2.3L ('83-'97) Reconsidering awful MPG

[bobbywalter]

assuming tweecer use. setting egr system type to 2 if system default is 0

 

[bobbywalter]

from there go with a ms3 system

 

[lowspeedpursuit]

I've never used it, so feel free to correct me, but before we worry about where to find the EGR delete settings in Tweecer, the program needs to support the computer, right?
Tweecer doesn't list any support for EEC-IV Rangers. It does list the 2.3L in the '93 Mustang. Are we assuming that's close enough, or have people actually done this?

Keeping track of the different ideas here:

• I've already played with PSI.
• Going back to Frank S's idea, I have some 27" tires I could "test" whenever, but results would be ambiguous. If MPG improve, was he correct that I'm actually undergeared, or did I just substantially decreased rotating mass?
• I've already tested running the manual computer without dealing with the EGR issue, and MPG actually gets slightly worse.
• A standalone worth more than half the book value of the truck is obviously right out.
• I saw a recent post in another thread IIRC by Shran that his 2.3L MPG has also kind of sucked, historically, compared to what other people are claiming, so maybe it is what it is sometimes.

For making the existing manual computer work right, we've got:

• Build EGR. I actually have most of the components, but the wiring would need to be built from scratch, and I'm not sure about the '95 pipe I have.
• Bypass DPFE. I've thought about this before, and it actually seems plausible conceptually: tap the computer output to the solenoid, convert from PWM to analog, adjust to the expected 0.7-5.0 output range, and send it back to the computer. Downsides are that I don't know enough EE to pull that circuit out of my ass, I would need to build out the same wiring anyway, and I might end up with knock.
• Tune EGR out with Tweecer, etc, assuming that works. Might still knock? Whether it's worth the money is probably borderline.

 

[Blmpkn]

assuming tweecer use. setting egr system type to 2 if system default is 0

This is good info for me.. I gotta get around to ordering my tweecer soon. Egr has been deleted so I definitely want the ecm to know what's what before I start doing rev-limiter donuts until the tires pop.

 

[franklin2]

• Bypass DPFE. I've thought about this before, and it actually seems plausible conceptually: tap the computer output to the solenoid, convert from PWM to analog, adjust to the expected 0.7-5.0 output range, and send it back to the computer. Downsides are that I don't know enough EE to pull that circuit out of my ass, I would need to build out the same wiring anyway, and I might end up with knock.
• Tune EGR out with Tweecer, etc, assuming that works. Might still knock? Whether it's worth the money is probably borderline.

I have thought about this before. I was thinking of putting a 12v bosch type 5 terminal relay on the same wires for the EGR solenoid. Let the computer activate the relay instead of the solenoid. When the computer activates the original solenoid, which sends vacuum to the original EGR, it expects a certain voltage level from the DPFE. So take the original DPFE wires, hook them through the new relay with resistors. When the relay was activated, it would put a resistor on the DPFE circuit and make the computer think it was really doing something, when it really isn't.

 

[lowspeedpursuit]

Assuming 12v is correct for the duty cycle signal, and the computer would be happy enough with two discrete values "EGR on" and "EGR off", rather than insisting on a smooth curve, that would be fairly simple. I think you want it the other way around, though: DPFE return voltage should increase proportional to flow, so it's going to expect 0.7V (resistors) at no EGR, and 5.0V (reference) at wide-open-EGR.

Pardon the shadows:

Really, I need to build out the solenoid wiring and figure out exactly what the duty cycle signal looks like, possibly the actual DPFE voltage that results under different conditions as well. Then test a simple bypass, see if you avoid the CEL, and if not, make it more accurate.

 

[nesralyrrej]

fwiw i have a tweecer on my supercahrged 4.0 '90, has a heavy winch bumper, heavy steelies, and 31's, on the highway i get 17-18 mpg

 

[bobbywalter]

fwiw i have a tweecer on my supercahrged 4.0 '90, has a heavy winch bumper, heavy steelies, and 31's, on the highway i get 17-18 mpg

which is decent.

 

[nesralyrrej]

which is decent.

definitely not the worst, considering the weight and extra fuel needed.

seems like the supercharger actually helped the mpg a little lol

 

[lowspeedpursuit]

Are you still on 87 or running better gas?

-----

EDIT: Predictably, my truck's EEC connector doesn't have provisions for Pin 33 - EGR Solenoid Control or Pin 27 - DPFE Return, so I can't trivially add or attempt to bypass EGR without the EEC connector from a manual donor.

 

[lowspeedpursuit]

I've still done negative real troubleshooting on this, but I wanted to follow up on something that happened recently:

Amps, real oil pressure, and engine temp all started reading obviously inaccurate on a big trip. Turning lights on and off moved the oil and temp needles, so definitely an electrical issue. Grounds all looked good.

Coincidentally noticed braking seemd to move the needles more than other lights. My brake light switch has been iffy forever, in that it had a deadzone towards the top of pedal travel where the brake lights would flicker off. Replacing the switch seems to have fixed the gauges.


The kicker is, I also pulled codes just in case, and I got 159 "Mass Air Flow Higher Or Lower Than Expected". I wonder if weird electrical gremlins could have been contributing to inaccurate MAF readings even before they got bad enough to break the instrument readings and trip the code.

In any event, I'm almost in the slow season at work, so I'll follow up on the EGR thing at some point.

 

[Brain75]

I only skimmed, but surprised no one said this.... Dirty MAF?

My GM has gotten progressively worse and worse and worse (gawd awful) mileage the longer I drove it... I accepted it as motor getting old... got back to a friend with the identical make/model/motor/trans/trim package who is one year newer - their mileage was fine.... long story short hunted my ass off on the forums and dirty MAF came up... clean the MAF with that MAF sensor cleaner and mileage rebounded right back to where it should be.

The other solution if cleaning didn't fix it... throw parts at it - replace the MAF.

since you are throwing MAF codes, the first thing I would do is clean the MAF.

 

[lowspeedpursuit]

Recent new MAF per first post, although yeah, there are a lot of details to sift through.

That new MAF was already a parts-cannon response in the process of dealing with a separate issue from low MPG. Code 159 was brand, brand new since the last time I posted.

 

[Brain75]

wow my bad.. I read read the first post then skimmed all the way through the rest... I shouldn't have missed that.

new electrical parts seem to have terrible crib death and still born rate... tried swapping back to the old MAF or... ugh... yet another new MAF?

 

[lowspeedpursuit]

I might throw another MAF at it if the code comes back. It's unfortunate that Motorcraft seems to be discontinued.

I actually have 3 that fit (original to my truck, new Delphi, and original to my '95 parts truck), and they all appear to perform the same day-to-day.