G60 Very nearly stalls possibly fixed - bad connection!

[CTWG60 0]

Last week whilst queuing in the petrol station (on a slight incline) my car a 90-91 G60 decided, even though it was up to temp to, to drop the revs to somewhere between 0-250rpm. I was stunned for a moment as have never had an idle issue when warm, it's always rock steady at 750rpm. I realised if I stalled and couldn't start on an incline in a very popular petrol station that I wouldn't be very popular and so blipped the throttle to help it out.Thought it could of been because of low fuel and being on a slight incline but I don't think so. Anyway as the next 7 days went by I started to notice it was very rough at idle when started from cold and now even dies after the first start. If you rev it a little after just starting idle drops down to 250ish before recovering it's 1000+rpm cold start idle. It's not been particularly cold here no frosty morning in the last 7 days, although tomorrow should be fun.

 

It has now I think about it dropped the revs after reving/reversing out my drive, on a cold start before and I may be paying a little too much attention after it's petrol station episode, but I think something in the engine bay has been on it's way out for a long time maybe since I bought it. I'm thinking ISV but am looking for some sort of diags procedures for it and other parts before I bend over and touch my toes at the local dealership. £225 inc Vat with a 10% discount for bending over so frequently.

 

Any ideas anyone?

[mattosmond 0]

i had a similar issue on my 2.0 8v golf - turned out to be the throttle body. but it was naturally aspirated so i dont know if it is an issue on the supercharged cars, but it is cheap and easy to find out... just take the throttle body off and give it a clean with brake cleaner.

 

sorry if this is of no use, hope you get it sorted. :)

[JMC 0]

I would also check the wiring to the ISV. On my G60 the wires had actually burnt though as they passed overe the manifold. 15 years of heat treatment and the insulation had cracked, and the copper corroded. I removed the section of wiring and replaced it with new wire, and it solved my problem (low revs and cutting out). The ISV can be cleaned as well, which I would recommend trying before buying a new one. There are plenty of threads for that on here, but I seem to recall it is cleaned with either carb cleaner or petrol.

[CTWG60 0]

Idle Stabilisation Checks

 

Not sure about the TB suppose it could be but have now tested the ISV as per the Bentley manual and ECU with a test loom I made from an old wiring loom and a few PC power connectors with the following results.

 

Idle with Blue Temp Sensor connected is 600mA - 620mA fluctuating (at around 800 rpm) and without 444mA stable (at around 500 - 620 rpm). They should be both 460mA + or - 60mA.

 

I accidently found that even with the engine warm I could not start the engine with the Blue Temp Sensor disconnected, which means I would not be able to put the car into open loop mode?

 

Also when looking at checking and adjusting idle that my idle speed should be 800 rpm + or - 50 rpm without the blue temp sensor connected?? When in fact it drops from 800 to between 500 rpm and 600 rpm which it has always done when checking the ignition timing!

 

So now I'm really confused. If I check the timing at 2000+rpm and adjust the idle to 800 rpm with the BTS disconnected and still get the same issue everything points to the ECU as being bad with regards to idle stabilisation. Anyone got a spare I could borrow/buy? I can have it picked up insured and returned to you via courier.

 

Other evidence I can think of is if I stall moving off at a junction (it's always done this) the car fails to start straight away but turns over like it does with the BTS disconnected with no attempt to fire up. Twice last year I returned to the car after parking for less than 3 minutes (not fully warmed up) and it failed to start straight away again like it does with the BTS disconnected.

 

Here are the Bentley pages and a pic of the test loom I made.

[CTWG60 0]

I would also check the wiring to the ISV. On my G60 the wires had actually burnt though as they passed overe the manifold. 15 years of heat treatment and the insulation had cracked, and the copper corroded. I removed the section of wiring and replaced it with new wire, and it solved my problem (low revs and cutting out). The ISV can be cleaned as well, which I would recommend trying before buying a new one. There are plenty of threads for that on here, but I seem to recall it is cleaned with either carb cleaner or petrol.

 

Hmmm. As above I think I've ruled out the ISV and it's wiring. I did also clean it out with petrol last night but to be honest it was very clean inside and only really got the petrol dirty because the outside inevitably got cleaned in the process. I blew it out with compressed air before refitting but it made no difference what so ever. Stalled again today still cold when I caught it by surprise moving off at a junction, and also when first started this morning it died instantly was ok 2nd time but still struggled to restore correct idle when cold from high rpm.

 

Oh other evidence BTS and CO pot replaced last year with new VAG items due to engine running rich. It was the CO pot at fault not the BTS.

[dirtytorque 0]

maybe the map sensor not responding to sudden throttle openings when pulling off at junction?

checking with another ecu setup should rule that out I guess?!!

what are your plugs like?

knowing you I guess you would have checked the 100 cm vac hose?!!!

[CTWG60 0]

maybe the map sensor not responding to sudden throttle openings when pulling off at junction?

checking with another ecu setup should rule that out I guess?!!

what are your plugs like?

knowing you I guess you would have checked the 100 cm vac hose?!!!

 

I'll check the plugs tonight but last time I checked them they looked a little lean burned but nothing to worry about. I haven't checked the MAP hose but I suppose it would be worth ordering another piece of hose from VW just to be sure. I just hope it's not some weird loom problem that will drive me nuts checking that lot.

[JMC 0]

How about the lambda sensor - have you checked that? AFAIK the lambda is important for correct idling(but I'm sure someone will be along soon the correct me if I'm wrong).