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low rpm misfire

Posted: Sat Jan 03, 2015 8:00 pm
by Aid
hi guys, i have a mk2 gtx, running an abf block on kr injection and ce1 loom.

car starts fairly well, though the idles a bit crap, the isv loop doesnt seem to be doing much, the isv doesnt buzz and nothing changes when i unplug the control relay, tried replacing it but no difference. when its warm it idles fine at 1-1.1k rpm

revved from idle it stutters the slightest bit but otherwise revs freely.
pulling away though and it drops to 3 cylinders, runs terribly, sometimes slowing down when i press the accellerator before continuing to accellerate. above 3k rpm its fine, and pulls well to the redline.

the misfire pulling away is worse if there is someone in the car with me, and going uphill. itll run along at a certain speed fine but if i add throttle to go a bit faster it misfires, sounds breifly like an impreza before smoothing out.

i've searched and searched for vacuum leaks, and can't find any, even using smoke blown though the lines.

so far, i've replaced the:
coil
rotor arm
dizzy cap
leads
isv control relay (ebay so unconfirmed if its working good or not)
plugs

tried changing the temp senders but gsf seem incapable of sending the correct ones, despite me getting a description off their sales guy what the picture was on his screen, and i still got the wrong ones, twice...

looking inside the dizzy cap and one terminal doesnt have the same arc markings, could this be the culprit, cheapo dizzy cap?

Image

its the no.4 cyl terminal and the spark is weaker on that one, ive tried various plugs and leads on it and made no difference.


any help would be greatly appreciated.

thanks, Aid

Re: low rpm misfire

Posted: Sat Jan 03, 2015 10:06 pm
by the edmundator
Is the jobby in the middle of the cap wonky?

Re: low rpm misfire

Posted: Sun Jan 04, 2015 11:47 am
by Aid
it is definitely wonky in the photo, but its spring loaded and apears to push into its recess straight, so i presume its straight once fitted. next change will be an oem quality dizzy cap to see if that makes a difference.


ive been offered a complete a3 1.8t for 250 quid. tempted to bin the abf/kjet its been so much hassle getting it to run right. annoying because ive spent so much on it :oops: :cry:

Re: low rpm misfire

Posted: Sun Jan 04, 2015 8:36 pm
by mark1gls
Sounds like it's running to rich, do you know what the Co2 is?
How is the timing?
The idle seems a little high, try dropping the idle to 900 - 950 and see how it idles but check the timing then mixture before adjusting the idle as any change in the other 2 will affect the idle.

Re: low rpm misfire

Posted: Sun Jan 11, 2015 7:39 pm
by Nate
have you checked the advance retard is working as it should?
decent branded cap and arm or ebay cheapy or even worse europrats white box rubbish?