car doesn't run with 24Lb inj and stock FMU

[1fstlx]

Thanks a lot for all the info!!!!! I will order the regulator tomarrow . I did put on the 2.75" blower pulley today . I will tell you, it sure does boost fast. Now I have a big traction problem. I also put on a fluid dampner.I can't wait to see my new times.What do you guys think I might run?I haven't put in the T-5 yet.I think I will run a very low 13 with the tires I have now.(245-50-16's khomo ecstas.)

[1fstlx]

I just want to thank every one for there help. I put on an adjustable fuel press reg. set it to 50 psi base and walla, it's fixed! I ran out at the track wednesday and ran a 13.4 @ 109.2 with hitting the rev limiter 2 times. my 60' was 2.45.this was all done with the stock aod .(no fmu) my BTM was turned off.with a little practice I'll be 12's thats if the tranny lasts.

[Goliath5.0]

Awesome! This is the kind of result we all love to hear! Glad that adjustable FP regulator worked out for ya!

Keep up posted as to when you hit the 12's!

-Chris

[fanglemeister]

Note from an eec-tuner user:

I've noticed in datalogging that adjusting fuel pressure too far from stockish 40 psi will cause the EEC to adjust the injector pulsewidth back to "normal". This "keep alive memory" adjustment is broken down into two parts, short term fuel trim and long term fuel trim, the long term is used at all times including wide open throttle.

What this means to you: if you adjust your base fuel pressure way high, say 54psi, the EEC will notice all the extra fuel during cruise via the O2 sensors and tell the injectors to cut injector pulsewidth a bunch to get the motor back to stoich. Over time the adjustment goes over into long term fuel trim, at which point it will think (incorrectly) that you need the same 25% of your pulsewidth cut back at all times, including WOT! Moral: if you run this way, you must reset the keep alive memory in the EEC often, or it will start to lean out your WOT settings as the short term trim moves into the long term trim strategy. This is fine for a track car but a PITA for a daily driver.

Getting back to 1fstlx's setup with the 24# injectors: based on the 109 mph trap speed, at estimated 3425 race weight you are making@ 350 hp.

At this power level you would need something that flows a little more than 24#ers at 40psi. To get where you need to be, you need to run those 24s at 54 psi at full boost. So what you must do at this point is subtract your total boost from 54 psi to come up with a number for base fuel pressure, which in your case (being conservative) would be 54-10=44 psi.

If you set your base pressure to 44psi, you will get a 1:1 pressure increase with boost. Right now with 54 base you are getting 64 pounds under full boost, but the EEC is probably cutting back a bunch of the fuel based on the O2 sensors reading megarich during cruise.

Final nugget: After playing with the eec-tuner and datalogging for the last year, I've determined that the best path is to try to use true numbers when possible, and not try to fool the eec, because it always ends up trying to figure things out on its own and goes places you don't want it to.
--
CJ

[Goliath5.0]

EXCELLENT POST fanglemeister! Very informative!

[TheHawk05]

Nice post Fanglemeister. I'm not overly familiar with tuning the EEC yet with my Crane Interceptor, but one of the things I've read and know about it's use is that you can't adjust anything with it below 2000 rpm. From what I understand the Ford engineers have set this computer up so that below that operating range the computer is constantly always trying to make the motor run with emissions in mind and that even if you change it, the computer will always fight to do what the engineers intended it to do. The Interceptor doesn't allow you to change parameters below that operating range by default which would explain why it got CARB approval. I understand the PMS will allow you to fool around down there, but it's not CARB approved which tends to be an important factor for us guys that have to go for emissions testing.

[fanglemeister]

One other thing I forgot to mention... 1fstlx, if you do further lower the fuel pressure in search of better a/f ratio, best to put the BTM back on at 1 and sneak up on the total timing carefully, esp. since you can only get 91 octane. Keep an eye on your sparkplug reads too.

[1fstlx]

Thanks for the info ! My last run was on 109 oct to be safe.My timing was 13 and no btm.yet no ping.If I can get traction with my nitto drags I know I will see 12's.I think I'll take off the front sway bar. My other buddy has the same set up,took off the bar and gained 4 tenths.I saw this in amazement.I'll keep ya'll posted on my times.Thanks again!!!!!!!!!!!!!!!!

[fanglemeister]

Originally posted by TheHawk05
but one of the things I've read and know about it's use is that you can't adjust anything with it below 2000 rpm. <snip> The Interceptor doesn't allow you to change parameters below that operating range by default which would explain why it got CARB approval. I understand the PMS will allow you to fool around down there, but it's not CARB approved which tends to be an important factor for us guys that have to go for emissions testing.

I'm not too familiar with the old Interceptor, just that it was the precursor to the PMS system. You could be correct that it won't work under 2k rpm to get CARB approval. What I do know, I believe you can only make changes in preset 500 rpm increments? So it could also be a matter of an internal memory size limitation on this product (compared to PMS).

There are no such limitations with the eec-tuner, you can tune right down to zero rpms, and make alterations within a few rpm of the previous mod, which is great for driveability fixes on cammed cars... but the eec-tuner is a low budget item for hobbyists & does not have the financial backing to even attempt for CARB approval, so there you have it.

As for needing CARB approval, I doubt any emissions testing deal would have any clue that there was a tuner on board, as you can dump your tuner mod file for the oem programming with a few clicks on the laptop. FWIW many people are actually using the eec-tuner to help pass emissions-- It really helps with cleaning up big sloppy injectors that have trouble with idle pulsewidths under 2ms. ;)