I've been having a bad defueling feeling in my truck when I hit about 3000rpm when running the quarter-mile. I thought truck was defueling because of tranny slip, so I ran some tests today. I tried all combo of stuff in my sig, and when propane is off, the truck pulls hard through all gears, but when it's on, the truck seems to fall on it's face around shift points. I love the drivability of propane for everyday, but would sure like to solve this problem when racing the truck.

Thank-you,
Rob

rob-

i really know nothing about propane. your sig has some very nice adds. just wondering.... have you tried pure propane (no predator) to get through the quarter? i'm just thinking that maybe it might be the culprit?

The predator alone, or paired with N20 runs very well. No problems at all. I haven't run propane alone w/o predator. I was so jacked that the problem was gone when turning off pane, that I stopped the test session.

Rob

What kind of pane system do you have? The ones I know of has noting to do with the electronics so defueling shouldn't be a problem unless you fall off of boost. Most all are activated by boost pressure. You can lower the on time at the boost control to get it to come on earlier and stay on at lower boost levels. But at 3000rpm, you should still be pulling good boost pressure.

The system is a Powershot 2000 bought new. The truck did it with factory settings, but got a little better when I increased flow rate and lowered boost setting, but still bad. Boost line is in SD manifold and pane line goes in through air box. Everything seems tight and hooked up right.

Rob

Sounds like the trans is causing the engine to defuel because of too much power during the shift. Just a hunch. Perhaps a CoPilot is in your future.

not sure if there is another place to take boost pressure off of, but on the lb7 i take it off of the wastegate line, the only difference from yours to mine

McRat, that's what I first thought. When running propane and predator without N20, truck would die. When running predator and N20, truck runs and shifts great. I feel that the power is quite a bit more with pred/N20 than with pred/pane. I feel, if it would defuel because of power, it would be doing it with pred/N20 combo also. I'm still very wet behind the ears on this stuff, and thank you and everyone trying to help with this problem.

"Honey, I need another grand for this super special trans thingy. Yep, it's called a co-pilot. I know, I know, you're a great co-pilot, but...please!

Rob

The system is a Powershot 2000 bought new. The truck did it with factory settings, but got a little better when I increased flow rate and lowered boost setting, but still bad. Boost line is in SD manifold and pane line goes in through air box. Everything seems tight and hooked up right.

Robperhaps running it trough the air boxx,is giving you the fit as boost increases,in the taller gears more lp flows could be screwing with the air sensor there,cant remember the exact name,or did they move those on the llys....mass air flow sensor maybe....

Good thought king d, I'll check and see if the supply line is past that sensor. I don't know what sensor that is, but there is a little gizmo hanging in the air stream.

Thanks,
Rob

"Honey, I need another grand for this super special trans thingy. Yep, it's called a co-pilot. I know, I know, you're a great co-pilot, but...please!

Rob

:lol:

Rob I run into the same issues. Make sure to keep water temp above 185. If you are doing 4wd launches try skipping the burnout all together. I am thinking the burnouts are screwing with the computer. Try giving it less than full throttle on launch. I run a copilot and it still spools right past the shift points at times. I have had more success with making sure the above mentioned items are followed also. Are you using T/H? Drive around without it and be light on the throttle for a couple of days before you go to the track. It is a real PITA!

this could be my problem as well, my truck the other night at the track was also running over the shift points witch it never does normally, and yes i was doing 2wd burnouts, then going to 4wd launches, from the vides, it was a 2-3 and 3-4 shift problems:eek:



Rob I run into the same issues. Make sure to keep water temp above 185. If you are doing 4wd launches try skipping the burnout all together. I am thinking the burnouts are screwing with the computer. Try giving it less than full throttle on launch. I run a copilot and it still spools right past the shift points at times. I have had more success with making sure the above mentioned items are followed also. Are you using T/H? Drive around without it and be light on the throttle for a couple of days before you go to the track. It is a real PITA!

I don't do burnouts before staging. But my water temp is rarely above 160. It's been chilly here, and I let my truck idle for a long time. Still can't get the temps up. My truck does it on 1/2 and 2/3 shifts. I'm thinking it's not so much of a pane problem anymore, I think it's the trans going "what the @#$% just happened to me"

Rob

I don't do burnouts before staging. But my water temp is rarely above 160. It's been chilly here, and I let my truck idle for a long time. Still can't get the temps up. My truck does it on 1/2 and 2/3 shifts. I'm thinking it's not so much of a pane problem anymore, I think it's the trans going "what the @#$% just happened to me" Rob

I know the ECM automatically holds shifts higher when the water temps are not up. It was designed to aid in warmups. On cold nights I have to keep the truck running and idle it up to keep the engine temp up so it will shift when I run.