Throttle Sensitivity

Chubbs

Well-Known Member
Sorry for the zombie thread revival, but this seemed like the most appropriate thread for my issue.

Was the throttle sensitivity ever "solved"? My car is almost unusable in 1st and 2nd gear, during small throttle openings, like when pulling away from a stoplight. The car bucks and surges like I've never driven a stick before. The throttle is so touchy, it's just impossible to pull away cleanly unless I just mash it go. Fun for me, not always fun for the passengers.

I've tried adjusting the torque tables listed above, they don't seem to do anything. Did anyone ever figure out how to make them work, or find another solution to the super-sensitive throttle?

07 LSJ, if it matters.
 

ctuinstra

Goblin Guru
The throttle will be very sensitive compared to the donor but it can be very drivable. Ours was that way at first and now is really easy to drive. More than anything is to make sure you have a good tune. I assume you ha HP Tuners since you have adjusted the tables. Do you have a log file we could look at? Have you tuned your MAF and VE tables?
 

Gtstorey

Goblin Guru
Did you happen to put a non-oem clutch in? Some of those can be grabby and make first gear especially a little tricky. My clutch is a ceramic puck type and I have to pay attention when taking off.
 

Rauq

Goblin Guru
I've not messed with my tune specifically to address throttle jerkiness, although I did get good results in adjusting front shock settings. Turns out most of my issue was basically a phugoid oscillation in my foot- the ups and downs alternated pushing my foot into the pedal and back out of it, each time worsening both ends of the cycle. Putting my foot up against the tunnel also helped.
 

JBINTX

Goblin Guru
I've not messed with my tune specifically to address throttle jerkiness, although I did get good results in adjusting front shock settings. Turns out most of my issue was basically a phugoid oscillation in my foot- the ups and downs alternated pushing my foot into the pedal and back out of it, each time worsening both ends of the cycle. Putting my foot up against the tunnel also helped.
There may be some adjustments around the car that marginally help. The best advice I found so far is shove your foot against the tunnel to stabilize it. And, drive it hard through first and second gears........ ;)
 

ctuinstra

Goblin Guru
That’s also what I’ve been saying for a long time. These cars are super sensitive to throttle input and a bouncy leg will cause a lot of issues. I’ve seen it in a log file. I wish there was an easy way to put stiffer spring or damper on the throttle.
 

Gtstorey

Goblin Guru
Has anyone looked at how smooth the various stock tables are in the lower rpm ranges? The LNF supposedly benefits from smoothing the tables out, even going as far as to rework the column headers to increase the smoothness and to add in more precision on the lower rpm ranges.
 

Chubbs

Well-Known Member
Turns out most of my issue was basically a phugoid oscillation in my foot- the ups and downs alternated pushing my foot into the pedal and back out of it, each time worsening both ends of the cycle. Putting my foot up against the tunnel also helped.

This is exactly what causes mine....it isn't exactly the cars fault, it's really my foot that bounces around. I've tried stabilizing it with a little success, but not much.

I realize I'm trying to fix a human problem with a software fix, but surely there is a way to do it. There are certainly lots of fast cars that don't have the issue. A tesla for example, or maybe a corvette or a hellcat. All very fast cars, but have no issues with a bouncing foot.

I'm working through HP tuners. The car runs well, but I still have more tuning to do. Still plenty of "red and green" on my VE tables. It's getting better, but the surging/bouncing issue hasn't shown any improvement no matter what I do.
 

Gtstorey

Goblin Guru
A tesla for example, or maybe a corvette or a hellcat. All very fast cars, but have no issues with a bouncing foot.
Some of this depends on what HP Tuners has unlocked and gives access to. There may be a lot of tables that you can't change. I haven't researched the LSJ but the LNF has "hundreds" of additional tables.
 

Dsteinhorst

Well-Known Member
It's too bad the LSJ PCM doesn't have an option to scale the throttle input. My LAP PCM has a specific setting for this. I don't remember the exact name for it, but it allows you to change percentage 'delay' per RPM band.

As an example, if you turn ignition on with engine off and floor it, the throttle takes like 3 seconds to open with factory settings. If you're above about 2500 RPM, there's no delay. I've turned it down a bit, but found it helps my wife take off.
 

ncgoblin

Goblin Guru
I have been struggling with 1st/2nd sensitivity. Its worse since I switch to e85, stage 2 cams, and ATI balancer. Placing the foot on the tunnel cap helps but the best solution is slightly riding the clutch in first.

I even reached out to Alan from zzp who is tuning the engine and he lowered the boost in 1st gear.

I love that DF comes out with quality of life improvements like the shifter, IMO a customized pedal kit would be a hit for sure its really my only complaint with my car right now. My wife gets so frustrated lol...
 

r3drckt

Goblin Guru
I have to ride the clutch a bit as well otherwise I get the lurching in first and second. Even if I let off the gas, almost like it’s the tune and dropping to too low of an idle. I just did a log on mine and sent it back to Al as well. We’ll see what he says. I’m also stage 2 cams, ATI underdrive damper, but 93 octane fuel.
 

Ross

Goblin Guru
@ncgoblin, I'm curious how Alan is tuning the engine for lower boost in first gear.
On my LSJ, HP Tuners doesn't update the gear. I am guessing it is left over code from an automatic transmission?
Are you running the stock LSJ P12 PCM?
Maybe you could tell by comparing the speed sensor from the transmission with the known engine RPM, and calculate the gear.
 

ncgoblin

Goblin Guru
I have to ride the clutch a bit as well otherwise I get the lurching in first and second. Even if I let off the gas, almost like it’s the tune and dropping to too low of an idle. I just did a log on mine and sent it back to Al as well. We’ll see what he says. I’m also stage 2 cams, ATI underdrive damper, but 93 octane fuel.
I have a similar experience when I lift in first the RPMs dip hard seems worse at cold idle. We should compare tunes later I hope to have a complete e85 tune shortly. Curious did you also upgrade the springs/retainers? What size pulley are you running? 3.1 here.
 

r3drckt

Goblin Guru
I did a complete build of the engine. Diamond 9.5:1, molnar rods, new bearings, ATI underdrive, NBS, ported zzp head that came with 82# springs, stage 2 turbo cams, z57 entry turbo kit for the lsj, 80# injectors, BRFPS, HPX MAF, 2 step cooler NGK plugs, dual pass end plate, ZZP aluminum fly wheel, plus the ecotec required items for a rebuild.

Here's the baseline tune that Al sent me to start with.
 

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ncgoblin

Goblin Guru
I did a complete build of the engine. Diamond 9.5:1, molnar rods, new bearings, ATI underdrive, NBS, ported zzp head that came with 82# springs, stage 2 turbo cams, z57 entry turbo kit for the lsj, 80# injectors, BRFPS, HPX MAF, 2 step cooler NGK plugs, dual pass end plate, ZZP aluminum fly wheel, plus the ecotec required items for a rebuild.

Here's the baseline tune that Al sent me to start with.
I am running the OEM flywheel, OE clutch and supercharged so at least we can eliminate the flywheel from being the issue.
 

Keckster

Well-Known Member
I was about to ad to this thread asking if anyone found a cure but I think I did on my own. It all lies in the tune.... No i did not adjust any throttle setting but I did spend almost 6 hours dialing in the maf curve at low speeds minimal throttle
 
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