VR6 Misfire

[StormyTommy 0]

95 Corrado VR6 Storm

When car warms up after 10 mins get slight mis/hesition at about 60mph. Idle a bit rough. Problem worse in warm weather.

Had mobile tech look at DTC, he got code for engine speed sensor. Replaced following over a period of time, fault still remains:

Engine speed sensor

Spark plugs

Spark plug leads

Lambda Probe

Air Filter

Air hose to inlet manifold (this had broken)

 

After reading achives I'm wondering about possible MAF problem, dealer quotes £339 inc for new MAF.

 

Am I right in saying that test of MAF is to let car warm up, disconnect MAF plug and take on a test drive to check for difference?

 

Almost getting to the point of having the dealers look at it. :shock:

[chrishill 0]

good god...£339 for a new MAF? GSF have a 'AIR MASS METER-SIEMENS' listed for £75, is that an MAF under a different name?

[StormyTommy 0]

good god...£339 for a new MAF? GSF have a 'AIR MASS METER-SIEMENS' listed for £75, is that an MAF under a different name?

Having read thru earlier posts, it seems there is a big selection of these sensors across the vw range. Prices seem to vary from £70-£300+. :roll:

I was quoted that for the ABV engine code, 1995 model.

I've looked up the GSF site - don't know if that part is equivalent. It says Corrado ADY which I think is the 2.0 engine.

[dr_mat 0]

Jeez, sounds like your first investment should have been the Russek VR6 engine manual. Might have saved yourself £140 on the engine speed sensor for a start.. :roll:

[Roger Blassberg 0]

Look at "VR6 Owners Must read" 07 June in this forum section. Lots of help there.

 

Best wishes

 

RB

 

one day I'll learn how to put the link in properly.....

[RW1 0]

http://the-corrado.net/.archive/forum/viewtopic. ... hlight=maf :)

[StormyTommy 0]

Looked in "VR6 Owners Must read" & maf link above - thanks for pointers.

Tried driving car with MAF disconnected, it ran a bit worse without it (idle @ 1100 then down to 700). However, from MAF thread this doesn't prove conclusively that MAF's not at fault. Am considering still replacing it & have spoken to GSF re Sharon MAF @ £69 exc.

 

I've put an entry in the VAG-COM thread to see is there anyone I can ask to checkout the DTC's first.

[RW1 0]

Have you disconnected the battery at all just before this started?

 

Will useful to know what the ECU fault memory has in it.

 

Not convinced this is a MAF problem.

[StormyTommy 0]

Battery may have been dissed - problem started quite a while ago and was barely noticable at first, so not sure.

 

Are you thinking I need to do ecu reset procedure? I've read this is just disconnect battery, leave for 2-10 minutes, reconnect & drive the car to let the ecu relearn settings, no downside to trying this? The battery was almost totally flat recently after sitting a while - RAC had to jump start it. Don't know if that qualifies as a reset. :)

 

Or is there another reason for question about battery disconnect?

[RW1 0]

Given what you’ve said about the flat battery, it is quite possible that the ECU has lost it’s settings at that point and depending how you drove it (or not!, as idle for the first ten minutes causes a lot of problems with rough running and stalling) afterwards. The ECU typically loses it's memory inside about 10 seconds, so if you cranked the engine with a flat battery for that length of time, the ECU 12 volt supply could have dipped below acceptable lower limit to maintain the memory.

 

First you should establish that the ECU and all it’s sensor are OK, ie. there are no engine related faults otherwise the engine ECU can go into a reversionary mode to by-pass that fault in a few cases.

 

If there are faults, note them and then clear them from the memory (NB 00513 engine sensor fault code will appear if the engine is not running but ignition on. This will clear on engine start if all is well.). Take the car for a short drive of about 15 minutes and take it upto and past where the hesitation occurs. Now re-interrogate the ECU. If any faults have reappeared, then these must be dealt with first.

 

If there are no faults, then carry out the FULL engine ECU procedure in the knowledge based I have written starting with the ECU battery disconnection sequence if you want to drive it . It isn’t absolutely necessary to drive it that hard but it just quickens up the fine adjustments after 10 minutes have elasped. The first part can be just a drive with a couple of accelerations using a “held” accelerator pedal to make it constant for about 4 seconds, but do not idle the engine for the whole of the first ten minutes. The engine can idle during this 10 minute period for short periods of a minute such at lights. If fact, be sure to include at least one idle period of a minute and at least one overrun, throttle shut from 4,000 rpm to idle – 1,000 rpm range. Some parameters will take upto 30 minutes to establish but the ECU quick learn mode finishes after ten minutes for the VR6. After that only very fine adjustments are made to the factory dyno map offsets.

 

After about an hour of running the engine, could be a few days later, perform the second part of the procedure using VAG-COM. Put the ECU and engine through the “Basic Settings” sequence. Follow the instructions set out in the procedure for the appropriate ECU. In your case, it’s Basic Settings on display group 001 in VAG-COM.

 

Hopefully the hesitation will now clear.

[StormyTommy 0]

I think the RAC guy did leave it idling after he got it started.

 

Yesterday, before reading your reply I went ahead & did the first part of the ecu reset procedure. I don't have vag-com so can't do the basic settings or check for error codes. I'm going to make further enquires on the vag-com topic to see can I get it scanned. I've been caught out with the 00513 code already, when a tech diagnosed engine speed sensor fault.

 

This morning the idle seemed smoother, jury's out on the hesitation problem as traffic was heavy, but it wasn't as bad as its been. :)

 

Thanks for the detailed reply I'll post an update when I've driven the car for a few days.

[CazzaVR 0]

Sounds like the MAF. If you disconnect the MAF, the car should splutter and die within a few seconds. If it's knackered the car will carry on running with it unplugged. Could be wrong, but I've tested MAFs in this way before.

[dr_mat 0]

No, on a late VR6 the engine does NOT splutter and die when idling and you disconnect the MAF.

This may be true for the earlier cars, but not the late ones.

[Dutch24V 0]

err, I tried this yesterday on my '94 CP VR and she spluttered and died.

I had only just started her though and she was stone cold!?

[dr_mat 0]

Do you have the OBD - type ECU connector or a 2x2?

[Dutch24V 0]

OBD

[Kevin Bacon 5]

He won't have the 2+2 if it's a 94....

[Kevin Bacon 5]

No, on a late VR6 the engine does NOT splutter and die when idling and you disconnect the MAF.

This may be true for the earlier cars, but not the late ones.

 

How is the data gathering different on the CP to the AG where the MAF is concerned? I know the 462 MAF is a wire down compared to the earlier 5 pin 461, but surely if CP is extracting live data from the MAF as AG does, then it should splutter and die if the connection is terminated? If not, the ECU has already adapted itself using the TPS.

 

Dunno....I'm theorising. I'm sure MYFOB (sounds suspiciously like Blue Nothelle in his posting style to me) will be along shortly to offer some words of wisdom on this....

[dr_mat 0]

I dunno how it works. All I can tell you is that I and many other v.late VR6 drivers do NOT report a splutter and death when unplugging the MAF at idle. But I can tell you my MAF *is* working because the car drives like a dog if I actually attempt to drive off without reconnecting it.

Perhaps the ECU is intelligent enough to just carry on doing what it was doing before ... rather than suddenly overreacting? After all, the stall on your cars has to be at the request of the ECU. If the ISV, timing and injector pulses are left alone the engine will continue idling unchanged.

[CazzaVR 0]

I'm sure MYFOB (sounds suspiciously like Blue Nothelle in his posting style to me) will be along shortly to offer some words of wisdom on this....

 

Well spotted, Kev! :wink:

[Dutch24V 0]

...have been thinking about this and have come to the conclusion that my TPS is dead, or rather dieing!

 

Just unplugged it and no more stalling - obviously it takes alot longer for the revs to drop but they never drop out completely. So, plugged it back in and unplgged the MAF and she died instantly.

 

I have heard before that later VR6's do not stall when the MAF is unplugged and seem to remember years ago trying to diagnose another problem and when I unplugged the MAF I vaguelly remeber she didn't die.

 

Will purchase a new TPS tomorrow from VW and post back in a couple of days with the result.

 

Dutch

'94 VR

[dr_mat 0]

You can see pretty quickly if your TPS is dead using the VAG-COM measuring blocks. There is a measuring block that reports throttle angle. It should move smoothly from zero throttle (between 5-15 degrees) to full throttle ( greater than 90 degrees) position. If you see jumps, hiccups or the like in the numbers, then you need a TPS.

[Guest]

I'm sure MYFOB (sounds suspiciously like Blue Nothelle in his posting style to me) will be along shortly to offer some words of wisdom on this....

 

Well spotted, Kev! :wink:

 

Well done, you make Ray Charles seem sharp-eyed. The specification of my car has changed, hence the new username, not that it's any concern of yours. Why on earth should I offer help to a forum that puts post-count nepotism above knowledge? I may as well post in Chinese. No, I'll just sit back and laugh at the ineptitude on display. Carry on.

[chrishill 0]

what a lovely sunny disposition you have MYOFB

[Kevin Bacon 5]

DutchVR6, the TPSs have changed now. They're much smaller than they used to be and as a consequence you need to get some shorter bolts.

 

MYOFB, you're knowledge and help were never in question. It is your condascending and rude attitude that is not welcomed here.

If you continue to act like a miserable git, then people will ignore you or take the p1ss, so you've only got yourself to blame.