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Lt1 suddenly dies, help please

This is a discussion on Lt1 suddenly dies, help please within the General Help forums, part of the LSx Technical Help Section category; Car runs good for 15-20 min then suddenly dies. You can always tell when it is going to happen, the ...

  1. #1
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    Lt1 suddenly dies, help please

    Car runs good for 15-20 min then suddenly dies. You can always tell when it is going to happen, the car will idle up a few hundred rpm, then start missing and go dead. It wont start back up, but if you let it set for 15-20 mins it will start right up and then run good for a while then die again. Seems like it is flooding pretty bad when it starts missing and dies.

    Any ideas???

    1993 trans-am lt1

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    Life in the Fast lane sunsetorangess's Avatar
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    Any codes? With a shot in the dark i would say Map sensor or Coolant temp sensor...
    How long has this been going on? Does it reach Op. Temp? Any mods?
    J
    2001 SS, Its not the car its the Driver that matters....

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    Quote Originally Posted by sunsetorangess View Post
    Any codes? With a shot in the dark i would say Map sensor or Coolant temp sensor...
    How long has this been going on? Does it reach Op. Temp? Any mods?
    J
    It gets about 160 or so, not for sure, no mods and today is the first time I have cranked the car, so I dont know about problems previous owner had. I bought it with a bad opti and no info. I put new opti and fuel pump on the car started it and now have this problem.

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    Quote Originally Posted by sunsetorangess View Post
    Any codes? With a shot in the dark i would say Map sensor or Coolant temp sensor...
    How long has this been going on? Does it reach Op. Temp? Any mods?
    J
    Couple of questions, would the coolant sensor let it run fine for a while?
    What does the map sensor do? not familar with it. thanks in advance

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    Moderator Cutlass's Avatar
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    check for fuel pressure and spark after it stalls. I suspect no spark which would be a bad ign coil or ign control module since you already replaced the optispark

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    Quote Originally Posted by Cutlass View Post
    check for fuel pressure and spark after it stalls. I suspect no spark which would be a bad ign coil or ign control module since you already replaced the optispark
    I actually got it to crank after it died today, but that was holding the throttle half way and it ran at 3000 grand but if you gave it more or let off it died, and the exhaust smelled real rich.

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    Senior Member karpetcm's Avatar
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    Mine would do about the same thing when i had my LT1 Camaro and it was the OPTI and ofcourse was a 93 as well. I know you've replaced your opti but with what brand? There have been many people replacing there opti's and having the same issues if not worse, check your coil as well.

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    Quote Originally Posted by karpetcm View Post
    Mine would do about the same thing when i had my LT1 Camaro and it was the OPTI and ofcourse was a 93 as well. I know you've replaced your opti but with what brand? There have been many people replacing there opti's and having the same issues if not worse, check your coil as well.
    If as soon as it dies if I put spare plug into a plug wire and turn it over and have spark, that would eliminate opti and coil right?

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    Moderator Cutlass's Avatar
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    yeah if it cranks, but doesn't start and has good spark then yes your coil, opti, and ign module should be ok. then its some sort of fuel problem ie no injector drive, low fuel pressure, no fuel pressure, etc

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    Member kevnstac's Avatar
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    Quote Originally Posted by dirttrax View Post
    Car runs good for 15-20 min then suddenly dies. You can always tell when it is going to happen, the car will idle up a few hundred rpm, then start missing and go dead. It wont start back up, but if you let it set for 15-20 mins it will start right up and then run good for a while then die again. Seems like it is flooding pretty bad when it starts missing and dies.

    Any ideas???

    1993 trans-am lt1
    What about a crank sensor? I've gone through this same scenario before.

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    long and strong Willfully Armed's Avatar
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    EGR?

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    Quote Originally Posted by kevnstac View Post
    What about a crank sensor? I've gone through this same scenario before.
    This is prob gonna sound stupid, but where is it, I thought it was part of the opti.

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    Quote Originally Posted by Cutlass View Post
    yeah if it cranks, but doesn't start and has good spark then yes your coil, opti, and ign module should be ok. then its some sort of fuel problem ie no injector drive, low fuel pressure, no fuel pressure, etc
    I doubt it low fuel pressure because when it does it, the exhaust is so rich it runs you out of the shop.
    It seems that what ever the prob is that it floods the motor out. Havent got out to the shop to check spark, but pretty sure its not that cuz it trys to or does start just misses and floods bad, and I dont think the flooding is from not enough spark, because it floods terrible, but I could be wrong, beings Im not famaliar with the lt1 and its fuel, spark system.
    Last edited by dirttrax; 03-03-2010 at 08:40 PM.

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    Member kevnstac's Avatar
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    Quote Originally Posted by dirttrax View Post
    This is prob gonna sound stupid, but where is it, I thought it was part of the opti.
    I just saw this is a 93. I don't think a crank sensor was added until 1996.
    Sorry.

    In 1996, the front cover was again revised to accept a crankshaft position sensor for OBD II misfire detection.

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    Moderator Cutlass's Avatar
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    Quote Originally Posted by dirttrax View Post
    This is prob gonna sound stupid, but where is it, I thought it was part of the opti.
    it is

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    Moderator Cutlass's Avatar
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    kinda sounds like when the computer goes into closed loop, it starts dumping fuel in. Might be a bad sensor somewhere telling the computer some bad info (ie coolant temp sensor, O2 sensor, etc). It might take a scan tool to figure this one out

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    Quote Originally Posted by Cutlass View Post
    kinda sounds like when the computer goes into closed loop, it starts dumping fuel in. Might be a bad sensor somewhere telling the computer some bad info (ie coolant temp sensor, O2 sensor, etc). It might take a scan tool to figure this one out
    I actually checked the on board diganostics and it pulled a code saying temp cooling sensor so im gonna replace it and try it. It also showed a code that pertained to the evac air pump I checked it and it had a blown fuse, replaced the fuse and it blowed again, so I guess the pump is locked up. How important is this pump? I know for emmisions its important, but will it affect the car running?

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    Life in the Fast lane sunsetorangess's Avatar
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    Yepp i figured it was the coolant temp sensor.
    Its purpose is to get the car into "closed loop" then your 02 sensors take over. It sends the temp of the coolant to the computer which then converts it and adjusts the fuel and Egr accordingly. When they fail or get "lazy" they send wrong readings so when your car is running at temp it still thinks its cold so it continues to dump fuel into the cylinders causing it to Run like poo or die due to overloading the cylinders with fuel. You can test the switch with a multimeter and check the resistance in the switch.
    As far as the fuse blowing, i would again suggest a multimeter to check the wiring for resistance to ensure its not a ground or short somewhere, then isolate the pump and test it also.
    Just emissions crap...
    J

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    Thanks to everyone who replied.

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    Junior Member MRBIGGDADDYWIGGS's Avatar
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    Just had that same problem with my 96' T/A, replaced everything that I thought was the problem, int the end it was my Crank Position Sensor, it is designed to cut the voltage down to the system but when it went bad it fried my coil, the ICM and blew the ignition fuse. The symptoms were at first it shut down while i was driving, then i had to wait a few hours to restart it, then after awhile it wouldn't start at all. Had to let the shop fix it. Hope that helps.

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