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I never actually checked this with my original LS1, but my LS3 throttle won't open all the way with the accelerator floored. Yes, the throttle cable bracket is adjusted so that it just closes at 0% throttle. At first, I thought there was too much slack in the cable (the part that joins the pedal to the cruise) so I cut the bead off the end at the pedal and shortened it to take up the slack (I assumed this was due to stretching?). This helped some, but not completely.
The throttle is a 92mm unit I bought on eBay. Yeah, I know, eBay, but it was still almost $100, so it isn't super cheap either. Just not a $500 name brand. I have a couple of ideas of how to fix this:
1) I bend the throttle pedal bar to lift the pedal higher at idle for more travel.
2) I grind on the throttle body cable mount to effectively shrink the radius and pick up the slack with the adjustable cable bracket.
I don't really like either of these solutions, so I am looking for ideas. Anyone else with a similar setup ever check to see if your throttle opens all the way?
Is the throttle supposed to be partially-open at the start? I just put my phone on top of the air filter with some weights to stand it up and filmed it while I hit the gas with the car off.
It occurred to me that there are two holes to mount the end of the throttle cable to the side of the throttle body. I thought they were for two different lengths of cable, but now I am thinking that they are at two different distances from the axis for different tip-in ratios. Mine looks like this (sorry that's the best angle I could find online) and I used the mount which pulls the cable out further (on the right in this pic) but is also further from the axis.
I'm not certain if the mounting hole alone can define throttle ratio, or if the radius of the pulley itself must also change. I'll check this this weekend.
The good news is: I fixed the problem. The bad news is: not before I started grinding on the pulley.
If anyone comes across this thread some point down the line, the issue was this: the dual spring setup in the throttle body was overpowering a spring that is built into the Bosch cruise unit by the battery. That spring is likely part of the traction control system, and allows the throttle pedal-connected pulley to turn independently of the throttle body-connected pulley if enough force is applied. I stumbled on the solution accidentally when I removed one of the two throttle body springs for test fitting. Now that the spring is out, I get WOT before the throttle pedal hits the floor (which is good, because floor mats can get in the way, and full travel is a bit of a stretch for me).
The top white, plastic pulley is for cruise control (ignore it). The middle pulley is the throttle pedal cable, and the bottom one is the throttle body cable. The first time I press the gas, it works as it should, but that is only asking for part throttle. When I go full throttle on the second pass, watch how the pulleys no longer turn in unison. Removing the second spring on the throttle body fixes this. It is supposed to be there for "increased control," but it clearly won't work with my car.
Remove the throttle cable first. There is a little Allen stop screw which clamps the throttle body cam to the shaft. Find the right size Allen wrench and loosen it just enough (don't take it out) to slide the cam off the shaft towards the passenger side. It will unwind the spring and twist as you pull it off. Pay attention to how it twists so you can put it back together the same way again. Once the cam is off, the springs come out together. Twist one to unwind them from each other. Then reassemble.
Remove the throttle cable first. There is a little Allen stop screw which clamps the throttle body cam to the shaft. Find the right size Allen wrench and loosen it just enough (don't take it out) to slide the cam off the shaft towards the passenger side. It will unwind the spring and twist as you pull it off. Pay attention to how it twists so you can put it back together the same way again. Once the cam is off, the springs come out together. Twist one to unwind them from each other. Then reassemble.
Awsome, I fixed it, and I am seeing 100% throttle pedal fully depressed. What a life saver.
Man I'm glad I ran across this. I thought I was losing my mind not being able to get the adjustments right. I took a chance on the cheap eBay throttle body and it's showing.
I pulled one of the tb springs which allows me 100% throttle but it doesn't have enough resistance to get me back 0% throttle. I'm gonna have to come up with another solution but thanks for posting this. It helped get me on the right track.
My throttle pedal is light, but it returns to zero, no problem. I would try to look for some kind of binding in your system, as that should not happen. If the throttle body outside the car does this, the throttle butterfly shaft is binding. If it jams inside the car, trace the throttle linkage for kinks, and hopefully you find the obstruction.
My throttle pedal is light, but it returns to zero, no problem. I would try to look for some kind of binding in your system, as that should not happen. If the throttle body outside the car does this, the throttle butterfly shaft is binding. If it jams inside the car, trace the throttle linkage for kinks, and hopefully you find the obstruction.
You were right. I had adjusted the blade when I had both springs in but it needed to be re-adjusted once I went down to one spring.
Now I've created a new issue. I think during all of the tinkering around that I must have stretched the spring in the traction control unit. When I pull the tb cable I can only get to about 4.4v. I can push the blade just a touch more and it will finally hit the bump stop. I think the tc spring may have lost some strength due to me pulling on it too hard. It also has an issue when using cruise control. Shortly after setting the cruise the "tcs off" light comes on and it sets the check engine light for the tps sensor. As long as I don't use cruise both issues never occur.
So I'm thinking replace the spring in the tcs unit (if possible) or just try another tcs unit from a different car. Thoughts?
A little update on mine. One of the plastic bushing in tcs module was cocked and causing the unit to see more resistance than it should. I put everything back together and it works like it should. I highly doubt you could stretch that spring. It's pretty heavy duty. If anyone takes one apart in the future, be careful.
Randomly I get the p0121 code and it disables my tcs. I found a couple other threads showing the 5v signal for the TPS is shared with the AC low pressure cut off switch. Apparently this is a "known issue" when running a performance camshaft and should be disabled in the tune. Hopefully I can get it retuned if a few weeks.
Glad to hear you sorted it out on your own and thanks for the additional info. That was a pretty complex issue to trace down. In my case, I also swapped from an LS1 to an LS3, a 1998 ECU to 2001, rewired the harness, and swapped from an auto to a manual. One of those other things is probably the reason my cruise doesn't work at all now. I have to have my engine tuner sort that out for me, as I intend to do road trips in the car eventually, and the cruise definitely helps prevent accidental speeding tickets
11-06-2017, 08:08 PM
Throttle Cable Woes 
