Low RPM "shudder"- also, hard start at times.
10-16-2006, 08:07 PM
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Low RPM "shudder"- also, hard start at times. OK, this one is odd- it seems that ever since the 60#ers were installed I have had a couple of issues that I'm not sure if they are tune/injector related or something else-
a) the car has a 1200-2000 rpm or so "shudder" when slowly revving it or letting it wind down- not a misfire, almost like something is out of balance, like a wobbling/shuddering feeling that you feel in the wheel and shifter when free revving it. I was initially concerned it was another trashed piston, but compression is good. I am wondering if it is anything with fueling at all- it is odd, but who knows- I know it wasn't there before, and it varies with operating temps too it seems- not too bad at startup, and worse after driving a while- that is the ONLY reason I was wondering if it could be tune-related some how some way...
I did also just get the motor back together a couple of days before the injector swap and was taking it easy for a while, so I could have missed it previously, but I think I would have noticed it. Only other idea was that maybe the new pistons aren't a good weight match for the rest of them, but again, it varies with temp though- really odd, you'd think a balance issue would be a constant...
b) it is occassionally hard to start, at times it will crank quite a while until starting, others it fires right up. It seems like anywhere under 5-10 minutes from shutting it off is ok or after a few hours, anywhere in between and it will crank a while before firing. I checked pressure to make sure it is not bleeding down and it seems ok.
I should add the car is an 05 GTO LS2. Thanks.
Joe
a) the car has a 1200-2000 rpm or so "shudder" when slowly revving it or letting it wind down- not a misfire, almost like something is out of balance, like a wobbling/shuddering feeling that you feel in the wheel and shifter when free revving it. I was initially concerned it was another trashed piston, but compression is good. I am wondering if it is anything with fueling at all- it is odd, but who knows- I know it wasn't there before, and it varies with operating temps too it seems- not too bad at startup, and worse after driving a while- that is the ONLY reason I was wondering if it could be tune-related some how some way...
I did also just get the motor back together a couple of days before the injector swap and was taking it easy for a while, so I could have missed it previously, but I think I would have noticed it. Only other idea was that maybe the new pistons aren't a good weight match for the rest of them, but again, it varies with temp though- really odd, you'd think a balance issue would be a constant...
b) it is occassionally hard to start, at times it will crank quite a while until starting, others it fires right up. It seems like anywhere under 5-10 minutes from shutting it off is ok or after a few hours, anywhere in between and it will crank a while before firing. I checked pressure to make sure it is not bleeding down and it seems ok.
I should add the car is an 05 GTO LS2. Thanks.
Joe
