406 8v turbo irregular idle problem.

[wilsonT5]

hi guys im kind of new to all this forum stuff but i needed to give somthing a try.
my 1996 406 sri turbo has a irregular idle which sometimes causes the car to stall, it mainly happens just after starting it when it is warm. ive been to see my local dealer about the problem and he was no help at all, i was told it could be down to 1 of 3 things,

1 the idle air control valve but im stummped as to were it is located and if it has one,
2 the Mass air flow sensor again no idea of location,
3 my O2 sensor.

iv had a 406 glx 2.0 petrol before and all things are quite easy to find but on this im lost.
any help with this would be great as it is a real pain in the rear

thanks.

[mjb]

Hi Wilson. Thankfully I know this car

1 the idle air control valve but im stummped as to were it is located and if it has one,

Follow the huge air hose coming from the throttle body to the intercooler. About half way there's a roughly 3/4" diameter pipe coming out heading back into the throttle body via a silver cylinder about 1.5" diameter by 5" length. That's your ICV.

2 the Mass air flow sensor again no idea of location,

There is no MAF in this car, just a manifold air pressure sensor which is part of the ECU itself

3 my O2 sensor.

Get under the car and you'll see it sticking from the exhaust to the passenger side before the cat

[wilsonT5]

thanks for the reply, iv checked the icv this morning and when i disconnect the electric plug nothing happens is that normal or does that mean this is the problem.
i have also been told that when i go to the main dealer to ask for a compensator then they should then know what i mean, however im not sure if that is correct or not

[djvaliro]

Hi .. got a 406 2L Turbo xu10j2te 98model, same problems irregular idle which causes the motor to stall, not always though.
I've tested almost every sensor on the car by the book measurements with the multimeter. (dont have an osciloscope yet very useful if i had one).

Tested - ICS - idle air control valve cleaned also -measurements ok 20 ohms if i recall correctly - tested the car with another one from a 605 same results.
tested - CKP sensor - measurement ok .. tested with a new one .. made idling worse than the original

I made a diagnostic coz i have the PSA30 soket .. and the ecu gives me error 41 - CKP crankshaft position sensor / speed sensor, wiring, air gap, ECM,
beside that no other error.

What i need to mention is that before changing ditrubution and all .. tha motor was very silent, now beside this i have all types of noise coming from the water pump area. Do you think it has something to do with it!? If anyone has resolved this issue please share with us it's driving me crazy . Thank you.

[djvaliro]

solved the erratic idling - was a bad grounding. The last mecanic forgot to tighten the screws that holds the ground - minus - (-) to the engine case. After tightening everything works like a charm.
So remember to verify grounding.

Update : Done another diagnostic .. no erros. Still remains the sound from the timing belt area, makes a irregulate grrr sound (i think might be too tight as i've seen on youtube or google'ing .. but not shure).
If someone had something like this and solved please share the experience. We are techy guys so we can handle .Thanx. Learned to repair 406 in 80% proportions - Very educative for your pocket.

[teamster1975]

Well done mate, thanks for letting us know!

[wilsonT5]

thanks for that bit of info djvaliro that will be the next thing i will try, it's driving me mad .
im finding it very hard to find spares for this car and hope it can be resolved with somthing as easy as that.

thanks for all this help guys much better than my local dealer, i will keep all informed on my long struggle for perfect idle.