VR6 lurching and stuttering under acceleration

[MarkFoster 0]

Hey chaps, my Rado has become very displeased with me recently and I could do with a little advice on how to get back into it's good books! :(

 

The car appears to be really struggling to control it's fueling and surges and lurches under anything other than a very steady throttle position. To give a bit of background, I'd recently disconnected the battery to carry out the inline-fuse headlight switch mod and when I'd finished I connected everything back up and fired up the car to put it back on the drive. The idle was a bit erratic and stalled once but it settled down and I put the car away and thought no more of it. The following weekend, having forgotten all about this, I took the car out, it started fine, drove around town, ran a few errands and chucked a bit of V-Power in it and headed home. There's a fast(ish) road on the way back so I was happily giving it a bootful and listening to the VR roar it's way round the rev counter when, after 5 mins or so of good old fashioned ragging, the car began to stutter and lurch as if it wasn't getting enough fuel, and then was suddenly getting far too much.

 

I did a bit of a search and came up with a potential fuel pump issue or possibly an ecu settings issue. The ecu settings sounded plausible, considering the battery was disconnected to mod the head light switch, so I looked up the reset process and gave it a go today. It seemed to be going ok initially but as soon as I tried to push the car on a bit it was back to the tantrums and tears. I have to say it is remarkably tricky to follow the process to the letter on public roads, but I think I was fairly close to it and the car did seem to be running better, until of course I started driving normally.....

 

So, I'm back to the fuel pump theory but was wondering if anyone had any suggestions, experiences or thoughts as to what's be said and done....?

 

All comments welcome,

Cheers

Mark

[VR6 0]

Any chance of getting it hooked up to VAG-com?

[MarkFoster 0]

Unfortunately I don't have VAG-Com which obviously doesn't help...

 

I have no problem with a little hypothesising in lieu of hard facts from my fellow Radoites though....

[Supercharged 2]

Yeah you need to go through basic settings on VAGCOM, you can't really disconnect a battery on a VR6 without this.

[VR6 0]

If you just want some options, CPS, TPS, MAF, fuel filter, fuel pump, fuel pump relay, lambda etc.

 

It's a pretty long list hence the VAG-com comments.

[MarkFoster 0]

Ahhh, point taken.... Will have to find a way to get the codes read.

 

Thanks anyway guys

M

[RW1 0]

To give a bit of background, I'd recently disconnected the battery to carry out the inline-fuse headlight switch mod and when I'd finished I connected everything back up and fired up the car to put it back on the drive. The idle was a bit erratic and stalled once but it settled down and I put the car away and thought no more of it.

 

Wrong thing to do after a battery diconnect. It should never be left idling while it is rapid learning in the first 10 minutes after ignition is switched on. It will never learn mid and full throttle settings for a long distance, ie 5,000+ miles. So its wotrking without the settings set up in the ECU.

 

Disconnect it again for a few seconds, 10 seconds will do. Reconnect the battery and from when you start the engine, drive it straight away, no particular way other than not to sit with the engine idling. About 2 mins of idling in the first 10 will be fine, just drive the rest. Ragging won't be necessary.

 

Do the battery disconnect with the engine warmed up, ie. when the oil is 90'C or above. See if that cures it. If so, stick with that and carry out "Basic Settings" on the ECU as in the wiki when you get a chance with someone who has VCDS (VAGCOM).

 

.

[MarkFoster 0]

Yep, that's what I tried today. It did seem to go better initially but after running through the driving sequence several times (well for 20 mins or so) the car started playing up again. I think VAG-com is my only friend now ... :(

[RW1 0]

Besides the headlight loom and battery, where else did you look at??

 

Check the fuse/relay panel, fuse & relays are fully home if you access the headlight loom by removing the small under shelf covering the fuse/relay panel area.

 

.

[fla 9]

where are you in London? I'm in Middx if that helps, for VAGCOM.

[CazzaVR 0]

It's worth checking the coilpack.

[MarkFoster 0]

where are you in London? I'm in Middx if that helps, for VAGCOM.

 

 

I live in Hackney, near Victoria Park, but keep the car near Colchester in Essex. Thanks very much for the offer though Hasan, it's much appreciated.

 

Mark

[Abdul 0]

Hassan, right it looks like you need to drive over to essex and help both me and Mark lol.

 

Good luck sorting it mate.

[MarkFoster 0]

Right, thought I'd better bring a bit of closure to this so that it helps any future searches. First off, big thanks to Kev Haywire for helping me out and reading the car's fault codes (and for the spin in his VRT - awesome piece of kit!). Following advice from some of the kind folk of the forum, I was following the view that the ECU needed resetting and mentioned this in a conversation with Si over at Strictly Dubs (booking car in for MoT) but he felt this was unlikely and much more likely to be a coil pack/ HT lead/ MAF issue.... Anyway, with this in mind, I had a quick rumage under the bonnet one last time before heading to Kev's, and found a slightly loose HT lead and then noticed the MAF cable wasn't actually properly clipped in. The car drove perfectly to Kev's, so feeling a bit of a prat I confessed to Kev that it looked like loose cables had been the culprit - a quick scan of the faults seemed to back this up and following a reset and drive round the block all was well in the world once more and I was a very happy chappy!

 

After a complimentary trip in the Haywire-World-Reverser (I so need a turbo!!!), I headed home with a smile on my face and, to celebrate, gave the old girl a good boot as I pulled onto the A12. This did not go down well at all. As I lurched into a layby and stalled I was contemplating whether it would be more satisfying to burn the car or watch in plumet off the cliffs at Walton, when I thought I'd just check the cables again and sure enough the MAF cable had unclipped. Back in the car, and everyone's happy again. For 10 mins. Next layby, bonnet up, clip cable back in, oh happy days!! After 3 stops (it's a 20 minute journey!) I arrived back and started taking things apart. The cable has a damaged cover on it and apparently some water had got down and made it's way into the MAF connector - I'm not sure if it was shorting out or if it was heat doing it, but the cable kept popping itself off as soon as the revs built up a bit. So, some temporary electricians tape and a thorough drying of the MAF connector and I seem to have gotten to the bottom of things.

 

Think'll I'll be adding a new MAF cable to the to do list when Strictly tackle the chains and MoT.....

 

M.

[andy 0]

Interesting, you can buy new plugs for MAFs, I did last year, they come with short (6 inch ish) flying leads which need to be joined to the existing loom. The wierd thing is that yours is just popping off, it implies a seating problem or a spring clip problem (the spring clip that retains the plug). Check the position of the water seal, check it hasn't slipped and now interfering with the fit of the plug. Also maybe a bit of lubricant (wd40, gt85 or similar) may ease the spring clip if its sticking.

[lilfuzzer 1]

Nice one mate just read this glad you got sorted :clap:

[Kevin Bacon 5]

Just noticed this!

 

I'm wondering if the plastic notch on the MAF that the clip on the plug clips onto, has snapped off?

The engine movement is yanking it off too easily!

 

Glad you liked the spin in the VRT, amusing aren't they? :D

[MarkFoster 0]

They certainly are!! ....Need to start saving up :D

 

I'll have a good look at the cable again, it does seem to click in fairly positively but there's obviously something not right. I've not had chance to 'test' things properly since I took it all out and cleaned and dried it so fingers crossed that may have resolved things.

 

Will let you guys know...

 

M

[ZippyVR6 0]

Hi All,

 

Car was sat for 2 weeks whilst on holiday, and battery died. When I charged it up again, i had a lumpy idle, and hesitant acceleration under load.

 

I believe it to be the coilpack on my 93, Dizzy Vr, as it was arking.

 

Is this the right one to replace it with.

 

http://www.eurocarparts.com/ecp/c/Volks ... 3aa87&IGCO