Cori Nicole Posted February 14, 2017 Report Share Posted February 14, 2017 So this is gonna take a lot of explaining, please hang in there with me. I recently bought a 02 Volvo s40 1.9t, shortly after buying it, it needed some work done so I took it to a mechanic around here who boasts about his skill with imports. When I got my car back for the small fix, he informed that he accidentally broke my MAF in the process. He proceeded to tell me to drive it for 20-30 miles and the new MAF should acclimate itself to my car and the rough idle should go away, didn't trust it but I had somewhere I had to be so I left. I drove it for about 120 miles and not only did the idle/running rough problem get worse a check engine light came on. I pulled over and checked the codes and I got misfire on all cylinders and a dreaded p0171 code. I called him back and he took my car in, said it was a "faulty MAF" claimed he fixed it and sent me on my way. Two miles later the CEL is back on. I call him back and he tells me I'm on my own and he's done helping. I've checked the fuel pressure using a gauge, all clear. Checked all the hoses, all clear. Checked the MAF with a multimeter, all clear. I called a Volvo dealer and they told me it's likely the Fuel Trim code needs reset. I've had another mechanic tell me he believes it's the fuel filter/pump/regulator. My only concern is if it was one of the mechanics suggestions wouldn't the fuel pressure test not came back all clear? There's no fuel spillage into the exhaust, no smoke, no fuel smell in the engine bay. Only the CEL and the occasional stutter. The stutter only happens when I'm stopped and then start to excelorate it's like it loses power, bogs itself down then surges back to having power again. Please any and all suggestions are greatly appreciated. I didn't know where else to go or ask, and this seemed like the perfect place. Thank you in advance! Link to comment Share on other sites More sharing options...
gdog Posted February 15, 2017 Report Share Posted February 15, 2017 Well I'm not an expert on these particular cars but the bottom line is you should probably find a good indy volvo tech local to you. Check reviews, etc. I think your first attempt was a swing and a miss.. Are you still getting p0171? If so, my guess is your "mechanic" hosed something up and is reneging on his responsibility to fix it (or can't). But as i said, that's strictly a guess based on the info you've presented. Assuming the MAF is functioning properly, then I would look for vacuum leaks. https://www.obd-codes.com/p0171 Link to comment Share on other sites More sharing options...
hootie6828 Posted February 15, 2017 Report Share Posted February 15, 2017 Yeah, I think you need to start looking for broken/loose intake and or vac lines. My guess is that your mechanic either knocked a line off or broke something and either didn't realize it, it just left it anyway. What was the outcome with the maf he broke? Did he replace it, or "fix" it? Link to comment Share on other sites More sharing options...
Ihatespeedbumps Posted February 15, 2017 Report Share Posted February 15, 2017 I will echo the suggestions above to look for a broken/missing vacuum hose. If he used an off brand MAF that could also very likely be the culprit. One other easy check and common failure on this model is the fuel pressure regulator located just above the throttle body. Pull of the vacuum line after running the engine and see if raw fuel is present. Link to comment Share on other sites More sharing options...
Cori Nicole Posted February 15, 2017 Author Report Share Posted February 15, 2017 I planned on checking the fuel pressure regulator today, and as far as the hoses go he "claims" he did a smoke test but I'm not sure I believe it. Same with the MAF he said he replaced the faulty one with another new one, I checked it with my multimeter and it's reading good. I'm gonna check over everything a thousand times till I find it. Thank you all for your suggestions. 😊 Link to comment Share on other sites More sharing options...
Ihatespeedbumps Posted February 15, 2017 Report Share Posted February 15, 2017 Can you see what brand the MAF is? Just because it checks out with a multi meter doesn't mean it won't set a fuel trim code. At this point I would take everything he told you with a grain of salt, check the hoses yourself or find another reputable volvo tech to do ti for you. Link to comment Share on other sites More sharing options...
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