Scott 0 Posted April 2, 2003 Well my VR has been as good as gold for the six months have owned it... (over 6k miles too) drove it too Bolton last night to drop missus off and got a lot of jealous looks at it as I drove past *:)... she was purring (the VR that is) parked up for an hour then started her up (again the VR) and straight away I knew something was wrong... she is chugging on idle (VR?) and hesistant to accelerate.... as though I'm mis-firing... Anyone got any ideas / things for me to check? - I cant get it on diags until Sat and that means no car till then if I cant fix it - couldnt do anything last night as was cold, dark and engine was red hot - from looking at exhaust its obvious the fuelling isnt right hence why suspect ignition problem! - I refuse to drive it like this for fear of causing harm! Cheers, Scott Quote Share this post Link to post Share on other sites
Kevin Bacon 5 Posted April 2, 2003 It might be your O2 sensor but a diag test will tell you for sure. Kev 94 VR6 Quote Share this post Link to post Share on other sites
Scott 0 Posted April 2, 2003 It might be your O2 sensor but a diag test will tell you for sure. Kev 94 VR6 Can anyone explain the role of the O2 sensor on a VR6 ? Im thinking coil pack at moment........... Quote Share this post Link to post Share on other sites
Kevin Bacon 5 Posted April 2, 2003 Yes it continuosly monitors oxygen content in the exhaust gases and this is done for two reasons:- 1. To protect the cat. Running too rich or too lean will eventually destroy it. 2. Optimum performance and economy. The Motronic management reacts to the resistance differences in the O2 sensor and either weakens or enrichens the mixture accordingly. If the sensor dies, the motronic acts blind and usually loads a 'default' get you home map, which is usually rich. This can give bad running and jerkiness, but mainly when driving. Your problem could be the coil pack although I don't think that will show up on VAG-COM as it's not monitored, as far as I know. You could try unplugging the leads one by one until the faulty pack reveals itself. Kev 94 VR6 Quote Share this post Link to post Share on other sites
Scott 0 Posted April 3, 2003 I thought that was the job of the lambda sensor? *:) Update: Whipped all the plugs out last night to find number one cylinder spark plug covered in thick carbon to the point where the spark it was producing was very poor! - Cleaned them all up and chucked them back in - hey presto - smooth and powerful again :shock: So am now trying to work out what has happened as the engine is mint! My conspiracy theory?: Car was lady owned from new and I suspect she never really used the power and toodled around town in it - I then bought it and run it on nothing but optimax and do drive it hard quite alot (obviously when up to op temps)... with the result that I have loosened some carbon inside the cylinder head..... I believe optimax does have some cleaning properties too... Plugs had only done 6k miles.... bosch standard plugs for 2.8 VR6 Im told.... am off to get some NGK plats this weekend *:) Anyone got any suggestions as to why this has happened? - rest of plugs were spot on... Checked leads, coil pack and plugged in VAGCOM - no faults or anything! Oh... fixed me ABS too *:) heh So she is now all ready for the MOT! Cheers, Scott Quote Share this post Link to post Share on other sites
Kevin Bacon 5 Posted April 3, 2003 Lambda is just another name for the O2 sensor. Any car with a cat has a Lambda/O2 sensor. What colour were the deposits on the spark plug? Black sooty deposits = running rich, grey/light brown deposits = spot on, white deposits = too lean and black oily deposits = burning oil. Cyl no 6 (battery end, front) is usually the first cylinder to show signs of burning. Carbon doesn't flake off the engine and then adhere to the spark plugs I'm sorry to say. All 6 plugs should be the same colour, indicating a healthy engine. Were they all the same except no 1? Kev Quote Share this post Link to post Share on other sites
Scott 0 Posted April 3, 2003 Lambda is just another name for the O2 sensor. Any car with a cat has a Lambda/O2 sensor. What colour were the deposits on the spark plug? Black sooty deposits = running rich, grey/light brown deposits = spot on, white deposits = too lean and black oily deposits = burning oil. Cyl no 6 (battery end, front) is usually the first cylinder to show signs of burning. Carbon doesn't flake off the engine and then adhere to the spark plugs I'm sorry to say. All 6 plugs should be the same colour, indicating a healthy engine. Were they all the same except no 1? Kev Another name for same thing then *:) - knew what it was all along - *:) LOL Nope number six cylinder was spot on.. as were all the plugs (grey / brown colour) - it was number one cylinder... thick black sooty matt deposit on plug and Im pretty sure it was carbon / fuelling deposits... am wondering if perhaps number one isnt firing cleanly poss due to bad lead or something and so is carbonning up? The engine has been pronunced in excellent health by VW and various specialists including an engine builder and is giving excellent compressions so I cant see it being a problem with oil burning! Cheers, Scott Quote Share this post Link to post Share on other sites
Joe M 0 Posted April 3, 2003 Plugs had only done 6k miles.... bosch standard plugs for 2.8 VR6 Im told.... am off to get some NGK plats this weekend *:) Scott Dont know for sure, but I thought the 2.9 used different plugs from the 2.8. Quote Share this post Link to post Share on other sites
Scott 0 Posted April 3, 2003 Plugs had only done 6k miles.... bosch standard plugs for 2.8 VR6 Im told.... am off to get some NGK plats this weekend *:) Scott Dont know for sure, but I thought the 2.9 used different plugs from the 2.8. Yeah you are right they do - they use plat type plugs from 1993 onwards..... but people have been using 2.8 plugs for years with no probs was told! Quote Share this post Link to post Share on other sites
Kevin Bacon 5 Posted April 3, 2003 Have you got a part number for the 'correct' plugs as I've got regular Bosch twins in mine. Cheers Kev 94 VR6 Quote Share this post Link to post Share on other sites
Scott 0 Posted April 3, 2003 Have you got a part number for the 'correct' plugs as I've got regular Bosch twins in mine. Cheers Kev 94 VR6 I have but its at home *:) Correct Plugs are NGK BKREU5P or something like that! *:) P denotes PLATINUM! *:) Bosch twins are 2.8 V6 plugs... same as what is in mine! Quote Share this post Link to post Share on other sites
Kevin Bacon 5 Posted April 3, 2003 Out of interest, what are you hoping to achieve by fitting expensive platinum plugs? It won't improve performance or running. The only reason I've ever used platinum plugs was in a forced induction engine to stop the spark blowing out. I can't see what value they have in a NA engine, other than longevity perhaps but Bosch twins and triples aren't exactly known for their stingey service life. Kev 94 VR6 Quote Share this post Link to post Share on other sites
Scott 0 Posted April 3, 2003 Out of interest, what are you hoping to achieve by fitting expensive platinum plugs? It won't improve performance or running. The only reason I've ever used platinum plugs was in a forced induction engine to stop the spark blowing out. I can't see what value they have in a NA engine, other than longevity perhaps but Bosch twins and triples aren't exactly known for their stingey service life. Kev 94 VR6 Correct plugs = BKR5EKUP Well seeing as the plat plugs are only £1 more than the non plat NGK plugs then I cant see how much more expensive they are! *;) They do have better longetivity yes - I dont really hope to achieve anything to be honest - VW specify plat plugs for 1993 VR6 onwards therefore thats what my VR6 is going to get *:) simple! How long they last isnt a issue to me anyway as I usually change them every 5k miles but Im a firm believer if main dealer says they were standard fitment then it gets that or better *:) One of the reasons VW might have used plat plugs from 93 is due to the higher voltages produced by the coil pack? or poss to prevent plug fouling ? but most likely to extend service intervals.... no idea! *:) Scott Quote Share this post Link to post Share on other sites
Kevin Bacon 5 Posted April 3, 2003 Fair enough, it's your money. I will ask the dealer and Stealth about this tomorrow because whilst I agree VW use things for a reason, I am dubious about this one. Especially as the Bosch plugs are a couple of quid each and all the Golf VR6s use them, even the late ones with the same DIS coilpack. Kev 94 VR6 Quote Share this post Link to post Share on other sites
Scott 0 Posted April 3, 2003 Fair enough, it's your money. I will ask the dealer and Stealth about this tomorrow because whilst I agree VW use things for a reason, I am dubious about this one. Especially as the Bosch plugs are a couple of quid each and all the Golf VR6s use them, even the late ones with the same DIS coilpack. Kev 94 VR6 I never skimp on good quality service parts *:) - If VW says it should have them then it will *:) I get NGK Plats for £6 each *:) - you ask how much VW want for them *:) Quote Share this post Link to post Share on other sites
Kevin Bacon 5 Posted April 8, 2003 Well I was in the dealers today and asked about these platinum plugs. Corrados never had them apparently. They only list a NGK BKR5EKU (VAG p.no - 101000035AB). I asked him to check for the BKR5EKUPs and they are for an Audi S3/TT/LEON CUPRA R/GOLF 1.8T etc. I bought some of the former anyway for my next service as they only had 6 left and were only £4 each. They are just Bosch twin clones and labeled on EKTA as 'Longlife' plugs. If you notice a difference with the plats, let me know and I might try some. Kev 94 VR6 Quote Share this post Link to post Share on other sites
