Engine has a slight stumble @ idle and right off...is it a misfire?
10-08-2010, 11:55 AM
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Engine has a slight stumble @ idle and right off...is it a misfire? Basically she kind of has a slight stumble or twitch at idle sometimes...
And when you first engage the clutch she shudders a little at first.
I just bought the car so I knew it needed some refreshing.
The shudder at first I thought was more the tranny mount...which I replaced and the old was pretty bad. So no regrets...and it did get better right after but u could still feel it some....and that it originates from the engine shuddering some.
Car had never had anything replaced on it...and at 92K I figured let me throw some plugs at her. NGK iridiums gapped at .052 .......when I first pulled her out I could swear it was baby smooth....no problems and the shudder thing was gone....but cant say for sure it was late and I was tired.
Couple of days later I started to definitely feel the slight stumble at idle and the shudder ...it all seemed to come back altho maybe I wasnt paying attention closely that first day out. I had not done the wires out of FEAR of having to route them in their stock locations.
Recently I did the wires and added a MSD Blaster coil......seems a little smoother. But yea there's still a slight stumble at idle thats keeping it from being baby smooth. I unplugged each injector like I had done before and this time each one produced a misfire very pronounced...as opposed to before there were 3 cylinders that when the injectors was unplugged they didnt seem to change much......Im not sure if this is a great way to detect a misfire..but it helps some.
Sooo....plugs, O2 sensors, wires, coil....and still a slight stumble....one of the wires is arcing against the plug itself...it's the #7 on drivers side...the stock OEM metal boot protector is arcing slightly on the plug itself. Im hoping this turns out to be just the wires not properly engaged onto the plug. Has anyone seen this happen with the metal boot protector?
Any other suggestions to fix.
Im stuck with possibly swapping out the plugs to autolites this time and a shorter gap of .035 or .040. But will blow a gasket if that doesnt cure this.
Its hard to beleive this coil wont fire this gap on these new plugs...its a stock engine.
Oh and before I did the wires I gave her 2 new ACdelco 02 sensors.
At this point i've got some good money and elbow grease in and getting tired.
And when you first engage the clutch she shudders a little at first.
I just bought the car so I knew it needed some refreshing.
The shudder at first I thought was more the tranny mount...which I replaced and the old was pretty bad. So no regrets...and it did get better right after but u could still feel it some....and that it originates from the engine shuddering some.
Car had never had anything replaced on it...and at 92K I figured let me throw some plugs at her. NGK iridiums gapped at .052 .......when I first pulled her out I could swear it was baby smooth....no problems and the shudder thing was gone....but cant say for sure it was late and I was tired.
Couple of days later I started to definitely feel the slight stumble at idle and the shudder ...it all seemed to come back altho maybe I wasnt paying attention closely that first day out. I had not done the wires out of FEAR of having to route them in their stock locations.
Recently I did the wires and added a MSD Blaster coil......seems a little smoother. But yea there's still a slight stumble at idle thats keeping it from being baby smooth. I unplugged each injector like I had done before and this time each one produced a misfire very pronounced...as opposed to before there were 3 cylinders that when the injectors was unplugged they didnt seem to change much......Im not sure if this is a great way to detect a misfire..but it helps some.
Sooo....plugs, O2 sensors, wires, coil....and still a slight stumble....one of the wires is arcing against the plug itself...it's the #7 on drivers side...the stock OEM metal boot protector is arcing slightly on the plug itself. Im hoping this turns out to be just the wires not properly engaged onto the plug. Has anyone seen this happen with the metal boot protector?
Any other suggestions to fix.
Im stuck with possibly swapping out the plugs to autolites this time and a shorter gap of .035 or .040. But will blow a gasket if that doesnt cure this.
Its hard to beleive this coil wont fire this gap on these new plugs...its a stock engine.
Oh and before I did the wires I gave her 2 new ACdelco 02 sensors.
At this point i've got some good money and elbow grease in and getting tired.
Last edited by License2Ill; 10-08-2010 at 12:13 PM.
10-08-2010, 12:07 PM
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I remember a thread recently where the op was using iridiums and that had something to do with it I think. check second or third page.I had a miss pretty bad was burnt 6 / 8 wires. changed plugs too and still missed a little. plugs backed out. tightened them and good now.
10-08-2010, 12:38 PM
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i was thinking motor mounts could do that too. i know when my tranny mount ripped in half it would be a lot more louder banging when i was driving aggressively. you should probably replace them. i replaced mine with polys. a lot of people like solids. up to you. more vibration in the cabin though.
10-08-2010, 12:57 PM
#6
The motor mount is a very good possability since the trans mount was busted, i would almst bet the mounts are no goos as well.
these aluminum head lt1 are very sensitive to the type of plug, never put autolights in a gm car, they like AC delco or NGK plugs.... .52 is great for stock. if the wire is arc ing then it must be torn or improperly installed, the wire is made to keep the energy in the wire not for it to shoot out anywhere, if you see this start there and fix that first. i also recomend torq down the plugs. its a bitch but will save a ton of hard ake from chacing what seems to be goast. i have had my #8 back out on more than 1 time and it sucks. That being said make sure the wires are far away from hot and moving objects since thats the 2 most reason why lt1 miss after tune ups, they will burn or tear in a second if not installed correct
these aluminum head lt1 are very sensitive to the type of plug, never put autolights in a gm car, they like AC delco or NGK plugs.... .52 is great for stock. if the wire is arc ing then it must be torn or improperly installed, the wire is made to keep the energy in the wire not for it to shoot out anywhere, if you see this start there and fix that first. i also recomend torq down the plugs. its a bitch but will save a ton of hard ake from chacing what seems to be goast. i have had my #8 back out on more than 1 time and it sucks. That being said make sure the wires are far away from hot and moving objects since thats the 2 most reason why lt1 miss after tune ups, they will burn or tear in a second if not installed correct
10-08-2010, 01:22 PM
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try to check your fuel pressure, my car is doing the same thing, damn thing was running at 33 psi at idle and 38 while driving, I unhooked the vacuum line on the regulator and it runs at 40psi the whole time, still stumbles a lil bit, but that will get fixed this saturday with a new pump
