stevefoster Posted May 23, 2002 Share Posted May 23, 2002 16V VX on 45's Running perfectly. Left the car outside on trailer. It got wet. Wetter still driving to Lydden 3 weeks ago. Barely started for scrutineering, coaxed her to life on 2/3 and then a alumpy 4 cyl with slight but persistant lumpy / uneven running at ~2000 rpm. It has never done this, been out all night in thunderstorms and heavy rain before trackdays and started faultlessly... I managed to race and at above 3500rpm no sign of misfire. Got a 3rd place in last race smile.gif Ok, having changed the plugs: no difference, checked all the fuel filters and jets for crud: no crud, changed the ECU from 3D mapped Webcon to 2D MBE: no difference, changed the plug leads for new plug leads: no difference, had loads of new fuel through her: no difference, fitted a dry sump system: no difference (that was a bit of an extreme attempt to fix it wasn't it :-)! urrm ok, After 3 weeks of dry running and the car nice and hot on the track and the road I still have the problem.... Could it be, the crank sensor... the coil pack (= GM wasted spark), or a hydraulic valve not lifting quite as it should... god no not that! But why should it do this and then almost clear but leave the afore mention sympton? Just now I am sad.gif for the lumpiness and smile.gif that the dry sumping went so well with no decernable leaks. Thanks to Alex and Arnie for advice and pictures.... Many thanks also to Phil (bugger I skinned my knuckles on your BL***DY car again mate) mechanic-Waters (who also has a sad.gif, not as it should 7, see threads about total & utter hair loss and grown Phil's crying....) Please help me before I drink the whole bottle of wine and wake up with a bitch of a hang over and a not quite as it should be race car.... Edited by - stevefoster on 23 May 2002 22:08:34 Link to comment Share on other sites More sharing options...
stevefoster Posted May 23, 2002 Author Share Posted May 23, 2002 Yeah, and we would get out more if our cars ran properly.... Link to comment Share on other sites More sharing options...
Simos Posted May 24, 2002 Share Posted May 24, 2002 Well if this is a brainstorming session. My car did(does) what you describe when the air filters get wet (K&N) at low revs the partial vacuum has a hard job pulling air through but on full chat the harder vacuum and bigger air flow is fine. It goes away when dry though - I'm sure you've checked given the scope of what you've done so far but are your filters clogged/knackered ? Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted May 24, 2002 Share Posted May 24, 2002 ECR had not dissimilar problems which finally was traced down to alternator connection problems. Alex Edited by - Alex Wong on 24 May 2002 11:12:20 Link to comment Share on other sites More sharing options...
Dave H Posted May 24, 2002 Share Posted May 24, 2002 Sounds like a fuel/air problem - I had something similar on my old xflow, turned out to be an air leak between a carb and the manifold. At low revs it was trying to run on a weak mixture in one cylinder, but once the throttle was open the mixture picked up, and away we went. Good luck Dave H Link to comment Share on other sites More sharing options...
Jason Plato Posted May 24, 2002 Share Posted May 24, 2002 You could do a compression test to check the internals . My bet is the coil pack or associated wires . Dave Link to comment Share on other sites More sharing options...
Simos Posted May 24, 2002 Share Posted May 24, 2002 Forgot to say I also had the same with alternator connections as mentioned on another thread. Link to comment Share on other sites More sharing options...
ECR Posted May 24, 2002 Share Posted May 24, 2002 As well as the alternator problem that Alex has mentioned I also had a problem with water collecting in the plug on the end of the crank sensor wire (due to the routing of the wire). It did not give exactly the symptoms that you describe but worth a look ayway. Link to comment Share on other sites More sharing options...
John Posted May 24, 2002 Share Posted May 24, 2002 Does it do it with the air filters removed? Does it do it when not under load? John Edited by - John on 24 May 2002 14:14:30 Link to comment Share on other sites More sharing options...
stevefoster Posted May 24, 2002 Author Share Posted May 24, 2002 Thanks for all the pointers... I forgot to say that last night it ran and seems better until things started to warm up... BTW she starts on the button hot or cold. I have had the filters off to check carb balance and looked to see if there was any sign off fuel getting past the float valves, no sign of problems. It still had the problem with the filters off. The alternator connections I will check. The batt is certainly getting charged. I will make some measurements. The coil pack / crank to ECU loom is totally separate for the 2 difference ECU's I can run so it would have to be the coil pack or the crank sensor / wire themselves. I will check the carb to inlet manifold 'O' rings. I can't hear anything getting past them but it could be that. They the new moulded type but are 5 years old and I have two new ones hanging on the wall. I wondered about a dodgy earth strap engine to body and will take off and clean. The batt one to the engine obviously works and I had it off to re-position the bat... The level of the problem now, doesn't explain the very, very poor damp start I had a Lydden. I wondered about spraying water on to see if I could recreate that environment on each suspect bit one at a time and see what happens. A fun weekend ahead. Link to comment Share on other sites More sharing options...
Morls Posted May 24, 2002 Share Posted May 24, 2002 My 2.0L Vectra company car is, (sorry was, as the cam belt snapped last week and now it's proper broken), on it's 3rd crank sensor in 70K miles. Each time it goes the car wil run above 3500rpm fine, with the low rev behaviour very erratic (and frightening in a seven on a wet track I would imagine). It feels like someone is randomly pressing a "Go on to 2 pots" switch every so often. Could you borrow one to tryquestion.gif Mark Link to comment Share on other sites More sharing options...
stevefoster Posted May 25, 2002 Author Share Posted May 25, 2002 Ok. Having cleaned and checked alternator electrics and earth straps and replaced the carb 'O' rings, checked out the float chambers for cleanliness and function it still farts about (it's not a misfire, just not clean running, fluffing/burbling/not on it and probably down on power) and there is now the odd backfire on lift off from 2500 rpm down. But no backfire if she has been running at higher rpm... It idles ok. It is 1400 - 3000 rpm that is not quite right. Compression is a 16 bar on all cyls apart from no.2 that is just over 16 bar. There is also a slightly different sucking sound out of no.4 cyl through the trumpet. It has always done this (2 yrs in my ownership). I suspect a sluggish valve but would that not show up something on the compression test. They all whomp up to pressure at the same speed / number of crank turns. Any further ideas warmly received. Edited by - stevefoster on 25 May 2002 13:47:31 Link to comment Share on other sites More sharing options...
stevefoster Posted May 25, 2002 Author Share Posted May 25, 2002 The fluffing misfire after quite a bit of checking, cleaned alternator contacts, earth straps, choke and jet checks, new carb 'O' rings (don't you just love that job), changed plugs, swapped plug leads, swapped ECU's and a perfect compression test turned out to be the FUEL. I had 40l of Sainsbury's SUL with me to Lydden. That was what was in the tank the whole time. Never more will I buy SUL at a Supermarket... 15l of Total SUL put it right in one go.... Now I can get out more....teeth.gif What is in fuel that can do this? Edited by - stevefoster on 25 May 2002 19:00:31 Link to comment Share on other sites More sharing options...
mav Posted May 25, 2002 Share Posted May 25, 2002 more likely what is not in the fuel that can do this? Link to comment Share on other sites More sharing options...
Jason Plato Posted May 25, 2002 Share Posted May 25, 2002 Maybe water ??? Link to comment Share on other sites More sharing options...
stevefoster Posted May 25, 2002 Author Share Posted May 25, 2002 I have used Sainbury's fuel loads of times so I is just one of those things I guess. I have never had bad fuel before so this was a bit of a wake up... more data in the diagnostic database wink.gif Edited by - stevefoster on 25 May 2002 21:23:31 Link to comment Share on other sites More sharing options...
paul jacobs Posted May 25, 2002 Share Posted May 25, 2002 Yep, I have had exactly the same probs. with Sainsbury's fuel, except it was in a VW Type 4 campervan, about 6 years ago. It cost me a fortune, checking ECU, new airflow meter [ still got a perfectly good one sitting in the garage now] etc. I've never used any supermarket fuel since, always go for ESSo or Shell or BP whenever possible, more recently have found Optimax works OK. Wasn't Saimsbury's fuel responsible for causing Vx engines to blow up some years ago? Link to comment Share on other sites More sharing options...
stevefoster Posted May 25, 2002 Author Share Posted May 25, 2002 Shell had problems with their last (previous to Optimax) big new fuel drive with VX engines. They have tested Optimax on lots of VX's this time around so say. Link to comment Share on other sites More sharing options...
Asklepios Posted May 25, 2002 Share Posted May 25, 2002 Steve, Dave surely has it --water. Heavy rain,low revs and perhaps some water in fuel from supplier. Nonsense to suggest Sainsbury`s fuel to blame.In all probability they source from one of the big suppliers. If you get a poor fuel ,and it does happen, then blame that garage rather than "supermarket" fuel. Carb icing ,the end point you experienced from you water in fuel,is common in light aviation and at low revs, when the donkey stutters, it takes a fair bit of control to resist the temptation to jam open the throttle. If you do this a rich cut can result. If you have bad contamination you may have to drain the tanks to clear out the cr** below the fuel take off. Link to comment Share on other sites More sharing options...
stevefoster Posted May 26, 2002 Author Share Posted May 26, 2002 Agreed, It is not Sainsbury's fault and they probably look after their tanks as well as any one else... Having run carbed cars in Scandinavia I know a bit about carb freezing. They put pure alcohol (0.5l to a small tank) in during winter to absorb water that will have condensed in the tank during summer. The winter fuel has alcohol already in it. Injection cars are much less prone to this freezing than carbs. So back to my problem. Damp day, car out all night. Some dodgy fuel with water in the tank and you have a bad start and then lumpy/fluffy progression until the fuel is changed. Have we solved it then? A shame I cannot go and buy the water absorbing alcohol from the local BP, OK, Q8 garage isn't it. Edited by - stevefoster on 26 May 2002 08:55:06 Link to comment Share on other sites More sharing options...
elie boone Posted May 26, 2002 Share Posted May 26, 2002 Steve, Maybe you should take a look at the filler & fillerhose from your car, it is always possible that water has entered this way. Just to make sure you do not overlook things. Link to comment Share on other sites More sharing options...
paul jacobs Posted May 26, 2002 Share Posted May 26, 2002 Nope Steve, in my case I put the blame squarely on Sainsburys or at least their fuel supplier. Once I'd discovered that my engine ran perfectly on anyone elses fuel, I then filled my tank with Mr Sainsburys best and exactly the same thing happened again. I really was mad, but I cannot prove anything, although I was several hundred pounds out of pocket and much time running my vehicle to different garages, none of whom fixed the "bad" petrol. As I said I've never touched the stuff since - which is more than I can say for one of Scotlands best exports, teeth.gif Edited by - Paul Jacobs on 26 May 2002 20:27:09 Link to comment Share on other sites More sharing options...
Simos Posted May 27, 2002 Share Posted May 27, 2002 Curiouser and curiouser. Lets assume the fuel is acceptable for the average tintop or else thousands or irate people would be complaining to sainsburys. Perhaps we can assume the difference is the advance/map on your engine and that if it were retarded it'd run ? The question then comes down to, how does your car behave on 95 octane unleaded, and, if it is the same could it be they put UL in the SUL tank and ripped you off ? (doesn't explain Paul's campervan which I can't believe is a tuned SUL only beastie) Link to comment Share on other sites More sharing options...
stevefoster Posted May 27, 2002 Author Share Posted May 27, 2002 I get a tad of pre-ign at 1100 rpm and hard foot down on 95 octane. Otherwise fine. It does not do this on SUL. According to Webcon I have a higher compresson ratio than the normal VX's they see and I have a Formula VX map in the ECU for this reason. Bear in mind it still did the messing about with the MBE 2d mapping... Link to comment Share on other sites More sharing options...
matthewgardner Posted May 27, 2002 Share Posted May 27, 2002 I had a similar problem with Sainsbury's fuel about 6 year ago when I filled up my mum's Peugeot 205. The problem was caused by the excessively low octane rating of the fuel. But since I had filled up with diesel instead of petrol I will not blame Sainsbury's. Link to comment Share on other sites More sharing options...
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