Help with engine miss/rough idle.
06-16-2008, 05:22 PM
#1
Staging Lane
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Help with engine miss/rough idle. I just finished doing a head job on my 95 LT1 and during the process I replaced the following items which are all brand new and unused:
stock cam with a Comp Cam 306
Comp Springs
Valve seals
BBK headers
Bosch water pump
Delphi Distributer
Moroso Wires
NGK TR55 plugs
Fel Pro gasket head kit
The situation is this... I blew a head gasket about a year and nine months ago. The car sat unstarted for about a year and a half before I had the time to do the head job. I replaced everything stated above and now that I'm done the car runs, but idles very roughly and won't stay running without feathering the gas pedal. The engine also shakes very badly as well at RPM's over 1500.
One of the things I tried while the engine was running was pulling each of the fuel injectors to see if they were bad and found one of them to not be working so I replaced that as well. After doing that it helped a little, but the idle is still bad and seems like the engine is still misfiring. I also checked the plug wires and plugs for spark and they all had spark too.
One other thing I tried was using a Hypertech Power Programmer thinking that would help with some computer modifications, but found that it doesn't do what I needed it to do so I returned the programming back to stock.
The "Check Engine Soon" light was on until I bolted the exhaust back on and now it is out. Any ideas or thoughts?
stock cam with a Comp Cam 306
Comp Springs
Valve seals
BBK headers
Bosch water pump
Delphi Distributer
Moroso Wires
NGK TR55 plugs
Fel Pro gasket head kit
The situation is this... I blew a head gasket about a year and nine months ago. The car sat unstarted for about a year and a half before I had the time to do the head job. I replaced everything stated above and now that I'm done the car runs, but idles very roughly and won't stay running without feathering the gas pedal. The engine also shakes very badly as well at RPM's over 1500.
One of the things I tried while the engine was running was pulling each of the fuel injectors to see if they were bad and found one of them to not be working so I replaced that as well. After doing that it helped a little, but the idle is still bad and seems like the engine is still misfiring. I also checked the plug wires and plugs for spark and they all had spark too.
One other thing I tried was using a Hypertech Power Programmer thinking that would help with some computer modifications, but found that it doesn't do what I needed it to do so I returned the programming back to stock.
The "Check Engine Soon" light was on until I bolted the exhaust back on and now it is out. Any ideas or thoughts?
06-16-2008, 06:48 PM
#3
Staging Lane
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I was planning on doing that, but the only place I can find to tune an LT1 in Houston wants $550 and it's a forty five minute drive from my house.
As it stands right now I can't drive the car. It also seems to start overheating sometimes too, which kind of baffles me since I have bled the radiator hoses and filled it up numerous times. It doesn't always do that either which really doesn't make sense to me.
As it stands right now I can't drive the car. It also seems to start overheating sometimes too, which kind of baffles me since I have bled the radiator hoses and filled it up numerous times. It doesn't always do that either which really doesn't make sense to me.
06-16-2008, 10:43 PM
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Staging Lane
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06-17-2008, 07:49 PM
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I've been going over this in my head trying to come up with something I screwed up on and I can't come up with much. The only thing I can think of was when I put the distributer on after installing the cam. The service manual shows that the cam pin is in the 3 o'clock position when piston 1 is TDC and the little dots on the gears in the timing chain are at 6 o'clock (for the top gear) and 12 o'clock (for the smaller bottom gear).
Now, to install the distributor the service manual as well as the intsructions for the distributor show and state the cam pin to be in the 9 o'clock position and also TDC, but on the upstroke on piston 1 rather than the down.
When I put the distributor on I turned the crank so that the cam pin was in the 9 o'clock position, as stated in the manual, and pistons 1 and 6 were up; 1 being in the upstroke, firing position and 6 being in the downstroke, exhaust position.
My question is will the car have the kind of rough idle I described initially if I put in the distributor incorrectly, or would it even run at all if it was wrong?
Now, to install the distributor the service manual as well as the intsructions for the distributor show and state the cam pin to be in the 9 o'clock position and also TDC, but on the upstroke on piston 1 rather than the down.
When I put the distributor on I turned the crank so that the cam pin was in the 9 o'clock position, as stated in the manual, and pistons 1 and 6 were up; 1 being in the upstroke, firing position and 6 being in the downstroke, exhaust position.
My question is will the car have the kind of rough idle I described initially if I put in the distributor incorrectly, or would it even run at all if it was wrong?
