problems tuning with meth. help!!!
 

well i have a progressive kit and i can tune(AEM) it in 4th gear and make the afr's hold very consistent, but when i do a pull in 1st, 2nd or 3rd the afrs are all wacked. it usually goes lean for about a second(14-15afr) coming into boost. kinda seems the pump isn't keeping up the volume when the engine accelerates faster in the low gears. is there anything i can do? I'm about to use an on/off setup. is there an accel enrichment that might work? thanks everyone.

I don't think you are going to be able to solve your afr problem that easily.

If your progressive system is manifold pressure driven and made no reference to RPM and Gear position, you won't be able to get a consistant afr in all gears.

Assuming you have all the above inputs, if the water pump speed is not responding fast enough to your load change, you will always have a afr gap.

I suggest tuning your progressive kit over-rich at 4th gear and hope the lean condition disappears at 1st, 2nd, 3rd gear pull.

I have mentioned this problem tuning a progressive system before on this forum
and I suggested the a fix delivery rate (on/off) system gave less tuning problems.

This is just my opinion of your present situation and I am not bashing the concept of a progressive kits against an on/off system. Please do not take it as such.

Richard L

PS Before abandoning the system for an on/off system, you can consider the following setup:
https://www.evolutionm.net/forums/sh...51#post2691951

hi-res download:
http://www.aquamist.co.uk/forum/plus-2d.pdf

I wonder if will make any difference in tuning the afr if you set the Progressive system to a "full bore" trigger compared to a "full on" with the on/off system.

I still think installating an AEM driven PWM valve (HSV) will improve your current problem by a good margin. Just use your current system to pressurised the system.

Everyone, the gear driven fueling was one of the many reasons why I coverted to using the NOS fueling and Ign map once the alky kit was activated and making pressure. You are right when you say the car accels so fast the alky kit activation is behind its normal turn on point. If you can use the NOS maps it will solve 95% of your problems by only activating then when the system has pressure. In result you won't end up with a lean or high ign timing during your pull due to the pump not making pressure on time.

Check out the write up in the AEM section. This writeup I did for a SMC kit but I believe that an alky control kit can be used as well. If you have alky control contact VTECH8TR and he can help you get the componets you need to impliment it.
https://www.evolutionm.net/forums/sh...d.php?t=151383

GTVEVO,

It is a good write-up.

Did you have problem ironing out the static and transient fuel mapping (trimming fuel) to accomondate different gears?

i noticed the smc uses a checkvalve body right before the nozzle. I might give that a try if it doesn't effect flow. My lines are also about 2.5 feet long which doesn't help and i believe the meth gets syphoned out the nozzle while cruising around. then when i need it the line has to pressurize fully which might be causing part of the delay.

No not at all. Since the NOS map works the same way the main fuel talbes do just except in a percent subracted it transends well. Upon switching you never even feel it, you only can only tell its on by seeing the IC spray light come on in your dash.

With the different gears the mapping came out the be the same as a pump gas map, a very small liveable varience (.1+/-). But for both pump and with alky I run O2 feedback constantly so there is no difference at all.

Hope this helps. {thumbup}

FYI I run a trunk tank also and it works just as well with either because nothing activates until pressure is built by the pump into the lines. Remember once the system is primed the lines don't expand and the fluid don't compress so turn on latency should be little to nothing. Also if the check valve is working correctly you shouldn't loose prime in the lines at all before or after the valve.

I was wondering if the close loop O2 method is used to keep the afr in control, how would you recommend someone without a widenad O2 sensor?

I don't think many production car are equipped with wideband.

Richard

setting the alky start psi to max is an interesting idea. can use a progressive almost like a on off