96 LT4 misfire?
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Intermediate
Joined: May 2001
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From: Miami,FL
96 LT4 misfire?
I leftwork and was sitting at ghe light, the car was warming up and all of a sudden it starts misfiring.The check SES light comes on blinking then steady then blinking.I had filled it up 1 maybe 2 days before so i'm thinking bad fuel.When i get home disconnected ECM fuse to maybe reprogram fuel curve or whatever it is supposed to do but when started it back still misfired but no SES light.Any light shed on my dark cloud would be appreciated.
Missing my S FLA ride
Dave
[IMG][/IMG] :cuss
[Modified by dr96lt4, 1:08 PM 3/1/2003]
Missing my S FLA ride
Dave
[IMG][/IMG] :cuss
[Modified by dr96lt4, 1:08 PM 3/1/2003]
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From: Texas
Re: 96 LT4 misfire? (dr96lt4)
You need to scan it (or take it to a shop to scan) and see what it's doing. Otherwise, it's just guessing and that can cost you a LOT of money. Unfortunately when you reset the PCM, you blew away the error code that might have offered a clue.
Simple checks would be to verify the plug wires, plugs, and air filter are good. Check for vacuum leaks. Check the impedence on the injectors (12 ohms), etc.
Simple checks would be to verify the plug wires, plugs, and air filter are good. Check for vacuum leaks. Check the impedence on the injectors (12 ohms), etc.
Thread Starter
Intermediate
Joined: May 2001
Posts: 26
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From: Miami,FL
Re: 96 LT4 misfire? (Zpeedstr)
I've been letting it sit because i ordered a scanner. Hopefully i'll be able to sort this out. I've been running it thinking it might be bad gas. When it first runs its smooth and runs fine but after a little while it just starts misfiring and puttering? maybe when it switches from closed loop to open? I don't know .I checked the wires they all seem to be tight and no frays. The filter looks good and i can't see or hear any vacuum leaks. Thanks y'all! :banghead:
[Modified by dr96lt4, 8:14 PM 3/4/2003]
[Modified by dr96lt4, 8:14 PM 3/4/2003]
Thread Starter
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Joined: May 2001
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From: Miami,FL
Re: 96 LT4 misfire? (dr96lt4)
I hooked up a scanner and got a p0300 code multiple misfire. Great i was hoping to get a more specific problem. Anybody have a clue cause i don't.
I was looking at the data and noticed the history of misfires occured mostly on the even numbered cylinders.
[Modified by dr96lt4, 8:42 PM 3/7/2003]
I was looking at the data and noticed the history of misfires occured mostly on the even numbered cylinders.
[Modified by dr96lt4, 8:42 PM 3/7/2003]
Thread Starter
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Joined: May 2001
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From: Miami,FL
Re: 96 LT4 misfire? (No Go)
When i went through the scanned data (i'm using obd-2.com software & cable)that i recorded while engine on the misfire waaas constantly changing on #6 so i unplugged it, looked good and put it back on making sure it was on tight on both ends.I hooked the laptop back and it showed misfire on #6 this time, cleared it and it did not come back up. I'ts getting late i'll take it for a long spin in the morning to see if it comes up again. :yawn: :steering:
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Thread Starter
Intermediate
Joined: May 2001
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From: Miami,FL
Re: 96 LT4 misfire? (No Go)
No i haven't done any work on it recently.Checked it this morn and got SES light and misfire on #6 again.Going to change plugs and wires.
Any ideas which plugs to get?
[Modified by dr96lt4, 12:52 PM 3/8/2003]
Any ideas which plugs to get?
[Modified by dr96lt4, 12:52 PM 3/8/2003]
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From: Texas
Re: 96 LT4 misfire? (dr96lt4)
I like and have had good results with NGK TR55VX platinum plugs. Right now I have Denso IT20s (step colder than stock). RapidFires are another option.
I recommend a seach of the C4 Technical Forum archives. There's a ton of info.
Since you have a hard code and misfire counts specific to one cylinder....Before buying parts, one thing you may want to do is swap the plug wires between #6 and #8 (at the plug and the opti!) to see if the misfire "moves". If it does, the plug wire is bad. If it doesn't, swap the #6 plug and an easy to get to one (i.e. #4). If the misfire "moves", bad plug. If the misfire remains at #6, it's likely not the plugs or wires.
:cheers:
[Modified by 96GS#007, 11:54 AM 3/10/2003]
I recommend a seach of the C4 Technical Forum archives. There's a ton of info.
Since you have a hard code and misfire counts specific to one cylinder....Before buying parts, one thing you may want to do is swap the plug wires between #6 and #8 (at the plug and the opti!) to see if the misfire "moves". If it does, the plug wire is bad. If it doesn't, swap the #6 plug and an easy to get to one (i.e. #4). If the misfire "moves", bad plug. If the misfire remains at #6, it's likely not the plugs or wires.
:cheers:
[Modified by 96GS#007, 11:54 AM 3/10/2003]
Thread Starter
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From: Miami,FL
Re: 96 LT4 misfire? (96GS#007)
Changed the wires Saturday, that wasn't it.Ran fine for little while then the sputtering.Monday morning changed 1 plug to test it out, hooked it up to the laptop while running and no new codes.Cleared the memory waited a few minutes, no codes.Shut her off, started looking around the engine compartment, aw crap! dexcool on the serpentine, floor and under hood.
No leak on top of waterpump so i assume it's coming from bottom and more than likely getting on the optispark causing the misfire.I don't know if i wan't to tackle the waterpump and possibly opti swap.
Thanx for all your help
David
No leak on top of waterpump so i assume it's coming from bottom and more than likely getting on the optispark causing the misfire.I don't know if i wan't to tackle the waterpump and possibly opti swap.
Thanx for all your help
David
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Re: 96 LT4 misfire? (dr96lt4)
p300 is bad o2 sensor. but theres 4 of them so you have to find which one is bad and replace it. if #6 is misfiring, find out which 02 sensor is responsible for that cylinder.
h good luck!
[Modified by eamador11, 5:33 PM 3/22/2003]
h good luck!
[Modified by eamador11, 5:33 PM 3/22/2003]
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From: Texas
Re: 96 LT4 misfire? (eamador11)
p300 is bad o2 sensor. but theres 4 of them so you have to find which one is bad and replace it. if #6 is misfiring, find out which 02 sensor is responsible for that cylinder.]
