LS1 rough idle, early shifting
Thread Starter
Teching In
Joined: Apr 2013
Posts: 47
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From: FL
LS1 rough idle, early shifting 99 C5 LS1, headers, intake, exhaust, ECS tune.
Hi everyone
For awhile I started to notice I had a rough idle at stop lights and if I just touched the gas and raised the idle up 50 -100 rpms it smooth out. It was dropping to about 500, I believe c5 AT's are supposed to idle at 550?
So I changed plugs and wires and sent my pcm away to ECS to be tuned. Had them raise my idle to 650 and it helped a lot but I could still feel the idle wanting to drop when I came to a stop.
And I also fixed afew air leaks I found prior to that. One was pretty major and it didn't help... at all.
After the tune everything was great, I'd punch it at about 25 30 and spin the tires shifting at 60. Just did afew test runs when I first got the PCM and then went back to my daily routine of driving to work no WOT or anything over 3500rpms at all for about a month.
Now its back to stumbling and really wanting to drop down.
Also about a week ago I had to gas it to avoid a red light ticket and noticed it would only rev to 5400 maybe even 5300 and shift roughly. Tried again on the way home and sure enough it wont rev past 5400 and I have a VERY noticeable power loss, its very slow to rev also.
I've gotten afew suggestions for the shifting problem. Tune or Fuel delivery problems
As far as the idle goes I'm stumped and about to take it to a mechanic. It also smokes alittle in the morning for afew mins.. thin white smoke.
I know its a lot. I really appreciate any suggestions. I plan on taking it to a guy and just having him make a list for me.... Just have to save up and I'd like to fix anything I can.
Hi everyone
For awhile I started to notice I had a rough idle at stop lights and if I just touched the gas and raised the idle up 50 -100 rpms it smooth out. It was dropping to about 500, I believe c5 AT's are supposed to idle at 550?
So I changed plugs and wires and sent my pcm away to ECS to be tuned. Had them raise my idle to 650 and it helped a lot but I could still feel the idle wanting to drop when I came to a stop.
And I also fixed afew air leaks I found prior to that. One was pretty major and it didn't help... at all.
After the tune everything was great, I'd punch it at about 25 30 and spin the tires shifting at 60. Just did afew test runs when I first got the PCM and then went back to my daily routine of driving to work no WOT or anything over 3500rpms at all for about a month.
Now its back to stumbling and really wanting to drop down.
Also about a week ago I had to gas it to avoid a red light ticket and noticed it would only rev to 5400 maybe even 5300 and shift roughly. Tried again on the way home and sure enough it wont rev past 5400 and I have a VERY noticeable power loss, its very slow to rev also.
I've gotten afew suggestions for the shifting problem. Tune or Fuel delivery problems
As far as the idle goes I'm stumped and about to take it to a mechanic. It also smokes alittle in the morning for afew mins.. thin white smoke.
I know its a lot. I really appreciate any suggestions. I plan on taking it to a guy and just having him make a list for me.... Just have to save up and I'd like to fix anything I can.
Thread Starter
Teching In
Joined: Apr 2013
Posts: 47
Likes: 0
From: FL
Thread Starter
Teching In
Joined: Apr 2013
Posts: 47
Likes: 0
From: FL
After all the air leaks I fixed and new plugs wires, new intake, maf clean, TB clean... It does seem like it could be something more serious like that.
What about a head gasket leak? I had a little oil on my plugs but I read somewhere else that it was normal?
I've only got 58k on it
Burnt crispy oil or wet oil? You should not have any on the plugs. If you do the rings are bad or your valve stem seals need replacing. Do a wet compression test on all the cylinders.
White smoke is usually coolant from the head gasket.
White smoke is usually coolant from the head gasket.
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Thread Starter
Teching In
Joined: Apr 2013
Posts: 47
Likes: 0
From: FL
I guess after 14 and years and almost 60k miles i'm not surprised if the valve seals and head gaskets leak. They're plastic/rubber right?
makes perfect sense.
Hopefully its not the rings with such low mileage.
No one has any ideas about the early shifting besides a broken spring? I've got no ticking what so ever. I started getting a ride to work from my buddy just incase though.
Ok thanks guys
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Thread Starter
Teching In
Joined: Apr 2013
Posts: 47
Likes: 0
From: FL
Thread Starter
Teching In
Joined: Apr 2013
Posts: 47
Likes: 0
From: FL
Yes I do actually. Factory. That would be great if that's the problem. I'm in FL so I can go get them replaced with straight pipe and disconnect that annoying air pump that whines for 20 mins on start up.
That could cause a bad idle, i know, but could it have anything do with the early shifting?
