Basic acceleration issues

milosch01 · Post by **milosch01** » Mon Jul 17, 2006 5:20 pm

029R, MS 2.2, 3 coil wasted spark and TBI on a 68 Pontiac OHC 6, MT 2.5

I think my TPS is working. I can set closed and full throttle, and see the bar move correctly in between in the realtime display. I have tried TPS and MAP based acceleration setups and settled so far on TPS. I have newly rebuilt injectors on a TBI from a 4.3L engine, and mine is a 4.1L. Now that my wheel decoder is stable, I am still having this basic problem.

When I step on it, then engine tries to die. If while parked I raise the RPM steadily, it seems fine. For this motor, I am just not sure of what values would be needed in the acceleration wizard to help counter this. I think I need a LOT of enrichment. Maybe I just don't have enough fuel pressure. I have a Carter pump which is supposed to be a replacement for the Ford Econoline pump mentioned in the documentation. I don't have any fuel or air leaks in the fuel line as far as I can tell.

I recently changed TBI adapters to a 1" TBI spacer with a TBI-to-Qjet adapter plate. This helped remove air leaks from my previous setup of adapter and 1" Qjet spacer. The problem was there before the swap.

kg6dxn · Post by **kg6dxn** » Thu Jul 20, 2006 8:16 pm

It souns like you are too rich on your squirt. Try to reduce the squirt duration (value ms). The v/s is how fast you open the throttle, the duration is how much fuel is added during the squirt. Reduce the "value ms" in the lowest bin to 0.5 and work up from there. If it "pops" add more fuel.

snillet · Post by **snillet** » Thu Jul 20, 2006 11:51 pm

I found a way to establish the lowest point where i want the enrichment to kick in, i set the lowest millisecond-bin to a high value (too high) abd then i tried lower and lower voltages until it kicked in where i wanted it to, then i did the sema with the other millisecond bins.

Was a VERY fast way to find descent "step on gas" points to start up with.

Did a "trial´n error" before that but that was not near as quick to setup.

milosch01 · Post by **milosch01** » Fri Jul 21, 2006 5:31 am

Thanks guys, I'll try that. kg, can you tell me what values you have in your acceleration bins currently? I am probably way off from any defaults at this point.

milosch01 · Post by **milosch01** » Sat Jul 22, 2006 9:27 am

That seems to have helped a lot. I lowered the numbers in the lower v/s and ms bins then added more ms until it stopped backfiring. Not perfect but it's driveable now. Thanks!

p.s. After 3-4 months of hacking on this I took the car to get it inspected. So, another person was able to drive the car without killing it. I hope I am down to minor tweaking now.

kg6dxn · Post by **kg6dxn** » Sat Jul 22, 2006 11:36 am

Remember, the ECU will average the values in all 4 bins if your engine goes outside those perameters. Make sure all 4 bins "make sense" in order to have a smoth accel. If you have the lowest bin close try to double the value (v/s & ms) in the next bin and the next and so on. this may help get you close.

milosch01 · Post by **milosch01** » Sat Jul 22, 2006 12:06 pm

Thanks. Currently the values more than double going up, with 25 in the topmost v/s bin. Not sure where that value came from since I don't remember typing it.

edit - changed them now to the following and it is better:
4 8
2 4
1 2
.5 1

But on the meter which displays v/s I rarely see it hit the upper bins. Maybe my foot is just too slow...

TV Super Bee · Post by **TV Super Bee** » Sun Jul 23, 2006 9:36 am

The factory default is 25 v/s in the top bin. I'm not sure how they came up with that value. Most of us could only reach that value if we slammed our foot on the pedal as fast as humanly possible. No one drives like that unless you are a drag racer. With the engine OFF land the key ON, look at the "realtime display", watch the accel bar move up and down with the throttle movement. This will give you a visual of how fast you move your foot on the pedal. You can then guesstamate where the highest bin could be. remember the ECU will average the values in a linear fassion, so set it for street driving unless you are a racer.