156 wonky idle - THE FIX !!!! - Page 8 - Alfa Romeo Forum
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Originally Posted by Fanl145 View Post
Dear Alfa-BR.
In order to make an apropriated noise filter we must understand how is the signal. If the signal is a simple logic high or logic low, the filter is simpler, also, a filter would decrease the response time of the signal, there are many items to be studied and the first step is to understand how is this signal. That's why we need an osciloscope.

PS: I gess u're Brazilian, I am Brazilian too, and I have a feeling we two belong to the Alfa Romeo BR club... my name is Felipe de Andrade Neves Lavratti.
Oi Felipe,

I'm from Sao Paulo, but I'm not in the AR-BR club, so I don't think you know me. Are you from SP?
Cheers.
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Does anyone know where the loom connects under the passenger carpet?
One of the alfa mechanics told me that it comes a little loose sometimes, and this gives you the same erratic circumstances.
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I have had to disconnect wire again as my idle actuator has gone again I think, I had a new one about a year ago
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I don't think its the idle actuator, they should last longer than a year!
I was told its the cambelt most probably.
Next job Cambelt, tensioner's and variator. Is it best to do the seals while I'm at it!

Last edited by CroBaron; 26-07-11 at 13:30.
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Oi Felipe,

I'm from Sao Paulo, but I'm not in the AR-BR club, so I don't think you know me. Are you from SP?
Cheers.
Hi.....
I am from Porto Alegre =]

Let me know if you need anything.
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Originally Posted by Maverick View Post
The speedo takes its signal from the ABS, from the speedo the signal is repeated to the climate control and to the ECU. I am guessing the signal to the ECU is telling it the car is still moving so keep the idle slightly higher than when stationery, this seems to be the problem it cant keep it high.
If you read the thread from the start you will know as much as we do, i have not met anybody on here who can explain it but it works with no side effects that i have found.
Several people on here have managed to fix the problem by replacing different parts and thats great for them, this seems to be a fix for those who have tried all those things and got nowhere, so the debate goes on cut it or not cut it, the wire and the choice is yours.

Have fun
Have you kept eye on fuel consumption before/after?
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When gear is on, and speed is decreasing (when you are breaking with engine)
the ecu tells to cut down the petrol injection.

In this way the engine doesnt consume any petrol during the engine braking.

And that is the way how it should work.

BUT if the ecu doesnt know that the clutch is being pressed - the
engine stalls.

Anyway ecu doesnt let the engine die, so when the rpms reaches the minimum possible - the ecu gives a command to start inject petrol again and the rpms rises to 1500?!?

This goes on and on and on, as long as the speed decreases enough...

(pardon me my bad english, do you understand this?)

But if you cut the wire from the speedo the engine thinks that the speed is "something something" and it doesnt cut down the petrol injection at all when engine is breaking?!

AM I RIGHT?
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I have a similar problem with my 1998 156 2.5 v6. I stop at a junction, let go the clutch, the idle drops down the black line..around 500-600 rpms.. then goes back to 900 rpms. But sometimes, as it drops down..it hesitates, and stays low causing the car to stall. I have had a new genuine Bosch Maf fitted recently, and changed the throttle body with a second hand one (cleaned and fitted).. First impression was that it fitted perfectly..but 2 weeks later, I happen to have similar stalling problems..

I suspect the culpit is the lambda sensor..The car has 167.000 km on it currently.
So..guys, do you have any idea to solve this idle problem..?
Any body to guide me where to look for, what to suspect..?

Thanks in advance.

--
1998 Alfa Romeo 2.5 V6
Metallic Silver Grey + Black Momo Leather, 17Ē GTA wheels, 215/45/17 Kumho Ecsta KU31, Full Zender Body Kit, Brembo Disks, Ate Brake Pads, Bilstein B4s, Vogtland -40mm, Supersprint Muffler
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My lambda sensor has also been replaced with a genuine BOSCH one...but still I have this erratic problem. I am sick of it. Sometimes the engine stalls in a parking lot..sometimes at the speed bump.. It is becoming really dangerous.

I will clean the throttle body again, but I think the culprit is the small stepper motor on the side of the throttle body.
Does anybody know if I could get only a new stepper motor without buying whole throttle body..?

All the best.
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hi my 156 2.0 ts is manuel ticks over at 1500 then drops to1000 after a miniute.tried ecu reset didnt work,any ideas thanks.also convertin selespeed to manuel
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Originally Posted by selimgencoglu View Post
My lambda sensor has also been replaced with a genuine BOSCH one...but still I have this erratic problem. I am sick of it. Sometimes the engine stalls in a parking lot..sometimes at the speed bump.. It is becoming really dangerous.

I will clean the throttle body again, but I think the culprit is the small stepper motor on the side of the throttle body.
Does anybody know if I could get only a new stepper motor without buying whole throttle body..?

All the best.
Hi,

what I have found is that when you replace lambda sensor you HAVE to clear errors AND reset self-adaptation engine settings with alfadiag or fiatecuscan, then keep it idle for couple of minutes and then give it a good trash for a few miles.

For me there was no difference after replacing the lambda sensor but resetting adaptation did the trick.

Sometimes you may need to do this couple of times. For me after the first reset it was nearly fine, then I did another one and I left my car idle for 15 minutes and then went back home. On the next day my revs were at about 2000rpm all the time so I reset it once again, left for 5 minutes and then drove about 2 miles changing gears at 5-6 rpms. Now it's just perfect.
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Maverick / Marlon - you are my heroes!
I've been plagued by the wonky idle for about a year. Had several things changed on the car in an attempt to sort this but the problem always comes back.
Done the snip tonight, [mines a '98 156 2.0 TS] Minor problem in that I couldn't actually see any labels or numbers at all on the wire blocks attached to the Speedo, going on Pete McK's advice I cut the green/white one from the larger plug. [Leap of Faith]

Anyway, been out for a spin, idle drops to maybe 600 but then sits at 850/900 rock solid. I can't believe how happy I was driving once again where I don't have to worry about it stalling!!

Will post again in a week or so to give update. - Oh and someone asked if anyone had monitored MPG pre/post snip, I've been calculating mpg's for the last three months on mine so will update that too at somepoint.

Just a real thumbs up to M&M for this desperate yet amazing fix!!
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If you snip wouldnt it causes a speed sensor code fault in alfa diag.

Last edited by CroBaron; 26-07-11 at 22:40.
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Any body know how to cure a bouncy revs when cold problem?
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If you snip wouldnt it causes a speed sensor code fault in alfa diag.
From what I can remember having done this to my first 2.0 TS
Nope, no fault code, no engine fault (injector) light. Just a steady idle
 
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From what I can remember having done this to my first 2.0 TS
Nope, no fault code, no engine fault (injector) light. Just a steady idle
Must be specific to certain model!
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My problem

Hi guys,
Ive used this forum for a while and its helped solve a few problems ive had but this is my first post as a cry for help.
A couple of months ago whilst sitting parked with engine running it just cut out after about 5 mins. This has happened again a few times since. The car always started straight away though.
Worryingly for the first time yesterday whilst driving, i was coming up to a set of lights and the car cut out, im pretty sure it was when i dipped the clutch. Even worse it would not start again. it would turn over fine but wouldnt start. After being stuck in the middle of the road for about 2 minutes it started and off i went. i pulled over further up the road and sat there for 10 mins with the engine running and it cut out again, although this time it started staright away.
This morning i decided to start it and leave it running to try to find out more about why its happening. so i started it when cold, it started fine and sat idling at about 1100-1200 as always and as it warmed up its dropped down to around 800-900 as usual but after a while at this it sounded like it dropped then it cut out, started staright away again.
its only ever not started the once when i was in traffic (typical) and that was the only time it ever cut out too. but it predictably seems to do it everytime i sit idling for a while once its warm.
i have thought about this snipping the cable but my idle does not seem to bounce around.
Any help would be great and sorry for the long post
Dan
Car is a 1.6 156 ts. 2002 80k miles

Last edited by dahmet501; 16-10-11 at 14:33.
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Crank sensor

Quote:
Originally Posted by dahmet501 View Post
Hi guys,
Ive used this forum for a while and its helped solve a few problems ive had but this is my first post as a cry for help.
A couple of months ago whilst sitting parked with engine running it just cut out after about 5 mins. This has happened again a few times since. The car always started straight away though.
Worryingly for the first time yesterday whilst driving, i was coming up to a set of lights and the car cut out, im pretty sure it was when i dipped the clutch. Even worse it would not start again. it would turn over fine but wouldnt start. After being stuck in the middle of the road for about 2 minutes it started and off i went. i pulled over further up the road and sat there for 10 mins with the engine running and it cut out again, although this time it started staright away.
This morning i decided to start it and leave it running to try to find out more about why its happening. so i started it when cold, it started fine and sat idling at about 1100-1200 as always and as it warmed up its dropped down to around 800-900 as usual but after a while at this it sounded like it dropped then it cut out, started staright away again.
its only ever not started the once when i was in traffic (typical) and that was the only time it ever cut out too. but it predictably seems to do it everytime i sit idling for a while once its warm.
i have thought about this snipping the cable but my idle does not seem to bounce around.
Any help would be great and sorry for the long post
Dan
Car is a 1.6 156 ts. 2002 80k miles
That sounds like the crank sensor (also known as RPM sensor) starting to fail. If you can get the fault codes with a scanner it could confirm that.

Cheers!
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I would agree that this is most probably a failing crank sensor
Had the same issues - engine would stall when warm and idling for a while.
Its a quick and (relatively) easy job to replace the crank sensor.

I did pick up the errors with alfadiag though, so it would be a good idea to check that first before you go ahead with the replacement.
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Cut Or Not To Cut...

Sorry to bring up this thread again but I am coming to the end of my teather...

I have been having the wonky idle for some time now, some days are ok but recently it has been getting worse.

I am contemplating snipping the wire but unsure which one to cut???

Earlier on this thread it says green+white but I read later green+black???

Please can someone confirm which one it should be?

Car is a 156TS 1.8 1999.

I've taken some photos, hopefully this will help
Attached Images
File Type: jpg idle1.jpg (50.1 KB, 21 views)
File Type: jpg idle2.jpg (50.6 KB, 19 views)
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Sorry to bring up this thread again but I am coming to the end of my teather...

I have been having the wonky idle for some time now, some days are ok but recently it has been getting worse.

I am contemplating snipping the wire but unsure which one to cut???

Earlier on this thread it says green+white but I read later green+black???

Please can someone confirm which one it should be?

Car is a 156TS 1.8 1999.

I've taken some photos, hopefully this will help
Its the green and black wire
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Definitive solution!

Hi guys,
Iíve been willing to write this post for a long time. Sorry for not doing it sooner.

I got rid of the bouncing in my car for a long time now and I can confirm that the definitive solution is to flash the ECU with an updated map file which corrects this annoying idle problem. I have searched for a ďcureĒ for many years and although I had found a relief after cutting the ABS wire, I was never completely satisfied with it, as cutting the ABS wire gave me other problems like DTC errors and an almost stalling low idle.

This is what I found out: Alfa Romeo had already identified this problem back in February 2000 and had issued a bulletin to the dealers all over Europe with instructions on how to fix this problem and what engines and chassis numbers were affected. The dealers also received a couple of floppy disks with the updated files for each engine and version. They also received self adhesive labels to identify that the ECU had been updated.

After flashing my carís ECU with the new file it stopped bouncing completely. After reconnecting the ABS wire that I had cut, the idle is perfect and never bounces. Itís like a completely new car!

I think the idle problem was related to a special feature that the 156 TS ECU M1.5.5 has. When the car is warmed up and not moving the ECU tries to keep the idle at 840 RPM, but when the car is moving (and the ECU knows the car is moving because of that ABS wire discussed here) it keeps the idle a little higher, at around 1050 RPM. This is probably to prevent a dangerous stalling when you turn the wheel or the AC compressor kicks in while driving. When the ECU detects the car is not moving anymore, it lowers the idle down to the 840 RPM again after about 2 seconds.

For some reason, this idle control feature had a bug in the original map file causing the idle to bounce up and down while the car was moving with the clutch depressed. Cutting the wire kind of fixed the problem as it would make the ECU think the car is not moving and so it would try to keep the idle at 840 RPM every time you disengage. But 840 RPM is a bit too low in some situations and could be dangerous.

So, my advice is: take the car to a dealer and have the ECU software updated.
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If they knew about this bug would they flash it at dealers free of charge? If not how much would a reflash cost? Would angel tuning be able to remap with simular effect!
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Dealer x Remap?

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If they knew about this bug would they flash it at dealers free of charge? If not how much would a reflash cost? Would angel tuning be able to remap with simular effect!
The dealers did not charge at the time, but I'm not sure if they would charge now, 10 years later. I guess Angel Tuning should be able to deal with it, check with them.
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My wonky idle seems to be better sometimes with air con on!

Last edited by CroBaron; 08-03-12 at 17:20.
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