120k 51 reg vectra - went for service with Vx Dealer, and lpg pump "cleaned out" as reluctant to cut across to gas from petrol until warm. This problem resolved, but within 50 miles of service now suffering intermittent misfire (hiccup really) when going from overrun to drive (easing off on motorway, negotiating roundabouts, picking up drive in traffic etc). Only seems to happen on gas, not petrol. Back to dealer - he says gas injector on one cylinder faulty (identified by clamping off gas pipe to faulty cylinder), but all need replacing at c £800! Left me with diagnostic light on - said he'd been trying to clear down all afternoon without success. Any ideas? Diagnostic light no longer on - cleared down myself by repeated start-stop of engine. Misfire more of an annoyance than anything else - seems really coincidental that only happening since the service - I can live with it rather than stump up £800!
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On current Vauxhalls, short duration faults put the fault light on but turn it off with no fault logged if the fault clears within 30 secs. Longer duration faults store the fault code and keep the fault light on until, I think, the ignition has been turned off and on 20 times when the light goes off and the fault code is cleared. Vauxhall dealers can clear the fault code before 20 starts, using Tech2. Of course, if the fault is still present the fault light will still come on and the fault code will still be present.
Has the Vauxhall dealer actually used Tech2 to diagnose this problem or is he going on guesswork?
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martinw
Did the dealer give you the actual code reference? How does "clamping-off the pipe" help to diagnose a transient, single-cylinder, misfire that's only apparent under load?
Given that LPG is slightly more difficult to ignite than petrol, could this fault be the initial manifestation of the "usual" 16v GM coilpack breakdown?
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Didn't give me the fault code - and was surprised by the technician saying he wasn't able to clear it down. I managed it whiling away the time stuck in a queue on the M6 ;-). Got the impression that they had been running it in the workshop and had managed to pin it down to a single cylinder by some means or other. Your comments reassure me - I too was highly sceptical of the diagnosis given, but as I hadn't been charged for the investigation thought it better to escape. I think I'll keep driving and keep an eye on the coil pack. Thanks for your help/comments guys.
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