Rich at idle and lean at high loads after rebuild

A

Altenius

Greenie N00B Member
Greenie Member
Hello everyone, I need advice on how to troubleshoot a problem with fuel trims. At idle, the fuel trim drops to nearly -20. Under light load, it increase to around +/-5%. As load increases, however, the fuel trims increase to 20+. Mods are autotech internals, catless downpipe, and JBR Tru-3.0 Intake, and a base tune. The problem persists with the stock intake as well. Engine also makes a rattling noise around 2500-3000 RPM.

Any kind of advice would be great.
 
Hold up. Base tune. What exactly do you mean by that? Who made it?

You are switching intakes with same tune?

edit: And then I read the user name. So maybe you know things. :-)
 
jsmith said:
Hold up. Base tune. What exactly do you mean by that? Who made it?

You are switching intakes with same tune?

edit: And then I read the user name. So maybe you know things. :)
Click to expand...

It's the base high flow down pipe tune from VersaTune. The MAF is calibrated for the correct intake :).

Also, I know much more about software development and reverse engineering than I do about engines, unfortunately.
 
Does Versatune have two values for fuel trims? Long term fuel trims (LTFT), or short term (STFT)?

If so, which are you referring to with the -20 / +20 trims?

You have a gen one, right?
 
jsmith said:
Does Versatune have two values for fuel trims? Long term fuel trims (LTFT), or short term (STFT)?

If so, which are you referring to with the -20 / +20 trims?

You have a gen one, right?
Click to expand...
I’m referring to LTFT + STFT. It’s a gen one.

A valve was burnt before the rebuild so it’s possible this was a problem before.
 
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