Lt1 bad misfire and loss of power helphelp
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Lt1 bad misfire and loss of power helphelp
so i got my temperature and overheating issues fixed and changed out the plugs, i put the ngk tr55s in. the car was running pretty good after i changed the plugs so today i decided to go for a long drive. i drove around for an hour or so then i stopped to check out a fishing hole and left the car idling for 20 mins. after this it started to miss real bad but then work ok for a min although it felt down on power. could this be an o2 sensor? spark plug wires? any help would be greatly appreciated. hope its not the optispark
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Re: Lt1 bad misfire and loss of power helphelp
oh and the reason i replaced the plugs in the first place was because the gap was too big and metal deposits had started to build up trying to bridge the gap.
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From: Kansas City
Car: 1991 Trans Am
Engine: L98
Transmission: T56
Re: Lt1 bad misfire and loss of power helphelp
Could bad o2, bad opti, bad coil or bad ICM. The ICM I believe is right near the coil on the front of the driver's side head assuming you have an fbody lt1 pullout. These can be easily tested at most auto parts places along with the coil. How old are the o2 sensors? What year is the engine?
Re: Lt1 bad misfire and loss of power helphelp
It could really be about anything.
If you have new ceramic coated headers, they will destroy o2's at first. Just some of the new coating gets to the o2's. However, when you mash the pedal and hit full throttle, the pcm no longer calculates in the values of the o2's.
What would be the most helpful for me trying to figure out it out would be to get a datalog recorded from tts datamaster program by connecting a computer up to the LT1 PCM via a ALDL cable.
You could do these tests though:
-Check oil, antifreeze, plugs.
-Check fuel pressure and see if fuel pressure holds when car is shut off
-Check fuel pressure regulator by taking the vacuum hose off of it after car is shut off and see if gas pours out then its bad.
-Check MAF by disconnecting it then starting up the car(puts the LT1 in speed density mode) and driving around, if performance is better than could be the maf
-Check if exhaust is hitting frame causing knock sensor to pull timing
-Check map sensor connector or really every connector and make sure none of the tabs are broken that hold connectors in place
-If you still have the stock crappy rubber elbow that goes to the throttle body, definitely look that over for holes/cracks
If you have new ceramic coated headers, they will destroy o2's at first. Just some of the new coating gets to the o2's. However, when you mash the pedal and hit full throttle, the pcm no longer calculates in the values of the o2's.
What would be the most helpful for me trying to figure out it out would be to get a datalog recorded from tts datamaster program by connecting a computer up to the LT1 PCM via a ALDL cable.
You could do these tests though:
-Check oil, antifreeze, plugs.
-Check fuel pressure and see if fuel pressure holds when car is shut off
-Check fuel pressure regulator by taking the vacuum hose off of it after car is shut off and see if gas pours out then its bad.
-Check MAF by disconnecting it then starting up the car(puts the LT1 in speed density mode) and driving around, if performance is better than could be the maf
-Check if exhaust is hitting frame causing knock sensor to pull timing
-Check map sensor connector or really every connector and make sure none of the tabs are broken that hold connectors in place
-If you still have the stock crappy rubber elbow that goes to the throttle body, definitely look that over for holes/cracks
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mdtoren
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Aug 16, 2015 05:45 PM
