92 lt1 Need Help
Thread Starter
Advanced
Joined: Sep 2007
Posts: 96
Likes: 0
From: Catonsville Maryland
92 lt1 Need Help
All of a sudden my 92 starts runniing very poorly. Car has 120k normally runs extremely well. Starts up normally,, idles fine. Drives fine for about 15 minutes .. then ....after warming up..wont drive faster than 25 miles an hour..You can hear a slight miss in the exhaust. No codes present. No service lights. Did the pin check jumping out A and G. Code 74 dimiming resistor on dash..Changed fuel filter. Cleaned out throttle body. Plugs wires replaced 15k ago. I'm hoping the opti isnt failing, but thought it would throw a code if this were the culprit....I would appreciate anybodys help... The sudden change in performance is very weird..........Initially I was suspecting contaminated gas...put in dry gas 'heet" ............ .Where do i Start ?......Thanks Jim 
Burning Brakes
Joined: Apr 2009
Posts: 1,185
Likes: 33
From: Charlotte Michigan
Might want to check the coil and the module mounted on that. I thought it might be the opti, but it had just a couple of thousand miles on it when I bought the car. Other possibility is the ground wire. One of the problems with the coil is heat from the engine. I spaced mine out with some nylon washers. At least that is much less expensive of a fix.
Navigator
Joined: Sep 2010
Posts: 9
Likes: 0
From: Bow NH
92LT1 same problem
I'm having similar issues. Just posted info.Now won't start, but before if you got on the gas it would just bog down but if you kept the rev's up and smooth on the gas it was ok. Trying to restart it popped back thru intake. Looking for help. Injectors maybe ? Feels like fuel not electrical.
Thread Starter
Advanced
Joined: Sep 2007
Posts: 96
Likes: 0
From: Catonsville Maryland
lowsy performance = failing opti and 1 injector
Bearing in optispark bad..Rotor worn.. and contacts inside cap covered with green oxidation ( acid ?). rust on internal shielding. internal gasket cracked. signs of oil seaping in etc. One injector reading 1.5 ohms.....( kinda funny when i checked them 2 weeks prior all of them in the 13 range)....Guess my mulitmeter is going in the trash..Thanks for everyones help...Couldnt do it without you guys......Cheers Jim 
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Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
A miss when hot can also be caused by a bad thermal connection between the ignition module and the plenum. Pull it off and put thermal grease under it. Be generous. The excess will get squished out. Just wipe it up and you're done.
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