well, i have had a miss for a long time over 5K rpms......heres what i did to try and remedy it:
NEW opti, plugs, wires, coil, coil wire, o2's
car pulls like a bastard, then it misses at 5k at the same point ALL the time, it appears to be ~5100 rpms. i dont know what left to do.....all the parts are like 1 month old and 1,000 miles TOPS. the only SES light i have gotten is a low rpm IAC thing (P1508). i doubt this is it. my buddy suggested maybe the ignition module??
car is a 1996 camaro Z28 with a T56.
any help would be great.
brian

 

Brian,

I really wish I could help you, as I have the very same problem. Almost a year now and still no answer. Getting ready to do the Opti, but not really convinced that it is the cause. If you find a solution, please let me know, or post it on the message board.

Thanks,
Bill H

 

i wish you could tell. if it means anything the car gets worse through the gears, ie in 1st its barely noticeable, 2nd slightly, and in 3rd its pronounced. havent tried 4th cuz that entails speeds of 120 mph, and dont wanna do that. please help.....
brian

 

Fuel Filter
Fuel Pump
But I still think its a OPTI or Igin Coil

 

i have a new fuel filter.......but a fuel pump could cause this?? any one else?
brian

 

Put a fuel pressure guage on it and see if the presure is droping at 5000. That will tell you if the pump is bad or not.

------------------
-Slim
Red 1997 Pontiac Trans AM A4.
3" ASCD Cowl hood, IRS Stage II heads, Portmatched Intake, Comp Cam XE 230/236 112LSA, Comp Cam R lifters, Borla, IRS MAF, Moroso Intake, March Pulleys, 3.73 Gears, Hypertech 160 Powerstat, Air Foil, BFG Comp TA's & G-Force KDW's, Aluminum DS, Vigilante 3800, Jet Hot coated Hooker Longtubes and Mufflex Y-pipe, Ed Wright Magic.
Street Illusions Racing
My Car
My Bike

 

thanks, thats a good idea.....any others?
brian

 

maybe you should log some scans at WOT to see if anything out of the strange shows up. personally that would have been my 1st move and long before changing out the opti.

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1997 Z28 M6
T-tops, chrome rims, all options, SLP Dual/Dual, cutout, !CAGS, FIPK, LT4 KM, Air Foil, TB bypass, pro 5.0, TR55s, OBD1, !EGR, !AIR, CSI waterpump, 160* thermostat, 1LE intake elbow, PCM tuning by, www.PCMFORLESS.com , taylors, singe-cat SLP shorties minus the cat!

 

Could you be loosing some timeing at the upper RPM's? ... Sorry I'm not at all familiar with this opti spark bizz!

Is there a way you can crank up your base timeing about 5-10* for diagnostic purposes? It just sounds to me like your experiencing symptoms of a warn distributor.

Ron

 

Although my setup is different than yours I had the EXACT same problem. My car was pulling timing (missing) at WOT and was progressively worse through the gears and by the time I was in 4th at 120 mph it was real bad. I checked everything and finally narrowed it down to false knock. I ended up zeroing my "Spark Retard vs. WOT" table from 3000 rpm on up. I manually adjust Boost retard from in the car to control detonation. If I was you I would try running race gas and see if you still have the miss, If you don't than timing is your problem. Good Luck

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94 Z28,M6,355ci,8.9 CR Vortech S-Trim w/Aftercooler,Tunercat Prog.,DIY desensitized KM, Forged Internals,Port.&Pol. Heads w/3 angle grind,Bal.&Blue.,Crane 215/224-532/532-112LSA cam, 1.6 RR & Fireball HI-6R Ignition ,36# SVO Inj.,Magnecor Plug wires,Edelbrock Shorty Headers with Flowmaster,High Flow Cat,BBK 58mm TB ,K&N CAI,Eibach Pro-Kit w/Panhard Rod ,Global West SFC's,,RK Sports 5-way adj. shocks & LCA's, Slotted Rotors, Auburn Posi w/Motive 3.73, Niche J-series 18" rims 10.5 rear,9.5 front,Autometer F/P & A/F & Boost Gauges ETC.

 

i have run autotap various times on my OBD2 computer, before nad after the new parts and they all look normal. like i said, nothing that causes an SES light. now i have pcmforless's OBD1 cpu and its still happening....i really appreciate the ideas, and you can bet i will try them all. please keep them coming, i know that this will help many people aside from myself if we can solve it. i will certainly post when i fix it (or IF i fix it).
thanks,
brian

 

I had this.The fix is to get a ignition amplifier.My Accell 300+ rocks.6000 rpm.Clean&crisp.

 

I added the Accel unit and a new coil and still have the same problem. I too notice the miss in higher gears. Not at all in first or second, for sure in third, and really bad in fourth. Runs fine when first warmed up, can get in one good run pulling like a bull to redline in every gear. Second or third run and its back to miss-ville!!

I also checked my fuel pressure at the rail while driving, WOT and other loads. All looks good. Also have run many many scans. Does not throw codes, no knock retard, or misfires recorded!! I am truely stumped.

Please keep this thread going - I would love to solve this.

Bill H

 

i will keep it going, and like you bill, this stumps the heck outta me. i would love for the person that knows teh answer to post it and put us out of our misery....im very frustrated with it. and while i dont normally drive at or above 5k, i have aspirations to redyno and go to the track, which both require ~6k, and wont until i pull that high.
please help...
brian

 

still happening......
brian