I really need some feedback on my current mod. I am tring to delete my FMU by using a Wlabro 340 intank and Lucas 42lb injectors. Can this be done on a speed density application?

 

I'm pretty sure you will need to change the chip to one that has a different fuel table in it.

 

Yes i am planning of reprogramming the chip. But i am getting negative feedback with the tuning for drivability and them saying it can't be done because it is speed density and not MAF. Anyone out there running a speed density system without an FMU?

 

I was told the same thing as you on my '93. I guess the reason is there is no MAF table to play with.

 

Yeah I'm running SD without the FMU. Although I'm running a 749 ecm for a syty and a 2 bar map, so my computer corrects fuel/timing for boost. But to answer your question yes its possible.

 

You get horrible driveablity without a FMU and 1 bar tune.

Think about it,

The MAF gives some sorce of Fuel Delta boost, only on the really wild cars does the MAF try to read above its limit. So MAF gives some flexablity over supercharged/turbo cars


The 1 Bar MAP cars are completely completely blind as soon as they see 1 ATM, So say your spinnning 3500 rpm under light gas and making 1 atm. Hows the computer going to know if your makeing 1, 2, 3, 4, 5 pounds etc. Besides when the car is in/out power enrichement at 3500 rpm and >100kpa its going to deliever the same amount of fuel regardless of manifold pressure.

The result, from what i've seen, tried/experienced, and heard from otthers is that you get a car that runs good around town and runs like hell wide open but anything in between you get bucking surgeing etc. Ask a guy named Teeman here, I think his email is wall9@juno.com he will tell you the same thing.

He had a 93, 42 SVO's, and no FMU and the car would run good around town and at wide open but as soon as you nailed the gas the car would dump a ton of fuel and fall on its face. Also had some bad surge when you got in the car mildly aggressively.


Now, if you want to swap out to a 7749 PCM thats a differrent story. They have the ability to see boost and up to 2 bar (stock calibration). If you want to do that and need help tuning let me know, a 7749 can effectivley and safefly replace a FMU and BTM.


My .02c

 

If you use 7749, make sure you use 7730 memcal with Ty prom loaded at 04000 address. Ks will be terrible otherwise.

Be prepared for poor idle if closed loop (surging). 7730 idles smooth.

7749 has funky learn enable temps and other things a lot diff than 7730 settings.

I ran from 27 up to 37 lb inj with both ECMs at 8 and 10 lbs boost. 383 ran better on the 27s and 29lb stock SYTY injs.

Biggest problem I have is KS. Worse with 7749 than was with 7730 and no FMU.

I only found 1 person in US and 1 in Canada that said could make bin and they didn,t work. ($800 down drain).

Good luck,

Bob H

 

With a lot of time and some patience you can get the 749 to run smooth as the 730. As for the idle issues they weren't all that hard to takle once the fuel tables were properly trimmed.

 

I'm with you, a 749 can be very smooth. It just depend on the amount of time you put in it.

Anyone want to agree with me on the 1bar tune and no FMU? That was his orginal question in the first place

 

Thanks for all the input on my subject. I learned a lot. So here is my decision for the mean time. I will tune with the FMU for now and in the future look into a 749 ecm swap. Thanks, again