ccernst

I've posted this question in a few other Ranger forums with little success, thought I might try here.

I got a Ranger about a year ago and love it. It is a '98 Ranger SuperCab 3.0L 4x4 manual. The owner before me tried to take care of it, but the mechanic she took it to was taking her for a ride I think. When I got it, it ran very bad. I did a pretty big tune up on it and it runs pretty good. But I do have one quirk.

I have no CEL on, but when I hook my Acctron 9180 scanner up, it reads the following:
o2s11 0v
st ftrm11% ranges from -1.0 to 0.8
02s12 0v
st ftrm12% -100.6 solid
o2s21 0v
st ftrm21% ranges from -2.2 to 0.0

I made these readings after a 20min drive home from work. My fuel trims are at extremes.

Anyone run into this?

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1998 Ranger SuperCab 3.0L 4x4

J-Ri

O2s11 is bank one upstream sensor
O2s12 is the only downstream sensor there is
O2s21 is bank two upstream sensor

I'm not familiar with that scanner, but if it is a lower cost one, I wouldn't necessarily trust it for the voltages, get an oscilloscope and look at what the voltage actually is. The STFT will usually read near 0, as it will "pass" the counts on to LTFT if it stays above/below +/-10%. Will that scanner show LTFT? I'd be more concerned about that than STFT. Those STFT numbers look very good. +/- 10% is where you want it to be, it's no better to have it at 0% than it is the have it at 8%. I have not been able to try it, but I've been told that if you check a brand new car it will read a few % away from 0. You might want to take it to a shop that does the BG induction flush. I have seen that get the FT closer to 0 many times, it also cleans up the O2 sensors a bit, but generally if the sensor's bad it's bad, you're not going to fix that with chemicals.

For the B1S2 STFT -100.6%, that's not a valid number. The maximum is 100%, and the SES light should illuminate at (I think) 20% for any FT number. I think you probably have a computer problem, either the scanner or the PCM. If it's a cheap scanner, I'd suspect that first. If the O2 sensor voltages were actually 0v, you would have a code for each one, and quite possibly multiple codes for each one.

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'04 Cavalier coupe M/T 2.2 Ecotec
Supercharged 14 PSI boost, charge air cooler, 42# injectors
Tuned with HP Tuners

When you buy something... a bottle of pop for example, who gets the profit from it and what do they do with it? Maybe your money's going to groups that want to hurt you. I think everyone should do a search for things they purchase regularly "____ supports". Might just find a company you won't buy stuff from anymore.

ccernst

The scanner is able to read live data, so it isn't the cheapest unit on the market. It does not give LTFTM...it goes through a process where it checks for a possible 109 values...then starts reading what it can.
My cousin runs his own mechanic shop and has a real scanner where it can run diagnostics against the various computers...he said all of them passed.

I get to change out my radiator, so while I work on that, I'll see if I can get my computer code and see how much a new computer is.

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1998 Ranger SuperCab 3.0L 4x4

ccernst

Bit of an update. I've recorded some data with the scanner, here is what I've recorded. Each reading is about .5 seconds time.



Edit, this is a bit from the manual that describes the difference between "ST FTRM1%" and "ST FTRM11%"

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1998 Ranger SuperCab 3.0L 4x4