LT1 running rough at idle.
Thread Starter
Teching In
Joined: Jul 2012
Posts: 13
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LT1 running rough at idle. i have a 95 trans am with the lt1 i am new to this site, this is my first post im not sure if im in the right spot, please be patient if i dont know what im doing.
the past couple of weeks the car sometimes starts and runs perfectly and others it will start then stall then i restart it holding my foot about 1/4-1/2 on the gas pedal it runs really rough for about 30-50 seconds after this the rpms kick up and the car idles and runs perfectly untill the next time that i shut it off. it has been starting more rough than perfect lately.
trying to fix this problem within the past week (and also taking measures to prevent future break downs) i have changed the opti, coil, ICM, CTS.
the fuel pressure is strong at 42psi at idle even when the rough start happens. the pump is a 3 month old walbro and the injectors are bosch 30#
any help would be great please and thank you. im stumped
the past couple of weeks the car sometimes starts and runs perfectly and others it will start then stall then i restart it holding my foot about 1/4-1/2 on the gas pedal it runs really rough for about 30-50 seconds after this the rpms kick up and the car idles and runs perfectly untill the next time that i shut it off. it has been starting more rough than perfect lately.
trying to fix this problem within the past week (and also taking measures to prevent future break downs) i have changed the opti, coil, ICM, CTS.
the fuel pressure is strong at 42psi at idle even when the rough start happens. the pump is a 3 month old walbro and the injectors are bosch 30#
any help would be great please and thank you. im stumped
Thread Starter
Teching In
Joined: Jul 2012
Posts: 13
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ive tried unplugging the O2's, same thing. the TPS is newer and has good voltage via a datamaster scan. the datamaster does not throw any codes.
i have a feeling its the MAP but theres no codes. where is the heater circuit?
ive tried unplugging MAF and IAC sensor...same poor start.
thank you for your help
i have a feeling its the MAP but theres no codes. where is the heater circuit?
ive tried unplugging MAF and IAC sensor...same poor start.
thank you for your help
Thread Starter
Teching In
Joined: Jul 2012
Posts: 13
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the car throws no codes i have the solomon tune.....the engine was built 3 months ago...355, LE1 Heads, 306 Cam, l/t pacesetters headers, A4 2800 stall, p&p intake, 58mm t/b, egr,AIR pump ect delete. the car ran fine on this setup for the past 3 months i dont know what happend.
thank you
thank you
TECH Resident
Joined: Apr 2010
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From: T E X A S
hmmm, I would rule out any electronic stuff for starters; then, check on the mechanical aspect IE valvetrain specifically lifters and lash, could be a bit off.
edit...
actually when's the last time you checked the plugs and wires? verify gap and "read" all the plugs.
edit...
actually when's the last time you checked the plugs and wires? verify gap and "read" all the plugs.
Thread Starter
Teching In
Joined: Jul 2012
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the plugs are delco ....newerabout 12 000 miles them. the wires were changed the sametime NGK, i thought it might be that but the car gets out of its rough mode and runs perfectly for however long i need to drive it. however im not ruleing it out thats the next thing that i am going to check. i hope its not that since they are relatively new thank you
does anyone know what the correct MAP sensor reading should be on datamaster?
does anyone know what the correct MAP sensor reading should be on datamaster?
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Thread Starter
Teching In
Joined: Jul 2012
Posts: 13
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hey guys
i just changed the plugs and wires....omg what a PITA ive got the pacesetter longtubes and it was still .....time consuming loll. the plugs were black the wires seemed okay but i changed them anyway w\e.
the car did the same thing the first time i tried to start it after the plugs and wires swap...i think maybe just unburned gas that was dumped in and never used? i hope but since then i drove it around all last night with no problem starting and running smooth.
id still like to know the proper MAP readings on datamaster if anyone knows please?
thank you
pm
i just changed the plugs and wires....omg what a PITA ive got the pacesetter longtubes and it was still .....time consuming loll. the plugs were black the wires seemed okay but i changed them anyway w\e.
the car did the same thing the first time i tried to start it after the plugs and wires swap...i think maybe just unburned gas that was dumped in and never used? i hope but since then i drove it around all last night with no problem starting and running smooth.
id still like to know the proper MAP readings on datamaster if anyone knows please?
thank you
pm
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