My pretty much stock '88 Vette with automatic tranny responds too abruptly to mashing the gas. For example when starting off from a red light, as soon as you touch the gas pedal, it throws your head back. This may sound desirable, but it is not really that the acceleration is overwhelmingly fast, it is just that it is EXTREMELY difficult to start off smoothly. Especially bad when you have a passenger like my lovely bride who does not appreciate having her head jerked back. It accelerates great after that first fraction of a second, shifts smoothly, and is lots of fun. The throttle just seems uncontrollable.

Is there an adjustment somewhere that might help or something else happening that would cause this? I plan to drive to Corvette Expo in Sevierville, TN next week and would like to avoid the neck stretching that I get now.

 

The L98 is known for the low end torque. They are no slouch like people think they are. It also sounds like you have the 3:07 rear (rpo G92, G44). I'd say to be a little more easy with the throttle or you can get sideways.

 

In my limited experience with my stock 1989 L98 auto trans with 3.07 rear, it takes a very, very light foot on the accelerator to get the smooth, boring, sedan-like launch that you desire from a dead stop. It takes practice, but it is possible. I tell people that if there's one word to describe the car, it's "responsive". Steering, acceleration, braking, handling, you name it, she responds to your commands -- a most desireable trait in my opinion.

 

Id say take a look at the return spring.

 

You should check the base timing; stock is 6deg BTDC, higher will accentuate throttle response, little less should dampen it a bit.

Also you might use your foot to play with idle a bit to see what gives smoothest launch. I think that if you manually bring up the idle a little and then ease off the brake pedal you can control the launch.

Then there is throttle spring; adding a stronger spring will make it harder to get a smooth launch, IMO. After I installed a BBK 52mm TB in my prior '88 Vette (much stronger spring than stock) it was difficult to not launch hard.

 

 

i agree with a spring check, and a double check on the timing, but i'd also throw a voltmeter on the TPS, and check the upper and lower voltage values, along with a smooth voltage transition - that is, you don't get a big voltage jump by just cracking the throttle body a little. you should get a smooth, linear transition. is there any binding in the gas pedal linkage, and the operation of the throttle body (without the return spring)?

 

I'm not sure if the TB linkage is the same as on my 92. I have had the same problem a couple of times and found the cable had come out of the channel on the cam at the TB. Simply reset it and everything was fine.

 

with Joe, make sure your TPS is set to .54.. Like mentioned above, timing should also be checked.. You have to understand we don't get this question much, most people would want the throttle response you have, not try to get rid of it....WW
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.......... Pull the intake bellows off and lube the throttle shaft in the throttle body ... you can use silicone spray .. I use a dry teflon spray ... when the shaft ends are dry the throttle shaft will get sticky causing you to need a bit too much pressure to get it to move ... hence your jerky starts ..........

 

I agree with what C409 posted. Only time I've ever had a similar issue to yours was caused by a sticky throttlebody. Clean the shaft and blade and lube as suggested above.

 

i'm sitting here, and just had a brain fart - wasn't thinking before, but TB don't have a separate return spring - at least my 85, 90, and 96. the return spring is a integral part of the throttle body. in the back of my mind, i must have been thinking of an old carburetor set-up. i remember my 69, quadrajet, small block had a stiffer return spring, and it was a pain in the butt for a smooth launch, as noted by the OP. make sure there is no binding in the TB, and everything has smooth movement. also, i suggest pulling the TB, and giving it a good cleaning - inside and out.

 

Thanks to all for the suggestions. May be a couple of days before I can check out all of the suggestions though.

I knew it sounds like what most people would like to experience, but it is aggravating because it doesn't seem to be controllable. To get anything approaching a smooth start, I have to release the brake with it idling, and then after it starts rolling, I have to very, very gently press the accelerator. If I do this, every other car on the road starts off faster. Otherwise, it is like popping the clutch quickly with high rpm on a manual tranny. While this is okay when I want it, not what I want for my daily driving. Thanks again for all suggestions!

 

Check your transmission and motor mounts.

 

You should be easy on the bride and not jerk her head back, at least not right away. Actually, I'd like to buy your car (I haven't seen your wife yet).

 

The plastic gas pedal mount may be failing or dry @ the pivots. I used white spray can grease to lube mine.

I have also removed the throttle cable from the TB & lubed it. If you happen to have a cycle cable lube system it will be easier than the dripp in lube method.

With pedal & cable working properly operation remained "sticky" when the engine was cold. The PO had backed off the base idle adjustment, the throttle plates were hanging in the TB housing until the engine was up to operating temp. There is a procedure posted here on the forum to reset the TPS, base idle & IAC operation. I do not have a link to it.

Good luck.

 

The minimum idle speed adjustment procedure can be found here:

http://www.batee.com/corvette/dcrg/r...scuss_sim5.htm

 

Silicon will kill O2 sensors. "Sensor safe" needs to be posted on the label of anything entering the intake.

P.

 

its China's fault..or the Russians.

 

Thanks to all for the suggestions. Pretty fall day today, and I had some time to clean and lube the cables, clean the throttle body, etc. I also tried to make sure the cables were in place and worked them after lubricating. I did not get to the TPS and timing -- were next on my list. Anyway, bottom line is that after the cleaning, the accelerator seems to work great - the way it should! I can start off gently if I want to or I can stomp it and jerk my head back. Nice to have it working like it should.

Again, thanks to everyone who provided ideas. I felt like someone on the Forum must have encountered something like this before. While the fall weather is nice, I need to work on the rest of my to do list before winter. Already flushed the radiator, put new anti-freeze in, and cleaned the trash from in front. Also, got my new Corvette America seat covers installed last week although just the plain black simulated leather ones. Now I need to go under and change the oil & filter, top off the diff and tranny, grease everything, and clean the grounds. Whew, getting tired already but shouldn't be too bad since I can do this leisurely and have nice fall days to enjoy cruising after working on the Vette.