engine cutting out

[fla 9]

Hi all and a very happy new year to yall.

Fiddly one this - coming up to a junction the revs drop and sometimes the engine cuts out. As there's no idle speed screw I cant even do a temporary fix that way. It will then take several turns to start up again. Sometimes as I am slowing down, the relays click in, engine cuts and then starts up again. As I have an auto its not that the transmission restarts the engine. VAGCOM doesnt point to anything, but it obviously appears to be a loose connection somwhere. I've taken out and refitted the relays on the fuse panel, checked the fuses but dont really know where to go from there. Would welcome some help. What a start to the new year.

Cheers all

[dr_mat 0]

ISV and engine speed sensor are implicated.

Could also be relays, immobiliser, ignition switch, coil pack, plugs, leads, etc etc..

Use the search for more ideas, but it's a common problem and there's many possible causes.

[fla 9]

Cheers, although would the issues not be shown up through VAG COM? Coilpack leads & plugs are OK, dont know about the rest though. Is there any way to check the ISV and can this be taken apart to repair?

[adambob 0]

I had the same problem with my VR - Geoff at Dubsport solved the problem for about £40. That guy is a genius. It was a faulty component on my Throttle Body; I'm not sure what the component is called but it essentially serves as an absorber (like a shock absorber) when the revs drop right down. It ensures a progressive & smooth drop in revs to prevent the engine from cutting out.

 

This might be the problem? Good luck either way.

[fla 9]

That might be the ISV - its coming out and getting a clean on the weekend and I'll let you know if I get any joy. Apparently it sticks sometimes but I dont know if a gentle dremel and some wd40 wouldn't solve it. Anyone tried that at all?

[Kevin Bacon 5]

Adambob is talking about the dashpot. It's basically an adjustable damped spring that 'catches' the throttle as it drops down to rest, giving the ISV enough time to fire up and stabilise the idle and also protect the throttle from 'bottoming out' as the VR TB has one heck of a strong spring on it.

 

If the engine keeps cutting out, remove the ISV, clean and lube it, raise the dashpot up a smidge so that it catches the throttle earlier (13mm nut underneath), remove the oil residue from the throttle butterfly and inlet hose. Use VAG-COM when adjusting the dashpot to ensure you don't knock the TPS past the 14 degree idling threshold.

 

K

[fla 9]

Thanks for that Kev. A slight aside, my TPS shows the angles as 13.7degrees (closed) and 94(??) at full throttle. Mines an auto so would the fully open position be more (related to kickdown maybe?)? If so why and what can I do about it?

[Kevin Bacon 5]

Hi mate, your throttle angles are fine. The ECU full throttle is triggered at 90 degrees and you're over that, so no probs. I would imagine the Auto ECU possibly has a lower full throttle threshold, or maybe a secondary kickdown threshold set to 80 degrees or something? Dunno! But yep, your idle and Max angles are cool.

[fla 9]

I've cleaned out the ISV - not too much crap cameout but the dashpot seems a bit sticky when you press it by hand. Is there any way to clean and lube it at all without totally upsetting its current position?

[fla 9]

Terrible now. When the car is idling and I open the throttle, to anything above 3000 rpm, on releasing the pedal it ALWAYS cuts out, unless i really control the throttle down to tickover. This I've only tested in the drive as i'm too scared to take it anywhere in case it dies on me without any tools. ISV was cleaned out with carb cleaner, but I didnt use any WD40 or the like to lube the body - is it necessary? Also how do I get to the throttle butterfly? My theory is that probably the ISV needs lubrication, and as Kev has mentioned above the butterfly may be gunged. I've wound the dashpot in about 2 turns but I havent checked it on VAGCOM yet. Didnt seem to make much difference though.

[potatonet 0]

so you cleaned the Idle stabilizer and by doing that it made the problem worsen.... thats not right, sounds to me like that could be the problem. if you have a 4 cyl check your distributor cap. plugs etc. also the little black cube on the back of ure throttle body needs to be plugged in. check ure ECU for fried connections. the digifant one, mine fried one side of the board and caused the injectors to spray full. couldnt idle correctly and died unless I held revs. if the ECU is fried try taking it to VW, its a recall. as of 01

[fla 9]

No bud, mines a VR and I dont know if there are any related recalls on it. I hope that the ECU is not the problem, but I'll try and VAGCOM it in the next days. Otherwise, any suggestions gentlemen?

[Kevin Bacon 5]

Hmmm, mine cut out twice on Saturday but hasn't again since. It's always when you're at a low speed, crawling along in 2nd or 3rd and then you dip the clutch at the junction/lights and it cuts out.

 

I doubt it's your ECU mate as mine's been changed and it still does it.

 

From what you describe, that sounds like a really bad air leak to me. I remember my old MK2 16V did that once (at any temperature) and it turned out I'd forgotten to connect a hose! Reconnected it and it idled as normal. I'd go round the engine and make sure there are no obvious air leaks.

 

If not that then it's got to be the ISV if nothing shows up on VAG-COM. Try it with the ISV disconnected and see what hapens then. The engine should still run, albeit with a higher than normal idle.

Even with a knackered MAF the engine wouldn't just die on the overun in neutral, so I reckon it's air leak or ISV related.

[fla 9]

Do you think spraying some light oil into the ISV would help at all Kev? And how do you get to the throttle butterfly? Also, silly question i guess (but just goes to show I'm learning my way around the car), where would the air leaks be and how do i test for them?

[Henny 0]

also check that you have remembered to reconnect the throttle's idle switch (if the VR6 has one) as this will cause all sorts of odd running problems... :oops: :lol:

[dr_mat 0]

VR6 has the pot they were talking about above, Henny.. No position switch, just an angle-measuring sensor - hence the 13 degrees and 90 degrees idle and full positions. The ECU knows precisely what the pedal's doing.. :)

Going back to the original problem - using VAGCOM have you tried reading out the temperature sensor values?

Alternatively do you have another ISV you can try? It's still classic ISV symptoms, and cleaning them out doesn't always do the trick, sometimes the actuator motor is simply worn out and needs replacing.

[Henny 0]

ta, dr_mat, I feel a little more educated now... 8)

[Kevin Bacon 5]

sometimes the actuator motor is simply worn out and needs replacing.

 

If only that were true, but unfortunately I replaced my ISV and it STILL does it, LOL! It's basically a stepper motor and it's 'duty' cycle, or opening angle/amount/time open etc is governed by the Guv'na under the plastic cover and his team of sensors :wink: It only takes for the flap to jam once during all this and the engine will stall. Sodding things.....

 

Anyway, I've yet to hear of a VR6 that *hasn't* cut out at least once! Nature of the beast. At best you can reduce the occurences but I doubt the problem will ever go completely unless an alternative idling system can be found.

 

Fla, you get to the throttle body by removing the intake hose. Clean the butterfly with some carb cleaner. I usually spray the ISV with some silicon maintenance spray but I'm thinking Slick 50 might be better, LOL!

 

K

[dr_mat 0]

sometimes the actuator motor is simply worn out and needs replacing.

 

If only that were true, but unfortunately I replaced my ISV and it STILL does it, LOL!

 

It's true to say that this stalling problem doesn't appear to be solely caused by an ISV problem, but it's still worth trying it out as the first port of call isn't it! :)

[Kevin Bacon 5]

Yep, the solution is still like trying to find a needle in a haywire-stack though!

 

I think the engine simply goes too lean or rich on overun and the ISV struggles to catch it. I wonder if this area of the rev range is chip-able?

[dr_mat 0]

Trouble is you're onto the idle program as soon as you lift off the throttle.. I've never heard of anyone chipping the idle program, and therefore I'm not sure it's possible (other than altering the actual idle speed itself).

 

But you're right, there's *something* wrong no question, but so many people have had so many different approaches to fixing this that there's simply no single answer. I agree that the ECU will run the engine totally lean during the overrun cycle (for economy and emissions reasons), and I agree it's probably failing to catch it as the revs fall, but the question is *why*? Perhaps the revs are falling too fast? i.e. faster than originally designed? Perhaps that's cos the dashpot is not working right, perhaps the engine just has more friction than it should internally?

 

It's funny though, because I've heard of a number of the big V6 engines being prone to stalling, from various manufacturers. Perhaps they're simply more difficult to keep idling than smaller engines?

 

I wasn't aware that yours was still stalling tho Kev, I thought your ISV and CPS had fixed that!

[Kevin Bacon 5]

I wasn't aware that yours was still stalling tho Kev, I thought your ISV and CPS had fixed that!

 

It seemed to for a while but it's unhappy again!

 

Cleaning things out blah blah seems to stop it for about a couple of months though.....

[fla 9]

Ah, forgot to mention that I haven't reset the Basic Settings after replacement of the TPS (thanks to Mr Haywire). I'll do that on VAGCOM in the next days. Maybe this will affect it too? What is the effect of simply disconnecting the ISV apart from a faster idle? If it is simply a higher tickover then all we are doing is burning a bit more fuel at rest i guess? But performance and normal use-wise is ther any effect?

[Kevin Bacon 5]

Mine idled OK with the ISV disconnected and didn't cut out but it didn't run very nicely, a bit lethargic, so the ISV seems to affect the engine in other ways aswell as the idling!

 

Resetting the basic settings might help, not sure how you do that. Don't you need some kind of workshop code to do that?

[dr_mat 0]

Yes, reset the ECU. Definitely do that if you're replaced the TPS..

Resetting basic settings is just the same as resetting the ECU, it's just that you're supposed to copy over the original adaptation values for some of the sensors to the new, refreshed ECU.

The full procedure requires you to note down and re-instate things like lambda and MAF adaptation values. Of course, because you've changed the TPS, you wouldn't want to copy over the adaptation values for that...