Vectra lumpy acceleration

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Sun 1 May 2005 18:48
Vectra lumpy acceleration - simono
Hi all,

Have just spent all day dismantling the throttle body and idle valve on my 97 2.0 ecotec (SRi) Vectra. I replaced all the tubing and gaskets and used jubilee clips in place of the original spring clips. The car now idles beautifully and no longer cuts out or stalls! Fantastic, however, I still have a lumpy acceleration problem. Between 1000 and 3000 RPM the car is lumpy as hell. I tried the paper clip trick on the ECU and found no fault codes and the ECU light has never flashed on. THe car has had new plugs, fule filter etc within the last 10K and has only done 80K. HELP, its driving me mad. I though at first it could be the crank or camshaft sensor, but surely this would register a fault code?? HELP!
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Sun 1 May 2005 20:52
Vectra lumpy acceleration - elekie&a/c doctor
This could be an ignition/ht fault.Make sure the spark plugs are the Bosch twin electrode type.Possible problem with coil and/or spark plug leads.A faulty cam or crank sensor does not generally cause lumpiness.
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Sun 1 May 2005 21:10
Vectra lumpy acceleration - simono
Well, to have to say this was also my first thought. The plugs were fitted by a Vauxhall dealer recently, so it could be the HT's. However, the lumpiness is more pronounced when the car is warm and unoticable when cold. Not sure what this means?
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Sun 1 May 2005 22:18
Vectra lumpy acceleration - Dynamic Dave
Might be wrong, but it won't have HT leads if it's got coil packs.
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Sun 1 May 2005 22:36
Vectra lumpy acceleration - simono
It seems to have HT leads and a normal coil, but of course I could be wrong!
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Mon 2 May 2005 08:09
Vectra lumpy acceleration - Sprice
Has it only been lumpy since vauxhall got their hands on it? If so, perhaps wrong plugs (single electrode with incorrect gap etc) What worked for me once with a similar problem was a bottle of injector cleaner into the tank!
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Tue 3 May 2005 11:35
Vectra lumpy acceleration - Deryck Tintagel
Just wondering ... why would twin electrode spark plugs make any difference? Is there any benefit or reason to have them. Just thinking ahead to service time as I am not sure what my mechanic fitted last time - he generally replaces everything even though not part of the service schedule at the time.

PS I have a 1.8CDX if it makes a difference
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Thu 5 May 2005 12:38
Vectra lumpy acceleration - simono
Finally found the reason! The Cam-cover gasket had failed (only a little) and alowed oil to leak into the SPark plug channel between the cams. This caused the spark plugs in cylinder 3 and 4 to be completely submerged in black engine oil. After replacing the gasket and cleaning the plugs and leads the car is back to its best once again!! Wierd hey!
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