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Model specific boards => Golf mk3 => Topic started by: DCmk3 on 28 October 2012, 11:04
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Now I've replaced the cambelt and tensioner, the crank and cam are lined up, set the timing with a timing light.
I checked all the vacuum lines for leaks/breaks and they're all fine, but I still have an issue with the car idling at 1400 RPM when I put the clutch in, the revs only drop down to 1000 RPM once the speedo reaches 0.
I disconnected the speedo cable from the gearbox and each time I put the clutch in the revs drop to 1000 RPM even while moving..
So is this down to a speedo drive issue or something else? Since when it's disconnected the revs drop normally, but when it's connected the revs hang at 1400 RPM until the car comes to a complete stop.
Anyone have any ideas?
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In your first paragraph with what you say..it's not easy to understand what is effecting what without a bit of punctuation.. apologies for that.
But anyways.. the idle valve (ISV) i believe only takes over the idling once the vehicle has come to a stop, ie stationery no wheels turning, it's all in the electronics/ecu.
Disconnecting the speedo cable i guess isn't really helping, only perhaps pointing towards an obvious idle problem, possibly ecu related.
Without going out to check i can't remember if the idle valve is affected by clutch in/out at standstill but if so, again it's in the electronics engine management i'm sure.
Kinda assuming you've done the ole ecu and fuel relays, among the other usual tricks and jobs.
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I suppose I could have made it a little more understandable, I was in a rush to type it before heading out.
The car doesn't have an ISV of sorts as it's a 1.8i 8valve.
I've set the timing already and that's perfect, I set the throttle body with Vag-Com and all, there are no error codes either.
I just can't figure out why the RPMs stick so high when the clutch is in, then only go down once you stop completely.
I replaced the fuel filter two weeks back, checked the fuses and relays for the fuel pump and so on, they are alright.
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No worries ole chap..
Not having the idle valve then it might be a simpler problem,
I'm guessing a bit i know but if the clutch in/out is affecting idling then is it a clutch issue? what is the engine doing with clutch depressed in nuetral at standstill... and also clutch depressed in gear at standstill.
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It's an odd issue, even if I have it in neutral with the clutch out and if I push the car down the road the revs increase to 1400 as the speedo needle moves above 0. And as soon as the car stops (Speedo reads 0) then the revs drop to 1000RPM..
I just don't understand why it does that, my friend had a Mk3 with the same engine yet his never had this issue.
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It kind of suggests an engine management thing.. the wheels turn and the idle speed is being intervened in the same fashion as if there's an ISV in the system, although yours is behaving in more drastic way.
If it was me i'd have to go back to basics, check through all the known problem areas with these cars, even look at the earthing points.
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I've read up a little, could the MAP Sensor be at fault perhaps?
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It could.. but i'd be guessing at it only, the same as i might be thinking is the MAF sensor a culprit in the system..
It's one of those situations.. if it was me anyway that i'd first replace any associated items that aren't too expensive, like relays.. good things to do with an older vehicle and at the same time tick them off the list of possible fault areas.
Sounds like your getting all up to scratch with it so i don't know really..
Another thing i would do is look at the plugs, sounds like a dumb shot but i'd want to get an impression of the fuelling/engine health.
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Here's how my plugs are all burning;
(http://i433.photobucket.com/albums/qq59/crayzie/cleanburn.jpg)
Here's a little piece I got off a site:
Fouled Spark Plugs
Because a faulty MAP sensor can cause the engine to produce a rich fuel mixture, you may also notice the engine's spark plugs are fouled or coated with a white powdery substance. You can try to clean the spark plugs or install new ones, but the problem will not be eliminated until you address the faulty MAP sensor, which is reading the air and fuel mixture incorrectly.
Read more: Symptoms of a Faulty Map Sensor | eHow.com http://www.ehow.com/list_7468452_symptoms-faulty-map-sensor.html#ixzz2AbO3H8Ek
The car doesn't have a MAF either, so that can't be the case though..
I'll try price a new MAP Sensor, hopefully it's not too much and i'll go from there.
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The core part is very white isn't it.. might suggest a weak mixture if anything.. but again that can be caused by out of wack ignition timing also i think..
I guess if the Map sensor is cheap enough i'd replace it anyway.. as a means to piece of mind and eliminating it as a problem at least.
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Well I have ruled out the map sensor, they want £50 for the sensor, and they say it's more than likely not the sensor if there's no error codes from the sensor, and there are no error codes from the map sensor..
Rather lost now..
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If you can rule it out as you seem to have done then that's a bit more progress, a good thing no less!
Stick with it, it may be something simple..
I take it there's no mods on the engine.. or was it running right sometime before.. what has been done to it since then etc..
Your fault code reader, is it a professional diagnostic tool..
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The engine is completely stock, it has been running like this since I purchased the car a month or two ago.
I did a full service on the car, including a new distributor cap and rotor also, replaced the timing belt and tensioner.
The timing has been set and I can't find any error codes with Vag-Com yet the high idle is still there.
I have removed the throttle body and cleaned it, closed it back up and ran a Throttle body calibration via Vag-Com.
I just cant figure out where the gremlin is hiding..
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1000rpm is high for idle anyway, should be around 850
Have you checked all the vacuum hoses and crank breathers?
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I thought even 1000 was too high, what vacuum lines are there other than the one to the brake booster and the thin one from the FPR.. :undecided:
When you say crank breathers, are you talking about the one next to the oil filter on the block which joins to the inlet pipe?
Or are there more?
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I was speaking in general terms because I dont know your engine in detail.
The main vacuum hose to check is the one up to the ECU.
On my 16v I had problems with secondary ones but they will probably be different to yours.
So any thin tube check it!
Yes thats the main one from the crank. Again I have others.
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Alright ill take a look at the lines, it's just odd and rather annoying.
The crank breathers, I have cleaned those out recently.
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I suspect your timing is wrong - you don't use a timing light (aka dynamic timing) on the 1.8 or 2l mk3's - its all done statically by lining up crank/cam for machanical and the dizzy for the ignition timing.
Read this site, look at the diagram about 1/2 way down on the right.
http://faculty.ccp.edu/faculty/dreed/Campingart/jettatech/t-belt/index.htm (http://faculty.ccp.edu/faculty/dreed/Campingart/jettatech/t-belt/index.htm)
Don't use the crank cog, but use the flywheel reference by looking down the gearbox hole.
James
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The timing was lined up by the flywheel and cam when I changed the belt.. :undecided:
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Have a think about what javalin said.. your plugs kinda indicate a timing problem too..
Not a guarantee that it's defo the answer but has to warrant a double check through eh.
Keep at it..
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"set the timing with a timing light."
The ignition timing is set statically too.
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The distributor position was set to the line on the distributor when the engine was at TDC..
The picture of the spark plug was how it was burning before I had changed the belts, I had just at that point changed the oil, distributor cap, rotor and plugs a few days before the picture was taken of the plug.