do a lot of the maintenance himself on this vehicle. He thinks about 5 years ago he changed the fuel filter. Unfortunately he had a stroke 3 years ago, so now I do small maintenance on the vehicles and then send it to our mechanic for the rest. I'll look thru the mechanic records and see if there are any other clues.

[jonesg]

I would reinstall the original parts and see if those codes go away.
Your 'parts cannon' approach will become very expensive, stop buying parts.
It needs a proper diagnosing, not just "it kinda sounds like".
Get a new mechanic.
A smoke test will detect vac leaks, but theres no diagnosis pointing in that direction yet.

Has the throttle body ever been cleaned, did they read the fuel trims ?
Did they read the fuel pressure ?

[ProblemV70]

I reinstalled the original parts, disconnected the battery for about 30min and then reconnected. I cleared the codes and then tried to start the car again, trying to get live readings with our scanner. The car stalled out faster and even if trying to give a little bit of gas. Most of the previous codes came back:
ECM-2 400 Fuel pump relay; signal too low
ECM-6 806 turbocharger control system flow fault; flow too high
Central electronic module CEM-3 A01 fuel pump; signal missing

Visually, I don't notice any obvious cracks or disconnected hoses. I had it towed off to a local Volvo specialist. They probably won't have time to get to it for at least a week. When I hear back, I'll post what they found. I'll ask info about what the fuel pressure readings and fuel trims are in case that information helps anyone else with a similar situation.

[abscate]

Let us know what they come back with. If we have some nearby, post up your zip and maybe we can give you a hand on site too. That fuel pressure test should tell you if fuel delivery is the problem

[ProblemV70]

Luckily my problem ended up being an easy fix for the Volvo techs. The intake pipe was disconnected from the throttle body. So they reinstalled it and made sure that all other connections were tight. I forgot to ask about the fuel readings; I was so excited when they called and it was an easy fix for them. Now our old gal is up and running well again. I'm trying to drive her more often. Mainly the teenagers drive the Volvo, but one has gone off to college, so she wasn't getting started as much. She is definitely happier when driven multiple times a week.

Thanks for all the help.

[scot850]

Thanks for the update and fix.

Neil.

[jonesg]

alls well that ends well. !