5.0, CFI. Any proven mods for MPG's?

[crazyman]

'84 Grand Marquis, 29k miles. I hacked the EGR spacer between the barrels open to add plenum volume and cross talk and bumped the timing to 14 BTDC from 10, but you seasoned guys might know a trick or two to get these to please instead of wheeze.

Factory 5.0 shorties would require Mustang H/X/stock pipe with a custom intermediate pipe..

LOPO is the game, MPG is the gain...

[colebalster]

Forget about the motor. It will cost you as much to build a new motor as it would to make small improvements in MPG with the 5.0 by changing out heads, cam, intake, etc.

I would pull as much weight out of the car as you can and concentrate on "aero" for the best improvements. But it's all relative when trying to make an '84 Grand Marquis "slippery" in the wind tunnel. I couldn't help but think it might make the car look a little better though. I nice low air dam on the front, some sleek side mirrors, shave the antenna, maybe a diffuser in the rear, etc.


Cole

[Dan Timberlake]

whatt's your rear axle ratio?
Do you have a lock up torque converter and does it work?
Some of those low rolling resistance tires are actually worth a half mpg (your car) or 3 (prius etc).

The disappointing part about aero improvements is although the HP required to cruise is reduced, without a gear ratio change generally the engine operates at an island of worse BSFC, negating some of the gain of reduce HP.
Less HP is a straight vertical move downward on a curve like this,
http://forums.rennlist.com/rennforums/a ... c.jpg.jpeg

More grams of fuel per HP per hour.

conversely a taller gear ratio moves to a lower rpm, AND slightly increased throttle opening, which just about has to be move diagonally upward and to the left, toward ~ 10 o'clock.

[grandsport51]

What is current fuel mileage is EEC 4 is it advancing etc with that system there is no live data stream,therefore how are you going to adjust it timing is not adjustable even if you move the dist.
I'm pretty sure you should scan with snapon brick and repair codes first.
Remember this was always a pain in the ass system. Check for Vibration when she goes into lockup and vibration in lockup is missfire for whatever reason and should be corrected.
Also if the vehicle has dual exhausts it usually has higher numerically axle ratio
when we had them with singles in 80 81 they would murn up in towncars at 95k
hence the duals larger radiator etc you can get decent mileage but they are obsolete and there was a learning
curve.

Dave B
LM former Gold Medallion service Manager

[grandsport51]

IN THE OLD DAYS IN NJ WE USED TO CONVERT TO 2100 MOTORCRAFT AND HOLLEY BLUE REGULATOR
AND DURASPARK 2 SEE LINK WORKED PRETTY GOOD
http://home.earthlink.net/~rcfaulconer/ ... rk/eec.htm
LOL

DAVE B.

[crazyman]

It runs great. No misses. It's a 29k mile car. I replaced the plugs just because they were 1984. With the distributor advanced, even if it didn't affect the timing, it idles slightly higher and revs out much quicker. Stock gear, IDK ratio, single exhaust. I scored this beaut for my grandma to replace her 97 4.6 cougar that only got 12mpg.

[crazyman]

I read that in the late 85 production run, the police cars got a plate between the EGR spacer and the TBI to improve A/F distribution. The rear cylinders run rich and the fronts lean, this factory plate that only had a 6 month run fixes that. Did some digging, found it. The throttle blades tip down at the rear directing all the fuel to the rear cylinders, but the plate breaks up the flow. This plate might even help roundie cars with Holleys.. Maybe even some Chevy TBI guys would benefit from this theory that Ford put into production...

[donsboy]

how did grandma only get 12mpg in a 974.6 cougar? was the od turned off or was she driving in 2nd gear. i had one that got 30mpg on the highway and even at 200K miles was still good for low 20's. and you are replacing this car with an 85 cfi grand marquis?

[crazyman]

IDK. The cougar ran great, it just has pinged and gotten 12mpg since she bought it with 50k miles.

[Tuner]

Because the computer expects to see the narrow band O2 sensor voltage oscillation of approximately .1V (lean) to .9 Volt (rich), you can use an Innovate MTX-L WBO2 AFR Gauge to replace the NB sensor and program one of the analog voltage out channels to a leaner AFR, such as 17.5/1 AFR = .1V and 17/1 AFR = .9V and the computer will be none the wiser, it will continue to control the part-throttle AFR but the engine will run at near 17/1 AFR.

You can program the MTX-L (actually, you can do this with any Innovate WBO2 device) to any AFR you choose between 7/1 and 22/1, just like changing jets in a carb but with your laptop.

You feed the ECU the same voltage signal it was seeing from the NB sensor, except it is “adjusted” to a leaner AFR than 14.7/1. When the throttle is opened beyond the threshold programmed in the ECU it goes to open loop and whatever program Ford put in it for WOT, that is not affected by this trick.

As it is now, like every NB O2 system, it averages 14.7/1 by firing every other time rich and lean, perhaps as rich as 12.5 or 13 and as lean as 17 or 17.5, to average the stoichiometric ratio of 14.7 (more or less). In a cruise condition, every time it fires on the rich side it is wasting fuel. When you use the WBO2 to fib to the ECU it stays on the lean economy side of stoichiometric AFR at light load like an old time carburetor.

http://www.innovatemotorsports.com/products/MTXL.php

[crazyman]

I ended up making the plate. I didn't install it until today with some other modifications. I installed new smaller injectors from a 3.8 CFI and a Kirban adjustable regulator. I jacked the pressure from 38 to 50 as a starting point, but the mod works. Before I'd have to be a 1/4 into the throttle just to get it to putt up to speed. Now I can lay into the pedal about a half inch and it's climbing. 55 is maintained with my foot BARELY on the pedal.

The car got 14.72 mpg before. I'll have to get the new mpg's after a few tanks..

I had forgotten that I did this mod to a dakota v6 once successfully. Smaller injectors at a higher PSI = more finely atomized fuel.

[dieselgeek]

Having tested the above idea on a number of EFI engines (reprogramming a wideband to simulate a narrowband output, then shifting the output for leaner operation (richer reporting)), including EEC-IV Fords - it doesn't work that way at all.

Every ECU has a limit to how far off it's measured air and fuel flows can be from the pre-calibrated air and fuel flow tables, and then they simply log an error on the O2 sensor input, run in open loop mode, and light the MIL.

The other thing that raises an eyebrow is believing that the ECU or engine will run at 17:1 AFR in cruise. A cheapo / entry level lambda kit may say it's running 17:1, but unless you're on some kind of exotic fuel with a 17:1 stoich value - it's not happening.

It sounds like a neat idea but the OEMs can't let their engines die a horrid death by leaned mixture readings from a $13.00 oxygen sensor, and the EPA/CARB even has rules about error checking for misleading O2 sensor readings.

[Tuner]

What raises an eyebrow is you don’t know an ECU or engine will run at 17/1 (and leaner) and you don’t seem to understand O2 feedback engines don’t actually fire every cycle and run at stoichiometric, they only average stoichiometric by oscillating between rich and lean, 13-17-13-17-13-17- etc.

I find it odd you don’t know that pre-emissions tuned carbureted engines ran as much or more than 15% leaner than stoichiometric in cruise and moderate acceleration load. Nearly all engines get the best fuel economy with the AFR as lean as just rich enough to avoid misfire.

You better crack the books a little more often. Cybergeeks with mad computer skilzz but no prior tuning experience gleaned from carburetors commonly make comments such as yours. It’s true, what they say, “If you don’t understand analog, you can’t make it work digital.

I don’t know why you couldn’t make it work with the EEC-IV Ford you mention because it works for other people, you must have done something wrong. You mention “richer reporting”, that isn’t how you do it. You “report” the same voltage oscillations as the original sensor but shift the input parameters to a leaner and narrower range. I described the procedure in the post above, read it again.

The only way an early ECU like that will light the MIL (in the context of this modification) is if the O2 input doesn’t oscillate the normal .1V ~ .9V. routine or hangs too long high or low.

I guarantee you it works as described on OBD-1 GM and the mileage improvement is dramatic. A WBO2 set up as I described above eliminates the 50% of cycles on the rich side of stoichiometric you get with NB feedback oscillations between .9V and .1V. It’s not simply running lean in cruise (like a pre-emissions carburetor) it is the elimination of the rich half of firing cycles wasting fuel by fueling them with the same lean AFR as the other half.

This is obviously not something to do with a catalytic converter equipped engine as the converter requires the rich-lean-rich-lean oscillations for proper function.


LOL – you’re funny, you don’t think engines will run at 17/1 – LOL – I guess E-10 is “exotic fuel” ?? – LOL – dieselgeek, I thought you were a pretty smart guy, but….??

[dieselgeek]

I'm a calibration engineer at an OEM that sells emissions certified engines that run on multiple fuels - I understand pretty well how a catalytic converter works, and believe it or not I'm also responsible for carbureted applications on our crate engines as well.

My post above pointed out that your suggested method doesn't work on his application, period, but it sounds like you want to get personal. You can give all the advice you like, so can I - the readers here can decide who understand versus who is talking over their heads.

Further, this comment: "The only way an early ECU like that will light the MIL (in the context of this modification) is if the O2 input doesn’t oscillate the normal .1V ~ .9V. routine or hangs too long high or low. " - a quick count of gov't mandated OBD codes shows no less than 72 codes related to O2 sensor output errors. And you missed my point, it's not the O2 sensor that sends the computer into Open Loop - it's the fact that the computer is adding or subtracting fuel to maintain a certain AFR that convinces the ECU the O2 sensor is bad. And this isn't a rule I wrote, it's federally mandated over here in the states.

Regarding engines running at "17:1" - we could get into that, but what fuel are you talking about, pump gas??? Pump gasoline here in the states, I can see a cheapo / entry level O2 sensor (kinda like an Innovate product) SHOWING you numbers that say 17:1, have you ever attached two Innovate/Bosch LSU kits to the same exhaust runner and seen them be 2 full points different from each other, in the same tube within 2" of each other? I have, every single time I did it. Which is why I don't use those types of sensors for serious tuning. You might, and that's fine by me. NTK is what I use when budget is small, and it's straight to ECM when budget is average or better. You may think you're running a pump gas engine at 17:1, and your budget priced O2 sensor kit might show you a number that says 17:1... but in reality, that's crap.

Also, another correction for you - his engine doesn't run "rich/lean/rich/lean" every other combustion event as you say. A typical emissions program cycle rate is nowhere near once per combustion cycle per cylinder, or even per complete engine cycle. This is done to keep the catalyst healthy, and if you run the engine "your way" (even if it did work on any but maybe one OEM application that I've never seen, and that's a rare one), the catalyst will also be ruined. No need to clarify, I understood exactly the instruction you were giving, and I'd challenge you to demonstrate that it would work on any EFI vehicle manufactured in the past 20 years, as opposed to taking personal stabs. I don't claim to be the smartest EFI or carburetor guy, but I know very well what works and what doesn't based on actual experience.

Arguments and your personal complaint aside, I'm curious if you can share how many times have you tried your suggestion above (trying to fool a narrowband O2 sensor input on an OEM ECU) and how did it work?

[Runit]

dieselgeek: How much O2 correction is allowed before defaulting to open loop in OEM ECUs?