GolfGTIforum.co.uk
General => The garage => Topic started by: Deefadog on 24 August 2004, 08:21
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Very strange things happening here :) My idle from cold and then when warm was all set, was spot on, I then had the head off for some work, and now when i start the car from cold it idles at 960/1040 and when fully warm is is dead on 1200rpm? Should be the other way around I would have thought!
Could it be as simple as some sensor has been pluged in the wrong way round? Any ideas guyz?
Cheers
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if the head was off then id check to see that the ISV/Cold Start temp sender is connected properly (on the right of the head beside the water outlet)
you know the drill, turn the ignition on then feel the ISV to see if its buzzing/vibrating. if not then check the sender.
sounds like your mechanic has just would the idle screw out so that it idles correctly at cold. basically just to get you out of the garage!!
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Thanks mate, I'll check the ISV/Cold Start temp sender!
If this is ok what's the next step? Follow the idle setup guide again, I have the link somewhere vortex i think!
Whay would the idle setup have changed?
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well if the ISV temp sender aint working the car will be very hard to start when cold and will idle somewhere around 600rpm for about 5mins before gradually getting upto operating temp and rpm
so after they get it started they just turn the idle screw to wind the rpm up that bit extra
look up GVK motorsport - infact i might make it a sticky on this forum. :)
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http://www.btinternet.com/~gvk_motorsport/16valvestall.html
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Sorry to be a pain but can you shoe me with a pic which one is the ISV/Cold Start temp sender.
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there is 3 senders around the water outlet on the side of the head
of the top of my head, the wiring is as follows
blue one is for ECU
green/red is for the ISV
red/yellow is dash temp gauage
all are interchangeable, but as a rule i tend to leave the ECU one alone for obvious reasons!!
if your dash temp gauge works then just swap it over with the ISV one and then test the ISV or dash temp gauge
just clean the spade connectors up, and make sure the connectors are tight, if the ISV loses the signal for a millisecond then it will stop working until the car is turned off then restarted
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Thanks I'll check it out
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Took a look today, got home late and it was dark but these three senders are they the single spade ones (one wire)? Also there are three other connectors on plastic snap on casings with a few wires in them, ones blue, ones white and the other is brown I think what are these?
On the weekend I think i will take remove and clean all connections as some have alot of gunge on them!
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yes mate they are all single spade connectors
did you feel the ISV to see if it was buzzing with the ignition on?
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Yep, the isv is buzzing
which spade is the ISV is it the top, left ot right one?
Also I forgot to mention (it may mean nothing) but when i start the engine from cold, the revs shoot up initially 2 around 2250 revs and then slowly come back down to around 960 revs
What is the oil temp reading when the revs are supposed to go to normal? I noticed that the revs were settling upwards from 80 C and 1200 revs at over 90 C (roughly)
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you no probs with the ISV/Cold Start it all seems to be working perfectly - does exactly as your describing - just sounds like the idle is set a bit high
its probably worth setting the idle yourself. just warm the engine up to normal operating temp then disconnect the red wire at the coil, then turn the idle screw until it idles at 960rpm then reconnect the red wire.
if that dont fix it then look for airleaks, especially around the idle screw, the wee O-ring goes hard after a number of years and aint a tight fit
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I'll give it a go when I get home, one small question do i discontect the red coil wire when the engine is still running or turn engine off, disconect and then restart the engine?
Also the idle screw has already got some silicone around it from when i bought it so the seal may have gone! may have to get my silcone gun out :)
Thanks
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yeah you can disconnect/connect it with the engine still running
im assuming your timing is correct also
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Well I assume it is, had the timing belt changed si the timing must have been set, but my local garage does very good work as a good price but he aint to VW specialist! There is a VW specialist (old skool) does everything with a screw driver, and "how much is that then mate" ahhh call it a tenner :) but he did the timing on it last time so i may take it down there on the weekend to get it check
Thanks
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Ok, The top one is for the temp gauge, so I put it in to the other two and the temp gauge worked fine with them so senders are ok :)
Ran the car up to temp, unplugged the red lead and the idle screw took exactly one full turn (clockwise to get to 960 rpm)
Now all i got to do is let it get cold and start her up and see if the idle works when cold!
A few questions?
1) from cold what should the idle be (choke working)
2) at what oil temp does the idle resume to normal?
3) what does the red lead from the ISV do?
4) If from cold it revs very low and turning the idle screw back to where it was cures it, what could be the problem?
Thanks again for your help
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Got to work all is good, idles as it should :) Thanks again gambit!
I would still like my few questions answered if you would not mind, just so i know for the future
Take care
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1) from cold what should the idle be (choke working)
on first startup, the car should start and fire up to approx 2k then drop gently down to about 1100-1200rpm, also the Warm Up Regulator will increase the fuelling for the 1st 7secs - call this your auto choke
2) at what oil temp does the idle resume to normal?
havent a clue!, my general rule of thumb is never take it higher than 4k rpm till the oil temp is 88 degress
3) what does the red lead from the ISV do?
that tells the ECU what rpm the engine is at, so if you try and set the idle with it connected the ECU will constantly be fightin against you
4) If from cold it revs very low and turning the idle screw back to where it was cures it, what could be the problem?
its just not setup correctly!!
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Great! really helpfull!
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Car was running great so i treated it to a tank of Optimax :) Amazing felt much more nimble from the leaving the garge!
Only problem now (when warmed up) is that if I dip the clutch or put into neutral the idle drops to around 450-500, nearly cuts out and then recovers to 960 rpm, any ideas, i have noticed that when i press the accelerator I here a sight whistle noise like a faint turbo noise (I wish) Does this tell me I have an air leak somewhere and does this account or the revs dropping?
If so, what the best corse of action to find it, I can get hold of a can of gas leak detector that plumbers use, just deposits a thick solution via a spray head, this any good?
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the CO% is not set correctly. needs set to 2% at idle with the engine breather on the airbox disconnected
that link details setting the CO%
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Yes I did check that, but first just to settle my curiousity I sliconed up around the idle screw (it was previously siliconed) and now it is running fine idles perfect, I must have disturbed the silicon that was previously on there, put on I guess as you mentioned about the rubber ring had probably worn.
Thanks again.