'93 LT1, hesitation at idle, doesnt want to crank - LS1LT1 Forum : LT1, LS1, Camaro, Firebird, Trans Am, Engine Tech Forums

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Old 07-26-2011, 04:54 PM   #1
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Default '93 LT1, hesitation at idle, doesnt want to crank

Hi guys, 93TA LT1 stock except for msd opti upgrade. New gas, plugs, wires. Idles fine at about 800rpm, but when I give it gas it hesitates up to around 1500rpm. More throttle seems to bring more hesitation. If I ease on the gas I get a stutter before it revs, if I punch it, it tries to (or does) stall out completely, and often backfires before finally revving up. It also doesn't want to crank up cold. Battery is fine, so I guess this is probably related to the issues at low rpms.

My 1st thought was mass air, but when I went to unplug the sensor, I realized I don't have one (kind of a newb here). Now I'm thinking maybe backflow pressure or EGR. Just looking for advice on where to go next from people who have more experience than I do. Thanks in advance for any help you guys can provide.

Last edited by Bandit93; 07-26-2011 at 05:02 PM. Reason: better info
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Old 07-26-2011, 06:56 PM   #2
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have you put a fuel pressure gauge on it? see what it does, at priming, start up and while reving. it almost sounds like fuel pump, but the cold cranking throws me off....but i would start there....
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WAIT, it's been built! 385 c.i. rear mount turbo, T-56 built by Savers trans, pensacola fl. starting at 5lbs, and breaking in then engine. hopefully will get it to 12psi in a couple months on dyno tune..
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Old 07-26-2011, 10:08 PM   #3
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could be a leaking injector, or a bad fuel pressure regulator.
Check the regulator first as it is the easiest. Remove the vacuum line from the fuel pressure regulator, it is located at the back of the intake and see if fuel comes out. If not, its probably good and next try the injectors. If you have the clips holding the injectors to the fuel rail, remove the 4 bolts holding the fuel rail to the intake manifold. Then gently pry up the injectors/ fuel rail, until the injectors are separated from the intake. Then while holding the fuel rail/injectors away from the intake, have someone turn the key to the on position without starting the car. If there is a leaky injector, you will see gas dripping/ spraying from a injector. If there is no loss of pressure, then that rules out a leaky injector. Try these two things, and let us know the results.

hth

andy schuck

Last edited by andys94t/a; 07-26-2011 at 10:10 PM.
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