156 stalling under slow speeds

Cool, thanks Jug, I thought it my copy of elearn seemed a little erm... rustic!

Replaced the spark plugs now, which were well past it, and acceleration is noticeably smoother, although the stalling is still there.

I'll check out the idle speed actuator soon and let you know how it goes. I know there's alot of information on here about the idle actuators so I'll read up before asking any questions.

A mate down the pub just suggested to me something interesting though that I would love to here your feedback on.

He suggested to me that the problem might well be vacuum related? He said how something called a "Plenum valve" might well be where the problem lies. He was going along the lines of there being a either a perished rubber pipe or seal around the area of under the inlet manifold or throttle body that might have gone.

He said he had seen a Vectra and an Alfa both into the same garage with the same symptoms as mine, replacing all the usual failing points, and end up being this Plenum valve being the failing point???

Would really appreciate your opinions on that new angle of solving my problem, and as you now know my elearn CD is buggered, could somebody please give me a clue on where to inspect this valve and what it looks like?

I really do appreciate all your patience here guys, as I am a complete noob to car mechanics and this is my first experience in anything like this. But I am enjoying getting more confident and experienced with every day spent oily, so I can only thank you all again!

I'm also feeling my way towards similar thoughts on the manifold being leaky / suspect on mine. The manifold is a bar steward to get at. Theres a black plastic barrel device on the LHS (as you look down at the manifold) with a 2 pin connector attached - this could be it.

If you pull off the connector with the engine running and then reconnect it theres a linkage underneath that activates. Mine has a loose rubber something - possibly a seal - moving around on the linkage as if it's fallen off/out. You can't see any of this you can only feel it with your finger tips. It needs an Octipus Mechanic or the whole manifold off - nightmare. This also applies to tracing the 4 pressure tappings behind the throttle body.

I'm coming to the conclusion that I am going to have to take the manifold off mine to rule it out once and for all. Day off work job which may involve rebuilding again to fix any faults found. I'm getting my bike MOT'd before I launch into this.

Any advice from the panel about manifold removal ?

I agree about your exhaust especially if it's a small leak downstream of the lambda sensor. Don't think injectors or fuel pump are iffy as yours goes well at maximum fuel demand as does mine.

Yeah cool RT, I think we should go down the same route for investigation.

Please post your progress of the job as you do it though as I'll be needing all the tips you can give me! I'll do the same from my end too.

I think I'll start mine tomorrow (Wednesday 14th) when I have a whole day ahead of me.

Yeah the performance of my engine is spot on. The 2.0l tspark 156 is supposed to have a top speed of 134mph, and I have no doubt mine will get there as I can already hit 130mph with 3 riding along pretty easily and whenever I need lol.

I'd like to try patching up my exhaust, as from what I've inspected, there's only a small leak in the back box but the whole exhaust is a hard thing to inspect without good clearance under the car which I don't have.

So reiterate RT's request, can anybody help us out with manifold removal tips? I would greeeeeeatly be forever grateful if somebody would post a few jpegs off there elearn CD of any diagrams! Thanks

Theres still a few basic things I want to bottom out with mine before embarking on the major surgery of the manifold. These are;

1. Last night I disconnected both of the blue hard plastic push on pipe connecters on the LHS of the engine bay (looking in) next to the shock mounting. I think these are the in and out lines for a cannister on the fuel tank breather line that reduces petrol vapour being released to atmosphere. If there is a problem with the cannister the fuel pump will be sucking against a partial vacuum. The blue pipes disappear into the front wing - neighbour reckons the cannister is accessed through the wheel arch but I can't see anything to take off.

Anyway disconnecting the connectors means your tank is now vented direct to atmosphere (if i'm right ?) and this seemed to imporove mine on a test drive last night . However I have said this before only to be disappointed again . My faults seem vary with weather, pressure and temperature (A66 summits was worst ever) suggesting air leaks, manifold etc...

2. I also adjusted the throttle stop screw until it just contacts the the throttle arm with the engine idling ie. it only stops the throttle arm dropping below it's normal idle position. The screw isn't the idle speed adjuster - you can prove this by turning it out until it's no longer doing anything - the idle speed won't change.

3. Still haven't found the fuel filter despite my thread Q? I have an e-mail out to grant69 who has done his will let you know ?

New plugs ? how old are the plugs in your car ?

RT has already replaced the plugs on his car. He has done all the same things I have replacing the MAF, Lambda, crank sensor, spark plugs all with no joy.

Yeah it takes a proper town drive really for a real test drive of whether the problem is cured. I think I'm gonna order a new elearn CD from a better seller than the one I bought from ebay.

I had an inspection all round the manifold on wednesday with the engine on to inspect for air leaks/cracked pipes to suggest a vacuum problem, and I couldn't see squat really.

Although??? If my hand was wet, maybe I would feel the air leak more sensitively.... hmm

Access is very limited without moving the MAF and its vent pipes, and from the other side access is not available at all. I think I'm gonna have to jack it up as high as I can to get my whole arm in round the back of the manifold to really have a good grope around. I *think* this is gonna be impossible though, as my arms could only just reach the crank sensor, and the manifold is higher than that??

Am eager to learn of your progress with adjusting the throttle idle position though RT, so let us know mate!

Again only intermittent improvement from my last 2 fiddles.

I haven't done my crank sensor yet and still no reply to the fuel filter location. Mines now 127k so if there is a fuel filter and it's never been changed then it's still a good possibility. Basic maintenance of all renewables is half the fight with fault finding.

I am puzzled by the purpose of the 'idle' screw and am not convinced that it is actually intended as an adjuster (see Gazza82's web site). This is because mine idles perfectly with daylight visible between the throttle arm and the stop screw. It also idles perfectly with the idle actuator taken off the side of the throttle. This suggests to me that there is an idle air supply that bypasses the throttle. My latest question on my thread asked if anyone knew what the 4 pipes just behind the throttle body did - one of them could be just that.

Access to the underside of the manifold is also nigh on impossible even with the throttle body taken off. I suspect the engine may be fitted from under the car with the manifold in place.

Remember mine drives perfectly below 3000 rpm and problems only exist above this so our faults may not have the same origin.

PS

By the way - the 'idle screw' isn't the idle adjuster. I just wanted to make sure it wasn't making the fuel injection think I was pressing the pedal when I wasn't ie. you need a small gap at idle to ensure this. Not sure why it's even there at all ?

Have you read the latest on 'Kangarooing 156 - now desperate' - very interesting stuff about that black device on the LHS of the manifold - apparently it's a variable manifold actuator.

Originally Posted by rt05492

I'm also feeling my way towards similar thoughts on the manifold being leaky / suspect on mine. The manifold is a bar steward to get at. Theres a black plastic barrel device on the LHS (as you look down at the manifold) with a 2 pin connector attached - this could be it.

If you pull off the connector with the engine running and then reconnect it theres a linkage underneath that activates. Mine has a loose rubber something - possibly a seal - moving around on the linkage as if it's fallen off/out. You can't see any of this you can only feel it with your finger tips. It needs an Octipus Mechanic or the whole manifold off - nightmare. This also applies to tracing the 4 pressure tappings behind the throttle body.

I'm coming to the conclusion that I am going to have to take the manifold off mine to rule it out once and for all. Day off work job which may involve rebuilding again to fix any faults found. I'm getting my bike MOT'd before I launch into this.

Any advice from the panel about manifold removal ?

I agree about your exhaust especially if it's a small leak downstream of the lambda sensor. Don't think injectors or fuel pump are iffy as yours goes well at maximum fuel demand as does mine.

That valve you speak of is the mainfold length valve, it should activate around 3000 RPM, but all your problems sound like a TPS/IAC to me.

Hate to mix threads but... I have a terrible kangaroo problem that I have been trying to track down for 7-8 months now! Randomly tried clamping the vacuum hose to the variable inlet manifold half way home tonight and flippin heck I may have found my problem. So if you suspect an airleak just clamp the vacuum hose to the variable inlet manifold its an easy test. The other thing of course is to clamp the vacuum hose to the brake servo, but you have to be a brave (re:stupid) man to go for a run afterwards as you will have very little brake power. I havent dared try it personally and I dont advise you to unless you know of a very controlled environment you can use without crashing, I dont have one here.

To Doc G - mixing threads is the only way get those of us unfortunate enough to have real problems onto new ideas and suggestions and help our sanity. By clamp the hose - do you mean the small one that goes into the top of the cap or is there another one underneath ?

To Smaky

Assume TPS means throttle position sensor - not sure there is one on 98 TS's, I think they may have come later ? If true, it could only be the same electronic device as the idle actuator and I don't think it's possible to combine these 2 devices electronically. Plus the idle actuator only puts a bias onto your foots throttle butterfly position for cold starting and to stop stalling when the revs die ie. it can only put a positive bias on your own throttle position - it can't make the revs drop or stutter. Iv'e proved this to myself by running mine with the idle actuator still plugged in but taken off the side of the throttle body - made absolutely no difference at all, blah blah,

What does IAC stand for ? Please don't say idle actuator control

Sorry StevenJW for hijacking your thread again but it got us some fresh ideas !

[quote=rt05492;1809970]To Doc G - mixing threads is the only way get those of us unfortunate enough to have real problems onto new ideas and suggestions and help our sanity. By clamp the hose - do you mean the small one that goes into the top of the cap or is there another one underneath ?
QUOTE]

Yes clamp the thin rubber hose going into the top of the cap. Thats what Ive done. All it will do is alter that the variable inlet manifold no longer works. Have you checked also that the EVAP system with its actuator is working? Disconnect the blue pipe at the side of the variable inlet manifold actuator after you have been for a decent drive (dont stop it and leave it idling), you should get a phut-phut vacuum on the union you disconnected the pipe from.

Nah nah, its fine. Was going to get back to this thread anyways as my problem seems to be getting worse. It's stalling more frequently now, and just after startup, sometimes it runs like a dead dog like for a couple of mins as if its not getting enough fuel in the engine for some reason. No throttle response is available at all and its sounds like its going to stall. I think I may have blocked injectors from that, but I think that is more to do with me running the car with so little fuel so often.

The idle is also alot worse too, with the idle constantly bouncing off the point of stalling, its very frustrating, as that idle problem is ALOT worse now.

You guys have provided interesting insights for me to try though, as until I get a proper e-learn/decent manual, I won't be attempting to remove the inlet manifold for inspection as looks like a MISSION for someone as inexperienced as me.

I had the same problem with the idle cycling from nearly stalling back to 1500 rpm and then back again but it was me that had caused it while fault finding. I had managed to disconnect the lambda valve sensor plug and not re-connected it. As soon as I realised and re-connected the plug it was cured.

You can also test whether it's the idle actuator by taking it off the side of the throttle body and then driving the car with the connector still pugged in (keep ECU happy) - has never made nany difference to any of the faults on mine.

This manifold actuator stuff may be getting me close to my cause at last. I had a good look and listen to mine last night and theres a definite chattery air leak noise coming from it as well as the dangling bit of invisible rubber (your mate from the pub may have been right about mine). Then rain stopped play - but I am going to dismantle mine tonight. See new instructions on the latest threads of 'Kangarooing 156'.

If your manifold actuator is stuck in the high rev position it could be why yours stalls when the revs go down but goes like stink above 3k.

Originally Posted by jug

hang on a minute, i've just read the original post for the first time, cutting out when warm is almost always the crank sensor.

Almost but not always, try the reset, if not, swap the TPS and reset again.

Cool.... well I did replace my lambda sensor so I'll go back and inspect my work again to see for any thing obvious, as the heat shielding was a little small I remember.

Thanks for the point in the direction for the Kangarooing 156 though!

Getting the injectors out is easier than you would think. Getting the petrol out of the fuel rail without torching the car is the hard bit. There's a valve on the end of the fuel rail you can crack with a nail and catch the petrol with a rag or crack the connector above the fuel rail. You really should do this with the engine cold - watching petrol vapour hiss onto a hot engine is an underpant filller believe me !

Once you've drained it disconnect all the wiring harnesses. Unscrew and release every thing step by step - no harder than doing the plugs really. Once you get the injectors exposed they are just sealed in with o-rings which can be a bit sticky. Spray WD in and wait and wiggle and they will pop out with a moderate pull. Not much to see just a very small hole in the top which will either be obviously blocked with gum/crap or not. You don't actually need to take them out as you can see the small hole in the top once they are exposed. Only sure test is to swap out and test drive. I think I checked Alfa and they wanted £120 each ! Mine were all 100% clean so I filled the fuel rail with Redex and put it all back together ... and yes you already guessed no difference at all to anything.

Another word of caution. You must completely re-assembe the whole lot - don't be tempted to re-start the car early to see if it's worked. The injectors are sealed by the o-rings but they are held inplace by the fuel rail pressing them in. If the fuel rail isn't fully screwed back in place it's another full undies job. You only learn the best stuff the hard way.

May be a worthwhile exercise for you even if it only eliminates a possible cause. I'm still working on this manifold actuator because of the 3k coincidence - mine stutters at 3250 rpm. Also looking into the EVAP system and actuator as hinted by Doc G - email query on whereabouts of this stuff currently with Doc G ?

Originally Posted by rt05492

May be a worthwhile exercise for you even if it only eliminates a possible cause. I'm still working on this manifold actuator because of the 3k coincidence - mine stutters at 3250 rpm. Also looking into the EVAP system and actuator as hinted by Doc G - email query on whereabouts of this stuff currently with Doc G ?

Check you email mate

I also dismantled injectors and cleaned them in an ultrasonic bath - one of the cheap jewelley ones you can buy with injector cleaner as the liquid. Oh what a difference, but I still have a kangaroo

Thoughts on the EVAP system.

I disconnected the blue plastic pipe at the back of the manifold and plugged the hole in the mating metal pipe that runs down underneath the manifold somewhere (presumabaly it runs into the manifold via the solenoid controlled EVAP valve). Surely with the pipe plugged it means the manifold is now sealed and the valve can open and shut (or do nothing) but should not be able to affect the manifold vacuum ?

A test drive showed no change to my stuttering at 3250 rpm on a light throttle. This logic is enough for me to rule the EVAP out of my enquiries.

Anybody see any flaws in this logic or know better ?

I'm working on the assumption that the EVAP valve opens the metal pipe to the manifold vacuum which draws the vapour from above the fuel in the fuel tank through the carbon can in the wing and and then into the manifold if theres any left ?

I also checked the whole length of the fuel and vapour lines for being trapped or kinked and found nothing amiss.

yeah you've ruled out the fuel vapour system.