JeffDavison

And what the diagnosis / fix was?

When the engine has not been started for a while (basically a cold engine but at any ambient temperature) the engine will "surge" at idle between 850 rpm and 1000 rpm with an occasional misfire.

When driving off the misfire gets a little worse and the engine stumbles as throtle is given. The car seems to "buck" when the misfires occcur, almost to the point of not being able to drive it at all. Once in awhile, usually when more throttle is given and the engine buck happens, the check engine light comes on. The error codes read by VagCom say random misfire, and there are about 4 to 5 occurances of the dtc, but no other info.

When driving gently and throttle ease up when 1st misfire occurs the engine can be driven gently until it the misfire goes away...usually when the engine gets a bit warmer. No dtc's are thrown.

When the engine is warm, any restart has no problem whatsover, and runs perfectly.

The ignition amplifier has been changed, the plugs are new & clean. All hoses have no leaks. Could it be a bad coil?

BTW....1.8t with APR St.3.

Input guys?


Jeff Davison

Surfdamtns

Same thing happened to me after a snowstorm. Stopped the car got out.. Restarted everything was OK hasnt happened since. Figured I had something in fuel line or condensation in air intake. Haven't thought about it since

JeffDavison

waiting for the guys to get back to me

AndrewM (azdaspeed3)

well, the symptoms you described fit my car to a t. i had the check engine light come on 3 times, and each time the dealer replaced something different. first time it was the fpr. second time it was just some plugs. third time it was the coolant temp sensor.

none of these remedies has prevented the problem from ocurring. btw, all these ocurrences were before the apr chip went in my car. to be completely honest, the problem has decreased in frequency and harshness since the chip. i havent had a check engine light since last august, and i put the chip in about september.

my ocurrences all happened about a month and a half apart from each other. i dont have a clue what it is, and the dealer doesnt either. i asked them to flush out the fuel system for me and replace all the plugs, but they refused and said that they can only fix something that comes up as defective on the computer. aaargh!!!

anyways, its pretty much better now, or so it seems. periodically, ill get the misfire whent the engine is DEAD cold and i just dont have time to let it warm up in the garage a little. hope this helps!

®ob

How many miles? A bad 02 sensor could cause this type of problem

EdP

I have tried this and it helped. Only thing I can thik of is that the fuel rail needs to pressureize, or there is air in there. BoostD and Tom pointed this one out; the bigger injectors don't help. I too get that.

JeffDavison

going to try and induce the misfires again and see which cylinder(s) are being read as misfires.

Brett said maybe a blocked injector but we ruled it out because the symptoms are not constant, i.e. wouldn't really be engine temp dependant for the occurance.

Rob Andrews....car is only 30K and kinda young for a O2 to go bad but could be causing the temperature related issue...making the car run too rich thus causing the misfire but when up to temp all is OK....this sounds like a good call, definately woorth checking out. One 02 sensor is brand new...(but you never know)

I'm going to do a plug chop and see what condition the plugs are in.

Just got off the phone with Brett and will give him the VagCom info and description of the plugs & we'll go on from there.

the saga continues.............

JD

AndrewM (azdaspeed3)

btw, the first time this happened was at 7000miles, and im at 16500 now

Cool Craig

My 98 1.8Tq would fail at cold starts, fall over itself into 2nd gear, not restart for 1-2 mins and run rough for 2-5 mins, then OK, just a DTC everytime.

Dealer replaced EVERYTHING imaginable, coils, plugs, sensors, O2's, Cat, FPR, BPV, time belt, tensioner, headlight, turbo, waste, manifold, 35 feet of turbo tubing!! even the t-body and IC!!
Then they complained about the hot ECU (man, whatta cool dealer!! Continental Illinois) so i got another hot one and it still did it....and another, and another.

I have the on board computer (trip comp) and it would occasionally warn of low oil pressure. Tested out as a bad sensor, the pump was in spec. Unfortunately, the pump was only in spec above 2500RPM to 5500 RPM, the rest was something called anything but oil pressure!!

Bottom line, my oil pump fell apart in my techs hands, once it was replaced, the car has run fine.

EdP

give me the blocks you are tracking. I can do the same...