wishmaster22

Hi,

I am getting bad gas mileage 14mpg and I did a full tune up already.

I have 192k miles and I am sure the previous owner didn't do anything.

Should I change the o2 sensor, If so which one or both? I am planning on cleaning my maf sensor to see if that helps. Should I replace maf or just clean it?

Also I have a small hole in my muffler where a weld broke by one of the hangers. How much would this affect things?

Thanks

mt_goat

If you have a 94 you should have a AFM not a MAF. The AFMs don't need cleaning like the MAFs do.

If you have two O2 sensors the rear one just tells you if the cat is working or not. It's the front one that helps the ECU with the A/F ratio and could effect performance or gas mileage.

wishmaster22

Seriously, Man I thought I found something to clean that might get this thing running better. What about the o2 sensors?

itsmeagain5789

i'll tell you what, i'm in the same dillema, did the whole tune up except the o2 sensor. I'm getting exactly 14 mpg even with premium in the tank. i'm gonna have to replace the o2 sensor if things don't change. I got 157000 miles, and i'm pretty sure its never been replaced. does anyone know how much a good o2 sensor goes for?

wishmaster22

O2 Sensors

Denso OE identical O2 sensor 234-4052 234-4052 FRONT
Non California $91.22








O2 Sensors

Denso Universal O2 sensor 234-4050 234-4050 FRONT
Non California $52.94

wishmaster22

this is from sparkplugs.com

Not sure what the difference is between them.

itsmeagain5789

yea, i would definatley get a denso, or something really close to oem.

itsmeagain5789

either way, i don't have the money right now, because I just spent $150 on the 1.5 inch rear coil springs.

wishmaster22

Hey I do have a MAF Sensor! I just don't know how to clean it. It is this part# 22250-65010 Denso # 197100-2920

Any info on the process for a 94 v6 3vz please let me know!

Thanks

mt_goat

You do? How'd you get that? You clean the little wire inside the tube by spraying it with electrical contact cleaner. Don't touch the wire with anything.

Elton

think its a afm and not a maf sensor

wishmaster22

Although the part number comes up as saying it an MAF . I believe Elton is correct its an AFM. So I don't think I can clean it. Any suggestions on if I should change my 02 sensor? and any info on how to tell if my o/d works would be great. As I had stated or maybe I didn't - no light comes on or off upon pushing it.

mt_goat

Do you have a multimeter? If so there is a test proceedure in the FSM:

http://personal.utulsa.edu/~nathan-b...01heatedox.pdf

runethechamp

Premium will not give you any better gas mileage, it will probably make it worse.

machpoint92max

Somewhat of a newbie here; my 93 Dlx is also getting the same 14mpg. I've been considering changing the o2 sensor (sensors) also. Can't think of anything else to work on, as I also did the tune up routine, but still 14mpg. It starts right up and runs smooth. It has plenty of power and acceleration in 1st, 2nd and 3rd, but feels like it starts to weaken out in 3rd to 5th when going up even what I feel is a mild grade. On the highway going up a moderate grade, I have to downshift to 4th or I'll be holding it almost to the floor. Is this a symptom of bad o2 sensor?

Also, could someone tell me what is AFM and MAF and where are they found? Do you think this is related?

Also, unrelated, when it's cold it spits little drops of black fluid out the exhaust pipe for a few minutes, until it warms up. Sometimes when I shut it off, I often smell coolant, but coolant level in radiator is always full and never changes. Resevoir too. There are no leaks. Head Gasket Problem? Strange.
Thank you,
Richard

mt_goat

Welcome Richard, an AFM (air flow meter) sits on top of the air box on the 3.0 and measures the air intake by volume. It does this by how far the little flap inside moves.

A MAF (mass air flow sensor) is on the newer trucks about 96 and up. The MAF measures the air intake by estimating the mass. It does this with a little wire that is heated and the more air that moves by the wire the more it is cooled. It is inside the air intake tube just behind the air box.

I changed the O2 sensor on my 93 3.0 at about 100,000 miles thinking it might help the MPG, but it did nothing to help. My advice is to test it, or just wait for it to throw a CEL.

14 mpg is not really unusual with the 3.0, the motor was designed in the 80's and fuel economy was not a priority. If you remember oil was around $10 barrel in the early 80's. I think the biggest problem with them is people run them at near wide open throttle (WOT) all the time and this causes the computer (ECU) to run in open loop a lot where they run rich to protect the motor from melting pistons and valves.

wishmaster22

I plan on testing my o2 as recommended. Is there a reason my o/d light does nothing?

machpoint92max

Thank you, Dale, for the info on AFM/MAF. My 93 Dxl has a 4 cylinder, 22R-E 2.36 Liter fuel injected engine (144.4 cu.in.) which is totally stock as far as I know. I also have a carburated 22RE in an 88 2wd that that gets about 27 mpg. Seems to me that 22RE should do better than 14 mpg. I'd rather have a full sized truck with a v-8 if I'm going to get that kind of mileage. What do you think? I checked the gearing, and jacked up one rear wheel, marked the rear wheel and driveshaft. I have an open differential and the shaft turns approx 2.05 to 2.1 revolutions for one revolution of the tire. So I'm thinknig it has 4.1 to 4.2 gears. Are these stock or should they be different? I suppose I should invest in the FSM soon. Thanks
Richard

machpoint92max

Correction, the 88 has a 22R engine, but it's the same displacement 2.3L (144 Cu.In.)

williemon

When the OD light lights up after you press the OD button, you should not be in overdrive. Major mileage killer. When the button is pressed in, OD light comes on, truck goes into overdrive.