Don Schuette

I drove my friend's 1993 LT1, mainly stock except for flowmaster exhaust, some ram air filter, a larger Holley Throttle Body and some programming, I guess.

The throttle body is Holley's 52mm.

We opened the hood, and when he puts the gas pedal to the floor, I can still hand rotate the throttle body lever almost another 30 or so degrees. Seems like the cable is not pulling it far enough open. It has the ASR box, which I guess is the traction control.

I take it the full range should be a total of 90 degrees?

Are there adjustments available on these?

Thanks in advance,


Don

Rohn

Did you check Holley's website for installation instructions? May need an aftermarket throttle cable bracket that is adjustable.

C4fan

There is an adjustment procedure in the FSM. It will adjust the Throttle cable, Accelerator cable and transmission TV Cable at the same time. But if done incorrectly a bad adjustment on the TV cable can mess up the auto transmission quickly. There is a thread here that shows the procedure.

http://forums.corvetteforum.com/c4-t...-problems.html

vettef6

The adjustment procedure might help a little but it wont solve your problem.
I have a Holley 58mm TB and had the same problem as you a few years ago.
Here is a link that got me started and finally solving the problem: http://forums.corvetteforum.com/c4-t...ttle-body.html

Don Schuette

Update: First, that link above to the older thread was actually started by me. I did find that and reviewed it yesterday. We went through the steps to adjust the cable from Holley at http://www.holley.com/data/Products/...99R10020-2.pdf

Same results, we don't get 90% of rotation on the throttle body (TB). What I did find by taking the cover off the ASR box and doing the steps is that when the accelerator cable is pulled by the gas pedal, at about 60% of the distance, the pulley & cable that go from the ASR box to the TB lever stops progressing past 60% but the pulley is still being rotated that is tied directly to the gas pedal. I am suspecting that the spring that is on the Holley TB is too stiff for the ASR system and past a certain point (certain resistance), the connection between the gas pedal cable pulley and the TB cable pulley starts to slip or give way. I can prove this because when I went to the 2nd or 3rd detent/hole on the side of the TB for the return spring, it would open up the TB all the way, which is what we want, but it wouldn't then return the lever to the idle set screw. So, too much tension at the end seems to put a strain on the ASR pulleys.

During those steps from Holley, they have you put a drill bit through the 3 pulleys (cruise pulley, pedal pulley, and TB pulley). That essentially holds all three together and allows you to rotate it with a torque wrench per their instructions to synch things up I guess. We did get some clicks like they mentioned, but same results.

I then put a stiff wire into those same three holes to keep everything connected, but that probably mechanically disables the ability for the ASR system. With this wire in place, we get full throttle activity AND it returns to idle. We then took the car for a ride, shutting off the ASR. The car ran a lot quicker with more acceleration.

So, why is this ASR hanging up and giving after about 60% of travel? Is it some kind of design flaw or does it need replacing? This car has 41,000 miles and is very clean and never driven in inclement weather.

Just my update, any ideas?

vettef6

Like I wrote before, adjusting cables wont do any good. Here are two different ways of solving your problem. I found these pictures a while back and saved them. What I did was, I filed the ramp until I got 90° rotation. Worked for me...
The fastest way is, to do it like in picture #1



You can file until you get this ramp

C4fan

I have the Holley 52mm also but hadn't had a chance to drive the car since installed because the transmission went out on the maiden test run for the new TB. I was not aware of these tuning issues but after picking mine up yesterday from the transmission shop I am throwing codes and the car is running like a turd. It feels like I am not getting full throttle like your friend. I guess I'll be trouble shooting mine but I get the feeling I'll be finding the same issues you are describing. I can say that Holley makes a specific TB for the 93 Corvette but the one I have is for the later F body.

http://forums.corvetteforum.com/c4-t...tle-bodys.html

Hairy W Bush

sorry for the old bump but I need to know exactly what you did here before I spend $$$ on a different brand. I don't quite understand. I have a Prodessional Products tb and I am having the SAME issue here. It only opens up to 86% according to the scanner