Misfiring On 1.9gti Motronic 8 Valve

[jayblack-gti 0]

Just been out to fuel up and thought id do a little test, noticed some misfiring the passed couple weeks. Ive noticed that if i accelerate hard, i.e give it wide open throttle from between 1400 and 2000rpm there is alot of misfiring and obviously loss in power, ive tried this in all gears and the same problem occurs. however if i accelerate slowly through the revs from idle to 6.5k rpm there is little and some times no misfire. ive checked the dizzy cap and rotor arm, cleaned them up, plugs seem ok and leads i hope are fine because there only 6 months old, gonna replace the coil and ingition amp in the week. should i just buy all new parts n replace everythin just incase. can some1 shed any light on 1 possible thing. thinks its gonna be change the lot i reckon if new coil hasnt solve problem

 

cheerys jay

[brianthemagical 1]

if you get a haynes manuel or the like it will give you details of testing the coil with a ohm meter, if you haven't got one i will try and post the details if you like. i've cured 2 missfires without changing the coil, not sure how i fixed them though and both were different to yours.

[Pug_101 0]

Just been out to fuel up and thought id do a little test, noticed some misfiring the passed couple weeks. Ive noticed that if i accelerate hard, i.e give it wide open throttle from between 1400 and 2000rpm there is alot of misfiring and obviously loss in power, ive tried this in all gears and the same problem occurs. however if i accelerate slowly through the revs from idle to 6.5k rpm there is little and some times no misfire. ive checked the dizzy cap and rotor arm, cleaned them up, plugs seem ok and leads i hope are fine because there only 6 months old, gonna replace the coil and ingition amp in the week. should i just buy all new parts n replace everythin just incase. can some1 shed any light on 1 possible thing. thinks its gonna be change the lot i reckon if new coil hasnt solve problem

 

cheerys jay

 

First off try running your car on a tank of super unleaded and see if it makes a difference.

I wouldn't go buying the expensive new parts straight off and if you buy 2nd hand how good are they.

Look at replacing the Spark plugs (make sure gap is correct), leads, cap and rotor to start with (sevice items anyway). Mine went just like yours when I changed these items. I suspect the leads mostly as they have now fallen apart (Don't buy Bosch). Also have you still got the gasket fitted to the dizzy cap?

 

Anyone recomend a good supplier of these parts?

 

At the same time check for air leaks, poor electrical connections, blocked breathers etc.

If you still have problems I would retrack the AFM as to the article on the main Web site & check the throttle switch is working & adjusted correctly.

If this has not worked then look at things like the coil etc.

Also have you considered a fault code reader? I am getting one.

Hope this is useful

Cheers

[pug_ham 244 3 Cars]

Last time one of my car suffered from symptoms similar to you describe it was the dizzy cap but once I looked inside at the contacts it was obvious why it was.

 

I replaced the cap & rotor arm with new ones & after that you could drive at just above idle in fifth & it would pull right through the rev range without any hesitation or complaints.

 

Graham.

[jayblack-gti 0]

thanks for all the input, been away a week so havent had chance to replay

Also to add havent driven the car in a few days and it now has problems starting. takes a good 15-20 secs to turn over and then just fires straight up. but when warm starts fine

 

cheers jay

Edited June 27, 2006 by jayblack-gti

[Richie-Van-GTi 71 2 Cars]

Id suspect your fuel pump is getting lazy and taking its time to get the pressure up. If someone is local and willing try theirs in your car as its only a ten minute swap.

[jayblack-gti 0]

think ive curred my miss firing problem, turns out that a set of new plugs have sorted it, engine will pull from idle to limit in fifth with no miss fire, think ill give it a couple of days before my minds at rest though, pugs n electrical problems, one min there there, the next there not

 

jay

[Guest noop]

think ive curred my miss firing problem, turns out that a set of new plugs have sorted it, engine will pull from idle to limit in fifth with no miss fire, think ill give it a couple of days before my minds at rest though, pugs n electrical problems, one min there there, the next there not

 

jay

 

I've got a similar misfiring problem with my L Reg 1.9. All kinds opinions received so far. Took it to Warwick Wright in Edgware but nothing electrical was found on the diagnosis machine...they suggested taking the head off and @ £87 per hour x 10hours I said (politely) no thank you!!!! They suggested the AFM but this problem is long running and I've had my AFM recon'd and I even bout one from ebay recently and I'm running that with the same probs.

 

I'll try the servicable things 1st, but with tappets, burnt valve, coil, etc being mentioned I don't know where to begin!! And I'm not exactly knowledgable enough to do much beyond replacing the AFMs!! So any reputable Technicians are welcome!

[jayblack-gti 0]

why did they suggest taking the head off? if ur not using oil or water then cant b head gasket related, a compression test would confirm gasket gone i would have thought before any head removal. replacing my plugs seems to have sorted the miss fire but theres still some hesitation on acceleration but this has been like this for a while also, i think ill just live with it for now till i get my scooby. as you've stated try replacing servicable parts, i,e plugs, leads, rotor arm and dizzy cap, if its not electrical then cant think what else it, could be lazzy fuel pump or dodgy fuel pressure regulator

 

jay

[pug_ham 244 3 Cars]

What plugs have you used?

 

Graham.

[jayblack-gti 0]

The plugs are NGK BCPR6ES

 

jay

[Guest noop]

The plugs are NGK BCPR6ES

 

jay

 

Cheers for that Jay. The strangest thing: My car is doing 150miles per day(ish). And just yesterday the misfire seems to be better. Still not perfect, but power is up. How weird!

 

I'll try all that this weekend or next, still gotta get that service done. Anyone else heard of this?? What should I look at? I imagine it must be some kind of blockage/fuelling/air issue. Doesn't sound mechanical or it'd be terminal or electrical otherwise it would have turned up on Warwick Wrights diagnostics?? Right??

 

But i know jack diddely squat bout these things...!

[jayblack-gti 0]

Just had the MOT done and my poor cars running high emissions so gotta be ignition related i reckon, need to sort that out now, been suggested that it could be the airflow meter so might have to have a look, any other suggestions other than service parts, which im gonna do now

 

jay