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Idle prob after swapping 390cc to 450cc

Old 03-19-2005, 12:45 PM
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Default Idle prob after swapping 390cc to 450cc

I just have swapped my 390cc DSMs to blue top 450cc injectors. Since then my idle is not stable, it falls under 500rpm and then goes up to 1000rpm. Sometimes it is ok (750rpm). It happens not only at cold startup, but even at warm engine. I use SMC500. I tried to set idle at -35%, -40%, but no luck. I can not get rid of moving idle.
I also checked for leaking around fuerl rail, leaking at injector rings, but everything is ok.
Does that 60cc diff between 390cc and 450cc mean so much at idle?
lordie is offline  
Old 03-19-2005, 01:13 PM
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Default Re: Idle prob after swapping 390cc to 450cc

Have you adjusted your AF ratio to try and lean out those 450's a bit more to match where your 390's were running? Any wideband to use as a refference?
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Old 03-19-2005, 03:21 PM
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Default Re: Idle prob after swapping 390cc to 450cc

Sure i adjusted my A/F ratio (-5% at all rpm). It runs fine, but idles bad now.

Unfortunately I have no W/B lambda.
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Old 03-19-2005, 03:57 PM
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Default Re: Idle prob after swapping 390cc to 450cc

You need to take more out at idle do to injector latency.
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Old 03-19-2005, 04:10 PM
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Default Re: Idle prob after swapping 390cc to 450cc

I remember having to go as far as -50% at idle to get a decent idle with the AFC and 450cc.
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