Alright guys, had lots of help on this forum before so i hope you guys can help me now My 1990 mk2 golf 8v has had this problem ever since i got it (just over a year ago). The engine does not rev cleanly from idle. When i say cleanly, just before it rises from idle speed, it will jerk, and this makes throttle response when driving jerky, but it will not jerk at all once throttle is already open. Any ideas? Also, i get misfiring/juddering when the engine is decelerating below about 2500rpm. It also pinks on initial throttle, and this is usually below about 2500rpm as well I've changed the following: Coil Leads Dizzy cap Rotor arm Temp sender (blue) Plugs Ive also cleaned out the following: Throttle body and idle screw Rocker cover breather gauge and breather pipe ISV Had co, idle and timing set up so many times, with each garage saying its all spot on Only area i haven't looked at yet is fueling. Could either fuel pumps, filter or injectors cause this, or could it be the air flow meter? I know theres a lot to take in, but i just wanted to give as much info as possible. Any help would be most appreciated Edited by: Carl loader
Checked for cracks or rips on the air intake pipe from the AFM to the throttle body? Very common cause for the problems you describe. The cracks only open up and let air in once the engine is under load, which is why your emissions will be fine at a standstill.
Cheers, i have had a look at the intake pipe quickly but couldn't see any cracks. Can even small cracks in this pipe give the engine a jerky effect? Also, what about the pinking on initial throttle (half a second at most), do all digifants pink a bit until the knock sensor comes in?
Any other digifant experts got any ideas. Im thinking it could be the ISV itself. To stop the idle speed dipping to low when its cold, then settling again, i've had to set the idle speed to just over 1000rpm in set up mode, which is a bit higher than the 800rpm thats recommended by the haynes book of lies. Could it be this?
Haveyou checked the intake boot thoroughly, by taking it off? They often crack underneath, in the corrugations, and it doesn't take a big crack to make the car kangaroo on take-off. Otherwise my next point of call would be checking your idle/WOT switch is working right (and at the right point), and then look at the ISV.........
Cheers mate, ill have a proper look at the intake boot. When you say idle switch, i take it you mean the throttle switches? If so, they work fine (i can hear the switch click as you open the throttle) One other thing, i sometimes get a wiff of petrol. Could this be related to the whole jerking/pinking problem?
I doubt it, but it may mean you have perished fuel lines where they connect to the injector rail. Common problem. It's worth checking that the switch is actually switching - sometimes they just click but do nothing! Have you checked it's adjusted correctly? It should open just as the throttle quadrant starts to move.....
There are 2 switches btw, the idle switch is underneath the throttle boddy, the only way to get to it is to take the inlet hose off As for the pinking, I assume this could be caused by a faulty knock sensor, or perhaps it hasn't been done up to the correct torque? Loads of other VW/Audi engines have the same knock sensor. Well, they have different part #s/plug colours but from my research I'm 99.9% sure the colours/part #s only refer to the length of the cable. I fitted a sensor off an Audi 80 of some description and it seems to work just as well as the old one (which I suppose could mean its knackered!)
The pinking even with the timing set correctly is what makes me think it's most likely to be an air leak.......
Cheers for the replys guys. The knock sensor is new, but i'll have to make sure its done up to the correct torque setting. Im sure the throttle switches are working as the idle speed increases when i disconnect them. I know there also set right as i went through the procedure in the haynes, showing the gap at which the bottom one clicks when the throttles open. Im sure all the pinking/jerking and fuel smell problems are all related. I might have to check the wiring and fuel lines to the fuel rail/injectors, see if thats knackered Kepp the ideas coming
I had the same problem as this(juddering and pinking) It turn out to be the pipe which was split between the AFM and the TB .I couldn`t see the split until i took it off because it was in one of the folds. I replaced it now it runs like a dream
Cheers scottie, ill have a good look tomorrow if it dosen't rain I'll see if i can get a torque wrench for the low torque setting needed (20Nm i believe?) Cheers again to everyone, ill get back if its sorted
Right, im back I've searched the engine bay for leaks, and took off the air intake boot between airbox and throttle body, and theres no cracks. I've checked the knock sensor, and that is done to the right torque (20Nm) The injector fuel lines look fine as far as i can see, and i ran through the set up procedure for setting the idle speed correctly using the set up procedure. One thing that bothers me though, i've noticed that since i had the last engine tune, the idle speed drops to low when its cold for a second, making the whole car shake, then settles, and it still does it even after the set up i did (i set the idle spped to 900 rpm). Does this mean that my ISV is getting a bit lazy, or does it simply mean that i need to set the base idle higher. I just ask because if the idle speed doesen't need to be set that high (it says 800 rpm in the haynes), then surely it wouldn't make the idle speed dip to low when it was brand new?
It could be the ISV - best bet is to undo the hoses from it, plug them, and try it then. It'll be nasty when it's cold, but at least once it warms up you can see if the judder persists......
i`ve had this problem with a friend`s car ..... this turned out to the the mass air flow meter that was faulty even though it adjusted up when being setup for co emissions HTH
i had a similiar problem with my mk3 golf. i changed air mass filter, and it didnt solve the problem it ended up being the relay that feeds the cpu. it was only picking up 8volts from my battery,so my car was juddering and slow on pick up.all down to broken solder joint!!! so check your relays and check the solder joints on the circuit boards. if you find one is broken you can just re-solder it, or buy new. i solder mine and it runs like a dream. hope this helps
get haynes: (p12.26 and 12.27) adjust the throttle stop, then the two throttle valve switches, then check the overrun cut-off and full throttle enrichment.
Cheers for the replys fellas. I just thought id try thesecondcomings idea of removing isv and plugging up hoses. I couldn't find any thing to plug the hoses, so i thought id just disconnect the wiring to it. Took it out for a spin, the idle speed hasen't changed at all and isn't rough, and some of the juddering has gone, but its still there when i apply the throttle, but not when i take my foot off. Does this mean the ISV is buggered? Also, what number is the relay for the ecu? might try and replace that to see what happens Does anybody know if an airflow meter from a Pug 205 gti will fit as they look nearly identical to the golfs? Theres loads on ebay, thats why i ask
