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General => The garage => Topic started by: Snap on 24 February 2005, 15:53

Title: Mk2 strange problem
Post by: Snap on 24 February 2005, 15:53
After driving on the motorway for about an hour the power delivery of my car seems to be stange. If i want to go over 75mph the car starts to vibrate and after a while the shaking continues at lower speeds. Im forced to stop the car. I turn the car off and start it again with in 5 mins.

I set off and i reach 70mph and after 10 mins the same happens again. So i go through the process again and again but it gets frightening when im on A-roads as there is no hard shoulder. Its not an over heating problem as if i take routes with lots of traffic lights and speed of under 50 then there is no problem even though im driving for about 2 hours. So what could it be?

Title: Re: Mk2 strange problem
Post by: Justins145bhpMK1 on 24 February 2005, 16:08
Could be many things, check for air leaks, clean out the throttle body etc. There are quite a few posts on similar probs, especially with MK3 GTI's. Good luck.
Title: Re: Mk2 strange problem
Post by: Mr Blue on 24 February 2005, 17:30
does the car still shake when you come to a stop?

Engine mounts, CV joints cause bad vibration. Are the wheels aligned.
Title: Re: Mk2 strange problem
Post by: rubjonny on 24 February 2005, 17:52
Classic carb icing mate, check the warm air feed from the airbox to the shroud round the exhaust manifold is intact, and that the warm air flap opens correctly.

Check the heater on the front of the carb gets 12v when the ignition is on too.
Title: Re: Mk2 strange problem
Post by: Veedubgt18v on 24 February 2005, 21:29
Classic carb icing mate, check the warm air feed from the airbox to the shroud round the exhaust manifold is intact, and that the warm air flap opens correctly.

Check the heater on the front of the carb gets 12v when the ignition is on too.

 once you stop and let the ice melt it should be alright once its warmed thru. only used to experience it once on my car then it would all be fine after that
 i would check all you ht leads dizzy etc cos it could be an ignoition problem or an advance problem with the distributor
Title: Re: Mk2 strange problem
Post by: rubjonny on 24 February 2005, 22:34
Doesn't matter how warm the carb is, it can happen several times in one journey or not at all.  It depends on the conditions outside and how badly compromised the warm air system on the carb actually is.

I had the same on my Driver, on one journey it would start to missfire & loose power, then seem ok.  It did this twice before actually dieing completely and leaving me on the hard shoulder.  After 5 minutes it was fine and off we went!  During the weeks that folowed it was pot luck whether the car would stall when coming up to junctions or not driving to work & back, untill I eventually managed to fix the metal shroud back on the exhaust manifold.

The fact that it keeps doing it, and is fine if left for a few minutes points at carb icing more than anything else.
Title: Re: Mk2 strange problem
Post by: Veedubgt18v on 24 February 2005, 23:11
but for it to happen after an hour of driving is weird. 20 mins yeah in my experience but not an hour! sounds like a misfire to me, either way check both things got to be one of the other
 
but then if its a pierburg carb good luck cos theya re notoriusly sh!te
Title: Re: Mk2 strange problem
Post by: rubjonny on 25 February 2005, 07:36
No its not weird to happen after an hour, I would get carb icing problems at motorway speeds after hours of steady crusing. :)

Like I said it depends on the conditions and what is actually wrong with the carb.
Title: Re: Mk2 strange problem
Post by: Veedubgt18v on 26 February 2005, 10:48


and what is actually wrong with the carb.

like being a pierburg??

what if he turns round now and says it kjet or digi?  :huh:
Title: Re: Mk2 strange problem
Post by: rubjonny on 26 February 2005, 14:28
Then his sig is lying :)
Title: Re: Mk2 strange problem
Post by: Veedubgt18v on 05 March 2005, 18:52
Then his sig is lying :)

oh  :embarassed:

rubjohnny do you live near a waitrose branch?
Title: Re: Mk2 strange problem
Post by: rubjonny on 05 March 2005, 19:32
Yes mate :)
Title: Re: Mk2 strange problem
Post by: Snap on 05 March 2005, 19:47
Then his sig is lying :)

His sig is not lying.

I dont think its carb icing as if that was the case it woulnt just occur at speeds over 70 and never under 70. I think that the problem might be the vaccum unit, im thinking that from this write up below, i just cant think who the autor was????  :laugh:

Quote
Vacumm Unit Stage 2:
This opens the second throttle butterfly when you have your foot down, not had a problem with this myself but I imagine sympoms for a failed unit would be no power under full throttle.
Title: Re: Mk2 strange problem
Post by: elnigel on 05 March 2005, 19:51
what about the carb flange, my mates 1.6 jetta did a similar sort of thing until he replaced it, bout 25 quid from gsf
Title: Re: Mk2 strange problem
Post by: rubjonny on 05 March 2005, 20:06
Could be the flange I guess, wiggle the carb at idle and if the idle speed changes you got a problem with the flange.
Dunno if it could be the stage 2 unit, no idea what the symptoms are if it isn't working :)

It could still be carb icing, how badly occurs depends on the conditions and how bad the anti icing systems are broken. For me it was random, sometimes happening on long jorneys, sometimes it would cut out at junctions. 

It could also be something in the ignition system breaking down when the engine gets hot, leads, cap, rotor arm, coil etc :)
Title: Re: Mk2 strange problem
Post by: gstar-dubworld on 08 March 2005, 01:09
We've had a couple of our Drivers doing the same, problem most commonly pointing towards the distributor in the end, please check all else too, if the flange is suspect, start the car and then while running spray some WD40 or carb cleaner around that area where the flange mates the carb to the intake manifold, if you hear the revs rising while spraying then you have a leak.

Check out the electrics first and then move to the mechanics of it..