is this a failing optispark?
08-02-2006, 03:17 PM
#1
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Location: Ohio
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is this a failing optispark?
I'm trying to help a local guy diagnose his 94 Z28. He said it hesitates really bad under load so I hooked it up to Datamaster and did some logging. The car ran perfect for about 10 minutes of driving and then the problem showed up. At partial throttle, near and around 2000 rpm the spark timing is retarded anywhere from 5-9*, however in most cases, there was 0 knock occuring to cause spark retard. Other times, it would knock and retard timing simultaneously and I suspected bad gas (93octane from Giant Eagle).
After reviewing the datalog and seeing retarded timing with no knock occuring I began to change my diagnosis towards the optispark but I wonder if anyone else has seen this first hand. There are no SES codes present, although the light did flash for a while when I first hooked up to the car. However, no DTC's showed up on Datamaster while this was taking place.
The car only hesitated when Datamaster showed retarded timing commanded by the PCM.
After reviewing the datalog and seeing retarded timing with no knock occuring I began to change my diagnosis towards the optispark but I wonder if anyone else has seen this first hand. There are no SES codes present, although the light did flash for a while when I first hooked up to the car. However, no DTC's showed up on Datamaster while this was taking place.
The car only hesitated when Datamaster showed retarded timing commanded by the PCM.
08-03-2006, 12:41 PM
#2
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Join Date: Apr 2006
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Re: is this a failing optispark?
Saw the exact same thing a few weeks ago on my friends car. We replaced the plugs (visual inspection was ok, but internally they were failed) and rechecked the wires. All was good after that.
08-03-2006, 03:57 PM
#6
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Re: is this a failing optispark?
Originally Posted by 1FstFormulaV8
Long Tubes will cause it too. You're getting a false knock from somewhere.
08-03-2006, 04:41 PM
#7
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Re: is this a failing optispark?
Originally Posted by Green94B4C
My car has been having similar problems for quite some time now (changed opti, plugs, wires, almost every sensor, and O2's) and it is still acting up. These problems started up after I put long tubes on my car...can that be whats going on with it?
08-03-2006, 04:57 PM
#8
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Location: Houston,TX.
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Re: is this a failing optispark?
Originally Posted by plethaus
Get an LT4 knock module from Jason Cromer for cheap (I think it was like less than $30) and install it. You'll know right away if it's the long tubes causing false knock that was causing your problems.
08-03-2006, 07:16 PM
#9
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Re: is this a failing optispark?
Originally Posted by 1FstFormulaV8
Long Tubes will cause it too. You're getting a false knock from somewhere.
Also, false knock will still show up on the knock sensor. Most of the time when it was pulling timing, there was no knock being detected.
08-04-2006, 12:05 PM
#10
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Re: is this a failing optispark?
When my opti was failing, it would stumble real bad under load. With a scanner hooked up, you could definetely see knock being detected. The computer would retard it and make the problem even worse. Turned out the cap was badly worn and the rotor was destroyed. I replaced them with the msd cap/rotor kit and all is well.
08-05-2006, 07:42 PM
#11
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Location: Ohio
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Re: is this a failing optispark?
Originally Posted by autoxr
When my opti was failing, it would stumble real bad under load. With a scanner hooked up, you could definetely see knock being detected. The computer would retard it and make the problem even worse. Turned out the cap was badly worn and the rotor was destroyed. I replaced them with the msd cap/rotor kit and all is well.
Thanks so much.
***oops, sorry, this is mkent (the original poster)! I didn't realize dad was signed in here at his house!
10-01-2006, 05:37 AM
#14
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Location: Texas
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Re: is this a failing optispark?
Originally Posted by SMW
Do you guys know what the part number is for the LT4 knock sensor? Are any wiring modifications required?
Shoebox shows the difference on his site: http://shbox.com/1/lt4km.jpg
10-01-2006, 10:26 PM
#15
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Location: Corpus Christi,Tx.
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Re: is this a failing optispark?
Originally Posted by Eds69s
this is the type of reply I was looking for, specifically someone who has had a scanner hooked up. I will relay the information and hopefully it will fix the problem.
Thanks so much.
***oops, sorry, this is mkent (the original poster)! I didn't realize dad was signed in here at his house!
Thanks so much.
***oops, sorry, this is mkent (the original poster)! I didn't realize dad was signed in here at his house!