LT1 Help needed
08-15-2011, 01:09 PM
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LT1 Help needed I built my lt1 about a yr ago..ran the car for about 4 months with little bugs mainly in tuning...then cold weather came and after a month car started only starting when it wanted to ....and now even in warm weather doesn't want to start only maybe once or twice...when it does actually start ..it runs like a champ then while its running after a 5 mins..10mins ..sometimes 30 mins it will start to fall on its face ..misfire..spit.sputter..backfire and just die...then will not restart..just crank and backfire...i unhook the batt. for a day or so ..and after several attempts it will sometimes restart..when it dies i get no CEL..looking at the scan tool while its running i cannot see anything wrong....checked fuel press and getting 50psi...
I have the delteq coil ign system installed so i even went back to opti to see if it was a prob with delteq and still same prob.. I have changed the opti with 3 gm units to see if that was the prob...no luck...changed every sensor except IAC and MAF ...but again both seem fine on scan tool readings...Vats is bypassed through tune as well as air/egr valve...new delco 02 sensors..
Any help would be greatly appreciated guys!
I have the delteq coil ign system installed so i even went back to opti to see if it was a prob with delteq and still same prob.. I have changed the opti with 3 gm units to see if that was the prob...no luck...changed every sensor except IAC and MAF ...but again both seem fine on scan tool readings...Vats is bypassed through tune as well as air/egr valve...new delco 02 sensors..
Any help would be greatly appreciated guys!
08-15-2011, 01:12 PM
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I built my lt1 about a yr ago..ran the car for about 4 months with little bugs mainly in tuning...then cold weather came and after a month car started only starting when it wanted to ....and now even in warm weather doesn't want to start only maybe once or twice...when it does actually start ..it runs like a champ then while its running after a 5 mins..10mins ..sometimes 30 mins it will start to fall on its face ..misfire..spit.sputter..backfire and just die...then will not restart..just crank and backfire...i unhook the batt. for a day or so ..and after several attempts it will sometimes restart..when it dies i get no CEL..looking at the scan tool while its running i cannot see anything wrong....checked fuel press and getting 50psi...
I have the delteq coil ign system installed so i even went back to opti to see if it was a prob with delteq and still same prob.. I have changed the opti with 3 gm units to see if that was the prob...no luck...changed every sensor except IAC and MAF ...but again both seem fine on scan tool readings...Vats is bypassed through tune as well as air/egr valve...new delco 02 sensors..
Any help would be greatly appreciated guys!
I have the delteq coil ign system installed so i even went back to opti to see if it was a prob with delteq and still same prob.. I have changed the opti with 3 gm units to see if that was the prob...no luck...changed every sensor except IAC and MAF ...but again both seem fine on scan tool readings...Vats is bypassed through tune as well as air/egr valve...new delco 02 sensors..
Any help would be greatly appreciated guys!
08-15-2011, 01:55 PM
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im getting 12.8v to the ecu and coils...i am starting to think ive got a broken wire under the insulator some where..im going to check the grounds that mount to the front of the head by the icm to see if maybe all the twisting from takin that bolt off messed something up there..hopefully i find something there
08-15-2011, 02:04 PM
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Sounds like opti man, hate to say it, but those units can be the devil. I would check that system out really good. Check the coil, plugs, wires. It really sounds like secondary ignition.
08-15-2011, 02:49 PM
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he said it did it without the opti and with it....
Have you checked Fuel pressure or spark?
It could be the fuel pump getting hot and shutting down over time, this could be an internal issue or a venting issue if it is the pump.
First things first is to test FP and Spark.
Have you checked Fuel pressure or spark?
It could be the fuel pump getting hot and shutting down over time, this could be an internal issue or a venting issue if it is the pump.
First things first is to test FP and Spark.
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08-15-2011, 03:06 PM
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he said it did it without the opti and with it....
Have you checked Fuel pressure or spark?
It could be the fuel pump getting hot and shutting down over time, this could be an internal issue or a venting issue if it is the pump.
First things first is to test FP and Spark.
Have you checked Fuel pressure or spark?
It could be the fuel pump getting hot and shutting down over time, this could be an internal issue or a venting issue if it is the pump.
First things first is to test FP and Spark.
08-15-2011, 11:37 PM
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BTW how old are your injectors? the original Bosh, and Delphi units are susceptible to the "E" fuels. meaning the alcohol eats the varnish off of the wires that make up the coil, then the injector will short out, and on these systems it shuts down the whole injector circuit due to an over current situation. this happened to my sons 91 camaro V6, bought new injectors from FIE and back on the road again.
this does sound like injectors to me????
funny story; i bought a spare "used" 3.1 on a Saturday for the sons car, and the Son blew the original with 223k the next Wednesday, talk about timing. LOL
08-16-2011, 09:42 AM
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OK first thing to do is split the system in half. prove whether it is fuel or electrical. take a plug out, reconnect it to the plug wire, then lay it on a metal surface (ground) have someone crank the motor over. see if you have a blue spark, if you do, " it should not be an electrical issue" next get a 12vdc test light, connect it to the injector wires for one side, crank it over look for blinking, then check the other side.
BTW how old are your injectors? the original Bosh, and Delphi units are susceptible to the "E" fuels. meaning the alcohol eats the varnish off of the wires that make up the coil, then the injector will short out, and on these systems it shuts down the whole injector circuit due to an over current situation. this happened to my sons 91 camaro V6, bought new injectors from FIE and back on the road again.
this does sound like injectors to me????
funny story; i bought a spare "used" 3.1 on a Saturday for the sons car, and the Son blew the original with 223k the next Wednesday, talk about timing. LOL
BTW how old are your injectors? the original Bosh, and Delphi units are susceptible to the "E" fuels. meaning the alcohol eats the varnish off of the wires that make up the coil, then the injector will short out, and on these systems it shuts down the whole injector circuit due to an over current situation. this happened to my sons 91 camaro V6, bought new injectors from FIE and back on the road again.
this does sound like injectors to me????
funny story; i bought a spare "used" 3.1 on a Saturday for the sons car, and the Son blew the original with 223k the next Wednesday, talk about timing. LOL
08-21-2011, 11:06 PM
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Yes thats the one that can affect the pcm. How about the ignition switch getting hot a causing issues? I see a lot of them burn the plug up and the switch, would run great and bam shut off and not start again sometimes for hrs. Just a thought all power runs through it and it gets hot.
09-03-2011, 10:14 AM
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Yes thats the one that can affect the pcm. How about the ignition switch getting hot a causing issues? I see a lot of them burn the plug up and the switch, would run great and bam shut off and not start again sometimes for hrs. Just a thought all power runs through it and it gets hot.
desired idle was 3385
TPS pos was 128 with foot off gas and wouldnt change values when i did press it
ltfuel trim off
and I just replaced the ecu so it couldnt be that..
I will be diggin more into the prob with the tps checking wiring and sensor to see whats up with that..it is a new sensor when i get more time to mess with it
09-03-2011, 10:44 AM
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U said u tuned out the vats, i did the same and i still had problems starting it. Isn't there a follow up proceedure to this after u have it tuned out? Possible security issue with the injectors shutting down?
09-03-2011, 11:27 AM
#17
I built my lt1 about a yr ago..ran the car for about 4 months with little bugs mainly in tuning...then cold weather came and after a month car started only starting when it wanted to ....and now even in warm weather doesn't want to start only maybe once or twice...when it does actually start ..it runs like a champ then while its running after a 5 mins..10mins ..sometimes 30 mins it will start to fall on its face ..misfire..spit.sputter..backfire and just die...then will not restart..just crank and backfire...i unhook the batt. for a day or so ..and after several attempts it will sometimes restart..when it dies i get no CEL..looking at the scan tool while its running i cannot see anything wrong....checked fuel press and getting 50psi...
I have the delteq coil ign system installed so i even went back to opti to see if it was a prob with delteq and still same prob.. I have changed the opti with 3 gm units to see if that was the prob...no luck...changed every sensor except IAC and MAF ...but again both seem fine on scan tool readings...Vats is bypassed through tune as well as air/egr valve...new delco 02 sensors..
Any help would be greatly appreciated guys!
I have the delteq coil ign system installed so i even went back to opti to see if it was a prob with delteq and still same prob.. I have changed the opti with 3 gm units to see if that was the prob...no luck...changed every sensor except IAC and MAF ...but again both seem fine on scan tool readings...Vats is bypassed through tune as well as air/egr valve...new delco 02 sensors..
Any help would be greatly appreciated guys!
