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essayer
Original Poster
1,588 posts
63 months
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GF's Lupo started, ran really rough for 10 seconds then stalled and just wouldn't restart. So call the RAC, guy cranks it for about 2 minutes, started 'catching' and suddenly started up fine. (in a massive cloud of white smoke) He reckoned it had got flooded somehow.. something about no compression and bore wash. Starts up fine now. Done so quick the RAC guy didn't even bother with the paperwork  I didn't think in the days of fuel injection engines could get "flooded". I know it has had an intermittently faulty coolant sensor (sometimes reads cold when it's not) so perhaps - combined with quite a few short trips lately - it has had a long period of overfuelling? Seem possible?
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S7Paul
1,665 posts
103 months
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Don't know about the cause, but I've certainly had experience of fuel injected cars failing to start due to flooding. In every case but one I've managed to get them started by holding the accelerator flat to the floor & cranking the engine until it fired.
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cmsapms
551 posts
113 months
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Both 'er indoors Elise S2 and Mother's 2008 Fiesta have been known to flood. I may be wrong, but I think the act of flooring it whilst cranking tells the ECU to inject zero fuel to "dry" the engine out.
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SuperchargedVR6
849 posts
89 months
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Is it a single point injection Lupo, or the later 1.4/1.6 16V multipoint?
Single points can sometimes do that as they're essentially just a posh carburettor and have pretty basic control.
Certainly in multipoint injected VW engines, I've only ever seen proper bore wash occur when the injectors stick fully open. Due to either an electrical fault, or failed injector driver/s inside the ECU.
A failed coolant temp sender usually defaults the reading to a failsafe number. Normally 70 deg C in Motronic managed VWs, which should prevent over-fuelling.
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essayer
Original Poster
1,588 posts
63 months
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It's a 2003 plate 1.4 16v.
Will have to keep an eye on it.. and keep those jump leads handy in case another 2 min cranking is required!
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SuperchargedVR6
849 posts
89 months
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Did this suddenly happen out of the blue? Did Mr RAC man interrogate the ECU for fault codes?
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martycossie
86 posts
43 months
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if i was u ill be putting new teemp sener in as that could be faulty
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eliot
5,321 posts
123 months
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cmsapms said: I may be wrong, but I think the act of flooring it whilst cranking tells the ECU to inject zero fuel to "dry" the engine out. Indeed it is.
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DEANO87
745 posts
41 months
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martycossie said: if i was u ill be putting new teemp sener in as that could be faulty This is normally the case. In the eyes of the rac/aa they see it as problem fixed because it started but abit of investigation might have shown a faulty coolant temp sensor that is under reading and causing over fueling.
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essayer
Original Poster
1,588 posts
63 months
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Cheers all, I have ordered a new coolant temp sensor from VW and will fit it at the weekend.
There were two faults logged on the memory but I didn't get a chance to memorise them, I think one was about a lambda sensor, the other was about the coolant temperature being over or under voltage.
Lambda I'm not sure on, could this have been triggered by the rough start/flooding?
I will swap the coolant sensor, as this definitely reads zero from time to time, and if we get the check engine light again perhaps the lambda sensor is faulty?
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Nick1point9
3,416 posts
49 months
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essayer said: Cheers all, I have ordered a new coolant temp sensor from VW and will fit it at the weekend.
There were two faults logged on the memory but I didn't get a chance to memorise them, I think one was about a lambda sensor, the other was about the coolant temperature being over or under voltage.
Lambda I'm not sure on, could this have been triggered by the rough start/flooding?
I will swap the coolant sensor, as this definitely reads zero from time to time, and if we get the check engine light again perhaps the lambda sensor is faulty? Most ECUs ignore the lambda sensor until they are up to temperature, so it's probably related to the fact the dodgy temp sensor and the fact that when you crank without the engine firing you're effectively pumping fresh air down the exhaust, so if the ECU did listen to the lambda for some reason it would likely give "an impossible reading".
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Mr2Mike
9,444 posts
124 months
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essayer said: I know it has had an intermittently faulty coolant sensor (sometimes reads cold when it's not) so perhaps - combined with quite a few short trips lately - it has had a long period of overfuelling? Seem possible? The ECU and the dashboard gauge normally use separate sensors, so the gauge reading low intermittently does not mean the ECU is seeing the same thing.
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Pumaracing
1,175 posts
76 months
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Lots of clues in the first post which as usual no one has spotted. A cloud of white smoke would indicate coolant in the combustion chambers burning off which would obviously prevent proper starting as the spark plugs would be wet. Low coolant level, and/or an intermittent air lock in the coolant could cause the temp sensor to be in an air pocket or above the coolant level in which case it will read cold because it isn't sat in hot water to give a proper reading.
So it could have a blown head gasket leaking coolant into one or more cylinders. Check coolant level and do a compression test to verify head gasket sealing.
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essayer
Original Poster
1,588 posts
63 months
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Ouch, hope not. Makes sense, although maybe the white smoke was water vapour, it was late evening when Mr RAC showed up.
I'll check the coolant tonight, as far as I remember it's never used a drop. But it is a bit mystifying how it worked fine since forever and one day randomly just wouldn't start..
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