Short and long term are -100 on both?

1997 Mazda B4000 4x4 4.0 engine. I have only once code and it is the dtfe. I have already replaced this and the mil light went out and has not been back on. I may be looking at old codes. I am using a Snap on Modis with 9.4 software. and........... I am a rookie diy guy.

Why would the trims be so high on both? 02 sensors are on zero.

THE CATALYTIC CONVERTER HAS BEEN REPLACED WITH A STRAIGHT PIPE AND A BUNG WELDED TO PUT THE 02 SENSOR BACK WHERE IT WAS

I forgot to add that it runs pretty good?

Someone who knows for sure will soon chime in but I think with some vehicles 100% means "100% perfect" A trim of "+20%" would then register as "120%".
Also make sure the vehicle is at operating temperature when you check fuel trims - once it goes 'closed loop' it will start making adjustments then you
may see the short term moving up and down a bit.

my snapon modis said that it was in OPEN loop when I checked it.

I checked it today and the scanner said open. Sorry I missed stated what it was.

it won't go into closed loop. Engine temp fully warmed up was always 171 deg..

MIL light is actually burned out. Scanner says it has a MIL code on.

What are the codes that your scanner is reading?

Before starting the car up in the morning, do a Key On Engine Off and take note of the Engine Coolant Temperature and the Intake Air Temperature. They should be reading nearly the same.

Your reported engine temp being always 171 degrees is not right and it's possible the thermostat is opening too soon. The service manual says on your vehicle it should start to open at 192 deg F and fully open at 212 deg F

I was having trouble reading my truck on the two scanners that I have. I went into global and watched the data and it showed proper trims. so that is progress.

that information is helpful! I had put a low thermostat in it and like a dummy thought that was a good idea. I will put the higher one it like is supposed to be. then see what that shows. I am going to try to attach some files on this to see if you can view them in shopstream connect.

tloftis wrote: I am going to try to attach some files on this to see if you can view them in shopstream connect.

The forums won't accept .SCM files, unfortunately. Send them to me at wrenchturnsyou@gmail.com and I'll definitely take a look!

I just emailed a movie to you. First one that I have saved. I hope to learn more.

Got your email, thanks!

A few catch my eye. Between the MILFault and the DTC CouNT PID, your truck is pretty convinced there's some kind of problem. :silly: One of those codes is likely a P1000.

There'll also be at least one P04XX code for the DPFE sensor. Stuck at 0V. I see you replaced it, but this PID still isn't happy.

The last thing of note is the CASeGND PID. I've observed this PID across hundreds of Fords, and I've never seen it actually read something. :blink: Every one I've seen reads -.017V or close to it.

Don't panic or anything, 'cause I've also never seen any diagnostics or training information refer to this PID. I'm just genuinely excited to have an example of that PID actually working! :woohoo: