Another 2l 16V idle problem

[dghodges 0]

My idle has gone from intermittently causing minor idle problems to now it wants to stall all the time and now actually does stall. For months the idle has been fine. The first signs of a problem was when driving, the car was up to temp and started getting a bit jerky on/off throttle and the idle started bouncing at just over 1000 RPM. At first this didn

[kaiserVR6 0]

I am having a similar problem with my 1.8 16v, but without the stalling.....not tackled any sensors yet but i am going to take it to be serviced this week as its been 12k since the last one. the other thing with it is if you dip the throttle the revs go up rapidly as you would expect but it takes quite a while to return to 1,100rpm......sticking trottle??? what does everyone think?

 

one thing i did notice is the temp is up by a couple of degrees but i put that down to the car revving slightly higher

[kuipers23 0]

I have a similar issue. It has got beyond a joke now.

 

When I take my foot of the throttle the car still pulls along. If I dip the clutch the revs don't go lower than 2000rpm. When I pull up at a junction the car is screaming. The idle is just all over the place sometimes. It doesn't cut out though. If I stop and turn off the engine and the restart it it is fine for a little while.

 

It is going in for a service on Saturday but now I will have to get them to look at this problem.

 

I think it must be one of the sensors sending duff infomation to the ecu. It is not the throttle cable because I have tested it.

 

Thinking about selling the bloody thing as it has cost me lots of money since I bought it.

 

I will tell you what the garage said was causing it.

[kaiserVR6 0]

NNNNNOOOOOOOOOOOOOOOO dont sell her, you cant do that!!!!

 

i had a look under the bonnet last night and the throttle cable tension is fine but the lever on the top of the throttle body isnt returning to the rest position, mine is in tomorrow morning first thing so as soon as i know anything i will PM you both and let you know it wont be expensive but it will probably take a bit of time.

[dghodges 0]

A little update... I'm still unsure my ISV is working, well i'm slightly more sure it isn't now. I've stuck a multimeter across the connections to the ISV (with it unplugged), both with the ignition on and also with the engine running, both times I get a reading of 12V...correct i assume? Now when i plug it back into the ISV and remeasure, again with the igition on and with engine running I only get a reading of 0.245V. I have tried this with two ISVs with the same results. I'll make sure at work tomorrow that they do actually work when supplied with 12V.

 

So I'm now thinking (assuming ISVs are working, will check) that either the wiring is not very good and not capable of supplying the 1.5A (12V / 8 Ohms across ISV terminals = 1.5A) or something is more serious inside the ECU, duff regulator or bad earth to ECU?

 

I think this is a sensible line of thinking, any condtradictions or advice welcome...

[dghodges 0]

Other question was...Does anyone know which pins the two ISV wires go to on the ECU connector? Should be able to supply 12V across those to the ISV to eliminate either the wiring or the ECU. I've got another copy of the passat haynes manual coming tomorrow all being well, lost mine in the recent house move. Hoping the pins and wiring will be in there if no one knows.

 

Cheers

[easypops 8]

My bad idle was caused by 2 broken wires(burst inside the plastic covers) on the plug that attaches onto the throttle potentiometer.....only took about a year to find :D ....that was after a new MAF, distributor, leads, throttle potentiometer, fuel pump, and a replacement throttle body and many times cleaning the ISV .

Its worth a check as i'm sure someone else also had this.....and its free to look :lol:

Mine is also a 2.0 16v btw

 

If you haven't yet looked then use the search....there will be loads of reading as its a common fault.....with usually a few answers

 

Good Luck

[dghodges 0]

Cheers for that easypops, I have checked the switches in the past but not since this problem started. That would probably have been my next check had I not spotted that the 12V to the ISV drops considerably as soon as a load is presented i.e. plugged back in. I'll probably still check the throttle switches but i'd be surprised if the ECU would be clever enough to know when the ISV is plugged in and hence drop the voltage :?

 

I wouldn't be surprised if it is something like you suggest in KaiserVR6 and Kuipers23s case. Thanks for the input!

[dghodges 0]

Just found a good post on Club GTI http://clubgti.com/forum/showthread.php?t=49628 It seems to suggest that the ECU or at least controller (if exists on a 9A) is clever and detects the ISV being connected. I think i'll be doing as easypops says first i.e. checking throttle switch, and also seeing if the 0.25V I measured on my DMM is any different with an analog one or an oscilloscope. I don't get any buzzing though...with either ISV. I'll let you know...

[kaiserVR6 0]

after leaving my rado with the garage on friday they said that the throttle problem just needed the adjustment screw winding in......which seem to fix it for a few days.....but after the adjustment was made i marked the screw and it seems to have worked its way out under vibration and the car is idling at the higher rate again, new throttle body me thinks.......

 

:lol:

[kuipers23 0]

The ecu returned no faults so the garage didn't think it was a sensor problem. They resealed everything as they though it was an air leak. After driving for half an hour the problem returned. It now does it all the time. Sometimes it idles correctly but most of the time it is in between 1500rpm and 2500 rpm.

 

It is really pissing me off now. I nearly crashed the other day going round a rounabout. took my foot of the break and the car accelerated even though I wasn't touching the throttle. I also look like an idiot to passers by who must be thinking 'why is he reving his engine like that'.

 

It is now going into the VW specialist on Thursday. I hope to god the fix it because i am not enjoying the corrado at all at the moment. May go back to the 205's.

[kow 0]

Had similar problems in the past, and first I would clean out your throttle body which is favourite cause. Get some carb cleaner aerosol, remove the flexible intake pipe and some lint free cloths . Open up the throttle butterflies and give internals a good squirt of carb cleaner, push the rags inside with a long screwdriver etc. ( Don't go to agressive and lose them) and soak up the black gunge.(BE CAREFULL WITH FINGERS AROUND THE EDGES OF THROTTLES, THEY ARE LIKE RAZORS). Do it again until all the crap is out from the area of closed position. Pull off and clean through any adjacent vac lines, chck for splits etc. Reconnect all bits.

 

Then start it up and clear the engines throat, may miss a bit as carb cleaner gets pulled through.

 

Can do the same cleaning with the ISV as they get gummed up.

 

Throttle position switch is important as it tells the ECU the throttle is closed, at high revs on closed throttle (over run) the ECU will cut the fuel off at throttle closed position and as revs drop to 1000 or so the ECU just gives enough fuel for tickover, the ICV keeping the revs steady at 800 ish by air modulation. Check that microswitch clicks as throttle goes to stop, return springs and general stiction can cause throttle to be at closed but switch not made.

 

Good luck

[skinnyman9000 0]

I am having the same problem with mine. I've had it pulling itself along, i've had the revs fluctuating at standstill, and now it just sits at 3k rpm on tickover. Ive cleaned the ISV and replaced, altho i cannot confirm that one ive replaced it with it is working 100%. Another thing ive noticed on mine is that when i turned the ignition off the rev needle dies immediately. The engine slows down as you would expect, but the rev needle drops to zero in an instant. Could this point to a sensor issue?

 

The MOT has also ran out so i cant even drive it to a specialist for a once over :(

[kow 0]

Replied to this on your other thread.

VW's are basically a sound design, it's just a fault you have to work through to find the problem, which is usually an easy fix.

[kaiserVR6 0]

after leaving my rado with the garage on friday they said that the throttle problem just needed the adjustment screw winding in......which seem to fix it for a few days.....but after the adjustment was made i marked the screw and it seems to have worked its way out under vibration and the car is idling at the higher rate again, new throttle body me thinks.......

 

:lol:

 

well decided a bit of lock tight on the old screw might fix it, and guess what!? BONZA!!! cleared it up a treat - good luck with any further problems!

 

kaiser

[kuipers23 0]

The vw garage have called me amd they have diagnosed the problem.

 

My idle control valve is buggered.

 

Parts, diagnoses and labour £199

 

I have had this car less than six months and it has cost me £750.

 

I must like her as I am willing to keep spending money.

[skinnyman9000 0]

The vw garage have called me amd they have diagnosed the problem.

 

My idle control valve is buggered.

 

Parts, diagnoses and labour £199

 

I have had this car less than six months and it has cost me £750.

 

I must like her as I am willing to keep spending money.

 

Dude, i've had mine for 18 months, its spent 8 of those on my driveway, i've spent just shy of £2k, now i have this throttle problem and the master cylinder is knackered, and after the MOT it's going in the bodyshop for some repair work, coming in at just under £600. Then when you add on my sound system to that........

[Albie 0]

Dunno if this will help at all but the ISV seems to have an action which is not quite obvious. It is under the control of the ECU of course, and it is basically an electromagnet pulling its iron core in against a spring of known strength. But is isn't fed a varying DC voltage to set the tickover. The ECU is a digital device and I'm pretty sure will feed the valve pulses which the valve then averages out. If that is correct and you try to read the voltage level at the valve plug while it is in action with a simple meter you will get meaningless results. What you are reading with a DC meter is a stream of fast pulses and not a DC voltage!

 

One contact should read +12V supply with the plug disconnected and the other, the effective ground is under the control of the ECU. The only way to really check its action would be to stick an oscilloscope on it and look at the pulse stream to see if that is reacting correctly. Or use the right analytical software of course.

[kuipers23 0]

All fixed now. Idles perfectly.

 

Hope its not the ISV in other cases as it is quite expensive to replace unless you know what you are doing.

[skinnyman9000 0]

I've had enough of mine, its goin in the garage on tues!

[Ashun 0]

I had this and it was the TB full of crap and dry as a bone on the springs , there is a lower spring and the upper one get em covered in oil , I only had to take off the air pipe and i used carb cleaner and a brush then oiled that inside after , my tick over was 2.5krpm and now its 800rpm .

 

took me 30 mins

 

Ash