Misfire...

Hi all

I've recently finished changing the filler neck/cleaning the tank etc. Also had to put a new fuel pump on (as the old one siezed after doing all this :roll: ).

All was fine for about 30-40 miles but now it's developed a misfire. Sounds rough on tickover and when driving up to about 4000 revs. After that if you put your foot down it clears and pulls well. Dizzy cap, rotor arm, HT leads, battery and coil are all new as is fuel filter and pump (as stated). Also metering head was replaced a few months ago and I have a replacement WUR to go on. I'm guessing it's a fuel issue, probably linked back to the rusty filler neck but dont really know where to go from here…accumulator, blocked fuel lines ??. It's an 83 tin top GTi.

Any thoughts very welcome.

Thanks

Paul

Could well be an airleak in the carb making it run lean. Does it run better with choke??

rasputin22 said

Could well be an airleak in the carb making it run lean. Does it run better with choke??

it's an 83 tin top gti no carb there m8

See above, no carb mate. Thanks anyway.

Sorry people, just wondering if anyone had any idea's on this ?.

Since posting I left the car for a while (about ten days) and it was fine for about twenty miles, then started misfiring again. Seems that putting your foot down brings the problem back, but, once it's back, taking it past 4000 revs clears it until you slow down again or change gear ???.

Any ideas, could do with some advice on this one ?.

Thanks

Paul

you listed a few bits that you checked, but you missed acouple of things which you may of checked,

coil
plugs
timing
sometims a little thing can make bigger problems its hard on this issue becuase awhole range of things could be at fault here, places i worked before at times like this surgest replace the cheapest part 1st and work up

where in essex are you ?

have you pulled the injectors and checked that they are all flowing nicely and equally? (fuel injector test)

also, have you replaced plugs and checked leads?

Thanks guys.

Plugs are brand new as are the leads and coil. Timing should be ok as a new cam belt was put on it in december but that's something i'll check on. Also, good call on the injector test, I'll get on that in the next couple of days.

Thanks again lads.

Paul

Reading the faults you describe again I reckon you should check the hall sender in the dizzy, because if the ribbon cable inside was breaking up causing misfires then it would do it under varying vacuum and speed, basically it would move on part throttle and when the revs increase which sort of sounds like what you describe, best bet is swap for a known working one :-) HTH!

hi did you get this sorted as i m having exactly the same problem on my 1981 tin top gti ?

cheers
phil

Hi mate.

Sadly not yet sorted. Had a lot going on and funds have been a bit lean recently. Seem to be coming out of it now so hope to have it done in the next couple of weeks. I'll post up any cures if and when they're found, please do the same !.

Good luck.

Paul

Hi mate,

mine is pretty much sorted running better then ever. i changed the hall sender in the dizzy, took the wur off stripped and cleaned it and then set up the timing and now it is running lovely. does nt cold start very well but that is my 5th injector i recon

hope this helps

phil

I have the issue of rough running but it's not a miss fire I don't think, more of a judder/hesitation below 3k, more apparent at 2k but only when warm, when cold it is ok, got a WUR on the way as hoping it is fuel pressure related!

Hi Barty

Can you explain a bit more on the hall sender mate

 i.e…

What is it ? (I cant even find the words 'hall sender' in my haynes !)
Is it easy to find and replace ?.

It sounds like we had/have the exact same problem and if I can avoid workshop bills i'd like to. Trouble is i'm a real amateur with home mechanics.

Any tips really appreciated.

Thanks

Paul

hi paul,

the hall sender is inside the distributor if you look at the dizzy there is an electrical connection on the right side that has 3 wires basically that is connected to the hall sender. if you take off the dizzy cap and rotor arm you will see a metal cap that has 4 gaps in it and these runthrough a sensor well that sensor is the hall sender. there is a few ceiclips to remove to get it all out but not to bad really just watch out for the little woodruff key ( piece of metal) that stops the metal cap from not moving with the dizzy shaft.

i got mine from GSF but it was nt cheap £43 i think and it was a bit tricky to get hold of but vw is £123 and that was to trade !!!!

hope all this helps

cheers
phil

It helps !.

Thanks for the reply, hope to get on it this week. Fingers crossed it's the same problem.

Thanks again.

Paul