Black LS1 T/A

I have a VERY debilitating problem.

Since I got the 422 I have waa-aay more Torque and quite a bit more
horsepower (526 RWHP/651 RWTQ vs 486 RWHP/486 RWTQ) than my old FI setup and I've only brought the boost up to 8 PSI so far.

I am about to order taller tires to give me a better hook-up, but meanwhile I have a problem that I don't see going away without figuring out what I should modify in the PCM tables.

I'll have the shift points set similar to this:
1-2 = 6300
2-3 = 6500
3-4 = 6700

If I just stomp it, 100% throttle from the start, it tries to shift at those points, with some lag in the lower two gears allowing an overshoot.
OK... that's expected.

But, with such tremendous torque, I often have to feather the throttle off
the line... I absolutely have to, on the street. I never get past half
throttle in 1st gear on the street, even with ET Streets on.

When I feather, which sometimes requires even backing off the throttle
slightly, with the above shift points, it short-shifts like:

1-2 = 3700
2-3 = 4700
and then I will go all the way down the track in 3rd gear.
I lost a street race like this.
I spun mad in 1st, leaned out of it, it shifted to 2nd so fast you'd hardly notice, then into 3rd... ALL the way thru the quarter-mile.

Here's a sample EFILive log of what happens (this is at the track).

Feathering my %TPA on a run, not knowing how well I'd hook was:
%TPA GEAR RPM MPH
42.4 First 2041 1.2
81.2 First 2484 3.1
89.4 First 3059 5.6
88.2 First 3754 8.7
82.0 Second 4761 28.0
94.9 Second 5155 33.6
100.0 Third 5633 33.6
Third gear for the rest of the run.

RPM Shift points were at 6400/6600/6800.

I've raised the part-throttle shifts higher and higher trying to defeat this early upshift.
They are so high now, when I drive it on the street, it almost seems it's
not about to shift.
The problem only occurs as I roll into the throttle, get a good hook-up and am not quite at WOT.

Once, it even did it at WOT:
%TPA GEAR RPM MPH
28.2 First 1931 0.0
100.0 First 2043 1.9
100.0 First 2674 4.4
100.0 First 3041 8.7
100.0 Second 4171 26.1
100.0 Second 4905 32.3
100.0 Third 5402 34.8
100.0 First 5477 36.0
100.0 First 5820 37.9
100.0 First 6025 39.8
100.0 First 6106 39.8
100.0 First 6453 42.9
100.0 First 6766 45.4
100.0 Second 7105 47.2
100.0 Second 6129 53.4
100.0 Second 5018 57.2

Occasionally I get an intermittent P0121 every few days, then no more for a few days.
In a way it seems this could be related, but the events don't normally seem to coincide time-wise.
I've replaced the Throttle Position Sensor, checked the wiring and reseated the connector over and over.

Can the extreme torque difference be creating this issue? And how should I
approach it in LS1-Edit?

Thanks!

1dirtyZ

iTrader: (1)

why don't you take timing out at lower rpm's so you don't get as much power down low??
do you have relocation brackets for the rear control arms?

Black LS1 T/A

Someone just suggested that to me on a mailing list.

I now have:
Lower Control Arms
Relocation Brackets
Spohn Torque Arm
BMR SFC's

1dirtyZ

iTrader: (1)

where are your control arms mounted ( which hole?)

what pinion angle are you running???

taller tire would help i guess, so would higher gears ( numerically lower).

Black LS1 T/A

As I said in the post, I'm ordering taller tires so I get a better hookup.

Traction is not the issue I'm asking about here.

I need to fix the problem where it upshifts when I am at less than 100% WOT, but I am at a higher %TPA than where it is shifting at.

Let me re-state in a slightly diffrent way, and as short as I can. I know my first post was long, but I wanted to give those willing to read it complete information.

---

For First Gear:

RPM Shift Threshold for WOT at 6300 RPMs.
MPH Shift Threshold for WOT at 40 MPH.
Part-Throttle shift from 50% on is above 38 MPH.

Problem: Car shifts in first, at 88.2% TPA, at 3754 RPMs and 8.7 MPH.

Question: What could be wrong? Suggestions on how to fix?

Thanks, guys!

DaleMX

iTrader: (4)

I've never had an automatic so I'm clueless, but why cant you just watch the tach and use the shifter?

1dirtyZ

iTrader: (1)

why would you go less than WOT ???

could it have to do with the map reading different values than it used to (i'm not sure here , but doesn't the computer look at the map sensor to determine load?)


isn't there a table in edit for when you want the computer to consider WOT (like do you want wot to start at 75% ? 80% ?85% etc ???) can tweaking that table help??

Black LS1 T/A

The 4L60E does not shift accurately when done manually.
The fiorst time I tried that, it over-revved WAY past where I shifted.

Since I've had this problem, I did try shifting manually, and it hangs there a second or so, though it didn't over-rev wildly. I don't like it.

It should shift when I tell it to in the PCM. I'd really like to work out that problem.

Black LS1 T/A

Because I would spin all the ay thru first gear, so I need to feather 1st most of the way thru.

Hmmm... possibly. I don't know enough about that to say one way or the other. Perhaps someone else would know.

Again, I don't know.
But, as I mentioned above, I already tell it not to shift (when at part throttle) for values WAY above where it is currently shifting.

1dirtyZ

iTrader: (1)

i was just kidding about the WOT remark , sorry if it bugged you .

a good person to talk to about this is teamZR-1 .
he seems very knowledgable when it comes to tunning.

.... after thinking about your problem for a while now, i think i found the solution!!!! back-half the car and put a 4-link and 35" tires !! you'll be pulling the fronts across every intersection

Black LS1 T/A

hee hee!

1dirtyZ

iTrader: (1)

what version of edit do you have? ( just want to see if we have the same tables)

do you think the convertor has to do anything with this? or maybe the locking or unlocking of the converter as you go from wot to part throttle and back? ( do you have a lock up converter?)

just out of curiousity (sp) , are you using the stock tach??

Black LS1 T/A

Ver 1.1 - 8/10/2

I have the converter not locking up in 3rd at all.
It only locks up in Drive at MPH higher than the part-throttle shift points.

Yeah, I have the stock tach. I don't plan on shifting higher than 7000.

Thanks!

Plum Crazy Rob

iTrader: (3)

Even though I am an edit user with an automatic, I honestly don't know what's causing your early upshift, based on the information you've given so far....

However - what shift kit is in the transmission???
The "no manual control" condition sounds like what happens with the stock valvebody config...ie you shift to second and then it takes FOREVER to actually make the shift (right?)

If you have the Transgo shift kit you should now have viable manual control..I know I do! ask HPA about this (what did they do?)...(although I let the computer shift at the track) sometimes, along the lines of what you describe, I want the tranny to stay in 1st to a higher RPM without going full WOT, and that's when I use manual 1st then rev to my shift RPM and bang 2nd, etc...it works correctly WITH THE TRANSGO KIT IN...otherwise it is as you described

abarus

Did you find out how to fix the problem yet? I am experiencing the same thing. My car ran fine until I adjusted the TB bump stop screw. Now my car throws the P0121 error every couple of days, and when it does my car shifts exactly as you describe. My mods are listed below.


99 Red Z28 A4
GTP stage 1 heads, Comp Cam .224/.224 .581/.581 114LSA, 3.42 Richmond Gears, Hooker LT's, Hooker ORY, Hooker Catback, Powerslot Rotors, G2 Air Induction Lid with K&N, Fasttoys Ram Air System, BMR Strut tower brace, LCA's, Adj Panhard Rod, Spiderbar subframe connectors, MSD 8.5 ignition wires, 160 hypertech thermostat, Custom Programming, SS appearence package.

Black LS1 T/A

Some kinda way, I missed you making this post; did you determine anything?

I adjusted this screw way back in the day (as many have), but didn't have this short-shifting problem until the 422 went in. I'm leaning toward an elctrical wiring problem since I've replaced the TPS and VSS. I'm stumped.

WicketMike

iTrader: (13)

did you find anything on this?
thats how mine feels, like its upshifting way to early and i have the P0121 code also. it upshifts and then doesnt want to move.

Black LS1 T/A

ttt for ya...

GrannySShifting

iTrader: (10)

The 121 code WILL SCREW UP YOUR SHIFTING! it thinks the tps sensor is reading wrong it seems and makes its own mind up to shift

Black LS1 T/A

Even though I've replaced the TPS and VSS, I have this problem. I have gotten the P0121 at times (Throttle Position Sensor A Circuit Range/Performance). What replaceable part (other than the TPS itself) might cause this?