Need more "HOW TO"s

[tech]

I just spent 6 hours tuning a heads/cam f-body with 42# injectors. The car idles perfectly and LTFTs around -5. BUT, under throttle the histogram is full of -12s everywhere. MAF hooked up or not. :-/

I made changes to VE by adding the histogram values to VE. No change. None at ALL.
I tried adding and subtracting varioius percentages from VE. No change.
I tried scaling the IFR up a bit (48.83) without change.
I tried scaling the injector offsets by 10% either way. No change at ALL.
I tried scaling the MAF table up and down with no luck.

The car has a loose torque converter in it which means that the slipping stall keeps the car in the same area of the histogram the whole time.

It seems that with the MAF disconnected, it not running off the VE table. Is it running off Openloop F/A? :huh2: I got the light for the MAF.

[tech]

Thanks for all the help.... :huh2:

[tech]

Hhhhhhhhhheeeeeeeeeelllllllllllllllllllllllllllllo ooooooooooooooo?

[tech]

*crickets*

[Turo]

are you resetting the fuel trims everytime you make a change?

[MNR-0]

You can check for open loop F/A by examining the closed loop enable vs ECT table. It will stay in open loop while under these thresholds.

Reset the fuel trims bfeore relogging. Also, when tuning, disable LTFT learning. Switch off the STFTs instead. Finally, disable and DFCO and lean cruise (if applicable) to remove external influences.

Get your VE table dialled in off the STFTs. With a high stall under its stall RPM you wont get better than -4 to -8 LTFTs anyway. Thats OK.

The other thing you can check is the PE enable vs TPS. Perhaps you are entering PE too early with all the peddle stomping that goes with a high stall and you need to raise that at part throttle.

Good luck

[tech]

Thanks for the replies.

I always reset the fuel trims after each fueling change.

I understand your process but I don't understand how it will help me. Changes to VE didn't change my LTFTs at ALL in the typical driving sections of the LTFT histogram. None. Zilch. You are still suggesting tuning via VE? The Primary table or Secondary table?

Normally, I adjust VE and see changes. Now I can't.

[EpOcH]

If you have a secondary VE table, that is the one you fall back to with your MAF sensor unplugged. So tune that one. If your intending on putting a MAF back on at the end of this, then make sure the changes are put into the primary VE table also as thats what you'll be using with your MAF plugged in and working (NON SD mode)

[tech]

So I should just copy the Primary table over the Secondary table and tune it w/o the MAF hooked up. Then, copy the Secondary back over the Primary and hook the MAF back up. What should I do with the Secondary then? Should I add X to the Secondary so it's a little rich in case of MAF (or other sensor) failure?

[redhardsupra]

for earlier cars (non-01,02) you will have a secondary table, make changes to that. watch out, because it's half resolution of the primary, so it's best to do the math in excel first.

also, do a MAF calibration, otherwise your VE will be a corrective lie.

[tech]

for earlier cars (non-01,02) you will have a secondary table, make changes to that. watch out, because it's half resolution of the primary, so it's best to do the math in excel first.

also, do a MAF calibration, otherwise your VE will be a corrective lie.

Why is the risk any different if I make changes by %?

I adjusted the Secondary VE table and saw results... Now the bigger question...

Secondary VE is, as you said, half resolution. I can't just copy it over the Primary table and hook the MAF back up to tune the MAF. Is there a way to 'zero out' the MAF table so I'm using the Primary VE table?

[redhardsupra]

just read this, it's very nice, clear, and with lots of pics

http://www.zianet.com/ouija/images/hpt/tuning.html

once you're done with VE, come back and I'll show you how to get your MAF inline.

[tech]

That's what I did. The LTFTs are still at -12.5 under very light (<10%) or no throttle.

[redhardsupra]

ok, then send me your latest bin and some logs to marcinpohl at gmail dot com