Not running right..need a lt1 guru
06-15-2009, 03:51 PM
#1
Staging Lane
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Not running right..need a lt1 guru I have a 95 z28 that im having some issues with and hope someone can help.
Problems im having:
1.Car stall sometimes at stop lights and rarely when its sitting in my driveway at idle but will start back up.This happens and gets worse when the engine is at normal operating temp.
2.If im sitting still and rev the engine up real quick it will bog down/hesitate and sometimes let out a small exhaust backfire but if i ease the throttle it will rev fine.It also will do this if im in 1st gear(m6) about 1500-2000 rpm and put it to the floor,it will bog down,sometimes let out a exhaust backfire and then it will clear up and run fine.this problem also seems to get worse when the eninge is hot.It seems like once i get the car moving it will run fine.
I have replaced the coil,o2's,fuel filter, plugs and wires.
Anyone have any ideas?
Problems im having:
1.Car stall sometimes at stop lights and rarely when its sitting in my driveway at idle but will start back up.This happens and gets worse when the engine is at normal operating temp.
2.If im sitting still and rev the engine up real quick it will bog down/hesitate and sometimes let out a small exhaust backfire but if i ease the throttle it will rev fine.It also will do this if im in 1st gear(m6) about 1500-2000 rpm and put it to the floor,it will bog down,sometimes let out a exhaust backfire and then it will clear up and run fine.this problem also seems to get worse when the eninge is hot.It seems like once i get the car moving it will run fine.
I have replaced the coil,o2's,fuel filter, plugs and wires.
Anyone have any ideas?
06-15-2009, 03:54 PM
#2
I have a 95 z28 that im having some issues with and hope someone can help.
Problems im having:
1.Car stall sometimes at stop lights and rarely when its sitting in my driveway at idle but will start back up.This happens and gets worse when the engine is at normal operating temp.
2.If im sitting still and rev the engine up real quick it will bog down/hesitate and sometimes let out a small exhaust backfire but if i ease the throttle it will rev fine.It also will do this if im in 1st gear(m6) about 1500-2000 rpm and put it to the floor,it will bog down,sometimes let out a exhaust backfire and then it will clear up and run fine.this problem also seems to get worse when the eninge is hot.It seems like once i get the car moving it will run fine.
I have replaced the coil,o2's,fuel filter, plugs and wires.
Anyone have any ideas?
Problems im having:
1.Car stall sometimes at stop lights and rarely when its sitting in my driveway at idle but will start back up.This happens and gets worse when the engine is at normal operating temp.
2.If im sitting still and rev the engine up real quick it will bog down/hesitate and sometimes let out a small exhaust backfire but if i ease the throttle it will rev fine.It also will do this if im in 1st gear(m6) about 1500-2000 rpm and put it to the floor,it will bog down,sometimes let out a exhaust backfire and then it will clear up and run fine.this problem also seems to get worse when the eninge is hot.It seems like once i get the car moving it will run fine.
I have replaced the coil,o2's,fuel filter, plugs and wires.
Anyone have any ideas?
06-15-2009, 04:40 PM
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When you removed the old spark plugs, how'd they look? Did they show signs of an excessively rich or lean running condition? Wet-fouled? Black smoke out the exhaust?
Without a datalogger, it's difficult to tell which sensors may be causing problems, but it's worth the money to invest in an ALDL/DLC connector and Datamaster, if you plan on keeping the car for long. That, or a Scanmaster LT1, which is very useful on the 1994-1995 LT1. I believe 1995 vehicles have an OBD1 system with an OBD2-style diagnostic port.
If temperature is affecting the problem, that's typically a sign of electronics goofing up, but I'd still verify proper fuel pressure -- you can buy a test gauge at most automotive parts stores for $30-40. There's a schrader valve at the rear of the fuel rail.
Even though you replaced the ignition coil, you might try spacing the ignition control module (the thing on the back of the coil assembly) out away from the cylinder head -- heat has been known to cause issue with them. Better yet, swap it out completely if you have an LT1 buddy in-town, and see how that fares.
I'll refrain from mentioning the Optispark for the time being.
If there were a problem with the high or low resolution pulse, it should throw a code.
Without a datalogger, it's difficult to tell which sensors may be causing problems, but it's worth the money to invest in an ALDL/DLC connector and Datamaster, if you plan on keeping the car for long. That, or a Scanmaster LT1, which is very useful on the 1994-1995 LT1. I believe 1995 vehicles have an OBD1 system with an OBD2-style diagnostic port.
If temperature is affecting the problem, that's typically a sign of electronics goofing up, but I'd still verify proper fuel pressure -- you can buy a test gauge at most automotive parts stores for $30-40. There's a schrader valve at the rear of the fuel rail.
Even though you replaced the ignition coil, you might try spacing the ignition control module (the thing on the back of the coil assembly) out away from the cylinder head -- heat has been known to cause issue with them. Better yet, swap it out completely if you have an LT1 buddy in-town, and see how that fares.
I'll refrain from mentioning the Optispark for the time being.
If there were a problem with the high or low resolution pulse, it should throw a code.
06-15-2009, 05:27 PM
#5
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When you removed the old spark plugs, how'd they look? Did they show signs of an excessively rich or lean running condition? Wet-fouled? Black smoke out the exhaust?
Without a datalogger, it's difficult to tell which sensors may be causing problems, but it's worth the money to invest in an ALDL/DLC connector and Datamaster, if you plan on keeping the car for long. That, or a Scanmaster LT1, which is very useful on the 1994-1995 LT1. I believe 1995 vehicles have an OBD1 system with an OBD2-style diagnostic port.
If temperature is affecting the problem, that's typically a sign of electronics goofing up, but I'd still verify proper fuel pressure -- you can buy a test gauge at most automotive parts stores for $30-40. There's a schrader valve at the rear of the fuel rail.
Even though you replaced the ignition coil, you might try spacing the ignition control module (the thing on the back of the coil assembly) out away from the cylinder head -- heat has been known to cause issue with them. Better yet, swap it out completely if you have an LT1 buddy in-town, and see how that fares.
I'll refrain from mentioning the Optispark for the time being. If there were a problem with the high or low resolution pulse, it should throw a code.
Without a datalogger, it's difficult to tell which sensors may be causing problems, but it's worth the money to invest in an ALDL/DLC connector and Datamaster, if you plan on keeping the car for long. That, or a Scanmaster LT1, which is very useful on the 1994-1995 LT1. I believe 1995 vehicles have an OBD1 system with an OBD2-style diagnostic port.
If temperature is affecting the problem, that's typically a sign of electronics goofing up, but I'd still verify proper fuel pressure -- you can buy a test gauge at most automotive parts stores for $30-40. There's a schrader valve at the rear of the fuel rail.
Even though you replaced the ignition coil, you might try spacing the ignition control module (the thing on the back of the coil assembly) out away from the cylinder head -- heat has been known to cause issue with them. Better yet, swap it out completely if you have an LT1 buddy in-town, and see how that fares.
I'll refrain from mentioning the Optispark for the time being.
If there were a problem with the high or low resolution pulse, it should throw a code.I still have the old coil and wires that i might try again,i swaped the old one with a msd and i have the coil spaced out about 1 1/2 inches from the head.
I have a datalog but i dont have a laptop to take in the car with me but i hooked up my desktop and have a screen shot at idle if this will help....its a hotcam/bolt on car.
06-15-2009, 05:44 PM
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Cool deal. Did you get this "bogging" to occur during the datalog?
I'll check over the numbers if you send me a copy of the datalog file. (alex94tagt @ gmail "dot" com). -You can see a lot more values if you export to an Excel spreadsheet.
I'll check over the numbers if you send me a copy of the datalog file. (alex94tagt @ gmail "dot" com). -You can see a lot more values if you export to an Excel spreadsheet.
06-15-2009, 05:59 PM
#7
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this sounds like the symptoms i'm having though not as extreme...i'm hoping its a vacuum problem..i'mgoing out to check all my hoses after it has time to cool off.....(its 103 degrees here)
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06-15-2009, 06:18 PM
#8
Staging Lane
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I will send a copy,I couldnt get it to bog during the datalog,i really need to find a laptop so i can drive it and datalog.I have checked everywhere for vac leaks.Also when i mean it "bogs",its kind of like taking off in first gear then sticking it in 5th.
06-29-2009, 03:31 PM
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Sorry but my comp crashed and i didnt get to update this post....
I decided to change the cap and rotor,i noticed on the old dist cap, that the rotor was hitting inside the dist cap because one of the rivets was broke on the rotor.After the new cap and rotor, the car runs great now!! .....
Thanks Alex94TAGT and ss.slp.ls1 for helping out!
I decided to change the cap and rotor,i noticed on the old dist cap, that the rotor was hitting inside the dist cap because one of the rivets was broke on the rotor.After the new cap and rotor, the car runs great now!! .....
Thanks Alex94TAGT and ss.slp.ls1 for helping out!
