Help! Idle missfire
Help! Idle missfire Working on a 95 LT1 camaro and having a hell of a time with this idle problem.
Car runs great under partial throttle and full throttle, but at idle it gets a intermittent dead hole (You can listen to it run then miss, then run again)
History of the car is that it has a new opti/wires/plugs/fuel filter, recently replaced headgaskets and a temp sensor (That caused the original headgasket failure) The car had a full dead miss when it came it (Caused by the headgasket failure i believe) I tested out other injectors but had the same result.
Any ideas? This car needs to leave and this is all I have left to do so I can smog it. Also the car was sitting for a long time, but I swapped out the gas for new stuff so old gas shouldnt be the issue.
Car runs great under partial throttle and full throttle, but at idle it gets a intermittent dead hole (You can listen to it run then miss, then run again)
History of the car is that it has a new opti/wires/plugs/fuel filter, recently replaced headgaskets and a temp sensor (That caused the original headgasket failure) The car had a full dead miss when it came it (Caused by the headgasket failure i believe) I tested out other injectors but had the same result.
Any ideas? This car needs to leave and this is all I have left to do so I can smog it. Also the car was sitting for a long time, but I swapped out the gas for new stuff so old gas shouldnt be the issue.
Yah, I can barely feel it but its easily heard out the tailpipe. Im pretty sure it wont pass smog like this.
Also I tried disabling cylinders at the injector to isolate the problem cyl and its very hard to tell. It seems like the miss is random more than isolated to one cyl.
Also I tried disabling cylinders at the injector to isolate the problem cyl and its very hard to tell. It seems like the miss is random more than isolated to one cyl.
Vac leak? Check the intake for a vac leak. Had a GM master tech tell me a couple weeks ago when I was having him inspect a tahoe I wanted to by that there are a couple things you can count on from a gm from 94 to 99. Intakes will leak at some point and they will eventually **** oil out the center bolt valve covers. LOL i have no idea how true that is but the LT1's did have a habit of leaking at the intake.
Vac leak? Check the intake for a vac leak. Had a GM master tech tell me a couple weeks ago when I was having him inspect a tahoe I wanted to by that there are a couple things you can count on from a gm from 94 to 99. Intakes will leak at some point and they will eventually **** oil out the center bolt valve covers. LOL i have no idea how true that is but the LT1's did have a habit of leaking at the intake.
Im leaning towards the optispark being defective, but its brand new so I have trouble believing that.
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Verdad Gallardo Get your idle air valve cleaned to while your in there, its the one on the bottom of the throttle body DO NOT REMOVE THE THROTTLE POSITION SENSOR ON TO THE LEFT OF THE TB, IT WILL F*#$ S%&T UP IF YOU DO SO!!! You'll need a torques bit to get it off...not sure what size though...
I cant see the idle air valve causing a random missfire but ill clean it since I have the time.
try and Run The Car in the Dark.. Sounds crazy but i found My coil Was loose on the Bracket and was causing the Car to Misfire. it was Sparking to the block but could only see it with the lights off.
Tried swapping in a know good ICM, PCM and MAF with no results. Compression is good (180-190 on all) Im going to see if I can warrantee out the wires and maybe change the plugs (Though they look perfect). Any other ideas? This problem is driving me insane.
Datamaster is free for 20 collections I think, but you will need a cable ~$85. I suggest you invest in the cable collect data and then start collecting.
You look at TPS as you slowly open and close throttle. You verify the engine temperature is close to what the outside temperature is, also the inlet air temp.
Sitting with key still on collecting the knock count should remain at some number (Not change). If all this data looks good, start the engine. Collect data for say 5 minutes watching the knock sensor values and see if you are getting any codes.
You then look at all the codes and correct them and CLEAR them. You retest as above. you will be amazed what you can find, I ran through a few basics I suspect will likely be your problem area.
Once you correct the 'easy' problems you can post your data file on here for help with whatever remains. Words have different meaning to different people and often hard to follow what someone means.
Good luck
You look at TPS as you slowly open and close throttle. You verify the engine temperature is close to what the outside temperature is, also the inlet air temp.
Sitting with key still on collecting the knock count should remain at some number (Not change). If all this data looks good, start the engine. Collect data for say 5 minutes watching the knock sensor values and see if you are getting any codes.
You then look at all the codes and correct them and CLEAR them. You retest as above. you will be amazed what you can find, I ran through a few basics I suspect will likely be your problem area.
Once you correct the 'easy' problems you can post your data file on here for help with whatever remains. Words have different meaning to different people and often hard to follow what someone means.
Good luck
