hesitant vr6 - FIXED - and worse...

[dinkus 10]

Sorry to be pedantic, Dinkus. The coilpack has three coils each of which is connected to a pair of cylinders. The coils fire in order to both in their pair - one is on the firing stroke, and the other is not but gets a spark anyway. So if one of the coils fails you will drop 2 cylinders.

 

Best wishes

 

RB

 

Aye, then you get asked why it uses lost spark rather than sequential, plus you've got all the timing issues and getting your head round why it doesn't fire 1,2,3,4,5,6 either, but thought that'd be getting a bit complicated :)

[edd 0]

Usually give My MAF a good clean if i get hesitiation or stalling issues. Usually does the trick, incidentally happens far more regularly when am running my BMC. Just spray the hot wire with some carb cleaner...carefully tho last thing you want to do is break it. Mines a dizzy too by the way.

 

give it a go you never know

 

Edd

[Tifun 0]

I would suggest checking your HAL sensor on the distributer. It will pull timing and cause the car to hesitate and sometimes backfire under certain conditions. But it will feel like the car is missing a good amount of power, like something just isn't right. This had happened to me and mine was just unplugged. Yours might be a different situation though as our SLC's in the states only came with 2.8 :(

[grimmy 0]

Well i have it booked into a garage tomorrow for them to have a look over it. I've heard very good things about this place and its a vw audi specialist so hoping they can sort it.

BUT

 

Today trying to drive home things just got a whole lot worse. It completely lost the ability to pull the car up the hill i was on. Got to about 3k revs then just stopped pulling, and slowly ground to a halt... Dipped the clutch and rev'd the tits off it to get it to pick up again, and then another 10 meters up the hill the same thing happened. It sounds like a bag of spanners and won't go... :( unplugged the maf while the engine was running and nothing happened, so i figured it was duff, but then turned off and restarted the engine and it wasn't loving it at all until i plugged the maf back in, so it must be doing something.

 

I'm hoping its just a dizzy or something, but i have this terrible feeling something is seriously wrong with the whole engine. I do seem to be having some poor luck with cars at the mo. I'll be getting my salvage vr6 back soon so if worse comes to worse i can stick that engine in as it runs fine, but is a bit of an oil burner.

 

RUBBISH!

[CazzaVR 0]

Sounds like it could be a fueling issue :? Have you changed the fuel filter? Maybe the fuel pump is on it's way out.

[grimmy 0]

I haven't changed the fuel filter, i haven't had any time to do anything with the car as yet. Just hope i can get it to the garage ok, and they'll sort it all out :?

[CazzaVR 0]

Where are you taking it? Stonehouse? Hope they sort it for you!

[grimmy 0]

Yeah the stonehouse garage. I forget what its called, but they have a very good reputation. I got it to fire up today, was FUEL!! The fuel gauge says it has half a tank, had the fuel line off the injector rail and it wasn't spewing out any, topped it up a bit and it fired up fine. But its still running very hesitant and feel really weak and flat. Hoping the knock sensor will sort it?

 

If not they have all the gear to diagnose the problem. Hope i have it going properly soon :)

[grimmy 0]

I took my car to the garage, and it was a lead that was making it hesistant and not pulling right. But the also compression tested the engine, and cylinder 5 was only making 70 psi. Should be about 165 i think?? So they're taking the head off tomorrow and hoping its just a valve is burnt out or something similar. Hoping for a head rebuild, and they can whack the kent cams in for me. Just praying its not he block itself as its only 100k ol, and i've only had it two weeks :(

 

Isn't 3k a bit steep for a new engine fitted?? That was mentioned...

[grimmy 0]

I have my car back from the garage now, after having the head repaired. Apparently a valve wasn't seating right, and all the seals had gone hard. So had the head skimmed, new valves, and new guides. They also broke a head bolt, so had to take the sump off and gave it all a flushing out.

 

Only problem is its still hesitant, which is the reason i took it in there, only for them to tell me it was low on compression and have the head overhauled.

 

Also now its leaking oil, constantly when driving if its wet on the ground you can see drips every couple of meters! Will be phoning them back up first thing tomorrow morning i think :mad:

[ziderapple 0]

sorted yet mate? Must say I feel sorry for you, seem to have had a really sh*t time of it lately! Fingers crossed for you mate. :D

[dr_mat 0]

Sounds like a lean cut to me. You need to make sure all the engine sensors are in 100% working order, otherwise it'll run lean till the lambda detects it, at which point it will dump extra fuel in and take off. (Lambda is too far from the block on the VR6 to be fast responding.)

Key things to check:

- sensors (MAF, lambda, throttle position)

- air leaks - make sure there's no way you can leak air into the inlet manifold post-MAF.

- fuel pressure (you might have a faulty pump/FPR). If the pressure is low, the injector timings will be calibrated wrong.

 

The fuel pressure at least is easy to test.

[grimmy 0]

Right well i got the oil leak sorted, it was the oil pressure regulator or something? The large bolt to the back right hand side of the block. The copper washer on there wasn't up to the job so replaced that and now more leak :)

 

I think the poor running is definitely down to the knock sensors, but i can't buy any at the moment, even my garage said they couldn't get them??

 

One thing that concerned me, when looking under the bonnet to check for the oil leak, after just getting it back from the head rebuild, i saw these little fella's were all completely loose!!

 

 

 

All three of the bolts along the bottem of the inlet manifold were not done up.... Suprised it even ran!

[CazzaVR 0]

Blimey! :shock: Noticed any improvement since tightening them up? Just get the sensors direct from VAG. Ford may do them too, and if they do, they'll be cheaper ;)

[grey-vr6-dan 0]

I need a new knock sensor for my vr too, so if you find a cheap suplier of them I will be very interested!

 

I don't want to et one 2nd hand really as it will probably pack up again! It doesnt seem to affect my engine running at all though, maybe just less performance but I wont know until I replace it if it improves.

[grimmy 0]

Yeah the engine should run fine with a faulty knock sensor, just at a reduced performance as it'll pull the timing back as much as 10 degrees? Someone will correct me i'm sure. But i haven't had any luck finding a supplier yet. Avoiding dealer until its a last resort.

[dr_mat 0]

I believe it's 12 degrees full retard on the VR6 ecu, but it probably never gets all the way to 0 degrees retard except with VERY good fuel anyway.

[Toad 0]

Did you get the hesitancy sorted in the end? was it just the loose bolts at the end?

 

Mine is pretty poor at the moment, don't get any vag com errors, but when I open the measuring blocks up in vag com the o2 reading cycles from 1 and back... What's that about???

[CrazyDave 0]

Reading this again and some recent MAF research for something different, I'd now go for MAF problems. MAF is used to meter fuel quantity and a dirty or faulty one will give the hesitant response your talking about.

 

You've a dizzy VR so it'll be the early wire type MAF, expensive to replace and a prone to failure. I've had some ideas about retro fitting the later style MAF or even one from a late Golf, but as yet not tried on a car.

[Toad 0]

I've just been having a quick fiddle with my vr, trying to work out why it's underpowered aand having found no air leaks had a look at the MAF.

 

Can anyone tell me if unplugging my MAF should cause the car to splutter or stall? It's a very late VR with the CP (i think) coded ecu, and 4 pin film type MAF, rather than a hot wire unit. Is this the same set up as yours was Dave??

 

Cheers.

 

Tom

[dr_mat 0]

The car won't splutter and stall if you unplug the MAF on a late VR, even if the MAF is working 100%. You'll likely not notice it's unplugged till you try and rev it.. when it will splutter and cough.

[CrazyDave 0]

Pretty sure that if you unplug the MAF the ECU will drop into an error condition and run without it (based on throttle position and engine speed), so it'll run but not as good as with the MAF. Might need to drive it to notice the difference. Should idle fine. And yes I have the late CP ecu with film maf rather than wire.

[Toad 0]

Hmmm maybe I'll unplug it and take it for a run...

 

The car runs really smoothly, but massively underpowered, dunno what it could be. I've checked for air leaks, and there are no error codes (until I pull the maf plug off....)

 

The plugs are all a nice colour, and the fuel economy is around 28-29mpg, but this could be down to not having 5th gear all the time.

[curph 0]

Changing the throttle cable fixed both a lack of power issue and a stalling on start problem on my VR.

Cheap to do as well...

[grimmy 0]

I've only just noticed this thread is still going. The problems with my vr were fixed, the poor power was down to faulty knock sensors, but they should show up in vagcom? When these were replaced the car ran exactly as it should. Getting hold of the knock sensors wasn't so easy though, took the garage about 3 weeks?! Plus when fitting them they knocked a water pipe and split it so i had to wait another couple of days for them to fix all of that :?