[Redbrd]

update....not a blowed head gasket. replaced opti and i still have a random misfire. checked the coil like GM service manual said, it was good. pulled plugs again and they were black with soot on them. checked tail pipe and it has soot all over it. i can get into the car and it will start up (while cold) on first hit or after it has set for a while. let it run for a few seconds and turn it off and try to restart and it wont start until you open the throttle. opening the throttle is letting in air which is leaning out the car so it can start. does this sound about right?

i'm going to run the data log and send it to solomon and see what he says.

Not saying this will fix yours, but a buddy had the same problems down to the letter and it ended up being a bad coolant sensor.wtf?

 

[97 SS LT1]

Not saying this will fix yours, but a buddy had the same problems down to the letter and it ended up being a bad coolant sensor.wtf?

did he have a problem with a misfire? is this the coolant sensor on the drivers side of the block under the headers?

 

[Redbrd]

I will find out asap on location, but no that is one thing, no misfire with his.

 

[97 SS LT1]

I will find out asap on location, but no that is one thing, no misfire with his.

thanks for checking. i broke that coolant sensor while installing the headers a few months ago and had to replace it. i keep getting a random or #3 misfire. after i clear the codes, it make take a few mins to come on or it make take 20 or more miles to come on...it is random! i left the SES light on a couple of times for a few days, and the SES light turned it self off twice. this was after it was on for a day or two. i don't understand it...i'm thinking about replacing the coil now...:werd:

 

[LT479halfton]

ima trow this out there u should really never do a crap load of work to the top end of a motor with out at least putting a re ring kit in the botom end a motor gits so used to running the same way a drastick change in flow can ruin bearings r rings

 

[camaroz28383]

ima trow this out there u should really never do a crap load of work to the top end of a motor with out at least putting a re ring kit in the botom end a motor gits so used to running the same way a drastick change in flow can ruin bearings r rings

not true at all new rings wont help u that much and in fact can actually fail faster because they have to try and conform to a bore thats not perfectly straight anymore if you re ring you need to hone the block so they seat properly which equals motor out of car
many people do head/cam swaps without touching the bottom with zero issues

 

[97 SS LT1]

ima trow this out there u should really never do a crap load of work to the top end of a motor with out at least putting a re ring kit in the botom end a motor gits so used to running the same way a drastick change in flow can ruin bearings r rings

i don't agree! tons of people that i know have done more than i have and not had a problem out of the bottom end. if i was going to rev to the moon and race all the time then yes, i would have done a complete rebuild. but i have stated several times on here that i'm not building a race car or drag car, i'm building a good DD with some power and lope.

thanks for your input though.

 

[97 SS LT1]

another question...could a crank position sensor cause a misfire??

 

[CCLT1Z]

another question...could a crank position sensor cause a misfire??

it could.... make sure we didn't fubar the wiring or anything.

The functional objective for the crankshaft position sensor is the task of sensing engine RPM in order to determine the position and rotational speed of the crank. Engine management systems use the information transmitted by the sensor to control things such as ignition timing and other important functions. The sensor can also relate other crucial data including the relation of the valves to the pistons.

 

[97 SS LT1]

it could.... make sure we didn't fubar the wiring or anything.

The functional objective for the crankshaft position sensor is the task of sensing engine RPM in order to determine the position and rotational speed of the crank. Engine management systems use the information transmitted by the sensor to control things such as ignition timing and other important functions. The sensor can also relate other crucial data including the relation of the valves to the pistons.

i hook up the pcmscan and it detected a crank sensor code...thought maybe could be the problem...other program didn't pick it up!!

 

[CCLT1Z]

i hook up the pcmscan and it detected a crank sensor code...thought maybe could be the problem...other program didn't pick it up!!

it'd be worth a shot. if i didn't work you could take it back as "defective"

 

[camaroz28383]

another question...could a crank position sensor cause a misfire??

the crank sensor on the LT1 has nothing to do with timing or engine control it is simply there to detect misfires it in no way influences the pcm to alter anything

 

[97 SS LT1]

the crank sensor on the LT1 has nothing to do with timing or engine control it is simply there to detect misfires it in no way influences the pcm to alter anything

so could i have a bad crank sensor that is detecting a false misfire?? i can't tell that the car is misfiring when it is suppoosedly misfiring...does that make sense? i can't tell a difference in the car at any time while running or driving...if that makes any better sense.

 

[camaroz28383]

yea could be a bad crank sensor or maybe a defect in the reluctor ring that makes it think there is a miss on cyl3. So you cant feel the missat all? in my book that means false reading, but even a little hiccup sometimes will cause the miss code to pop

 

[97 SS LT1]

yea could be a bad crank sensor or maybe a defect in the reluctor ring that makes it think there is a miss on cyl3. So you cant feel the missat all? in my book that means false reading, but even a little hiccup sometimes will cause the miss code to pop

i can't feel it miss at all!! no difference in the way it runs or drives. the misfire is very random...sometimes it will come on after a few seconds of idle and sometimes it takes miles of running to set it off. sometimes it's a cyl 3 mis and sometimes it's a random mis....:werd: i climbed under the car and took a look at the sensor, and it has oil and coolant on it where i pulled the water pump both times and oil from the oil leak. i have a new crank sensor coming, it should be here monday so ill see what happens then.

 

[JAKEJR]

GM warns, in the 96 Vette FSM, that incorrectly installing the CPS can cause problems.

"IMPORTANT: When you install the crankshaft position sensor, be sure that the sensor is fully seated and held stationary in the engine front cover bore. A sensor that is not fully seated will cock in the engine front cover and may result in erratic engine operation."

A possibility?

Jake

 

[97 SS LT1]

GM warns, in the 96 Vette FSM, that incorrectly installing the CPS cam cause problems.

"IMPORTANT: When you install the crankshaft position sensor, be sure that the sensor is fully seated and held stationary in the engine front cover bore. A sensor that is not fully seated will cock in the engine front cover and may result in erratic engine operation."

A possibility?

Jake

i didn't take the sensor out of the case.....BUT there is a posibility that it could have been knocked around while off. i let a friend help out and he used a hammer and punch to remove the seals on the timing cover!! he had 2 off by the time i realized what he was doing:craz28:. i even had a seal puller laid out for him!!

i do have another sensor coming that will be here monday. i will slip it on monday night and see what happens. thanks!!

 

[97 SS LT1]

update...installed the new crank sensor. not throwing a misfire code anymore, BUT it throws a cranks sensor code when you start it up. i can erase the codes and drive it and the SES light will not come back on until you shut the car off and restart it. any ideas?

i made sure the sensor was seated, but the sensor is not made the same as the old one. the old one looks brass where it makes contact to the plate inside the cover where this one looks plastic...i didn't like that.

 

[BLK95TA]

Could just be moisture in the oil from the varying temps if you are not driving the car that often..

yeah mine smoked for 5-10 mnis when i started it yesterday and let it idle in the driveway. it hadn't been started in 4 months. once the car warmed up the smoke went away. it wasn't a lot though. i'm sure it was condensation from sitting all winter.

 

[JAKEJR]

update...installed the new crank sensor. not throwing a misfire code anymore, BUT it throws a cranks sensor code when you start it up. i can erase the codes and drive it and the SES light will not come back on until you shut the car off and restart it. any ideas?

i made sure the sensor was seated, but the sensor is not made the same as the old one. the old one looks brass where it makes contact to the plate inside the cover where this one looks plastic...i didn't like that.

What's the code number?

What brand did you buy?

Tight, clean connection?

Jake