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Discussion Starter #1
I gave 8t a decent amount of throttle from a stop and the Trac control kicked on and it back fired about 5 tines then died.. It now won't start and back fired still. I only cranked it with and without giving it throttle both with the same result,nothing..fuel pump primes and it's throwing no codes that would pertain to this.
Could is be my crank shaft position sensor? The car occasionally did have a longer than normal crank at start and sometimes would run for a second or two after I turned off the ignition ..
It is a 1997 z28 lt1 a4..
 

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Crank position sensor only measures misfires, but has nothing to do with engine running.

You need to put a fuel pressure gauge on the fuel rail to see if you have around 43 psi @ key on prime. Did you put an obd 2 scanner on car to check for codes, or go with the no ses light on to say no codes present?


I ask because the 3 ignition biggies, don't light the ses. So if you haven't done so, scan for codes. Has opti cap & rotor ever been changed? These are parts that slowly go bad over time. Also test fuel injector opening with a noid light.

Does your security light come on when ignition turned on, then light turn off again after a few seconds? This is normal. If light stays on, engine won't run because fuel injector operation is cut off.

To properly diagnose the optispark, you need an oscilloscope to check low & high resolution pulses. Pc scopes are available for around $70 on Ebay, Amazon, etc.

Have you checked to see if you have a good strong spark? You can also take icm to auto parts store for testing.
 

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Discussion Starter #3 (Edited)
Yes I ran codes with my scanner all that come up are ones saying my cooling fans are not working because I strait wired them.
It's just odd because it started back firing as soon as the Trac control kicked on and then instantly stopped running. I will try and disconnect the battery for awhile and reset stuff.
I'm very limited rite now as to how much I can do because I coasted it into a cemetery parking lot,how ironic huh..
I don't have a fuel pressure gauge or anything just a scanner . If I can't get it going by nights end I have to eat a towbill and might then just have a shop look into it.
I don't think it's my opti at all as she ran great up until this and had great power . Only issue was an occasional hard start or when keyed off it ran for a second or 2 then shut down.
I asked about the crank sensor because on my 99 Silverado 5.3 experienced the same exact thing and that was the issue
 

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On newer cars with coil pack ignition, the crank & cam sensor are very important.

Do you have a friend that can pull your car home with you steering it? Or better yet, a friend with a car hauling trailer? Will save a bunch of money on towing.

If your going to work on the modern car, you need to get the tools you lack. You've got the scanner, that's good, but you need these tools also; fuel pressure gauge, digital multimeter, noid light, pv based oscilloscope.

Those tools are essential for running tests on your car. The pc based oscilloscope is the only tool that will show the square wave output of opti & the 50 hertz square wave fuel enable signal that is part of vats security. The scope is a very versatile tool that can do many tests. It can even test compression on your car if you have the proper high voltage leads for it.

Finally, information is your friend. So go to the following link and download the 96 service manual. It shares 99% of info with your 97.
www.mediafire.com/?40mfgeoe4ctti
 

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Discussion Starter #5
No spark from the opti, shop wanted 1000$ to do the job..i laughed at them and will begin the work my self very shortly..i for some reason doubt the opti unit has failed as I've always known them to show signs of failing 1st not just an all a sudden fail, like mine did the second Trac control kicked on..still too odd of a coincidence..but who knows the new one comes with a new plug so I will try just that 1st in hopes it's a wire failure or connection with the harness..i know the shop won't test the wires and hopefully I have a tester light at least some where ..
So I will order a new water pump too while I'm down there
 

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If you want to properly diagnose the optical part of opti, buy a $70 pc based oscilloscope. You can get one on Ebay, Amazon, etc. With it you can see if low & high resolution pulses are present. And of the proper square waveform. A must have tool if you own a lt1 car.

If you test opti and find you need a new one, stay away from part store, & cheap import opti. With these 2 types, you have a 50-50 chance of it being bad right out of the box. Then if your lucky enough to get one that works, you then have a 50-50 chance of it failing within several thousand miles.

Do yourself a favor and buy only GM, Delco, or Delphi opti. They are no picnic, but are the best of a sorry lot.

If you doubt opti can fail suddenly, yes it can like any other electrical part. The icm is a part that usually gives warning they are going bad. But I've seen a bunch of them go bad suddenly with no sign of failure.

Same with the electric fuel pump. They usually show signs of failure. But can also die without warning.

The bottom line is; don't be a parts changer. You can run tests to see if opti, icm, or other parts are bad. If your installing a new water pump, drive a plastic fitting into the weap hole. Silicon around it. Attach tubing to fitting and route it away from opti. That way if wp springs aleak from seal failure, opti won't get a bath.
 

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Discussion Starter #7 (Edited)
Can you suggest a coil that has a hotter spark than stock because I will be ordering 10mm wires..i figure while down there might as well. And a local guy offered to do the job but I need to be the shop bitch while we work on it..which I do prefer as I get to learn not about this engine and he lowered the price then too so a win win for me..
And anyone ever run e3 .44 spark plugs ? I'm debating between those and the Bosch platinum 4x which I've used is almost every car I've owned with great results every time..but anyone I've known to try e3s has had nothing good to say about them.
 

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Discussion Starter #8
I settled with a stock reman unit , msd cap n rotor , msd coil , 10mm wires , e3 .44 spark plugs , knock off water pump kit and timing cover seals felpro
Wish me luck hopefully the helper knows what he's doing because we start today .
 

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Discussion Starter #9
So far so smooth . Just have to get a crank puller and installer and wait for the parts to arrive.it may have 100k miles ( just rolled it befor it died) but being a garage queen I fought not one bolt or one clamp. No heat or even pb blaster needed. And why do stock 97 lt1 heads have the casting in them GM 4 ???
Also to get the crank bolts out I used a chain and bolt around the sway bar.
 

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Discussion Starter #11
SHE'S ALIVE ..after the job , turned the key N fired rite up and didn't have to tinker.
I can't believe it even ran at all, noneless with such minimal minimal issues..
Well,look at them..one plug was even broke in half and only thing holding it together was the spark plug wire..
I didn't have time to make a drain tube for the opti but I don't see a need to tap it, you can buy little L screw in things make from plastic at a hardware store and run a clear rubber tube then to see even the most minimal leaks..but,I just didn't have time..
Well,I can't post pics so maybe time to become a paying member if I feel the car will last at least 6 more months..
Anyways some porcelain was broke off n missing behind the electrode tip on a few plugs , a few others there was NO electrode at all it was barely there on a few and was so far gone the porcelain protruded more..lol unreal
 

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Happy to hear your car is now running.

I believe you photo uploading problems are caused by the insanely small size limits this forum puts on uploads.

The best advice I can give is to join a file sharing site. Then upload pics & such to the file sharing site. Then when you post, put a link to the pics you want to be seen, in the post.
 

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Discussion Starter #13
Happy to hear your car is now running.

I believe you photo uploading problems are caused by the insanely small size limits this forum puts on uploads.

The best advice I can give is to join a file sharing site. Then upload pics & such to the file sharing site. Then when you post, put a link to the pics you want to be seen, in the post.
Any good free ones you suggest ?
I used to use photobucket .
 

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The opti could have launched the rotor off inside the casing and just obliterated itself, thats one way they fail sometimes, and would explain the sudden failure. Its all plastic in there, so when it gets old or oil or coolant gets in there, it just deteriorates and stuff eventually breaks. Most failures will come after some symptoms, but its possible it failed suddenly and catastrophically.
 
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