Chaps Got a slightly odd problem. Recently did some work on the car which included dropping and then refitting gearbox (broken quill shaft), dual mass flywheel regrease, new clutch bits and bobs, new thermostat. Put it all back together and now it struggles to idle or pick up on throttle. Runs OK once it clears the initial stutter (say, above 2k rpm). I don't have any OBD equipment to check any sensors but struggling to think it'd be that as none of them have been touched and I can't think which of them wold be causing the issue. It has all the characteristics of an air / vacuum leak (to my mind) so I replaced the idle control valve and checked all the vacuum lines I can see but still no Bueno. Its doing my head in. Any suggestions gratefully received.
Location? Lots of stuff could have been bumped, torn, unplugged doing the gear box and thermostat. is it throwing any codes? 2.7 or 5.2? Double check the plug wires, possibly unplug and re-plug each one at the coil. Recheck each electrical connector. Your most likely right about a vacuum leak. There are quite a few tubes and ports that attach into the intake plenums and throttle bodies. Its going to take some searching. good luck
Do you have a check engine light on? SD light? Did you need to disassemble anything above the gearbox for better access? Since you said "idle control valve" (singular), I guess you have a 5.2.
Nope, no lights on the dash or SD light. (its a 5.2) As for disassembling, not really. umplugging a few things (MAF, Idle valve, intake air temp, speed sensor) and oil lines but that's it. And I've reconnected the ground from gearbox to frame at the back. Really got me stumped. Pretty sure there's nothing around the thermostat area which would affect things?
Plug in an OBD2 scanner and run it on live data mode while the car is running. Look for O2 sensor signals and see which one is not moving around. Check the vacuum lines from the engine running toward the right side and then toward the back of the car. While you are there, check the vacuum line driving the bypass valve. Check the secondary air injector lines. Remove the connector to the Idle Valve and inspect its pins. Do the same for the MAF connectors. Check their wires.
Please remember to let the car idle until at least one fan kicks on, especially if the battery has been disconnected with no accessories turned on. If the car starts rough upon initial restart, shut off quickly and restart again until the engine catches a normal idle.
I've ordered an ODB 3 to 16 pin adaptor and an ELM327 so will see what that shows in the coming days. And also aware of the ECU learning cycle but this isn't normal. Going to check connections, spray some carb cleaner around and see what happens ahead of the OBD turning up.
No learning cycle on a 5.2 car. Just start without depressing the accelerator with all accessories off.
Well as usual, it turns out the problem rests with the one holding the spanner (i.e., me)! Started and went around with carb cleaner and all tight as a drum. So, decided to pull HT leads and the RH bank was sparking but no change to running when pulled. I therefore reasoned I had spark but no fuel. thinking back..... I had to pull the fuel lines that side to change the thermostat... Sure enough, I'd connected them back into the block back to front, so the RHS bank wasn't getting fuel. Switched them around and presto!,runs like charm. Lesson learned - check and re-check everything!
I tried to fire that same guy but he just keeps showing up. He works cheap so I have decided to keep him around for now.