HELP car is missing
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Joined: May 2005
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From: knox. tn.
HELP car is missing
My LT4 is missing when it warms up 
, the diagnostic 's is saying multiple cylinder misfire.I replaced the map sensor just put a msd coil on it last week & changed the temperature sensing unit on the water pump.What is going on , I also changed the plugs 2 weeks ago.Car runs decent till I floor it then its like every cylinder but 3 or 4 shut down.What is the piece above the coil that has a plug on it also & looks like the wires go toward the TPS on throtle body could this be the problem?Car only has 59,000 miles on it.
, the diagnostic 's is saying multiple cylinder misfire.I replaced the map sensor just put a msd coil on it last week & changed the temperature sensing unit on the water pump.What is going on , I also changed the plugs 2 weeks ago.Car runs decent till I floor it then its like every cylinder but 3 or 4 shut down.What is the piece above the coil that has a plug on it also & looks like the wires go toward the TPS on throtle body could this be the problem?Car only has 59,000 miles on it.
Le Mans Master
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From: Myrtle Beach SC
St. Jude Donor '05-'06
I have not heard too many good stories about aftermarket coils on a LTX engine.Most people say stick with stock.Why did you change the coil?Why did you change the MAP sensor.When was the last time it ran right?
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From: knox. tn.
I changed the coil when I put the msd digital 6 plus ignition box on.The reason I did this was so that I could use the box to back timing out of the car whenever I armed the nitrous , this was the main reason for the box the coil was just a added perk.It ran fine for 2 weeks after the add ons were done.The code was just a random misfire code , I'm thinking ignition module is on its way out!!
Le Mans Master
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From: Myrtle Beach SC
St. Jude Donor '05-'06
Originally Posted by ~db~
Did you say MSD box??? 
I would DEFINATELY look to that as a possible. I have had many problems with mine in the past. Might be worthwhile to bypass it temporarily so you can rule that out as a cause. 
I would DEFINATELY look to that as a possible. I have had many problems with mine in the past. Might be worthwhile to bypass it temporarily so you can rule that out as a cause. 
I have read plenty of horror stories on that too.
Le Mans Master
Joined: Dec 2004
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From: Myrtle Beach SC
St. Jude Donor '05-'06
Yours is a MAF car right?If the coil swap does not work try disconnecting the MAF and see what happens.When you do this it runs on speed density . If the maf is bad it will run like crap.
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Le Mans Master
Joined: Jan 2003
Posts: 8,596
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From: Portland Oregon
Sounds like a possible Opti-crap problem to me. Double check the coil output wire to the Opti for corrosion. Also remove the Opti electrical connector and check it for corrosion. The signal output from the sensors are low voltage and low current. Any corrosion there will cause timing and ignition issues.
Pro
Joined: Feb 2005
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From: Go Dawgs!
Originally Posted by LT4-Z51
My LT4 is missing....
I hope you find it!
Where did you last leave it parked?
Im not to familiar with the MSD set up, but is Opti-Spark still on there??
If so thats what yours sounds like and what my problem was above 4k RPM
-BirdMan
Last edited by A BirdMan Converted; Oct 2, 2005 at 10:18 PM.
Le Mans Master
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From: Scarborough ONTARIO
I had a similer problem on I-75 coming from mad dog tranny,
car died while driving on interstate i smashed the gas for about 1/8th mile than the car was running slow at very high rpm, pull the car on shoulder turn off the engine to see anything wrong under the hood, the only problem i saw was too hot, i let it cool down for a while than try to start "nothing" tried this and that for about 1 hour than called the towing truck, while waiting for towing truck i see something "click" sound the moment u turn the key ON very very small click sound at aound radio no codes throwing. Bottom line disconnect battry for 2 min's than reconnected viola car starts as if was never a problem.
So, may be u disconnect the battery wait for couple min's lets see. sometime no code but something somewhere mallfunction which goes away when u disconnect battery. Just sharing my exp if this helps. Oh well paid little tip to a tow truck guy.
car died while driving on interstate i smashed the gas for about 1/8th mile than the car was running slow at very high rpm, pull the car on shoulder turn off the engine to see anything wrong under the hood, the only problem i saw was too hot, i let it cool down for a while than try to start "nothing" tried this and that for about 1 hour than called the towing truck, while waiting for towing truck i see something "click" sound the moment u turn the key ON very very small click sound at aound radio no codes throwing. Bottom line disconnect battry for 2 min's than reconnected viola car starts as if was never a problem.
So, may be u disconnect the battery wait for couple min's lets see. sometime no code but something somewhere mallfunction which goes away when u disconnect battery. Just sharing my exp if this helps. Oh well paid little tip to a tow truck guy.
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From: Leominster MA
Originally Posted by LT4-Z51
What is the piece above the coil that has a plug on it also & looks like the wires go toward the TPS on throtle body could this be the problem?
Before anything, I would purchase a new OEM ignition coil and ICM at a part store. (But if you want atleast replace the ICM). Start at the ICM, if it fixes the problem, I would still get the MSD coil out of there soon.
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From: knox. tn.
well everyone we were all wrong , I can't believe it.The problem was a bad o2 sensor on the passenger side of the car!!!! THANKS FOR ALL THE INFO!!
Last edited by LT4-Z51; Oct 4, 2005 at 06:06 PM.