GolfGTIforum.co.uk
Model specific boards => Golf mk2 => Topic started by: H981CVV on 20 January 2009, 20:37
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Right i've been having major hunting issues with my mk2 16v, i've tried everything on this forum to cure it but so far no good, so i thought i would have another go tonight, and found that:-
From cold it idles perfectly for 30 secs to a min, then it hunts + - 750 r.p.m, until its warm (oil temp + 60)
tonight i found that if i disconnect the plug going to the micro switch on the throttle body, it will idle at 1000-1050 but steadily, why is this?
the micro switch is new, the i.s.v is clean and air there arent any air leaks in any pipes, the control unit behind the dash is new, i've checked all the temp senders on the side of the head under the dizzy, you name it i've checked it.
so can it be:-
fuel filter under car
lift pump
throttle body
e.c.u
please help
Ben
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I dunno about being a k-jet expert, but I can suggest a few things... I went through a huge list of possibilities to finally fix my 16v hunting problem - Perseverance is the key! You'll find it eventually.
Anyway, the throttle switch tells the ISV to "turn on" and start controlling the idle, so here's my thoughts:
1) The ISV may be clean, but it might be knackered, so when it "turns on" it can't control the idle. Is there someone nearby that can give you a known working ISV?
2) I've said before "yes, yes, I've definitely checked that..." and it turned out I hadn't checked it well enough. Air leaks, temp sensors etc. etc. - Double check them.
3) I replaced my ISV controller behind the dash with one that was supposed to be working (an ebay special), but it wasn't. Are you sure you've fitted a good one?
4) Have you done the Haynes test on the idle switch, even though its new? "Using a ohmmeter, check that when the throttle is closed resistance is zero across terminals 1 and 2, and infinity between terminals 2 and 3, and vice versa when the throttle is open."
5) Check unplugging the over-run cutoff valve doesn't cure it (this one's a long shot!)
To be honest, when mine was hunting I hadn't quite hit the sweet spot in the CO2 setting vs the idle screw, (although if I was being 100% honest the main solution on mine was a rare one - it was actually an oil change that cured mine - the oil must have been contaminated and the fumes were affecting the idle via the crankcase breather :shocked: ).
If you want to see the long list I made at the time, see here: http://www.golfgtiforum.co.uk/index.php?topic=71501.msg569972#msg569972
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Im sure this vid will be of absolutely no help at all but might be worth 30 secs of your time on the off chance
http://uk.youtube.com/watch?v=wpFX85Nv0xE (http://uk.youtube.com/watch?v=wpFX85Nv0xE)
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as above really, try another isv and check the idle & co! there is a how2 on it :)
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does anybody know which of the 3 senders wires under the dizzy work with the ISV and which one controls the temp gauge so i can just plug that one wire onto the sender and do some diagnostics. i would prefer to check that replace all the senders lol
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does anybody know which of the 3 senders wires under the dizzy work with the ISV and which one controls the temp gauge so i can just plug that one wire onto the sender and do some diagnostics. i would prefer to check that replace all the senders lol
Yellow & Red = Dash temp gauge
Blue & White = ECU / Ignition Control Unit
Red & Green = ISV Controller
Apparently both the Blue/White and Red/Green senders will have an impact on your idle.
PS... It takes a little while for the dash gauge to re-adjust when you plug it onto a different sensor (mine did anyway), so give it a second or two.
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thanks alot thats ideal, also i've just been playing, i did the test on the micro switch where you rev it to 2000 rpm ish and click it, now my rev's didnt blip/drop at all does that mean the switch it broken? it is brand new from vw so ??
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could be down to a bust idle control unit, or it isnt getting power. does the isv buzz nicely when ign is on but engine off?
test the throttle switch electrically also, note the haynes procedure is wrong, you test it like this:
1 Pull the wiring connector from the throttle valve switch.
2 Using an ohmmeter, check that with the throttle closed there is zero resistance
between terminals 2 and 3 but a reading of infinity between terminals 1 and 2. With the throttle open, the readings should be reversed (see illustration).
3 To adjust the switch, insert a 0.10 mm feeler blade between the throttle lever and stop (see illustration), then loosen the screws and move the switch towards the lever until the contacts are heard to click. Tighten the screws on completion and remove the feeler blade.
(http://vwtech.no-ip.info/images/golf/haynescorrect16vthrottle.jpg)
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thanks i'll try that later on and report back, also where abouts is the warm up regulator? i thort i might check it out as i havnt come across this component yet?!
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thats the metal thing on the side of the engine block, with 2 fuel lines to it :)
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right fingers crossed i think i've cured it!!!! finally lol
i took my time cleaned the air bypass screw hole and perform the co2 and idle set up guide, waited until the car was warm to do it etc i set the idle at warm with the isv and breather disconected to exactly 980 rpm and then with it all connected up i took it for a ragin it was idling a bit high so i just adjusted the screw ever so slightly in to bring it down and now it feels a different car. I waited until it was stone cold again to try it from cold and it seems fine....fingers crossed. Thanks for all the help anyway peeps as always this forum is a full of solutions
BTW if i disconected the red lead near the coil the isv was still buzzing and i had to pull the plug of of the unit itself is this normal?
Ben
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you disconnect the red lead to put the isv control unit into setup mode, the isv should still buzz!
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so i should perform the set up guide again with JUST the red lead disconected to put it in a different mode?! but the i.s.v still buzzing, because i just did it with the i.s.v disconected at the plug going into the back of it. So it is wrong then, bugger!! because this morning i drove to work and it was still hunting even tho it didnt yesterday after i let it cool down so im upset now! haha
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give it a try yeah, its possible the isv isnt healthy, but setup is free to try :)
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okay ive set it up properly, i also cleaned and fitted a different i.s.v which i assume was working fine and i've got a 100% working one on the way to try aswell. I've changed all 3 temp senders aswell.
So far its still the same, but i've noticed that there is a vacum pipe with no home and am wondering wether it should have.
as you follow the pipes from the over run cut off valve, to a t piece, one goes up to the air mass meter thing valve, and on to the plenum chamber and to something to do with the brakes and one goes and hangs down near the bottom pulley.
has anyone got a drawing or know where it goes, i tried blocking it off but it was still hunting, im determined to cure this then the golf is almost mechanically perfect lol
help please
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From [poor] memory, mines got two connections on the air intake pipe, one on the flying saucer pressure valve and one goes up to the brake line.
Defo shouldn't have an air leak! Looks like you found the culprit.
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Thanks mate, then shouldnt it stop hunting when i block it off ?! I put my finger over it and there wasnt any change in idle. I have this at the moment,
a pipe from the over run cut off valve, 3 way t piece 1 goes to the flying saucer valve, one to the brake servo, and one to thin air.
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a pipe from the over run cut off valve, 3 way t piece 1 goes to the flying saucer valve, one to the brake servo, and one to thin air.
Sounds like your missing the one to the underside of the big air intake pipe??
If you cover it with your finger, it will stop the leak, but maybe it needs to be attached to something to work!!
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you have 2 connections on the servo pipe. 1 goes to the ignition control unit in the scuttle area, the other is T'ed off.
One of the pipes runs to the dash clocks for the MPG display, the other runs to another T piece behind the throttle body, on this 1 runs to the inlet boot air temp sensor to operate the warm air flap. The other then runs round to ANOTHER T piece, one going to the overrun cutoff the other to the cold throttle enrichmnet valve.
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Awsome, connected the vacuum pipes up as you described....what a difference!!! so from stone cold it ran warmed up and idle'd perfectly!!
i decided to obviously set it up again as per the guide but its a lot harder to set up. I can get the idle on the bypass screw to about 960 but its missing like hell so i adjusted to co screw but i cant get it perfectly smooth unless i raise the rpm with the co screw and then bring it down on the bypass screw, is it okay to do that??
Otherwise it a million times better, and restored my faith in the car,
Ideal
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I reckon most people with 16v's have their idle around 1050/1100 - I do!
IIRC VW themselves suggested this.
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oh okay thats fine then. Just tried it this morning and what a difference, started fine, reved up and fell back to idle and its been idleing perfectly. Ill keep it set at 960-1020 then. I seems to be adjusted fine at these settings so i'll leave them there for a second.