2005 Volvo S40 (NA) with 100K miles - Engine stalls at idle
I currently have 2 codes showing up twice (P101 and P134) on my scanner. In the past, various related codes have come up but as soon as I address it and clear the code, the car stalls again and another code comes up. The codes are changing but the problem with the car is consistent. The car will stall at idle. Sometimes I can drive it a few miles before it shows up and sometimes it's immediate. It'll stay on as long as I feed it gas, but it will stutter if I don't give it quite a bit sometimes. In the past I've gotten codes for the VVT, 02 sensor, and I believe the IAC.
Here's a video of the current LIVE readings from the scan tool - https://www.youtube.com/shorts/ZOaj3qgvY2Q. I'm beginning to think maybe it's the FPR or fuel filter but I don't want to keep throwing money at this thing if I can help it.
So far, I've replaced the 02, VVT solenoid, throttle body (since the IACV is integrated) and MAF sensor. After replacing the VVT, 02, and initially cleaning the MAF and throttle body, the car did much better. I was able to drive it 100 miles with it only stalling once. But since then, it's gotten worse. I just cleaned the MAF sensor today and let it dry for a while. When I did that, it seems like it's running a little worse than it was before when I'm driving it.
I'm not the original owner - I bought it with the intention of flipping it, but decided to keep it for my son hopefully. Any ideas what my next steps should be?
So far, I've replaced the 02, VVT solenoid, throttle body (since the IACV is integrated) and MAF sensor. After replacing the VVT, 02, and initially cleaning the MAF and throttle body, the car did much better. I was able to drive it 100 miles with it only stalling once. But since then, it's gotten worse.
A DTC merely informs you what the ECU 'sees' as a problem area. Having a code triggered doesn't necessarily mean you should replace that part, only that further diagnostics are required. You stated you replaced the upstream O2 sensor, was it bad? Did you test it? Replacing a sensor without knowing whether it's bad can easily just create another issue, especially when using aftermarket parts. I recommend not buying anything else until you've identified the problem through a more deliberate diagnostic process.
Check the live data first to see what insight it gives. You might have a vacuum leak or a failing fuel pump, codes are often only the start of the diagnosis.
Correction... Today, it was the MAP sensor (not the MAF) that I cleaned. Also, I did get a code yesterday for the MAF circuit - that's why I replaced the MAF yesterday.
You should never clean MAP sensors. They are not very sensitive to dirt. They are easily damaged and should be replaced.