156 stalling under slow speeds

hey guys. just read whole thread, had lots of probs with my V6 idle few years ago. Alfa diag will show lambda output so you can see if its working right or not (lambda websites will show what type of output signal to look for). "Plenum" is the funny shaped box on the air intake but basic theory is as Jug says above - any air leak on intake post-MAF will give funny idle as more air gets in than the MAF reads.
V6 has no idle by-pass, electronic control of butterfly for idle. gunk on my throttle valve was culprit, lots on the engine side I only saw when took it off the engine.
Have read lots on the TS idle actuator and the by-pass valve (black plastic vac pipes with a bigger dia. part in connected around throttle / intake) elsewhere o this forum. Think they're pretty cheap.
I'd recommend a thorough inspection of throttle valve, idle atuator and vac hoses / valves.

Sorry if you've done all this but just spent 20minreading thread and wasnt clear to me, so maybe something might spark a thought. Good luck guys.

No no, that's all good Burnsy, I do need to give that area a good old inspection just to rule it out. I'm just trying to find the time to work on it that's all. I'll probably give it a good old clean with a toothbrush and petrol or something and get it all spangly clean so I don't encounter any of those problems later on too.

I'm pretty sure all the ducting post MAF on my car is clean and crack free, but I'll have to clean it up really to get a good inspection on black plastic.

I ruled the variable inlet manifold actuator out on mine. If you take the 'lid' off the actuator pot you can pull up the arm and wedge it it the up position - made absolutely no difference to mine.

How's yours Steven JW it's been quiet for a while ?

Hmm so so.

I got a new job a few weeks ago, and the regular running and clean petrol does seem to have reduced the stalling a massive amount. I've run some injector cleaner through, and popped some of Tesco 99 octane petrol in today, but my exhaust is blowing quite badly now, and that needs to be addressed very soon, as the MOT is up very soon, so once that it fixed, I will be able to rule out back box pressure.

I never got round to checking for any vacuum leaks unfortunately. As I'm still adjusting to this new job, the last thing I wanna do is screw up my baby on the Saturday, bricking myself about it on Sunday, and having no car to use Monday.

I'll have a probe around, but I'm thinking I might just take it to an Alfa specialist. I just wanna find one that won't mess me around trying all the obvious things, despite my receipts and word that they're all brand new, as then the labour charge will just be obscene.

Iv'e just had some success with changing my fuel pump unit (see my thread). Might be worth a try (Alfa prices will be staggering I would recommend finding a low mileage one in a breaker) ?

You can take the regulator out of the unit and change it - it has a Bosch part number which you can get from plenty of places other than Alfa.

Ok, so I just replaced my back box and centre pipe, and if anything it has made the stalling worse!!! I'm getting so sick of my car right now, I just can't stand the stalling.

Oh my god, it actually stalls EVERY single time now I try and slow down to a stop, or go slow enough in 2nd gear speeds. Its down right dangerous now, but the way it stalls now (eeeevery time) is kinda consistent with a part that had finally given up the ghost?

Does the idle actuator physically wear out? I have no idea what one looks like, but I'm so desperate to stop the stalling I just need a solution now.

I'm ready to fork out some money to replace my idle actuator, but from what I've read the idle actuator only really makes the idle unstable, and not really stall. The idle is ridiculously unstable, never settling, but all I want to do is stop the stalling!!!

PLEASE HELP GUYS I'M GOING OUT OF MY MIND!!!

recap: replaced MAF, Lambda sensor, crank sensor, spark plugs, mid section and back box, spark plug leads, and a diagnostic done.

The diagnostic wasn't done by Alfa, but I don't know what difference that'd make??

Looking back at your post no. 6 - when you say the HT lead was changed - did you mean just the HT lead or the square block coil and plug cap for the 2nd spark plug that fits into the underside of the coil.
If the HT lead was damaged it could have damaged either as well - the coil is most likely. Poor sparking tends to manifest itself at low revs when the alternator output voltage drops - however it is normally associated with stacatto misfiring before stalling.

If you don't have a misfire ie. it just dies, then the idle actuator is a likely cause. Iv'e driven mine with the actuator taken off the side of the throttle body (but still plugged in) and as well as losing the cold fast idle (bugger to get going), when warmed up I got exactly the same stalling as you but only when the revs dropped to about 2k would it die completely.

The actuator is the smallish black plastic box on the side of the throttle body held on by 3 torx bolts. I seem to remember it has a 10 digit Bosch number so you get get one anywhere including one from a breakers. Theres a few specialist Alfa breakers on the web, the one in Chesterfield seems OK.

See Gazza82's web site on how to change it out.

hmm.....

I hate to be over cautious, but it seems as if my stalling is fixed?

I ordered a new Idle Actuator from eb, (brand new at £95) my brother fitted it and it appears to be fixed... My idle is rock steady, yet too high at nearly 1100rpm.

I'll try resetting the ECU, but I heard from EB that the ECU sometimes needs a manual reset, as if its been running to long with a faulty Idle actuator the learning ECU can get stuck in its setting?

Wow, well, I'll post back in a week to report on if my problem comes back.

It seems weird my problem was made so much worse after I fitted my brand new exhaust, which would really correspond with a sensor misread/failing. Even the guys at EB said it was weird for a failing actuator to cause stalling, but I guess it if was 100% failing, it could have caused the stalling, even if it was worn just right to cause the intermittent stalling? Strange, there are times in which its stalling behaviour just doesn't correlate with a mechanical failing of a worn part, but hey, that's Italian for you I guess?! lol

I must say though, the standard exhaust sounds fantastic? I don't know why anyone would want to change it on the 2.0ltr t-spark. It has a nice deep burble that sounds tight and it even pops a tiny bit on lift off? - fantastic? Its even got a nice chrome wide exit tail pipe that even looks aftermarket? Now all I have to do is fix my exhaust shielding and it makes a horrid cheap rattle!

I would say a ECU reset is advisable...

The ECU's main function is emission control, it will alter the parameters of the engines running on the values given by its senors. If the parameters given to the ECU are not accurate then the ECU will alter another output to compensate untill the desire output is achived.

If these parameters stay like that for as little as 15minutes the ECU will or can adjust itself out of recoverable range, then an ECU reset is require...

What i am saying is that the ECU is use to the faulty actuator and has learnt to live with it...

If i'm talking out of my A**e please re-educate me

Excellent, sorted then. . I tried a complete throttle body and actuator change on mine - made no difference.

I don't blame Alfas for these irritating and expensive component failures. I think everything Bosch is over rated and they have just fallen into being the only engine management system manufaturer by luck and lack of competition rather than survival of the fittest or best. The over complexity and built in obsolecense can partly be blamed on the the enviromental neurotics.

I agree with Biffa on the reset, I think an ECU reset is recommended after changing out any of the sensors/components on the engine.

If that doesn't work you could check that the small grub screw on the throttle arm hasn't been wound in too far causing a fast idle. The idle speed seems to be controlled by the ECU and the idle actuator, so you should have small gap between the grub screw and the throttle body with the idle speed in the dark band below 1000 rpm. ? Do it with the engine fully warm.

Well it definitely is a learning ECU, as the fast idle has now settled lower at around 900rpm, but its starting to sit properly at 850rpm at times, and with its behaviour I think it should return to normal.

If I am not satisfied with the results I will give it another reset and wait and see whether it needs a manual reset.

Hi, are you yet satisfied with the performance of the car?
I have (or had, i hope!) the very same problem.
I also drive the '99 2.0. The problem has been now for around three weeks, coming and going.
And like you say. When the engine is warm, at low revs, like driving in town it could be a real pain to drive, but out on the roads it's a little to nothing.

Today however, I decided to install a new MAF, like mentioned several times in this and in other threads. And when doing that I had to take a closer look to the hose between the MAF and the air intake on the engine (as in picture).
It was wired with duct tape, done temporarily at a garage one year ago because the service guy found a "crack" in the hose.
Today, unveiling the duckt tape, we found the "crack" had grown to a large hole stretching across the whole underside of the hose.

We rewired the hose, this time with electrical tape, and O M G now she runs like a dream!

We also changed the MAF, but I will replace the old one tomorrow since I'm pennywise and didn't buy an original Bosch. Or I could now use the £170 I saved to get another hose.
I really hope now that this was the problem and that she'll stop hazzeling me.

Weird... today, after a week of perfect performance, she stalled on me on the crawl into my drive way....

I'm hoping this is just a glitch and a one off, as I think I'd seriously consider selling the car if this problem returns, as there's no possible reason it should come after being 100% cured over the last week or so and EVERY common problem part being replaced now.

My car has also started stalling.

Today it stalled just outside a garage, and they even had the time to work on the car immediately - and we got a rental car to use for free while they are checking the car.

Tomorrow we will get the suggestions they have after running diagnostics, and I am afraid they'll start a similar hunt as you have done here.

The car has some dents, it is a bit rusty, I have not been nice to it - it is behind on service and it has run too low on oil several times, so I think if it is too expensive to fix, I'll let the car rest in peace.

The symptoms goes like this:
* After running for some time (15 to 20 minutes) the car stalls
* It has only stalled while running at slow speed
* It feels like the fuel supply has been stopped
* The "Injection"-light shows when the problem occurs
* After some time (about 10 minutes) it is possible to start it again

After reading this thread one impression is that then it is the "crank sensor".

My question is - are my symptoms the same as you have been experiencing?

The thing that is most unclear to me is if your car(s) start again immediately or if you have to wait for a time, like me.

Regards,
Harald

Originally Posted by haraldb

My car has also started stalling.

Today it stalled just outside a garage, and they even had the time to work on the car immediately - and we got a rental car to use for free while they are checking the car.

Tomorrow we will get the suggestions they have after running diagnostics, and I am afraid they'll start a similar hunt as you have done here.

The car has some dents, it is a bit rusty, I have not been nice to it - it is behind on service and it has run too low on oil several times, so I think if it is too expensive to fix, I'll let the car rest in peace.

The symptoms goes like this:
* After running for some time (15 to 20 minutes) the car stalls
* It has only stalled while running at slow speed
* It feels like the fuel supply has been stopped
* The "Injection"-light shows when the problem occurs
* After some time (about 10 minutes) it is possible to start it again

After reading this thread one impression is that then it is the "crank sensor".

My question is - are my symptoms the same as you have been experiencing?

The thing that is most unclear to me is if your car(s) start again immediately or if you have to wait for a time, like me.

Regards,
Harald

That would say to me "CRANK SENSOR!!!", about 40 of our Scotish pounds (55 euros) to replace the sensor.

Sorry for hijacking the thread, the guy at the garage told us that the diagnostics shows the "injection valves" are defective (translated from norwegian term "innsprøytingsventiler").

Is this plausable? I think it is plausable that there may be problems with the valves, but are the symptoms consistent with this problem?

Regards,
Harald.

Injection valves are very expensive to replace new. I have just had mine tested and cleaned, huge improvement in performance afterwards. 3 of the 4 were showing very bad spray patterns with 1 of these almost not working at all. After cleaning they are all showing good spray patterns again.

As to whether its the cause of your fault I am not able to say, fortunately I've never had a stalling problem (just major kangaroo).

I recently had a stalling problem that was getting more frequent.
Took the car to a local mechanic (not Dealer) and he cleaned the injectors for £30.
Still early days (4th day since cleaning) but so far the car is performing like new .

Hope this helps someone.
Phil

Originally Posted by Doc G

Injection valves are very expensive to replace new. I have just had mine tested and cleaned, huge improvement in performance afterwards. 3 of the 4 were showing very bad spray patterns with 1 of these almost not working at all. After cleaning they are all showing good spray patterns again.

As to whether its the cause of your fault I am not able to say, fortunately I've never had a stalling problem (just major kangaroo).

So Doc, did the injection cleaning help the kangarooing at all ?

Originally Posted by rt05492

So Doc, did the injection cleaning help the kangarooing at all ?

Unfortunately not. On the positive side performance is awesome with very fast responsiveness, so if I can just fix the kangaroo she will be amazing once again.

Did you change the TDC sensor? The reason I ask is that Im sure I saw my RPM gauge bouncing tonight on the way home as if it was being impacted by a noisey measurement.