156 wonky idle - THE FIX !!!!

If it does it when cold it could be the temp sensor which is screwed into the thermostat.

That's what I was thinking anyway (NTC sensor - same difference), alfa diag should be able to tell me (I think, I'm sure it reads engine temp)

Is there only one temp sensor on the 156 (not got a workshop manual for that car)

yep only one....that I know of anyway !!!

Originally Posted by Maverick

That sounds like a problem idle actuator, from what i have read they rarely show (just like the maf)a fault unless they are broken. Like most things on the Alfa its just a guess

Any idea what is the part number for the idle actuator and where it is located? My mechanic does not seem to know; in fact, he said there is no such thing on the 156 and used to be the lead mechanic at the Alfa dealership here in Singapore.

Dont know what the part number is but it is located on the side of the throttlebody about the size of a cigarette packet and has an electrical connector on the bottom. People call it different things so call it idle control valve, i think the only car that has not got this actuator is the v6.

After mine was on Alfadiag (Thaks Maverick!) it didn't show a problem with the idle controller. It still did the wonky idle, especially if braking over a long distance (e.g. from 70-0).
The problem feels to be an over-reaction of the ecu to the idle speed, kinda "Whoops, it's gone too low, whack it open - whoops, it's gone too high, whack it closed" - then repeat until stationary!

I've just done the wire cutting as described and been for a short drive, so far it feels a hell of a lot better. No bouncy idle any more, the revs drop to 1000 then slowly down to 800 odd.
It makes driving a lot smoother - when it was doing the 500-1500 idle it used to catch you out and open or close the throttle just as you were slipping the clutch in, resulting in jerky changes especially at junctions.

If you're having a go, it's the green/white wire from the larger of the two plugs on the speedo back:

Glad it worked for you Pete. It used to drive me mad, well to go round cutting wires on alfa electrics you gotta be desperate lol.
Has your car been ok since we did the ecu reset.

Yep, cheers - it's been fantastic - like a different car. Still slightly hesitant when very cold, then she goes with a little click after a mile or so and she's as smooth as can be!

Hello
I am suprised to hear about cutting the wire.

I have also another solution.
( I think the better solution because cutting wires is not a Alfa solution )

First what i replaced:
1e The Lambda sensor
2e The idle speed motor

Nothing helpt so far

I connect the pc with Alfa diag and go to the actuators and let the ecu learn
the new idle speed motor.
Also that was not the solution.

After a lot off thinking i notice that most people have this problem after 150.000 - 200.000 Km.

The solution is easy.
Turn the screw on the gasket ( to adjust the air intake valve )
about 45 to 180 degrees.
After turning the screw ( see photo )nothing changed , but when you connent the alfa diag and learn the ecu the new mechanical position of the valve everthing is perfect.

If you turn the screw let say 360 degrees and do the alfa diag you going to see that he idle speed is to high.
After a while the idle speed wil go down to 800 rpm.
You must do turn the screw by traile and error.
Starting with 180 degree is a good starting point.

Now the reason why i did the screw.
When you watching the screw you can see that the screw is a little bit shorter if you compare it when the screw was new.
By turning the screw you put the valve again in the old position.

ONLY TURNING THE SCREW DOES NOT HELP.
Always after turning the screw connect the pc.

If you questions you can always email me.
jp.cretier@planet.nl.

( I hope that everbody understand me verry bad englisch story )

J.P. Cretier

Sorry JP

Didn't sort mine when I tried it

Also my car is only 60000 miles (about 100000 km).

Yep also tried this before i cut the wire and it seemed to work for a few mile and then went back to normal and it was attached to the pc to relearn. Glad it worked for you but made no difference to mine.

Finally got round to doing an ECU reset and the wonky idle fix this weekend. Idle seems to have worked a treat but not really clocked up any mileage to judge if the ECU reset has done anything. I've atank full of Shell V-power in her too so hopefully I should notice an improvement this week (I clock up ~300miles a week mainly on nice twisty country roads) so will update next weekend!
Cheers

A big thanks to Marlon/Maverick for the wonky idle fix. It's worked a treat, I haven't clocked up too many miles yet but certainly worked and makes driving a little smoother

The ECU reset is far more subjective. Had a real hard drive to work this morning, +30miles of empty country lanes at 6am. I'm sure the pickup was smoother and the slight hesitancy at 3-3500 revs appears to have disappeared. This could of course be my sub-concious willing me to notice an improvement! Either way, it was a fun drive to work

I just took the fuse out of ABS, it's the 60 amp fuse under the bonnet ye! No difference I still have the wonky idle with it removed

How do you do a ECU reset?

today I removed ABS 60A fuse also and no difference.
However I accidentaly find out that when I turned on aircon than rolling idle improved a lot. I dont understand what can be a problem.

Otherwise in local alfa garage I had throttle body cleaned and valve reset done, software update done, I have changed lambda, cleaned MAF, checked oil vapour separator valve, changed sparkplugs.
Car is driving nicely though, good acceleration, just crazy rolling idle.

Mine is now doing this. What happens is, when you start the car all seems ok at first. then the revs start to rise till just over 2000 at which point the ecu butts in and the revs drop off back to about 1200. then gradually back up again and the process repeats.

Also, whilst driving it is worse. when slowing down the revs stay high and it's hard to set off properly (the selespeed doesn't help much). you look a bit daft sat at lights with the engine revving to 2500 then back down again constantly.

Also, when turning the ignition off. The car jumps quite badly (I'm assuming the selespeed thinks you are trying to set off so it hasn't got the clutch fully in).

Going to try resetting the ecu again now and see if that helps.

Rob,

have you tried the idle fix thats in the original post of this thread? It was that not the ECU reset that cured mine of the wonly idle. Mines been fine since it did it..

Andy

Andy,

Don't fancy cutting any wires just yet. I'm pretty sure it's a problem with the idle settings, as it was fine until today when I cleaned out the throttle body a bit. Trouble is mine's a selespeed so you can't just push open the butterfly valve without damaging the body (drive by wire type) so I had to get my wife to press the accelerator when ignition was on and I used a cotton bud and some cleaner to clean around the butterfly. Since then this problem has occurred.

I've cheacked for leaks on the air inlet and all seems ok, so I think it's going to be the idle settings.

robf781 yours sounds like it needs the idle actuator reseting or possibly replacing. You could try the throttle reset that is well documented on here and 156.net, personally i`ve not got much faith it and prefer to reset with alfadiag but it cant hurt to try.

Having trouble getting alfadiag to connect. By the way, any idea how much the idle actuator is?

Hopefully it'll just need resetting, but just in case.

Shop4parts £125 plus del

Originally Posted by robf781

Andy,

Don't fancy cutting any wires just yet. I'm pretty sure it's a problem with the idle settings, as it was fine until today when I cleaned out the throttle body a bit. Trouble is mine's a selespeed so you can't just push open the butterfly valve without damaging the body (drive by wire type) so I had to get my wife to press the accelerator when ignition was on and I used a cotton bud and some cleaner to clean around the butterfly. Since then this problem has occurred.

I've cheacked for leaks on the air inlet and all seems ok, so I think it's going to be the idle settings.

My V6 is a fly-by-wire and I have cleaned it out at least a dozen times to no ill effect.

*gently and slowly* push open the butterfly with a finger (wear a rubber glove!) and spray liberally with carb cleaner. Thats all over the butterfly and round the opening of the throittle body. You only have to have the butterfly open little although I`ve often had mine fully open. Its likely that you have just built up a ledge of crud with your cotton bud.

Re-fitt pipes and start up to clear the excess cleaner.
Do the 90 second throttle reset trick.

You can reset the ECU now if you want to but I don`t beleive that you have to, the ECU soon learns whats going on. Go for a drive to make sure that its learning properly

BTW its quite normal for the revs to be too high after a clean whilst the ECU learns what's what, so you could do the throttle reset and ECU reset only if you don`t want to risk another clean.

Originally Posted by sa155ae

I just took the fuse out of ABS, it's the 60 amp fuse under the bonnet ye! No difference I still have the wonky idle with it removed