Stuttering
Stuttering
Author
Discussion

volospian

Original Poster:

494 posts

227 months

Friday 22nd February 2008
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The car has been laid up for a fortnight and I noticed today that when I jab the throttle it stutters.

It's OK in normal driving, but the pick up isn't great. I hadn't really noticed really as it's quite greasy out there and doesn't warrent a heavy right foot.

I only noticed when my neighbour came around yesterday as I was reversing onto my drive. He was carrying his little girl and pointing to the noisy brute (AKA my car biggrin).

I gave it a few blips (until Maddy started crying... ooops frown) and noticed it was a bit reluctant to rev.

Today I gave it another go when I got home and it was even worse.

I'm thinking it could maybe do with some new plugs? God knows when they were last changed. The fuel system hasn't long been overhauled (2 months?) as I needed new pipes and a filter, so I doubt it's that, although it was rather low when I left it in the garage.

Anyway, anything else I could do with looking at?

Also, what plugs are people using, and what gaps?

optimax sniffer

1,817 posts

245 months

Friday 22nd February 2008
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If it has been laid up, it could just be damp deep down. Put a full tank of fuel in and 'go for a pint of milk' biggrin

volospian

Original Poster:

494 posts

227 months

Saturday 23rd February 2008
quotequote all
Well, I changed the plugs today and it's a bit better, smoother, but still stutters a bit when you jab the throttle. I'll have to check for air leaks. The air filter is past its best. I'll fit a new one and see if that helps.

I've also noticed what looks like a crack in the exhaust header, on no. 2 cylinder (I think, front, drivers side). There's what looks like carbon deposits around the header and it looks like it's blowing a bit onto the lower fibreglass valance thing. I doubt that would make much difference though...?


marcus1970

1,217 posts

265 months

Sunday 24th February 2008
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volospian said:
Well, I changed the plugs today and it's a bit better, smoother, but still stutters a bit when you jab the throttle. I'll have to check for air leaks. The air filter is past its best. I'll fit a new one and see if that helps.

I've also noticed what looks like a crack in the exhaust header, on no. 2 cylinder (I think, front, drivers side). There's what looks like carbon deposits around the header and it looks like it's blowing a bit onto the lower fibreglass valance thing. I doubt that would make much difference though...?
Could make quite a lot of difference, as it may affect the lambda readings. Could be telling the ECU that there's too much unburnt oxyygen when there isn't really.

MB

Byker28i

92,187 posts

247 months

Sunday 24th February 2008
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Does it get better after about 3K revs? Best fire up the diagnostics and check your lambda settings as I had this and one of my Lambdas had gone.

It affected my mix so much at low speed/revs/traffic I overheated a cat and spat the expensive contents of it out over the road with a 25 foot roman candle effect

volospian

Original Poster:

494 posts

227 months

Sunday 24th February 2008
quotequote all
marcus1970 said:
Could make quite a lot of difference, as it may affect the lambda readings. Could be telling the ECU that there's too much unburnt oxyygen when there isn't really.

MB
Yeah, my doubts were because it's so close to the head I'd have thought that all gasses would be travelling out, rather than any managing to be sucked in. If gas is only going out, then the lambda should be ok, if gas is incoming, then there would be extra oxygen.

Although I suppose a pulse effect could draw air in when no.2 isn't firing?

volospian

Original Poster:

494 posts

227 months

Sunday 24th February 2008
quotequote all
Byker28i said:
Does it get better after about 3K revs? Best fire up the diagnostics and check your lambda settings as I had this and one of my Lambdas had gone.

It affected my mix so much at low speed/revs/traffic I overheated a cat and spat the expensive contents of it out over the road with a 25 foot roman candle effect
It's only when I'm jabbing the throttle at stationary. During normal driving, under load, it appears to pull happily enough.

It seems to me that if the air through the inlet is suddenly increased, the system is not adding fuel quickly. If the throttle is opened at a more sedate pace, there's no (obvious) issues.

Put it this way, if it were an SU carb I'd check my dashpot oil.