flatbed

Looking for insight,
Just drove from Georgia to Nevada in 89 22re 4x4 truck with 31x10.50 and need to fix problems before I drive back in a few weeks.

Before I left I did compression test, tuneup, and new o2 sensor since I was getting CEL error codes 21(o2 sensor), 25(fuel rich), 26(fuel lean). After that CEL remmained off but still had poor mileage 12mpg-13mpg. 900 miles into trip CEL came back on only for codes 25/26. Power cutt out and had to keep it floored to do 60mph at high altitude. Any ideas? vaccum leak? egr? Don't want to drive home 3000 miles with 13mpg highway.

thanks and Merry Christmas

ThatGuy1295

Fried injector maybe. Or clogged cat. Just thoughts.

I could see 17mpg for that truck, but you definitely shouldn't be floored just to maintain speed.

alltracman78

Doubt it's the EGR, that shouldn't hurt power that much.
Vaccuum leaks are relatively easy to check for, but one that bad should kill idle with an AFM, so if the truck is idling ok I doubt that.

Have you checked your O2 sensor signal?
When you're engine's warmed up it should quickly switch back and forth from rich to lean [~.3 to .7 volts]. If it's staying lean [below .4V] it may be a clogged/broken injector, misfire or a vaccuum leak.

It's possible your AFM is bad, if it's not sending the right airflow signal to the ECU your engine's going to run like crap.

Check the AFM signal wire [VS] at the ECU.
With the flapper closed it should be ~ 4.5V, and fully open ~ .2V. When you move the flapper from closed to open it should smoothly go from the high voltage reading to the low voltage reading.

Hope that helps out a little bit.

sixstringslut

I have a similar problem with a 94 4X4 22RE with 165 X15's with no CEL 15 MPG. Idles and runs fine other than little wimpy on top end. My 88 4X4 22RE w/31's gets around 24 MPG with CEL and runs great.
Maybe go 89 OCT fuel just for giggles? Maybe altittude switch stuck? Unplug MAF?

flatbed

Truck has no cat and 89oct gas did nothing different. Idle climbs to 1700rpm when started cold. Slowly drops to 1000rpm as it gets hot. If I set idle below 1000rpm it will idle rough and bounce between 400rpm and 750.

@alltracman
Do I check the o2 signal voltage at ox1 on diagnostic terminal? Guy before me hacked into harness and I only read .005v at ox1 while running warm.

What is propper way to check VS? I assume i dont dare unplug harness to check while running. Check VS by turning ignition to on? Poke into wire at harness while running?

thanks

alltracman78

You can check at OX1.
I generally prefer to check at the ECU connectors because that way I'm seeing what the ECU is seeing, and bypassing any possible faulty connections on any spliced circuits.

You can check both at the ECU connectors, I wouldn't probe into the wire itself, I would probe into the back of the connector where you can access the bare metal pin [no damage to the wire].

.005V Is either a damaged wire or something wrong with your O2 sensor.
Or your meter is set wrong.