mk1 cab GTi Missfire

Hi I dont know if anyone can help me with this.

I have a 1990 golf gti cabbi, with a ported and polished head, piper fast road cam and a lightned balanced fly wheel.

I had the car sat up for two months at the start of the year throughout all the snow, since she has returned to the road she has developed a missfire.

She starts and runs lovely from cold, but once she warms up she starts to miss between 1000 and 2500 rpm, once the revs pass 250 rpm it clears and runs fine.

I have changed so far, plugs, leads, dizzy cap, rotorarm, ignition control unit, warm up valve, idle control valve.
So im sorta stumped now with what else it could be.

I would be greatfull of any advice anyone can give.

cheers

Snap!

Same fault here - '91 GTi Cabrio.  But standard spec.

Not had it long, but before I change anything (like you have) I want to know if this is a common problem.

If it's not the stuff you've changed, could it be fuel pump/injector related?

I'll be watching this thread to see what answers you get!  Sorry I can't help though.

Cheers

I've had a similar problem myself.

My motor broke down randomly and had to call out a recovery truck. The recovery dude fooked around with the injection system to see if that was a problem.

It turns out to be a bad earth from the fuel pump, now that is rectified, ever since it has been running like a biyatch.

Changed HT Leads, Dizzy cap, Rotor Arm. Cleaned out the injectors and am now officially stumped. Also, noted that there was a bit of oil leaking out onto the manifold (I'm hoping just a rocker gasket) so am running low on oil! Cruising speed it judders up to about 30 - 40 mph but picking up speed is fine.

If anyone has an idea what the hell could be causing this, I'd be forever grateful. My mechanic friend has done all the work on it, and is trying different things to try and solve it. If anyone knows……

Kev

Hey Steve thanks for the post, sorta glad im not the only one with this problem.. lol

I spoke to a bosch specialist today, and he gave me one of two options either fuel pump or something in the bottom end of the block like a cracked piston or a perished ring.

am going to investigate more tonight with a diffrent fuel pump so will post upates.

Cheers

mk1golfgticab said

Hey Steve thanks for the post, sorta glad im not the only one with this problem.. lol

I spoke to a bosch specialist today, and he gave me one of two options either fuel pump or something in the bottom end of the block like a cracked piston or a perished ring.

am going to investigate more tonight with a diffrent fuel pump so will post upates.

Cheers

Good stuff.  I've just had the Piston Rings and Valve Stems done.  So I know it's not this.  Although I also know the timing is not set-up right.

Just get a feeling, it's something a little more though - very much like yours.  Just seems to hold back - 112bhp it ain't at the mo!

Cheers.

Steve-B said

mk1golfgticab said

Hey Steve thanks for the post, sorta glad im not the only one with this problem.. lol

I spoke to a bosch specialist today, and he gave me one of two options either fuel pump or something in the bottom end of the block like a cracked piston or a perished ring.

am going to investigate more tonight with a diffrent fuel pump so will post upates.

Cheers

Good stuff.  I've just had the Piston Rings and Valve Stems done.  So I know it's not this.  Although I also know the timing is not set-up right.

Just get a feeling, it's something a little more though - very much like yours.  Just seems to hold back - 112bhp it ain't at the mo!

Cheers.

kwl kwl, after doing a compression test on both sides all is gd no probs there, so im heading for fuel pump and filter next.

If your timing is out mate i would get that sorted before looking at other things. mine ran really bad before i set the timing up proper on my old head, got the timing right and that solved a hole load of problems i had.

Will keep on posting what i find though mate..

Yeah, timing is the next job for me.

Get a feeling it could be something more, but we'll see.

Keep me updated pal.

Try another coil. they normally start to breakdown when the engine reaches working temperature,which exhibits itself in engine misfire especially when the engine is under load (giong up a hill or high revs.) Another item to check could be a weakness in the LT lead from the coil to the distributer

a9wyn said

Try another coil. they normally start to breakdown when the engine reaches working temperature,which exhibits itself in engine misfire especially when the engine is under load (giong up a hill or high revs.) Another item to check could be a weakness in the LT lead from the coil to the distributer

Yeah, replaced plugs and HT/LT leads over the weeknd, with Bosch ones.

Also stripped adjusted Accelerator cable - was only opening the throttle 60% - not even enougth to activate the 'Full Throttle' link (if that makes sense - I know that's not the correct term for it, but can't rememebr what it's called).

Trouble is - not able to drive it until Tomorrow - been too busy.  So should know soon.

Cheers

Might be a long shot but have you checked the fuel filter?

I had problems with mine and changed EVERYTHING!!

I thought it was an ignition issue as it ran fine at start up but cut out or ran rough after a few mins.

it turned out it had run low on fuel and sucked all the crap out of the tank and blocked the filter.

Changing the filter sorted the issues.

I hope you get it sorted.

Steve-B said

could it be fuel pump/injector related?

Yes.  Pull the injectors to make sure they have a proper spray pattern (even cone-shape), are producing proper quantity of fuel, are not leaking, etc.  Check the fuel pressure to make sure it's within spec.  If it's not: clogged injectors, clogged fuel filter, faulty fuel pump(s), etc. could be the cause.

Also ensure that all of the ignition system components are in good working order and the timing (cam and ignition) are within spec.  Also, make sure all of the ground (earth) connections are clean.

ok i still havent solved the problem but it has improved. lol

I have put my original injectors back in to me Golf. If i drive her steady, say keeping her under 4000 rpm she runs sweet as a nut
with no missfire what so ever. I can sit in traffic for ages and still no missfire.
As soon as i start driving her a bit hard say over 5000rpm the missfire will strart and thats it she will missfire constantly. once she has been left over night i can get back into her and she fires straight up and no missfire at all (as long as i take it easy with her).

I have changed everything now for all new parts (apart from injectors)

Has anyone got any ideas or can point me towards a garage or a specialst that could help.

Cheers