Ok iam just wondering about it, i know at WOT 11.0-11.9 is ok for forced induction right? But what should it be at just cruising around i know it jumps around but where should it be jumping around at? Its going from 14's to 15's just cruising sometimes hit a 13 here an there. an last night i did a quick WOT an the a/f would stay around 11.2-.4 but i dont remember if its when it went to shift or what but i did see a 12.3 it spiked to but istantly came back to the 11's is this normal. I just wanna make sure cause i cant afford to buy a shortblock no time soon. Iam saving for a SHR tranny cause mine is starting to slip every time at the 3-4 shift an sometimes the 2-3 shift.


Brandon

Good question bro. Subscribed. :popblood:

Druing "closed loop" the PCM reads the o2 sensors and modifies the injector pulse width to keep the AF as close to 14.6 as possible, so you will see the gauge fluctuating between the 13's and 15's.

As for "open loop" aka Wide open throttle, that is the affected by the DA and the fuel tables. You need to datalog a 3rd gear pull from a very low speed up until you change into fourth. You must manually shift it into 3rd in order to keep it from downshifting. This is the best way to fine tune the AF as far as I'm concerned. This way you can identify exactly when you AF hit 12's and apply fuel to that RPM range.

you'd want to keep it out of the 12s. Sometimes i can see where you might be getting a little fuel pulled between shifts, but you would want to eliminate random spikes, say, if they're occuring in the middle of a gear with no shift on either side of the occurence.

low 11s makes for good safe running and daily driving and builds in a little room for some bad gas or slosh on low fuel.

WOT, 11.5 I read should be the target for FI, NA low-mid 12's, I'm set 12.2-12.4 WOT with my Johan tune, cruising bounces anywhere in the 14's to high 15's, that isn't an issue if there's no knock or detonation. That's what I'm going by anyway.

Agreed, everything I have read and been told is that 11.5 is where you want to be for FI. The problem comes in when you are partial throttle, still in closed loop, and seeing boost. The ~14.6AFR while in closed loop and seeing boost is not great for the engine. I find it difficult sometimes to avoid boost at partial throttle especially when daily driving in hilly areas. I am like a hawk now watching my boost guage to avoid this.

Agreed, everything I have read and been told is that 11.5 is where you want to be for FI. The problem comes in when you are partial throttle, still in closed loop, and seeing boost. The ~14.6AFR while in closed loop and seeing boost is not great for the engine. I find it difficult sometimes to avoid boost at partial throttle especially when daily driving in hilly areas. I am like a hawk now watching my boost guage to avoid this.

A meth injection kit will help that out dude!!

My part throttle boost A/F is in the low 12's to high 11's. You guys do realize the PTFC actually works, don't you? :)

I guess my point earlier in the thread was, don't trust just watching your AF gauge as you blast through the gears. You really have to remain in the same gear through the entire RPM range if you want to be certain of the A/F.

thanks everybody..an thanks Ant idk why i didnt ask you anyways i forget your good with the tuning, just dont like bothering you 24/7 with my crazy ?'s lol..an i think iam going to go with some meth injection to help cause iam always seeing boost cause iam still learning it an my boost gauge spikes to 0-1psi partial throttle.



Brandon

My part throttle boost A/F is in the low 12's to high 11's. You guys do realize the PTFC actually works, don't you? :)
.

Words from the wise. I wouldn't run boost without a PTFC. Especially you guys in the mountains that hit boost under partial throttle all the time.

I'm most likely going to be ordering a PTFC next pay day. It definitely is good insurance but it seems like a pain to install with having to chop the harness and what not. How long did it take you guys to install? Are the directions that come with it sufficient? I couldn't seem to find a true install write up on our Jeeps.

What is PTFC??

Part Throttle Fuel Controller. It is a device that senses when you are partial throttle but in boost and can add more fuel so that you are not running lean. For us that do not have a PTFC and have a Vortech we need to ensure that we are not seeing boost when not WOT because the fuel tables are different and can lead to a big BOOM. Boost + lean conditions = heat, detonation, other bad stuff

sounds like that device some guys use with E85 to get around from using larger injectors

Part Throttle Fuel Controller. It is a device that senses when you are partial throttle but in boost and can add more fuel so that you are not running lean. For us that do not have a PTFC and have a Vortech we need to ensure that we are not seeing boost when not WOT because the fuel tables are different and can lead to a big BOOM. Boost + lean conditions = heat, detonation, other bad stuff

Would I need one of these with my stage 2 water/meth system?

As soon as I reach 2 lbs of boost it starts spraying. Even at part throttle, I do see my wideband dropping into the 11's during this time.

More research...interesting comment from Johan.

http://www.cherokeesrt8.com/forums/showthread.php?t=38316&highlight=controller&page=3

OK thanks. Seeing that my motor will be totally built for boost and will be much stronger than stock, I dont think I will need to worry about this piece.

Thanks.

BUT if I was still stock.... I would get this.