Judder on acceleration

[monsi]

Hi all,

I've got an issue when slowly accelerating through the 2000 - 2500 rpm range, the engine revs judder causing the car to jerkily accelerate. This can also be heard/felt when just reving the engine through this range while parked.

The datalog shows this starting at the 6.5s mark, and I'm running on Spark and VE table 3.

Thanks

Simon

[Matt Cramer]

Looks like a bit of a misfire; I would try adjusting the fueling in that range.

[monsi]

Thanks Matt.
Is it just fueling I should look at or spark as well? And any idea which direction?

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[Matt Cramer]

I am not seeing any indication of a spark issue in that log.

[monsi]

Ok, that's great thanks

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[monsi]

Just to give you an update on this I've tried adding fuel in this area and was unable to fix the misfire even when it was very rich. I did remember that when my tuner was mapping the car we had some issues getting a nice smooth idle and he adjusted the injector timing (down to 180 around the idle region with a blend starting around 2000 rpm), so on a hunch I extended this area so the blend started around 2500 and the misfire has disappeared

I was also hearing a strange noise during acceleration once again I extended the area to incorporate the rev range where it was occurring and it disappeared.

Hopefully this will helps others with the same problems