g60 high idle

May 09, 2004 8 Replies

I got a corrado g60 since a couple of weeks. Runs fine and all, only the idle engine speed is too high. Most of the time it runs 1500 rpm, sometimes even more.



So I try to fix it myself, before hiring expensive vw mechanics to do it for me :^)



Today I replaced the blue temperature sensor and a few hoses which didn't seal properly, but it didn't help a lot >:^\ I also checked grounds and all, and a few weeks ago I brought it to an generic car workshop to fix any vacuum leaks.



Right now I'm suspecting the little switches on the throttle body. There are two of these, one for idle throttle, and one for wide open throttle.



So I tested the following:



I let the engine run with the throttle opened up a little, so the throttle didn't touch the 'idle throttle' switch nor the 'throttle wide open' switch.



Then I pushed the 'throttle wide open' switch. I expected the engine to rev up a little, because of extra gas received because of enrichment or something like that, but instead it revved down. I think that's odd.



Can anybody explain me how these switches should affect engine rpm?



I weakly remember something about two types of throttle bodies for the corrado, is it possible that they replaced mine in the history (before i had this car) and fitted the wrong one, where the buttons switched position on the connector or something? (Can be rubbish just as well ;^)) It feels like the buttons are working opposite or something, giving wide open throttle enrichment when idling, and idle throttle when throttle wide open???



When I turn on everyting electric (lights, heating, etc etc), it idles just fine at 850, so the engine doesn't steer it on purpose to 1500 rpms.



Any help will be greately appreciated, caus I wanna drive it!



I need to wait in traffic jams every day to get to my work and when your car is idling at high speed this sux :^D



Grtz, max


There's an idle screw on the back of the throttlebody, sometimes these fall out. Another thing to check is the isv valve. You can feel it vibrate when the ignition is on. Also check if it's clean and not stuck in the open position. It should be fully closed when it's not energized. When you push the full throttle switch it'll make the mixture richer which can cause it to rev lower. Lift the throttle a bit and push the idle switch in. It should now hunt up and down, if so then the isv valve is working. Hope this helps.......

SFC

"max" schreef in bericht news:409dfb28$0$135$ snipped-for-privacy@dreader15.news.xs4all.nl...

I checked the idle screw, is't still there and fitted firm. I also took the isv of the hoses and checked it, when the ignition is on, the valve goes in and out real quick. Also, I can drive the car in first gear or in reverse without touching the throttle at all. I thought that indicated a proper isv function as well. O, when the valve not energized it closed shut.

I'll check that

One other question. Since this is my first corrado, and my first injection car, what should happen when you floor the throttle? Does the WOT switch does make any difference?

Say I go from 95% (no WOT) throttle to 100% throttle (WOT), does that make any noticable difference?

Btw, when I push the throttle half open, and then press the WOT switch, the rpm also falls back. When should it start to rev up a little extra?

Thanks for the answer!

Hmz, as far as I can see the idle switch doesn't do anything at all. Should it have any noticable effect when pressed?

After replacing the coolant sensor did you reset the ECU?

I disconnected the battery during the time I took replacing the sensor.

Or isn't that the same thing as resetting the ECU?

Not 100% sure if it's the same. My '91 GTI (Digifant I in my case and I think G60 Corrados are Digifant I as well) has a procedure that involves disconnecting the coolant sensor for a minute and I think revving the engine past 2500rpms or something like that. I forget the details but it's in the Bentley how to do it.

Only when you lift the throttle a bit and the switch is no longer pressed. Hold it in this position and press the switch with a screw driver or something. The engine should hunt up and down a bit. High idle is just air by-passing the throttle plate. Also check if the throtlle is fully closed and check if the cable isn't to tight.

SFC

"max" schreef in bericht news:409e2d17$0$14630$ snipped-for-privacy@dreader19.news.xs4all.nl...

You can't reset it only the error codes can be wiped. When you shut off the engine there's no power going to the ecu so disconnecting the battery has no effect.

The procedure you mention is to cancel idle adjustment to set the basic idle with the screw in the throttle body.

SFC

"Matt B." schreef in bericht news:Knxnc.25752$fE.22565@fed1read02...

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