Jetta 5 2.0

[Mricco]

Hi gents, I'm asking this question on behalf of my friend, he has a jetta 5 2.0 that won't rev nd it nw doing this now nd then bt if it does rev it misfires nd service was done by vw bt it came back the same way.

[Mricco]

I forgot to mention that it's an 8 valve.

[panic-mechanic]

You need to get it on a diagnostic and see if there are any errors. It could be either the throttle pedal or the throttle body or a wiring/plug issue.
to diagnose things like this with simply the half worded description you give is kind of hard. missfires can be caused by all kinds of things like coilpacks or a plug or many other things and without some sort of diagnostic like a compression test and isolating the reason for the missfire it is hard to figure out why it is missfiring. can be an injector or a leaking valve too for instance.
If the missfire is bad enough it might cause the management to not open the thtottle - ie it has gone into some protected mode. But then VW should really be able to diagnose this kind of thing one would hope.

[Mricco]

I u understand because at times when u first start it in morning it is fine and maybe the whole day or it will be fine for a few hours and start this misfiring and once it starts to misfire it doesn't rev. I'll try and find someone who has vcds bt as for the vw dealer we took it to they failed to diagnose the problem.

[panic-mechanic]

Everytime you switch the car on it cycles the throttle body to make sure it can read t and that it reponds. Becuase it is drive by wire. If there is an error you will have no throttle response and if itnget an error while driving it will go into limp home to protect you and the engine. It is most often the actual plug on the tb that is faulty. You buy a repair kit form goldwagen or vw, cut the old plug off and solder a new one on.

[Mricco]

Thanks will try the kit.