fmessier

All vacuum hoses after the MAF are correct. What can explain the CEL code "missfire cyl. 1,2,3,4?? I swap the MAF with another guy, and my MAF on is car works correctly, His MAF on my car, same trouble!! Can it be the air/fuel sensor installed on the header?
Cheers Francois

[Edited by fmessier - 4/2/2003 2:07:06 AM]

jonny gav

iTrader: (1)

could be the timing belt is a tooth out!!!!!!!!



[Edited by jonny gav - 4/2/2003 5:25:09 PM]

fmessier

Hi guys!
My car have a little trouble at idle. The RPM range is from 680 to 715(OBD2 reading), the ignition timing is not constant, from 8 to 12. Check engine light is on and the code is missfire cylinder 1,2,3 and 4. My car is a WRX 02 completely stock. The spark plugs are ok. Any ideas???
Cheers François

fmessier

Is that possible de the valves are not adjusted properly? The engine has been rebuilt after a car accident, and some valves were bent!
Cheers François

SiPie

Can't speak about the 02 model but any idle irregularities usually point to a faulty MAF or O2 sensor....

Plenty of info on here if you do a search on 'hunting on idle' or 'MAF sensors'

Cheers and Good Luck

Si

Dyney

Have you checked all the pipe work after the MAF sensor? Leaks here can cause bad idle

Dyney

Is the dump valve leaking/sticking open?

fmessier

I made a dump valve swap with one of my friend, and still hunting!!
Cheers

fmessier

The engine is running correctly when power is needed, the problem is only at idle. The timing belt as been inspected and the position is ok. I suspect the valves adjustment or the air/fuel sensor. Am I wrong?
Cheers

scoobyboy

had it today the exact same codes and it was the 02 sensor it showed up on an emisions check the lambda reading was to high so it would have failed if it was an mot. but if you need one i.m have got 16 on back order, but that is what it will be i'm sure.

fmessier

I have changed the air/fuel mixture sensor and the engine still hunting, CEL came back! Since the beginning, I noticed a lots of back fires during decelerations. Any ideas?
Cheers

Brun

This one is simple.
Take it back to the gaff that did the re-build and get them to sort it.

scoobyboy

get them to check the neutral switch on the gearbox a bit weird i know but if it is not a definate on/off signal and is a bit mushy it can cause the problem you got.
also where abouts is the sensor you changed as it may have an 02 sensor and an air/fuel ratio sensor as these are now 2 different sensors.

swan

Hmm, what happens if you disconnect the MAF sensor? Should then idle high but shouldn't hunt. What about the o2 sensor in your down pipe?

fmessier

Hi swan,
If I disconnect the MAF, the engine will shut down. The O2 sensor that you are taking about is the one installed on the catalytic converter. In Canada, for gaz emmission control, the down pipe is a catalytic converter. I removed that down pipe to be straight pipe from the turbo to the muffler. The O2 sensor is installed at another location, near from the original location (room issue).
Cheers

scoobyboy

hmm sounds like you've hit all the sensors we have problems with.
i checked today and don't know if yours is the same but the one on the header is an air/fuel ratio sensor the one on the up pipe is an exhaust temp sensor and the one about half way down the car is the 02 sensor but if you changed these then you got me stumped.
we had another car in today a legacy with again all 4 cylinders got a missfire the emissions were ok but the neutral switch showed some resistance on a check only a minute amount but it should have been open so no resistance at all so thats what we are going with will let you know if it cures it.

fmessier

Hi Scoobyboy,
About the sensors on the exhaust line, it's the same thing as mind. A/F on the header, EGT on the up pipe and O2 on the down pipe. I'll wait for your neutral switch diagnostic!
Cheers!

scoobyboy

we put it in this morning and so far so good the cel has so far stayed off spoke to the bloke who done it and he said there was 200 milivolts still passing through it when it should have been open

scoobyboy

well next day complete and no phone calls so it must have worked!!

fmessier

I found another neutral switch, verdic, no success! but I think I found the problem. If I remove the air filter (p-flow), the engine shuts down. I start it again, and pass my hand slowly in front of the air filter tubing, the engine shuts down. I start it again, I blow air with my mouth very very very slowly, and the engine shuts down. I suppose that the MAF is to sensitive or there's electrical noise on a signal wire. To be continued
Cheers

fmessier

I have test the neutral switch, evething is correct. The sensor that I changed is installed on the header, just before the up-pipe. The O2 sensor (installed on the catalytic converter) as been changed since the rebuilt (two months ago). If I disconnect the O2 sensor, there's no diffence, in that situation, the computer is supposed to switch in safe mode and not taking care of the O2 sensor. Another stange thing, if I replace the original air box filter by a p-flow (aluminum tubing with maf installed on it), the problem is worst, it's running like a Harley Davidson! I'm out of ideas!
Cheers!

[Edited by fmessier - 4/6/2003 10:18:29 PM]