Count me in too,
I noticed this problem a couple months ago, but I think it must have gotten much worse since then. It seems to get worse with heat as you guys have said, but it doesnt seem completely gone when cold. I am gonna clean my maf sensor and throttle body today(figured I might as well, easy enough) and I am doing plugs and wires sometimes this week. I wish we could get some more experts in here... maybe we should compile a list of all of the symptoms/attempted fixes so we can make sure we are all talking about/fixing the same problems here.
I am also gonna take my car in to GM to get my EGR replaced, cant remember whther thats a TSB or a recall but I got a notice about it, and I also never took my car in for the AIR pump recall, so I am gonna do that too..
anyways, lets try and keep this post alive, hopefully we will figure out what seems to be the culprit in all of our cars. I for one know I am not going back to the track again with my car running like this. 100 degree weather in sacramento really makes me notice this problem, heh.
Good Luck everyone,
keep us updated,
-Alex

 

TTT for everyone with this problem. Sounds like a lot of people have it. Hopefully someone will hit the nose on it. I would start maybe even with the AIR recall. It is FREE so it can never hurt to do that!!

------------------
------------------
Dustin Scott
1997 Z28 Camaro, M6

Flowmaster exhaust, B&M shifter, Moroso Cold Air Intake, Hooker Header exhaust tips, CAGS Skip Shift Eliminator, Accel 8.8mm spark plug wires, Hypertech Power Programmer III, Hypertech Powerstat, Hypertech throttle body foil, Hotchkis Lower Control Arms, Hotchkis Panhard Rod, Eibach ProKit, Spohn Lower Control Arm Relocation Brackets, Dynamic Motorsports MAF Sensor, Mac TrueFit Headers with Offroad Y-Pipe, NGK TR55 Spark Plugs, LT4 Knock Module, Nitto 555R Drag Radials

Looking to sell: Stock Panhard Rod, Stock Lower Control Arms, Stock Springs, LT1 KM, 2 10" Punch Subs in Bandpass Box, One 10" Punch XLC Sub, One 270 Watt Coustic Amp

 

I would say it is not the air pump. The air pump is something that is only used by the emissions system for the first couple of minutes of engine warmup. Then it does nothing. Except for take up space and add extra weight of course.

 

I didn't think so, but at least the people in this post are aware of the recall (if they weren't already) and it is a free thing to do, although they can't do it themselves if they want it to be free. I have had both the AIR and EGR replaced on the car, new plug wires, new plugs, used some fuel injector cleaner when I first got the car and nothing like this has happened to my M6 at all. Seems kinda weird that everybody is having the same problem. Maybe you should protest to GM and get a recall started!!

------------------
------------------
Dustin Scott
1997 Z28 Camaro, M6

Flowmaster exhaust, B&M shifter, Moroso Cold Air Intake, Hooker Header exhaust tips, CAGS Skip Shift Eliminator, Accel 8.8mm spark plug wires, Hypertech Power Programmer III, Hypertech Powerstat, Hypertech throttle body foil, Hotchkis Lower Control Arms, Hotchkis Panhard Rod, Eibach ProKit, Spohn Lower Control Arm Relocation Brackets, Dynamic Motorsports MAF Sensor, Mac TrueFit Headers with Offroad Y-Pipe, NGK TR55 Spark Plugs, LT4 Knock Module, Nitto 555R Drag Radials

Looking to sell: Stock Panhard Rod, Stock Lower Control Arms, Stock Springs, LT1 KM, 2 10" Punch Subs in Bandpass Box, One 10" Punch XLC Sub, One 270 Watt Coustic Amp

 

yeah, I have experience with the AIR pump being a PITA when trying to get to certain things down there, I think I might just take it back off after GM replaces mine for free...
anyways...getting pretty damn discouraged over here, cars feeling very slow, oh well :/
I am gonna turn on my car later tonight when its dark and hope to see fireworks.
GL guys,
thanks,
-Alex

------------------
1997 30th Anniversary Z28
Exterior: Arctic White with Hugger Orange Stripes
Interior: Arctic White Leather with Embroidered 30th Anv Emblem.
17x9.5 17x11 ZR1's
LS1 Aluminum Driveshaft,
BMR Adjustable PHB, Moroso CAI,
CSI Electric Water Pump, 1LE Intake Bellows
http://filonic.fbody.com

 

I had the same hesitation with my '94 Z. I had the optispark, plug wires and plugs replaced. The hesitation was still present. So I check the output of the coil (which was a MSD coil, I don't think I installed it correctly) the output was not what it should be at. So I replaced with an OEM coil. The hesitation went away.

 

so just wondering how many miles since you checked your air filter i have moroso CAI and after about 15k mine started stumbling too so i looked and the throttle body it was nasty and i cleaned my air filter works fine
hope everyone figures it out

jake

 

My car has been doing it lately too. To be honest, it feels like the clutch is slipping.

 

I recently installed a moroso CAI also, and I had the same hesitation before/after so I dont think thats the solution for everyone,
its pretty discouraging that noone has solved this problem by changing their plugs and wires or the opti. I am going to try a couple things tomorrow but I might end up just taking it to a shop because I WILL NOT be satisfied just letting this go and trying things every once in a while. I didnt spend a whole bunch of money on my car to have it act like a slug at the track. I wish we could figure out EXACTLY what is universal here. Mine is DEFINITELY MUCH worse in high heat, and in general my car seems to run MUCH better in the first 15 minutes or so of driving. I let the car and drivetrain warm up with 10 minutes or so of gentle sub-3000RPM driving, then floor it from a stop? it takes off like a bat out of hell. But if the car has been sitting in the sun on a hot day, or I've been driving in traffic etc and the temps go up, not only does it take off like a slug, but when I try to start it it often sounds slightly weird, it still starts right up fine, it just sounds a little chunkier than seems right. Its always extremely hard for me to tell exactly what is happening and what is imagined.
Anyways, I hope someone who has the magic answer sees this message, hehe
thanks
-Alex

------------------
1997 30th Anniversary Z28
Exterior: Arctic White with Hugger Orange Stripes
Interior: Arctic White Leather with Embroidered 30th Anv Emblem.
17x9.5 17x11 ZR1's
LS1 Aluminum Driveshaft,
BMR Adjustable PHB, Moroso CAI,
CSI Electric Water Pump, 1LE Intake Bellows
http://filonic.fbody.com

 

I aint gonna read all four pages so perhaps someone after the first page already suggested the possibility of clogged fuel injectors?

Did you check everything that the manual suggests for a "15 Hesitation or stumble during acceleration"? i.e. Ignition system, fuel injectors, low fuel pressure.

Also, "17 Engine lacks power." i.e. incorrectly gapped plugs, air filter dirty, ignition coil, clutch slipping, among other things.

 

i'm leaning towards an electrical problem with the heat making it worse. i am going to clean the maf tonight but i'm thinking coil or coil wire. looks like it worked for at least one person.

 

Oye. No offense guys but throwing parts at it isn't going to fix the problem. Your's and my hesitation is during low load, low RPM not high load, high RPM. That means all parts can be ruled out, anything that works at a high rate would only work better down low. However there are reasons people get stall converters, do high RPM clutch dumps and this is it. GM set our idle down low to save gas, other none V8 sporty cars idle at 1200-1800 for no hesitation launches and gas isn't an issue in a four banger.

So if you want to solve your hesitation it's simple, get the RPMs up to 1500+ before launching. Basically if it isn't clear yet, when you launch down low, you bog the motor because you just dropped it onto a none spinning transmission/drive shaft/tires, once they start to spin up the hesitation is gone and off you go. If you launch higher up in the RPMs you have enough force to beat the innertia and continue accelerating without first bogging trying to get them spinning. Sticky tires only add to the problem since they're one more thing to get moving. Non sticky tires would break lose instead of providing innertia. A slipping slutch would also notice this less since the clutch is essentially feathering itself for you.

So again, your fix isn't hardware unless you want to change your idle to something higher or find a way to get everything spinning at the motor's rate without it getting to the wheels. Latter is brake line locks but the first is easy enough, get a stall converter or if M6 feather your launch at a high RPM on launch.

So instead of throwing money out the door, stop and think about what happens mechanically in a car during the event you're concerned about, then look at it from a physics point of view and compare to another event to find the problem. You'll have many more mods done that way than if you throw your mod money into unnecessary repairs. For the record my 95 Z28 is a winter driven, daily driver with all original parts, except for maintainence items(brakes pads/rotors, tires, belts, fluids) because most problems pass within a week, and others have such simple fixes that the original part can be kept. If I fixed problems the second they appeared even if they didn't come back I wouldn't have a parts matched Camaro and that would be bad now that their resale value is going up since GM stopped making them. Or at least that's what is happening up here in Canada.

Seta

 

Thanks for your info Seta,
but I think you are being extremely presumptious in saying that. For one thing, you dont even know that we are all explaining the SAME problem!
And for another thing, if such was the case as you are saying, there would be NO explanation for the seemingly intermittent symptoms, the sensitivity to heat, OR the fact that I, along with MANY other people on this thread, didnt used to have this problem, and have acquired it somewhere along the line. Anyways, although we all appreciate you writing a 2 page long message basically telling us we are idiots and we dont know how to launch, I think I'll stick with my former plan of trying to eliminate possibilities until this is solved.
Again, I hope someone with some in depth knowledge about this situation will come forward on thsi thread soon, as it seems there are lot of us in need of help. Please dont come on here and tell us "your car is just slow stock, get a torque converter".
Thanks,
-FiLo

------------------
1997 30th Anniversary Z28
Exterior: Arctic White with Hugger Orange Stripes
Interior: Arctic White Leather with Embroidered 30th Anv Emblem.
17x9.5 17x11 ZR1's
LS1 Aluminum Driveshaft,
BMR Adjustable PHB, Moroso CAI,
CSI Electric Water Pump, 1LE Intake Bellows
http://filonic.fbody.com

 

just curious but have any of you guys ever hooked up a scanner on your car to see if your problem is simple knock retard? if you mash down on the gas giving the car a sudden jolt, you could be causing false knock which will rape you of power(yeah its a long shot )

my car is a 6 spd with a 70k factory clutch which could simply be slipping on me. sometimes the car is a total beast and sometimes it acts like a honda so figuring out my problem isnt easy. i DO however think it is temp. related cause my car is a dog on mid summer days and very strong in the mornings and at night...and all winter. it is also a widely known and accepted fact that LT1s like cold weather which explains a lot.

id also like to add that 96-97 f-body owners shouldnt need to replace their coil since we have the updated(much improved) version.. also explains why you dont see any aftermarket coils for 96-97 LT1s.

------------------
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!

 

The coil/ignition coil location seem to be a bad design, and might be sensetive to temperature extremes. However, if this was the case, this problem would occur on new cars also. Mine didn't start hesitating until well after 80k miles. Plus, if this was an inherent design flaw, GM would have found it during their testing at their summer proving grounds. Spacing the assembly away from the head would be an easy fix that GM certainly could have implemented.

So if the coil/ignition module are to blame, it is because they are breaking down or deteriorating over time, and then become sensetive to high temperature.

One other cause could be the famous intake manifold oil leak. At high temps, the intake may be sepatating from the head, and creating a vaccuum leak, along with the oil leak. Either condition could cause the AFR to be drastically changed during idle and launch, but not be so significant above 2000 rpm.

Does anyone who has properly fixed their intake oil leak still have this hesitation problem?