drews92

Here goes, I have a 92 Pickup:
-Ext. Cab
-4WD
-22re
-W56
-31x10.50s
I bought the truck with 297k miles, it had a new timing chain, rebuilt head and new driveline, rearend, & clutch.
I got it to replace an 87 4runner with the same setup. Right away I noticed it lacked the power and mileage that my 4Runner had. I immediately did the following:
- Tune up (Cap, rotor, NGKs, Beldon wires, air and fuel filters)
- Corrected timing
- Cleaned EGR valve and lines
- Cleaned Throttle Body and butterfly
- May or may not have cleaned my cat. conv. housing
- Dumped injector cleaner in the tank
- Compression test (180 psi all across)
- Adjusted valves (Too tight)
- Replaced thermostat (180 deg.)
- Adjusted TPS
- Tires pumped to 42 psi

All corrective measures have either helped regain power alone, or regain power and fuel economy. I say regained, because it is lacking the power my 4 runner had. And even with the 31's, the Runner would get 18-21 mpg all day long. As for the truck, I'm doing good just to get 13 mpg!! With gas at $3.90 and rising, I'd be better off with a full size truck, but I need to fix my truck on my own, to try and avoid the $85 diagnoses rate of a shop that I'm not even sure could find the problem. So if anyone knows something I don't, like how to test the sensors and what not, please let me know.

tc

What gear ratio?

drews92

Stock - 4:11

ozziesironmanoffroad

4:10 you mean? no wonder... go up to at least 4:88

norcalsvx

i didnt see o2 sensor and check your afm

http://www.4crawler.com/4x4/CheapTricks/AFM/index.shtml

drews92

Oh yeah, O2 sensor was bad, so I did replace that also. But how do you check the AFM?

drews92

Oh, just noticed the link! Thanks.

infiltrator

I get 13.7 with my 3.0... I cry when I have to pay about $65 for a fillup. 31'' tires too! Stock gears.
What you might wanna consider is downgrading those tires, and using them when you offroad only (if you do at all).
Get some smaller tires for the streets. Try and and hell, they might just pay for themselves.

Either that, or a beater car.

tc

Stock gearing for the trucks that came with 31's was 4.56 for manual tranny ... so, your odometer is likely saying you haven't gone as far as you actually have AND you're out of the powerband and having to use more throttle than you should. Kinda double whammy for MPG ...

Junkers88

Yup it's the tires/gears combo. Either get stock sized tires (they're like 28" tall) or go with some deeper gears. I think that a set of 4.30's would get you very close to stock ratios with 31" tires, 4.56's will do the same with 32's and 4.88's will make you happy if you un 33" tires. If you plan on adding weight to the truck, i.e. trail gear/camping stuff etc, then I'd go with the 4.56's and keep the 31's. Just my opinion.

I've got the exact set up you have but with stock tires (and an 86 model truck) and I'm getting 22mpg and plan on gearing when I do the tires so I can maintain some sort of fuel economy.

drews92

Okay, aside from the gears and tires, I know what to expect from a truck with this kind of set up, because I have personally had this configuration on two 1st gen. 4Runners before I got this pickup. I figured out the speedo and actual miles driven deal long ago. Aside from that, my truck is still burning way too rich to be running at optimum power. The spark plugs indicate that, the performance, the mileage, and the ol sniffer smells it.

So, I checked out the AFM and it checks out good. (Thank God! I know that's a very expensive part!) Is there anyone who knows how to test the Temp sensors?? I can't figure out which part is telling the PCM that the truck is too cold and needs more fuel. My Haynes manual either doesn't know it exists, or refuses to tell me how to check it.

tc

FSM for a '93 truck
http://personal.utulsa.edu/~nathan-buchanan/93fsm/

ovrrdrive

You're actually getting better mileage than your math is telling you. As mentioned the truck came with 28" tires stock and both of your 4runners came with 31's. As the tire size goes up on the stock gearing the truck is probably actually getting better than it did on the smaller tires but when you divide it up its worse. You can either change the gearing or the speedometer gear to get it back right. Re-gearing it would also get you back some of the lost power too.

I don't think I've ever gotten much better than 15-17mpg in my truck since it was new. Our V8 4runner gets just as good.

rdlsz24

Since gas has jumped up my truck has hardly moved lol.

Rob

drews92

Okay this may seem a little off topic, but how do you use that FSM online?? I anything I click on just downloads something that can't be opened. What software am I suppose to have to access the FSM and where can I get it?

abecedarian

Maybe you need Adobe Reader? http://www.adobe.com/products/acroba...lversions.html

tc

Yeah, it's links to pdf's ...

mattynicks3

if you go to an auto zone they'll do a free diagnostics test for you! but ill tell you now.....i have a 1990 pickup, 4x4, 3.o v6 and got garbage milage. i did get a brand new motor for it about 10,000 miles ago and i got an average of 100 miles more per tank. yes, 100 miles.

tc

AutoZone (or anywhere else other than a dealer for that matter) can't do diagnostics on an OBD-I (pre-1996) vehicle

thook

Do you know where the coolant temp sensor is? If not, there's two sensors on the front of the motor.....more toward the pass side. The one on your right is the coolant sensor.....(not switch or sending unit). To test it, put in a pot of water and place the two probes of a DMM on either terminals. The resistance reading should be high as the water is cold, but then gradually lower as you heat the water.

You could test it on the vehicle if you figure out how to do it without pulling the connector. Pulling it, though, would cause the truck to run VERY poorly while waiting for it to warm up. So, I'd use the pot of water. It's easy enough.

Other thing....if the sensor has a lot of deposits on it, they can lose some of their sensitivity to temp changes. I've been able to clean coolant sensors and switches with good results. But, if it's simply gone bad, nothing will help and the truck just won't idle well and lack power. Oh.....and run quite rich.