Stalling VR6 is now being fixed (I hope!)

[Domi 0]

Hi Guys

 

Can't find my original post to add to?! Anyway, took to a VW garage and they have diagnosed (alledgedly) as coil and fuel pump problem. It was getting very bad and as agreed by all, quite dangerous when it stalls and the power steering goes!

 

Going to be quite expensive! But am hoping will be a happy Corrado at the end of it! Just hope they are not ripping me off, disadvantage or being female and not engine savvy. :(

 

Anyway, thanks for all your advice and will let you know how it is running when I get it back. Missing it already!

 

Domi

[Kevin Bacon 5]

That's good news.

 

Know what you mean about missing it. I've been without mine for 5 days now and I'm getting withdrawl symptoms.

 

Wanna swap invoices? I reckon yours will be fractionally cheaper than new timing chains, clutch & cylinder head :x

 

K

[Henny 0]

5 days? phhhhh! lightweights... ;)

 

I don't ever want to be without my 'rado for that long again though...

[Domi 0]

Hiya Kevhaywire,

 

Yes, can imagine yours will be somewhat more expensive, saw on another post that yours is at Stealth (right?).

 

I wanted to take mine to Vince, but driving it with stalling problem from Reading to somewhere in Warwickshire sounded like a nightmare! So decided I will get this problem seen to locally and then take a run up in the not too distant future to let him have a look at it and see if everything else is ok on it.

 

Are you local to Stealth, or do you all drive from all over the country to go see there?

 

So what is this "coil" they want to replace, I am sure I read somewhere else in here that they don't usually need replacing? The fuel pump sounds right, but do you think coil is likely too? I am just trying to establish if I should question anything, in the hopes that if I seem somewhat knowledgeable they will be less likely to take advantage and fix, change stuff that does not need changing.

 

As always, thanks for your advice! :)

[vr6storm 0]

it'll either be the coil-pack or they could be meaning the little immobilser in the steering column,that reads off your ign key......as ive heard this described as a "coil" too

[Domi 0]

Thanks vr6storm, but what would that have to do with the stalling? Or do you think it is just another problem they picked up on the VAG-COM? Guess I should have asked them really, it is just that they mentioned it in conjunction with the fuel pump so I assumed it was related.

 

And btw, what is with the immobiliser on the steering column, I noticed it, but don't see how it would work, not that it matters since it is equipped with separate alarm/immob, but curious all the same.

[dr_mat 0]

You're based in Reading too? What colour is your VR? Maybe I've seen you about?

There's a coil that sits inside the steering column, near the ignition switch, that reads the RFID tag (equivalent) in the key - if the key transmits the right code back to it, it unlocks the ECU and the car will run. If not (i.e. wrong key or no key at all), the ECU will kill the engine and prevent the car from being driven.

This is exactly the kind of thing that would show up on VAG-COM.

These things are common failures on pretty much ALL the cars they were fitted to, after a few years of use and abuse.

Where did you take the car to, btw? Ridgeway (I hope not!)?

[Domi 0]

I work in Reading (well just outside at Thames Valley Park), live closer to High Wycombe so it has gone to Rye Mill in Hi Wy. Hope they are good (fingers crossed!)

 

Mine is M Reg Aqua Blue, but I have only had it three weeks! Will keep eye out for you too !

[benson 0]

Phew! Nightmare keeping up with all these threads on sunroofs and stalling.

 

Domi - be good to know if you get the stalling sorted, as have been wondering about fueling on mine. Being a 94 it hasn't got the column immobiliser, but not sure she's ever had a new fuel filter either.

 

Dr Mat - any clues on what's supposed to happen in the VR's fueling when you hit the clutch at a roundabout and hence what may be playing up?

 

G.

[PhatVR6 0]

For the coil AND the fuel pump to be diagnosed as dodgy, I'm suspect the ignition swithc or ECU relay.

[dr_mat 0]

benson, not really.

AFAIK if the throttle valve is shut, the idle valve should open to allow air into the engine, but if the engine is on the over-run program (i.e. zero throttle and engine coasting in gear above idle speed) then it will put little or even NO fuel into the engine, so the ECU has to spot that the revs are dropping when you dip the clutch and catch it by pushing some fuel in.

I think it's worse if you drop the revs to around the fast-idle speed before dipping the clutch. It has always seemed to me that it's more predictable if you dip the clutch earlier, so letting the engine drop from e.g. 2000rpm+ , instead of 1300rpm.

That's just my observations of the occasional hiccup from mine - but mine hasn't really ever stalled, just the odd close call.

[benson 0]

Dr Mat,

 

Yeah - spot on same with mine - if I'm trying to demonstrate the cut-out to someone, it's a hell of a lot more likely to occur if I wait until the absolute last moment during an in gear junction approach before dipping the clutch. Seems to confuse it less if I dip from 2000rpm or so. I knew there was a purpose in VW making an auto version!

 

Still - what conclusion does all this DIY diagnosis lead to?

A slow to react ECU (low voltage from a duff battery? High resistance old wiring looms and connectors blocking the signals?) or something else?

Not sure what to check on the fuel side - does the engine buzz the actual fuel pump when it detects no throttle and in gear deceleration from above idle or does it boost the fuel some other way - as this mystery fuel boost function is another possible candidate for chief gremlin n'est pas?! If it boosts the fuel pump itself (in the tank), then a bunged up fuel line could slow down the all important impulse of fuel reaching the injectors in time before she dies.

I thought the fuel rail would have enough pressure in it though for such a short burst of extra gas. In which case are we looking at the fuel boost signal not reaching the injectors quickly enough, the injectors being mucky or the signal not being generated at all?

What does the little fuel regulator on the end of the rail do? Maybe a fault with that may send to much fuel back down the return (if there is a return?) and not hold enough pressure in the rail for the anti-stall?

 

G.

[PhatVR6 0]

have you checked the position of the throttle stop damper pot?

 

If it's not set right, it won't catch the throttle in time, and the throttle will close fully before the ISV has time to kick in ,which means it will stall.

[benson 0]

PhatVR6,

 

Yeah, I checked it a while ago - spot on at 3mm (using drill as suggested in the Bentley Manual).

 

Don't want to frig it by winding it out. Also thought about getting a new one in case it's dropping the throttle lever too quickly, but they're on back order from VW. Plus maybe half the times when it's cut out on me it's been when I'm totally off the throttle approaching a junction and THEN dip the clutch, i.e. can't be linked with the damper pot.

 

G.

[dr_mat 0]

The thing is Phat, we're talking about times when the throttle damper will have completed it's damping some time ago - we're on overrun coming to a halt, so we've not touched the throttle for a good few seconds. It's *one* cause, but IMHO it's unlikely to help in these cases.

 

The "fuel boost" you're talking about when it tries to catch the idle when you've dipped the clutch is nothing more than the ECU actually opening the injectors for a change. They open/close once every other RPM anyway, so they're unlikely to stick or be an issue.. UNLESS old, leaky injectors causing a problem by overfuelling during the overrun cycle and causing the lambda to read higher than the ECU expects, in turn causing the ECU to lean out the mixture even more than normal? That's all pure speculation, of course. I've heard from a few people that ultrasonic cleaning or replacement of injectors can help with running of the car in other aspects, so why not this?

 

I don't know if the ECU turns the fuel pump off on long downhill runs at zero throttle - I doubt it, cos the fuel pumps round in a loop back to the tank - the pump running keeps the pressure up at the appropriate 4 bar, that's all.

 

I doubt if the ECU is reacting slowly due to lowere voltages. It's reading the crank position sensor to work out the engine rpm constantly, and it manages to figure out when to spark each cylinder to within a few microseconds, so a stall situation is unlikely to come about as a result of anything other than bad data coming into the ECU, or a slow physical actuator somewhere on the engine.

[dr_mat 0]

(god I can write some waffle when I want to)

[PhatVR6 0]

Mine stalls every now and then too. but so did the other 2 VR6's I've owned.....

[Kevin Bacon 5]

The fact so many VRs do it leads me to believe the ECU is slow at acting on the transition from part throttle to no throttle (14 degrees on the throttle position sensor).

 

Trust me, you're wasting your time worrying about it and spending too much money/time on it.

 

I've spent hours on it and replaced ALL of the relevant components and it still does it from time to time.

 

A common problem with the idle valve is the internal vane binds. it sits right above the exhaust manifold soaking up loads of heat.

 

It's a VR quirk and not an easy one to cure I'm afraid. You'll end up living with it to be honest.

 

Unless someone (previous owner) has pissed about with the throttle stop, there isn't much you can do really.

[benson 0]

Dr Mat,

 

Yeah - bad ECU data is most likely - as a result of 10 years of wear and tear, but I really can't nail down what it is! Surely it must be something that we can replace? I've had 2 or 3 really scary roundabout moments of zero steering thanks to the cutting out.

 

Any ideas on my last little question though - regarding the fuel regulator thingy on the end of the rail?

 

Kev - just read your post while I was writing this reply. I know you've replaced a horde of sensors and actuators but this is really trying to throw a bit of new light on it from the fuelling side. Just seems to be an avenue that hasn't been fully explored yet and there are so many of us trying to rid this problem from our joblists!

 

G.

[PhatVR6 0]

you can learn to alter your driving style to get around it.

 

Trust me, I've driven a 24 year old Derby for the past year, it cuts out every time you stop (well, it used to). I could drive it without stalling it.

 

Try toe and heeling. blip the throttle when you're changing down. and when you're coming to a stop, drop the clutch a bit earlier, and if it stalls you'll have the momentum to bump it off again without using the starter.

 

Mine does it more regulalry with the lightened flywheel installed, but I've learned how to drive around that too.

 

Live Kev says, you're wasting money trying to fix it, they all do it from time to time. It's not a fault, it's "character" :mrgreen:

[Kevin Bacon 5]

It could be fueling related. VRs pop on the over-run after all which indicates a slightly over-rich mixture at idle/overrun, or burnt out exhaust valves if you're one unlucky son of a gun :wink:

 

As I say, I think it's just down to a lot of variables not fully in synch with eachother. By all means get the ECU chipped and lean off the over-run a bit but I still think you're driving down a cul-de-sac with this mate.

 

Try some mega strong injector cleaner. One or more of them could be slow to close on the over-run.

 

K

[PhatVR6 0]

Or just don't stop. Keep moving al the time.

 

Leave a bigger gap inbetween you and the car in front, you'll find that your driving is much less stop/start.

[PhatVR6 0]

If it's anything electric, then suspect the crank sensor. If that doesn't pick up a signal for one cycle then it'll stall.

[dr_mat 0]

The more I think about this now, the more the injectors seems to me to be a nice idea - anyone out there who's gone down the cleaning/replacement route care to comment?

 

I know I've heard that cleaning or replacing the injectors can help the car on cold starts - where it would take a few cranks to fire it now fires almost instantly..

Maybe there's a similar effect on overrun, going from shut injectors to normal operation?

Still, kinda expensive to just do "for fun" when there's six of the little b*ggers.. :|

 

Oh, and I really like the idea of just never stopping. It'll make my brakes last longer too, and improve my MPG. Might make parking hard though.. :)

[Kevin Bacon 5]

Or just don't stop. Keep moving al the time.

 

Leave a bigger gap inbetween you and the car in front, you'll find that your driving is much less stop/start.

 

That's what I do. It's easy to drive round this problem as you say. In fact, after a mega hard blat, I tend to put the car neutral whilst coasting down this local 1 mile hill to cool the engine down and get rid of some heat soak, so it's no biggy having to dip the clutch earlier than normal :lol:

 

Plus you don't labour the engine either, which I hear so many people do these days :roll: