ECU multi-pin plug

[Album56 0]

Having a nigling idle problem with my 92 G60, after idling at 850rpm when hot faultlesly for years it now varies anywhere between 850 & 1000rpm & varies up & down randomly when hot, runs perfectly apart from that. Not a big problem I know but could point to something developing, seemed to start after I had replaced the Bosch plugs, dizzy rotor & cap, all vacuum pipes have been replaced as has the idle screw, lamda probe (Bosch) & blue temp sender all ok. All earths checked & tightened, idle microswitch on TB tests ok, all electrical plugs/sockets under the bonnet sprayed with switch cleaner apart from the multi-pin ECU connector Which I cant get off to check. I have read in a couple of threads there is a piece of black plastic which slides forward to release the plug but I cant move anything even tried levering with flat bladed screwdriver but didnt want to break anything so didnt use brute force, also there appears to be a spring clip at the other end of the plug almost out of sight does this have to be released?

When I have checked the ECU plug/socket & sprayed with switch cleaner if the problem still persists I'll take the ISV off & clean/lubricate it.

Any help/suggestions much appreciated.

Mick

[Album56 0]

Bump

[Album56 0]

Anybody have tips on how to release the ECU plug?

[Yandards 0]

Pull the spring clip towards you and then the end of the plug at the spring clip should lever out and unlatch the plastic lug at the other end.

 

The sliding black plastic style ECU connector is not used on the G60s or KR cars, it's a later style ECU/electrical plug locking feature.

 

Sounds like one of your vacuum pipes is loose or the idle screw is not in the right spot and the ISV is trying to compensate, did you make sure the ECU vacuum hose is 1 meter in length?

 

Did you do the full set-up procedure after changing the idle screw (Timing check, CO mixture adjustment and idle adjustment)?

[Album56 0]

Cheers Yan, I'll try the ECU plug tomorrow now I know how its supposed to come off. As far as I'm aware the timing has never been adjusted or touched in 18yrs so its probably still at factory setting because she has always run well & started 1st time every time. Could be the idle screw or CO pot adjustments required tho as these have been changed.

I read that to make adjustments assuming the timing is already ok, get the engine hot, disconnect & plug breather on cam cover, then disconnect the blue temp sender which puts the ECU in adjustment mode & blip the throttle to over 3000rpm 3 times then adjust the idle screw to get steady 950 - 1000rpm . Reconnect the blue temp sender & breather pipe & the engine should settle down to the correct idle speed.

I'll check the ECU plug & give it a squirt of contact cleaner & then give the ISV a clean with carb cleaner then if necessary try the set up procedure.

Thanks again Mick

[psiburr 0]

just sorted a similar sounding problem with my G60, went through most of the checks and replacements you've listed and turned out need a bad connection in the fuel pump relay. one connection was "dry" and another loose, re-soldered and sorted 8)

hope this helps ?!

[Album56 0]

Thanks for that, yes I have been thinking I should get new fuel pump & ECU relays as these have never been replaced, assuming you can still get these from the dealers.

Mick

[Yandards 0]

You can still buy fuel pumps but be prepared for a very large bill..

[Album56 0]

Found that the ECU plug disconnects quite easily by pushing the clip at the back of the plug away from you towards the back of the car at the same time pivoting the plug on the plastic lug at the front. Replacement is the same in reverse, insert the front lug & then pivot pushing the back of the plug firmly home & the metal clip snaps into place. Have given the pins a good spry of contact cleaner although I didnt see any obvious corrosion. Will take it out for a run later to see if theres any change.

Mick

[Album56 0]

Replaced Digifant/ECU relay & fuel pump relay, they needed to be replaced after 140k miles but hasnt cured wandering hot idle, starting from cold everything is as it should be, 1000rpm idle for a couple of minutes when I stop at drive & lights at the end of the road. Then as it starts to warm it slows to 850rpm & is ok until there is a bit of heat under the bonnet & I stop in traffic or at lights & then the idle will climb to 1000rpm again & vary up & down anywhere between 850-1000rpm, something under the bonnet is being affected by heat. Beginning to wonder if the blue temp sender is faulty again, was replaced about 3 years ago VW part but it did appear to test ok with multimeter or maybe the idle microswitch is going HR when it gets warm.

Gonna take a bit more tracking down methinks..

Mick

[Yandards 0]

Replaced Digifant/ECU relay & fuel pump relay, they needed to be replaced after 140k miles but hasnt cured wandering hot idle, starting from cold everything is as it should be, 1000rpm idle for a couple of minutes when I stop at drive & lights at the end of the road. Then as it starts to warm it slows to 850rpm & is ok until there is a bit of heat under the bonnet & I stop in traffic or at lights & then the idle will climb to 1000rpm again & vary up & down anywhere between 850-1000rpm, something under the bonnet is being affected by heat. Beginning to wonder if the blue temp sender is faulty again, was replaced about 3 years ago VW part but it did appear to test ok with multimeter or maybe the idle microswitch is going HR when it gets warm.

Gonna take a bit more tracking down methinks..

Mick

 

Idle MS will give you a much higher idle (around 1500 rpm upwards)

 

BTS will have little input on a warm engine as the failed condition means the ECU assumes a value of 60 degrees coolant temp, giving you a stable idle in a warmed up car.

 

Only thing that really affects the idle that much at idle is the ISV, an irratic warm idle points towards the ISV failing as the resistance on the field windings is breaking down with heat or it cannot adapt quickly enough due to a oil contaminated jacking piston. Take it off and give it a clean out with carb cleaner and see if it improves. Note that it will only be a temporary fix and your ISV will need to be replaced.

[Album56 0]

ISV will be off & cleaned next week, hope that fixes it cos a new one is a lot of money.

Cheers Mick