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

97 lt1 missfire on #7 i need help!

Old 06-09-2018, 12:07 PM
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97 lt1 missfire on #7 i need help!

So yes ive searched and searched and read for days and days. Ive Googled ive yahood wut ever you want to call it and still have not found a solution to my problem. 97ss camaro with le2 heads and cam new forged 355 with stock crankshaft. Ecm reprogrammed by pcm for less, 36lb injectors, new msd coil etc etc.
Ok the problem is #7 won't fire correctly. Header won't heat up to the point where if i spray water on that tube it doesn't evaporate instantly like it does on the other 7 header tubes. Thats how i found what cylinder was misfiring. So i got a spark tester and it doesn't shoot spark continually it goes on and off... Ok it goes like this ".. .... .. .. . .... . And then no spark then it comes back. Why is the optispark not sending spark constantly to that one wire? Could it be the cap and rotor? Or the optispark itself?
The car ran fine for a couple of days and a few day later it started miss firing bad. Now i started off by checking the injectors accel 36lb brand new checked the signal too with doids has signal.. Scratched that off the board when i double checked the spark on that wire with spark checker and the second time it failed so i thought its the summit racing wire thats bad. I ordered msd super-conductor wires, same thing. Spark comes and goes at time doest see no spark. Why only #7????? Why oh why. Went and bought new map sensor, started easier but still the miss is there. Is there anything else i can check before i pull the damb opti off? I bought this car broken i put alot of time into putting it together and get it running i just would like someones opinion or maybe they had the same issue and found the solution.
Oh, i just got my 02 sensors gona install them but i doubt that will fix it..
Ome more thing, when i first got it running one of the coolant hose on the water pump was leaking and spraying coolant all over the place.
Any help will be appreciated

97ss
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Old 06-09-2018, 12:33 PM
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Re: 97 lt1 missfire on #7 i need help!

Originally Posted by 97sswcubes
Oh, i just got my 02 sensors gona install them but i doubt that will fix it..
Ome more thing, when i first got it running one of the coolant hose on the water pump was leaking and spraying coolant all over the place.
Any help will be appreciated

97ss
misfire on one cyl only....either plug, wire or opti assuming the injector for that cyl is good.

The note about spraying water....could have gotten "in" opti. Usually that would cause misfire over various cyl

what brand of opti do you have
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Old 06-09-2018, 01:30 PM
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Re: 97 lt1 missfire on #7 i need help!

Originally Posted by Chimera96
misfire on one cyl only....either plug, wire or opti assuming the injector for that cyl is good.

The note about spraying water....could have gotten "in" opti. Usually that would cause misfire over various cyl

what brand of opti do you have
Its just weird that only one cylinder is misfiring. With the boot off the sparkplug and the sprak plug tester on the new wire can clearly see its #7 not firing at times or not firing correctly. Its a summit racing opti. Yes ive herd only buy ac delco optis and i had one but it flooded during Harvey so i returned it and they didn't have any more ac delco in stock. So i bought a summit racing one. So you think its definitely the opti?
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Old 06-09-2018, 01:33 PM
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Re: 97 lt1 missfire on #7 i need help!

It seems unlikely to be the OPTI at this point but it certainly could be. Look first at the wire itself...maybe even replace it with an old one if you have one around. If that turns out to not be the problem and the spark plug is known to be good, then look at the OPTI...
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Old 06-09-2018, 03:26 PM
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Re: 97 lt1 missfire on #7 i need help!

Originally Posted by bw_hunter
It seems unlikely to be the OPTI at this point but it certainly could be. Look first at the wire itself...maybe even replace it with an old one if you have one around. If that turns out to not be the problem and the spark plug is known to be good, then look at the OPTI...
​​​​​​
1st set of wires are summit racing new. Thought it was the cheap wires so i ordered the msd. Still the same problem.

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Old 06-09-2018, 03:37 PM
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Re: 97 lt1 missfire on #7 i need help!

Given you have put 2 sets of wires on, check FI working and spark tester shows no or intermittent spark on #7.....pointing hard at Opti. The cap itself may have a defect on the #7. The caps used on the no name clones are cheap. MSD C&R is very good, not the MSD Opti though

If the Summit Opti is under warranty you can get another one and roll the dice on it.

To bad the AC Delco one you had was damaged in flood.

Occasionally rockauto has AC Delco remans
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Old 06-09-2018, 03:58 PM
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Re: 97 lt1 missfire on #7 i need help!

Originally Posted by Chimera96
Given you have put 2 sets of wires on, check FI working and spark tester shows no or intermittent spark on #7.....pointing hard at Opti. The cap itself may have a defect on the #7. The caps used on the no name clones are cheap. MSD C&R is very good, not the MSD Opti though

If the Summit Opti is under warranty you can get another one and roll the dice on it.

To bad the AC Delco one you had was damaged in flood.

Occasionally rockauto has AC Delco remans
Yes sir, shows some spark on that wire at times then fades off shooting spark every 2-3-5 seconds and even stops at times. Was hoping it would be some other reason why it was misfiring but not the opti itself. Didn't want to go threw the pain of taking it apart one more time. Drain the coolant and pull the balancer... Any way of squeezing the opti out without pulling the balancer out completely? Oh and yea rockauto is good on ac delco distributors but has been out of stock for a while now.
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Old 06-09-2018, 06:39 PM
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Re: 97 lt1 missfire on #7 i need help!

You only have to remove the damper/pulley portion, the hub does not have to be removed. Typical problem is rust on the hub, sometimes requires a 3-jaw or a crow foot (96/97) to get the damper/pulley loose.

http://shbox.com/1/pull_pulley.jpg
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Old 06-09-2018, 10:12 PM
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Re: 97 lt1 missfire on #7 i need help!

Originally Posted by Injuneer
You only have to remove the damper/pulley portion, the hub does not have to be removed. Typical problem is rust on the hub, sometimes requires a 3-jaw or a crow foot (96/97) to get the damper/pulley loose.

http://shbox.com/1/pull_pulley.jpg
Shouldn't have no rust on the bolts on hub or anything as its all new parts. Gona give it a go tomorrow and remove the opti and inspect it. Im hoping its just the cap or rotor but if it looks good I'll go ahead and call sumit and get them to send me a new one.
​​​​​Hopefully that will be the end of that.
Thanks for the advice
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Old 06-10-2018, 01:07 PM
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Re: 97 lt1 missfire on #7 i need help!

Any chance it could be the ignition control module ?
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Old 06-10-2018, 01:36 PM
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Re: 97 lt1 missfire on #7 i need help!

possible ICM, more likely Opti given it is specific to # 7

Typically a ICM fail is no start or shuts off after the engine gets to temp and won't restart

If you are pulling opti, remove cap and hold up to a bright light and look for any "tracking" (arc) between the paths imbedded in cap
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Old 06-10-2018, 03:56 PM
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Re: 97 lt1 missfire on #7 i need help!

Check the #7 wire terminal on the cap for corrosion.
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Old 06-10-2018, 09:50 PM
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Re: 97 lt1 missfire on #7 i need help!

Originally Posted by Chimera96
possible ICM, more likely Opti given it is specific to # 7

Typically a ICM fail is no start or shuts off after the engine gets to temp and won't restart

If you are pulling opti, remove cap and hold up to a bright light and look for any "tracking" (arc) between the paths imbedded in cap
Ok thanks for the info. Didn't get to tear it down today it was way too hot today. Drained the antifreeze out the radiator and gave the electric water pump a spin to circle any coolant out if the pump. Tomorrow gona dive in..
Forgot to mention one thing. The car flooded completely during Harvey that includes ecm. Didn't want to throw this into the mix since the car ran ok for a few days after i first started it. So im guessing the ecm survived even though it was under water.
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Old 06-11-2018, 11:02 AM
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Re: 97 lt1 missfire on #7 i need help!

Originally Posted by 97sswcubes
Didn't want to throw this into the mix since the car ran ok for a few days after i first started it. So im guessing the ecm survived even though it was under water.
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wtf...car was under water including the pcm…

was the pcm4less tune done after the flood?

so the opti was completely submerged also??
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Old 06-11-2018, 01:14 PM
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Re: 97 lt1 missfire on #7 i need help!

Originally Posted by Chimera96
wtf...car was under water including the pcm…

was the pcm4less tune done after the flood?

so the opti was completely submerged also??
Yeah wow, seems odd to mention this now. If the PCM was submerged, there isn't much of the car that wasn't (unless it was pointing severely nose down). Could even be dried silt inside the opti, disrupting the timing windows.
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