ETC Closes under WOT, suggestions??

[00 Z]

Working on an '03 5.3 conversion into an '86 GMC, 3500 Stall, TH 350 Trans, stock 5.3.

Truck runs and drives great, the computer was tuned by Texas Speed before we got the HP tuners software and really began to get the truck race ready.

The other day I noticed that if you Jack the throttle in neutral it revvs to 3k, then stops, immediately picks back up and goes to the 6200 set fuel cutoff. It's like you revv it, let off the pedal at 3K then floor it again. A quick log of the Accel Pedal Position shows a constant 51% when you floor it. Watching the ETC position and Throttle position shows 100% till 3K, then 28%, then 100% again, even though the pedal is all the way down the whole time.

So I decided to go on a test drive and sure enough it does it from a dead stop full throttle take off, a good hesitation at 3k then WOT again.

The truck has the 4L60 trans wiring bundled up under the hood and tucked away, with all pertinent codes deleted for the trans. I need to run the codes on it again to make sure nothing is goin on there. From what I can tell, they disabled the PRNDL status flag, it says NONE. A log of the trans gear PID shows Manual 2 all the time, not sure if this is important.

I'm new to the HP tuners thing, but so far it seems great. Does anyone have any idea on what table I should start into for this issue?? Does it matter if the PCM can't see a trans or gear?

Any help is appreciated greatly!

[00 Z]

bump

[Pro Street]

Post a log and your tune and I bet someone will help!

[00 Z]

10-4, i'll get a log file posted in the next few days. I would assume Pedal Position, Throttle Position, Desired Torque, and RPM would be the ones needed?

[00 Z]

Ok, here's the log. It didn't capture the throttle hiccup on the long 0 to 70 run, but at the end of the log, I blipped the throttle 3 or so times, on the 1st try you can see the Pedal Position is at 50% (to the floor) but the TPS% says 8 or so. it will do this every time you floor it when taking off or revving it. However it will not do it when you are in a higher gear or a 'loaded' situation, except for 1st gear when you romp it.

the frame is 521, timestamp 1.43.390

We also have a stock '03 GMC, for some reason when you floor his the throttle pedal position says 28% at WOT. Our '86 Conversion says 50% and the throttle is obviously a LOT touchier. not sure if this has something to do with it???

[00 Z]

Almost forgot, here's the current config file.

[00 Z]

bump

[00 Z]

I've fiddled without about every table as far as torque management goes, as well as done a search here. Maybe this is a problem that nobody has ran into? I'm planning on calling the people who did the tune in the 1st place, maybe they have some insight?

[00 Z]

Well, nobody has ANY idea, not even the original programmers. This is a real problem, when launching on slicks it bogs bad at 3K, then picks right back up and goes to redline. It's only on a hard takeoff when the RPM's rise fast. I'm almost certain it might have something to do with the stall converter. But that doesn't explain why it will do it just revvin in park?

I'm not looking for a handout, just need a little info as to where to go with this, i'm lost. maybe I came off wrong, and if so i'm sorry. I'm merely looking for someone to point me in the general direction.

[12secSS]

Try maximizing your ETC Limits tables. I have had similar issues with truck OS that when these tables were maxed, the throttle would go 100% when commanded. See attached image:

[00 Z]

Thanks 12 sec, i'll get out to the shop and give that a try tomorrow or so. i'll post back the findings, again, thank you!

[00 Z]

looking at my 1st post, i also forgot to mention that this truck has no VSS input. Also, it has no range selector input, it appears to be disabled in the tune, as the PRNDL is set to none. All the VSS codes are unchecked in the DTC chart. Not sure if this matters? I'll take a look at the table tomorrow.

[12secSS]

You should get a VSS input, as it will be needed for idle references. As for the PRNDL Enabled, it is correctly set. The truck transmissions have the gear selector indicator on the transmission shift lever, unlike autos (where it is on the shifter). So disabling it for your TH350 is correct, as the TH350 will not have a place to mount the PRNDL "switch".

[00 Z]

Thanks 12sec. I'll get the table checked hopefully tonight for ya. As for the VSS, it was in the works soon as it does cause some idle concerns, mainly when decelerating as it drops to idle when you let of the gas, kinda weird going 70 and it drops to idle.

[00 Z]

Ok, got the table changed, although the problem still persists. Here's a vid of what it's doing and the current tune.

Vid: http://www.youtube.com/watch?v=cPKaCTgOtuI

The rev limiter is at 6400, all the other pauses including the 2 it did when I 1st hit it are what we are fighting.

[goatkart]

its a random thought, and i may be way off base.... but whats the chance a CASE learn was never done... with an engine/pcm swap it could be just enough out of wack to get things screwy.... i've heard of engines RPM limited to 3000 rpm before because a case learn wasnt done.... never anything like this.... but hey... im just shooting in the dark here....

just my .02 (even though its probablly only worth .01)

[00 Z]

No, a CASE learn was never performed. Although this PCM/engine combo was all from the same parted out truck. It apparrently fell off the transport truck when new, the motor had only 5 miles on it.

There isn't a DTC set for CASE learn, but hey, it's worth a shot.

I'll try and get out and give it a try.

[goatkart]

yeah im shooting in the dark... just trying to think of ANYTHING that might cause the issue...

but hey... you never know... it could totaly work too LOL..






probally not..

[00 Z]

Gave her a try, but didn't seem to help any. Also, i noticed that if it idles long enough, it dips really bad, the throttle position drops to 0%, then back to 4 and it idles normally.

weird.

[goatkart]

lol did it fall off the transport truck and onto the TPS???