Steve91Z28 L98

My car has been doing this for a while. Especially when it is cold, like right after startup. When driving, the car feels down on power and then when right as the tach reaches 2500 rpm, the tach literally starts jumping around and the car surges like crazy. I can't figure out what it is and why it won't do it until 2500 rpm. All the ignition components are new including the distributor. Could it possibly be fuel related? I'm at a loss here guys so help me out please.

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1991 Z28 - 350 TPI, T56, McLeod street clutch, LT4 pressure plate, Pro 5.0 shifter, ported plenum & runners, AFPR, Holley Annihilator ignition box and wires, Hooker shorty headers w/o AIR, Flowmaster muffler, homeade ram-air, SSM subframe connectors, Kenny Brown STB, Global West steering box brace, Steve Spohn adjustable torque arm and T56 crossmember

Steve89GTA

Drop in a new distributor, it will correct the problem 4 sure. I had the same problem and then my pickup coil (in the distributor) blew to pieces, (or seized and cracked to $****).

Thanks

Steve91Z28 L98

The distributor is brand new. It's been in the car less than a month. Could it possibly be the timing? That was gonna be the next thing I checked. Someone also told me that it might be the fuel injectors.

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1991 Z28 - 350 TPI, T56, McLeod street clutch, LT4 pressure plate, Pro 5.0 shifter, ported plenum & runners, AFPR, Holley Annihilator ignition box and wires, Hooker shorty headers w/o AIR, Flowmaster muffler, homeade ram-air, SSM subframe connectors, Kenny Brown STB, Global West steering box brace, Steve Spohn adjustable torque arm and T56 crossmember

Steve91Z28 L98

Today I was playing around with different things when I noticed a very loud ticking sound coming from the back passenger side of the motor. I'm almost positive that it isn't an exhaust leak unless it is leaking from the actual header to head gasket(every other exhaust leak I've had since I got the headers has come from the collector gasket blowing out). I thought it might be the back injector on that side. I didn't have much time to mess with it but I put my finger on all the injectors and could feel the normal pulsing out of all of them except the back passenger side one. This is where the noise is coming from but I don't have a clue if the noise is related to the injector or not. Someone please hlep me out here. I'm running out of ideas. I really need to hook it up to a scan tool. Hopefully I will be able to do that when I get out of school on May 5th.

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1991 Z28 - 350 TPI, T56, McLeod street clutch, LT4 pressure plate, Pro 5.0 shifter, ported plenum & runners, AFPR, Holley Annihilator ignition box and wires, Hooker shorty headers w/o AIR, Flowmaster muffler, homeade ram-air, SSM subframe connectors, Kenny Brown STB, Global West steering box brace, Steve Spohn adjustable torque arm and T56 crossmember

Steve91Z28 L98

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Damon

If that tach's jumping around it's igniton related in some way. A dead or clogged injector might cause a miss but it won't cause the tach to jump. If you hadn't replaced the distributor I might also have guessed a distributor-related problem (pickup coil).

My next guess would be that the igniton box is pooched. Try putting the igniton back to factory (temporarily) and see if the problem goes away. If it does it could be that you jsut had something wired wrong with the ignition box to begin with or that you require some kind of filter/diode/resistor somewhere in the wiring to make it work correctly on your car. Holley's tech support line can help you figure it out from there if the problem is, in fact, related to their ignition system.

Beyond that you might be looking at a bad ECM or bad ground somewhere. Get a scan tool and look at it from the computer's perspective or you could be throwing parts at it for weeks.


[This message has been edited by Damon (edited April 28, 2001).]

Steve91Z28 L98

I won't be able to hook it back up to the stock ignition until I get back home. There is a wire harness that I need that is sitting in a box in my garage. I was definitely planning on doing this though to make sure it isn't the ignition box. What about the coil though? Could a bad coil cause this problem? I think I remember hearing somewhere that the high energy output coils like my Holley one will go bad much more often than the stock ones.

Steve91Z28 L98

Anyone else have some suggestions?

Vanguard

iTrader: (1)

I had a similar problem in which the engine would miss and the tach would jump when the A/c was put on High.

Turns out that one of the grounds that attaches to the back of the block off.

I replaced it and the problem went away. Cheap fix

fb305svs

dude- its the pick up coil... i think ya got a bad setup- we just went through this on my brothers z...

Steve

Steve91Z28 L98

That is strange that it would be the pickup coil. The distributor is brand new and it wasn't doing it when I first put it in. I guess it may just be a defective piece. I guess that's what I get for buying a reman distributor.

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1991 Z28 - 350 TPI, T56, McLeod street clutch, LT4 pressure plate, Pro 5.0 shifter, ported plenum & runners, AFPR, Holley Annihilator ignition box and wires, Hooker shorty headers w/o AIR, Flowmaster muffler, homeade ram-air, SSM subframe connectors, Kenny Brown STB, Global West steering box brace, Steve Spohn adjustable torque arm and T56 crossmember

[This message has been edited by Steve91Z28 L98 (edited May 01, 2001).]

CraZ-28

I know it seems strange that the pick-up coil(ignition module) is bad but it is possible. Those thigs are so sensitive to heat that they just die. I know here in AZ, if some body I know is having an issue like that, the first thing I have them replace is the module. 9 time out of 10, I'm right.

Now, if it's not the module, check the wires between the coil and the module. If any wire is exposed or cracked, it will cause the tach to jump and possible act funky. I had one wire that was showinf about an 1/8 of an ich of the wire and my tach did the same thing. Hope that helps. Good Luck!

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'91 Z-28 5.7, SLP 1 3/4 headers, 4 inch Mufflex/Flowmaster cat back, gutted cats, Edelbrock intake, 8.5mm Jacob wires, MSD Blaster coil, S&W subframe setup, Jacob Pro Street Ignition, complete Kenwood system.

JoelOl75

I have the holly ignition system and the tach jumping on occasion can't directly be linked to the bad running condition unless the holley box is bad.

My tach drops to zero with the turn signals because I never got the tach amplifier. Our factory tachs arn't 100% compatable with the box. It doesn't effect the running of the car though.

I would try a different distributer and/or running a stock coil off the module instead of the holley and see what happens. Just because it's new doesn't mean it can't be bad.

Are you running an aftermarket CD ignition coil? The stock one or stock type (Supercoil, ect.) are different and won't work right.

Steve91Z28 L98

Ok the ignition module is an Accel and it was put in the same time that the Holley ignition was put in about 4 months ago. I swapped it onto the new distributor when I put it in less than one month ago. I will put the stock module back on and see if that fixes the problem. Thanks alot for the suggestions.

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1991 Z28 - 350 TPI, T56, McLeod street clutch, LT4 pressure plate, Pro 5.0 shifter, ported plenum & runners, AFPR, Holley Annihilator ignition box and wires, Hooker shorty headers w/o AIR, Flowmaster muffler, homeade ram-air, SSM subframe connectors, Kenny Brown STB, Global West steering box brace, Steve Spohn adjustable torque arm and T56 crossmember

junkyarddog

my car does this same thing,it is an '84 Trans Am (305 HO) HEI dist. w/integral coil. so far,I've replaced the coil,pick-up coil,module (greased the heatsink),cap & rotor..............strangely enough, I replaced the knock sensor and that alone eliminted the problem for two months!!! it's starting to do this again though , I'm going to replace the carb & ignition with aftermarket (holley,mallory & accel) this will eliminate the need for the ECM. I'm not sure I have a grounding problem,because it seems to behave differently depending on how the gas pedal is pushed. sometimes letting off the gas,and then gently pressing it down,will take care of it......but jumping back on the gas will make it worse!?

does anyone have the wiring diagrams for thirdgen ignition systems??

Steve91Z28 L98

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