89 4runner efi 22re Another CEL Code 25/26 Problem (1 Viewer)

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Hello everyone, got another CEL diagnostic problem with a 89 4runner 22re efi. It is popping up the 25/26 codes, lean and rich. I have read numerous posting on the internet about it and am still kind of stuck. Any help would be greatly appreciated. I have tested:

MAF - Resistance readings in spec
TPS- Resistance readings in spec
O2 sensor - reading .7 at idle and .9 at 2500 rpm
Compression test all 90psi except for #3 which is 120psi
Air leaks - found a few, vacuum lines and manifold but still threw codes
Cold start valve
EGR- went to smog and this failed, (EGR Functional test) But I fixed it and it is operational - had a clogged port
Air Flapper valve works
Has great spark to all plugs
Replaced cap/rotor/plugs/wires
New alternator, battery
Might be losing a bit of coolant
Burns around 1/2 quart per 2000 miles maybe
Leaks Coolant out from somewhere near the starter.

Smog test1: rpm 809, CO2%=13.3, O2%=2.3, HC=187, CO%=.01 - Fail - Max HC=120
Smog test2: rpm 2649, CO2%=12.9, O2%=2.9, HC=370!, CO%=.01 - Gross Polluter - Max HC=180

I have not tested/checked:
Fuel Pressure
Fuel Filter
Leakdown test
and a lot more

Any thoughts? Might be head gasket? Valves? Rings? Just bought it from a guy who said the head was "done". I need some frickin oil to pour into cylinder to see if it is the rings, can't believe I don't have any. Thanks for any input!
 
I think the 25/26 code usually means bad O2 sensor... To really check the sensor, you need either a needle multimeter, or some fancy machine.. I can't remember... The sensor is supposed to oscillate between 0 and 1 like 10 times a second... I think...

Welcome to Mud! :flipoff2: We're gonna need pics.... :D
 
Cool, I checked it with my crappy multimeter and it was changing about 2 times a sec or so, was .7v at idle and .9v at 2500rpm. Running rich. 0 is lean and 1 is rich so it is really rich. The emissions test showed it too, idle was a little cleaner. I did the leak down test and there was a decent amount coming out the intake tract to the air filter. A little blow by through the rings and out the motor oil fill cap, nothing going on in the coolant - though the thermostat wasn't open if that matters. Maybe the intake valves are tight or leaking? I might pop the valve cover to check the clearances. It was hard to start with the #3 cylinder getting the pressure test, also had the highest, doing most of the work? Thanks for your help!
 
that link sounds believable.
in all the datastreams i look at when using my snap on modis, the values of a higher voltage indicate lean.
infact, that link states voltage fluxuates between .1V to 1.0V. I often see some as high as 4.8V
 
Anyone have any suggestions? I have a lot of info posted and maybe there's a red flag somewhere. The compression check was done inaccurately. There is a really rich condition. Thanks for any suggestions!
 

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