LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Horrible Running Z!!!Need Help...

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Old Dec 13, 2009 | 05:01 PM
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Default Horrible Running Z!!!Need Help...

i have a 96 z that i finally got put back together.soon as i got the high idle problem fixed now i have another prob. car starts fine when cold. but once it somewat warms up it stumbles.and if u cut the car off it will start for a split second then cut right back off or not start at all. i tried 2 different ignition modules and problem persist. and has 40+ psi of fuel pressure.

well today when taking the second ig module back off i noticed one of the ground rings was broken...ring still on stud but wire disconnected...would that be the cause of my problem. im going to reground it because i know it prob needs to be grounded regardless, but can someone be specific on wat electrical item its ground for? as in injectors,pcm, etc.....

thanks
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Old Dec 13, 2009 | 06:23 PM
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any broken ground needs to be fixed you will be amazed how one ground can mess stuff up, even if there is a second ground on other portions of the motor...
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Old Dec 13, 2009 | 06:49 PM
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thanks i know if it wasnt needed it wouldnt be there but is this the ground for the coil or something of that nature? shbox i know u know.......where r ya
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Old Dec 14, 2009 | 05:27 AM
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ttt....ttt
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Old Dec 14, 2009 | 04:25 PM
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still no replies.......but if i said something about stroking or boosting a lt1 then i'd get 20,000,000 replies.............
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Old Dec 14, 2009 | 06:16 PM
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Do what I did: Put your post under "100 dollars if you fix it". I got a ton of responses. My car is still under the weather though. I got some tuning software and a cable now. I will be messing with all of that later this week.
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Old Dec 14, 2009 | 06:22 PM
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have you fixed the ground yet? if not, go do so then report back and go from there. i looked today and i had, i believe 3 ground straps going to that front head stud. do you know what wire it was? one went from the head down to the "frame", the other two went and hid from me in some plastic wire cover......
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Old Dec 14, 2009 | 06:34 PM
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Originally Posted by thomas89xj
have you fixed the ground yet? if not, go do so then report back and go from there. i looked today and i had, i believe 3 ground straps going to that front head stud. do you know what wire it was? one went from the head down to the "frame", the other two went and hid from me in some plastic wire cover......
cant get out there to fool with car...raining. its one of the wires that runs off into the harness...
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Old Dec 14, 2009 | 06:38 PM
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Originally Posted by Rick804
Do what I did: Put your post under "100 dollars if you fix it". I got a ton of responses. My car is still under the weather though. I got some tuning software and a cable now. I will be messing with all of that later this week.
i shouldnt even have to do that...this is suppose to be a tech forum for the lt1. but no one responds unless you're talking about something extreme....when i had my mustang 5.0 i never had problems getting help on "THE" mustang forum.............all i want to know is wat are these wires supplying ground to? simple
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Old Dec 14, 2009 | 06:39 PM
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ok, im not sure where they run. im going to try and do some work on mine tomorrow, i will split the line and try and find it for ya as my motor is out so its easy to work with lol.
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Old Dec 14, 2009 | 06:45 PM
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post up what you have done to the car, such as mods. that way if its not the gound people can look at other things that may cause this. never know someone may see something and have had the same problem you are....
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Old Dec 14, 2009 | 08:28 PM
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car is bone stock, except for rebuilt shortblock....
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Old Dec 14, 2009 | 09:50 PM
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Is it throwing any codes? have you had the codes read? it is possible it could be the opti, have you tested the opti harnesse for the correct voltage? have you tested the coil?
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Old Dec 15, 2009 | 09:18 PM
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Originally Posted by sepno77
Is it throwing any codes? have you had the codes read? it is possible it could be the opti, have you tested the opti harnesse for the correct voltage? have you tested the coil?
check engine light is not on. cant get the car running right long enough to throw a code.how do i test the opti? and every autoparts store i took the coil to cant test ignition coils.but they tested my module an it checks good everytime
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Old Dec 15, 2009 | 09:42 PM
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You could still get the codes read w/o the car started. All you need is the ign key turned, should do this even if it isn't throwing a code. You test the opti thru the opti harness, has 4 wires has 2 grounds and 2 postives that you need to messure for correct voltage w/ the ign. on the on position. I believe it should read 10v on the 1st and last wire the middle 2 are ground, if the voltage is less than 10 then its a bad opti. You could also pull the coil wire to see if its sparking when tring to start the car.
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Old Dec 15, 2009 | 10:10 PM
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after the car warms and u cut the ignition.whe u retry it the only way it attempts to fire is u have to hold the pedal all the way to the floor and crank for a while. then itll fire for a "ery very very" splitsecond.an no matter how many times you pat the gas to keep it running it dies.

i disconnected the air duct from from the stock factory airbox and sprayed starter fluid in the hose..still didnt start, but im getting spark and i have good fuel pressure
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Old Dec 16, 2009 | 06:14 AM
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ttt..
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Old Dec 16, 2009 | 01:16 PM
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Originally Posted by SmartOJ
after the car warms and u cut the ignition.whe u retry it the only way it attempts to fire is u have to hold the pedal all the way to the floor and crank for a while. then itll fire for a "ery very very" splitsecond.an no matter how many times you pat the gas to keep it running it dies.

i disconnected the air duct from from the stock factory airbox and sprayed starter fluid in the hose..still didnt start, but im getting spark and i have good fuel pressure
How do you know your getting spark? If you just tested the coil thats not good enouph. To me it sounds like the optical sensor in the opti is bad. Your symptoms sound identical to mine when my opti went out. You must not be geting one or the other fuel or spark cause if you had both the car would start. If you can't figure it out you could alwasy take it to a mech and pay for an engine diagnotic and have them tell you why it isn't starting.
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