FishWick 21 Posted April 3, 2004 Report Share Posted April 3, 2004 ...I need to sort a running problem out I just can't cure, so need some help if poss? This could be long, please bear with me The engine misfires at exactly 1000rpm and also 2000rpm. In between these two rpms, the engine bucks on part throttle like it can't make it's mind up whether to accelerate or slow down. And also it's just plain gutless at 4000 rpm....no pull at all, just gets noisey and coarse. I pulled the plugs and all 6 are the same colour with no oil on the tips but the white insulators had a weird green coating on them though?? Engine is 93K old, no smoke on over-run, idle or when accelerating. Uses about a litre every 3K.I have replaced *everything*, MAF, O2, Leads, plugs, CP, CPS, Crank sensor, TPS, ISV, Fuel pump, fuel filter etc.Ran a VAG-COM scan....nothing. All the parameters in the measuring blocks are within spec, no issues there either.Sprayed the coil pack with water ....nothing.Sprayed carb cleaner around all the pertinent hoses....no change in engine note.Alternator is supplying 14.4V.No chain noises although I will be lifting the rocker cover when I get the Schrick to check the upper blade though.It idles perfectly tho which is strange but it does want to try and cut out at junctions occasionally.I am totally at a loss now. I really want to get it running well before putting the Schrick on, otherwise I won't reap the full rewards of it.Oh and one other thing....if you pull the Knock sensors when the engine is idling, should the ECU throw a code? I pulled both and VAG-COM didn't report anything. Sorry for post length!CheersKev Link to post Share on other sites
jcorallo 0 Posted April 3, 2004 Report Share Posted April 3, 2004 re the knock sensors...I dont think the ECU throws a code when they are detached at idle. The ECU will however throw a code if you took the car for a drive with them detached as the ECU expects inputs when the engine is under load..... i.e. when you've got your foot on the fast pedal.Obviously best not to try this though! If you run the car without the sensors you WILL get pings which are not good!Hope that helpsJules Link to post Share on other sites
jcorallo 0 Posted April 3, 2004 Report Share Posted April 3, 2004 Looking at this, I was slightly out:http://www.geocities.com/MotorCity/1108/faq.vr6.html* Self-diagnosis: *The ECU recognized an open circuit if no signal from knock sensor I (G61) or knock sensor II (G66) is received by the ECU at an engine coolant temperature above 40° C (104° F). Link to post Share on other sites
FishWick 21 Posted April 3, 2004 Author Report Share Posted April 3, 2004 Cheers for the replies Jules....As you say, I don't really want to be driving it without the knock sensors connected!! So it would seem the ECU should recognise when they're not connected.....I wonder why it doesn't then?I'm starting to think my ECU is knackered, or perhaps the knock controller circuit?I will try a drive tomorrow without them connected but I won't thrash it. Just curious to see if the brain actually knows they are there!CheersKev[ Edited Sat Apr 03 2004, 09:11PM ] Link to post Share on other sites
FishWick 21 Posted April 3, 2004 Author Report Share Posted April 3, 2004 Actually someone else I've been speaking too said the green spark plugs is caused by pre-ignition...so looks my knock sensors could be the problem. Could kind of explain the hunting below 2000rpm if the ECU doesn't know whether to advance or retard... Make sense? Link to post Share on other sites
28v6r 0 Posted April 3, 2004 Report Share Posted April 3, 2004 I'd also look at a failing coil pack, normal on idle but misfire under load. Usually thats a sign that the coil is failing.... had this on my bimmer twice!! and on a volvo once. Look for an known coil pack that work OK and replace and see if it cures it before purchasing a new one...I think GSF will do one for £145, not sure though can't remember:-(Regards28v6r Link to post Share on other sites
jcorallo 0 Posted April 3, 2004 Report Share Posted April 3, 2004 Kev - I personally had a knock sensor go bad on my VR - but the ECU never stored a code until I actually thrashed the engine. I would hear the pings then I would see a code thrown in that order. This is different from what that link/ref above says...Do you hear any pings? I used to hear them around 3000 to 4000 when I suddenly planted the throttle (with a hot engine).When my car was pinging, it was really loud. It actually sounded like a bracket had come loose on my exhaust or something. Bad stuff. Definitely noticeable.There is also a possibilty that you are running lean. It could be the injectors?Jules Link to post Share on other sites
Macca 1 Posted April 3, 2004 Report Share Posted April 3, 2004 Has this problem just come along out of the blue, or has it occurred after some engine work (or has it been there since youve had it)? If there is nothing wrong with any of the electrics/ computing side of things it could be the timing is out on the cams or crank.i had this problem after my head gasket was replaced, the mechanic put one of the gears back one tooth out of sync, and it drove like shite. Link to post Share on other sites
patrick green 0 Posted April 4, 2004 Report Share Posted April 4, 2004 I don't know if this is any help but mine misfires at 2000rpm & from cold feels sluggish. When changing up, there's always a noticeable lag as if the engine can't be arsed to get going! At the RR day Vince put it on VAG.com & diagnosed a faulty ca,shaft sensor. It's probably not that on your car Kev but bear it in mind! Link to post Share on other sites
VR6Andy 0 Posted April 4, 2004 Report Share Posted April 4, 2004 These Vrs can be great but also pains in the butt. I had a 92 Vento VR6, this had very similar problems. at between 1 and 2K rpm it would cut out as if no fuel was present and then when I put my foot down it would hesitate, jerk and go. I did the following :- VAG com- No faults listed, i put on another coil pack which made no difference, new fuel filter no difference and finally new plugs and leadsthis made minor improvement. I sold the bugger in the end to cut my losses. Hope this helps and the problem you have described sounds the same as the Vento I had.I was also advised that the idle stab valve may have been the cause. The owner I bought it from assured me that it was fine before I got it and I only had the thing 6 weeks !!!! :? [ Edited Sun Apr 04 2004, 05:37PM ] Link to post Share on other sites
brett 0 Posted April 4, 2004 Report Share Posted April 4, 2004 check ecu relay and cam pos sensor, thats what it sounds like to me. Link to post Share on other sites
FishWick 21 Posted April 4, 2004 Author Report Share Posted April 4, 2004 Cheers guys, not had a chance to have a play today but I will keep plugging away! Yeah it has just come out of the blue. It was always used to pull hard and was smooth with it, but I've always had the hunting between 1K and 2K since I got it 14 months ago.I can't hear any pinking at all Jules.Agreed, VRs are a pain in the butt!! Brett, do you know which relay supplies the ECU?CheersKev[ Edited Sun Apr 04 2004, 08:17PM ] Link to post Share on other sites
jcorallo 0 Posted April 4, 2004 Report Share Posted April 4, 2004 Fuel pump relay? About £8 from ECP.heh - the list goes on!I fitted an inline fuel pressure gauge the other weekend. Pressure on mine is good and the FPR works OK. Also, holds pressure for a long period when the engine is off thus ruling out leaky injectors or the fuel pump check valve.Quality bit of on-baord diagnostic kit I thought!!Jules Link to post Share on other sites
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