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  #1  
Old 08-27-2021, 01:28 PM
ZJeepX ZJeepX is offline
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Default MT2500 not showing loop status or fuel trims

Hey all,

New here and new to the MT2500. Got a 1992 Jeep Cherokee XJ 4.0 AW4 4x4.
Hooked the red brick up for the first time today and wanted to read live data to check out my new stroker build. Almost everything shows up and works properly.

But I do not get Loop status or fuel trims?? Itís not that they are showing up as zero values, they are literally not there??

Shows rpm o2 and inj on the top of the screen
Then ign cycles 1-3 then goes straight to exhaust then map values?? Iíve scrolled through the whole list and no short term or long term fuel trims or loop status are shown.

Iím using the diagnostic cartridge up through 1997 so it shouldnít be the cartridge right? Also scrolled through custom setups to see if there were any other settings I could adjust to see those values. Nothin there.

Can anyone explain this to me? Iím probably just a newbie and an idiot but Iíve searched all over for answers and I canít find them. Seems the older renix Jeeps show this data no problem so I canít see why my 92 wouldnít show it as well?

Thanks for your time!
Zach
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Old 08-28-2021, 06:39 AM
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I agree that you'd think it would be there. I don't know why it wouldn't be, but it's easy to do another way. If your fuel trims are moving, it's in closed loop. Because STFT will always move, it's a solid indicator you can use in the place of Loop Status.
Joe
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Old 08-28-2021, 08:59 AM
ZJeepX ZJeepX is offline
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Thanks for the reply Joe!

Only problem is, I donít have stft or ltft showing eitherÖ I was looking at Exhaust - lean-center-rich to tell loop status. I believe itís center when open loop? And switches from lean to rich back and forth in closed loop?

I do have fuel% showing which gives me a tiny idea of what the pcm is doing fuel wise but not enough. Basically says 4 to 6% which tells me the pcm is spacing out injector firing by + 4-6% basically causing a slightly lean condition?? Is that right? Would make sense as I have larger injectors installed for the stroker. Also based on what info I do have I believe everything looks pretty good and within spec. Just wish I could see short term fuel trim live. Probably should have invested in a wide band instead of the brick!

Do you know if I tried another cartridge, maybe one that goes up to 99 mt25001099, would that potentially solve my scanner problem? Or are some cars just lame and donít give out all the data. My year was right at the beginning of OBD 1Ö Iíd rather not waste 40-50 bucks on a cartridge that wonít do anything different.

Thank you,
Zach
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Old 08-28-2021, 05:49 PM
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I'm pretty sure a newer cartridge won't help. The computer system on that vehicle is pretty primitive. If it is reporting Fuel Trim as a singe fuel% PID, then I bet that's all you're going to get out of it.
This guide may be helpful to tell you what every PID means: http://www.w124performance.com/docs/...l_Domestic.pdf

It won't tell you what specific data should appear on the vehicle though.

Joe
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Old 08-29-2021, 07:24 AM
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Thanks again Joe!

Answers my question mostly. Frustrating that the older Renix era Jeeps actually give more live information!
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Old 08-29-2021, 07:43 AM
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Quote:
Originally Posted by ZJeepX View Post
Thanks again Joe!

Answers my question mostly. Frustrating that the older Renix era Jeeps actually give more live information!
Yes they did, but didn't they also forget all trouble codes as soon as you turned the key off? Early diagnostics capabilities sure left a lot to be desired, but they were better than nothing. I do appreciate all the info computers provide today, especially misfire monitors!
Joe
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