Now, before you all yell at me to search, I have already and am asking if my diagnoses sounds correct... I am experiencing hung acceleration where the car kind of gets stuck at around 3.5-4k making around 3 pound of boost, this symptom can also be felt at lower rev ranges, say when accelerating on the highway in 5th. When the problem is occurring the idle will hunt in a cyclic fashion, ranging from say 300 (point of stall) to 1300 rpm, one cycle takes around 1.5-2 seconds. At other times it will idle fine, until you stab the accelerator, at which time it will fall into the hung idle. Also noticed the car is MUCH worse on fuel If I am REALLY smooth on the gas it seems less noticeable/possibly not a problem. When I first pulled over I thought it might be a coilpack connector or something, put pressure on them all, seemed to go away, drove off and it came back (had no way of securing it so I assumed I had found the problem) Tried securing it this morning with no change in symptoms for test drive. Since then I was trying to come up with potential problems, Datascan reviled very little... No codes on the ECU all sensors appearing to be working (killed my thought that the airflow meter may have stopped or become loose. Started to suspect PTU (92 models still have series 1 correct? fairly sure they do) Searched the forums for common PTU fault complaints and some things lined up, but Im certainly not getting any loud bangs and the acceleration doesn't stop for a second, its a much more prolonged effect. However I'm not sure how varied the effects can be... So do these symptoms sound like a PTU failure or not? Im leaning away a coil pack issue as its not like a miss (had a coil pack connector die in the past and it just made the car sound like a wrx at idle) I know the catch cry will be through one in and be done with it, but I'm more interested in potential other problems with a quick fix as I need to drive to Sydney in a couple of hours (from Canberra) and would prefer it not to use a whole tank of gas if its just a plug loose or something =P (my car usually has epically good economy too so Im not used to wasting fuel like this =S)
Hey IB, how's things? Only dash light that comes up is the hicas as that's only when the engine is hold close to stall for a while and only occasionally (longer dips in RPM)
iacv valve sticking? or a boost leak in the associated hoses can cause a hard to control idle.........
the more concerning problem is the hung acceleration... and I don't think it would cause that would it? A boost leak alone certainly wouldn't, unless it was a massive one and the metered air was no longer accurate, but the o2 sensor still jumps from rich to lean so that probably not the case either... also eng cont fuse is intact =(
hey mate here's a theory of mine, dose it feel like when ur in a certian rev range it struggles? and if u pull up to a set of lights its, feels like it wants to stall or it dose stall? if so then it could be crap fuel, or ur coil pack connectors need to take them off and get some wd40 or inox or what ever u can find, and spray it in the conncetors and put them back on and try that. but people say its an airleak but u can check.
if it was shite fuel wouldn't you expect the engine to be pinging like crazy? also I gassed up yesterday from a 1/4 tank, so I'd be suprised if it was that... Kinda feels like a really restrictive traction control system... maybe it is the AFM, I think I might go disconnect it and see what the difference is
or plausibly a working afm, but with the wire covered in oil from a k"n type filter? causing a wrong reading? just thinking out loud again...........
AFM My car did the same, turned out it was a dead AFM, when the ECU cant get a reading from the AFM it switches to safe mode and wont let you rev over 2500RPM, I hope this helps cheers
Might do some datalogging tomorrow and see if the sensor drops off Thanks guys... Made it to Sydney BTW, actually wasn't to bad on the gas either
TPS connector Check the security of the TPS connector. (looking at motor right hand side there are two connectors coming off the Throttle Position Switch) If the connectors are contacting and breaking its sending ghost signals to your ecu that your opening the throttle and it will dump fuel. It will be more apparent over bumps. Dave
