LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

97 lt1 missfire on #7 i need help!

Old 07-05-2018, 09:19 PM
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Re: 97 lt1 missfire on #7 i need help!

An old timing light with a clip-on lead for the spark plug wire should give you good indication of constant/reliable spark. I'm also curious if you have compression tested this cylinder (maybe it was mentioned previously and I missed it).
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Old 07-09-2018, 07:48 AM
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Re: 97 lt1 missfire on #7 i need help!

Originally Posted by shoebox View Post
An old timing light with a clip-on lead for the spark plug wire should give you good indication of constant/reliable spark. I'm also curious if you have compression tested this cylinder (maybe it was mentioned previously and I missed it).
I have a spark plug tester tool and have checked the spark. The spark comes and goes, sometimes disappears for a couple of seconds then comes back randomly. I tested the plug wire before number 7 and it sparks fine. So its #7 and i dont think i need a compression test on the cylinder if i can clearly see that im not getting spark from that #7 wire constantly on the spark tester tool.
Im gona take the car to get the Y pipe welded on to fix that exhaust leak right after the 02 sensor. Maybe that leak is causing the o2 to send some weird signal back to the pcm.
Thanks for the tip

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Old 07-09-2018, 08:18 PM
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Re: 97 lt1 missfire on #7 i need help!

I just like to rule out all possibilities, especially when it is something that does not follow conventional troubleshooting rationale and the trouble continues to go on and on. There might be something going on with your tester or test procedure that is throwing you off.
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Old 07-25-2018, 07:24 PM
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Re: 97 lt1 missfire on #7 i need help!

Originally Posted by shoebox View Post
I just like to rule out all possibilities, especially when it is something that does not follow conventional troubleshooting rationale and the trouble continues to go on and on. There might be something going on with your tester or test procedure that is throwing you off.
Might double check on what your saying.
Trying to find who will work on lt1s arou and here and drop it off. Fustrated with the damn thing.
Thanks for all the advice though

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Old 02-10-2019, 09:49 AM
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Re: 97 lt1 missfire on #7 i need help!


Just want to update this thread.
The problem was a header gasket leak on the driver side
Of cylinder 3/5
Also had the wrong gaskets on there maybe the reason it started leaking. I had 1405 felpro instead of 1406
1405 is a square portso they actual fit small on the exhaust port.
So about the gasket leaking out the bottom of the flange where it wasn't visible and only with time it got noticeably louder till i decided to take the header off to inspect.
Gasket was toast so replaced it and now motor is running good.
Misfire is gone and no loss of power as i can tell .
All this trouble caused by header exhaust leak
Hope this helps to others in taking close look and inspecting for the smallest exhaust leak before the O2 sensors .

They can cause havoc for you. Lol

Last edited by 97sswcubes; 02-10-2019 at 12:42 PM.
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