I'm trying to figure out if my fuel trims are good. Is there a guide? My car ran a 13.6 with all the mods but cats. I'm going back to the track and I want to make sure its faster. I put in a new set of ngk ix iridum plugs. The car already had the ngk laser iridum plugs in it, which might have been the originals. I'm stumped on what could be causing it to be slower.

 

On the version of torque I have it doesn't say short or long term fuel trims. It just says f/t bank 1 sensor 2 etc. Is there a way to tell if it's the short or long term?

 

It won't be LTFT. But, at WOT the PCM uses a simpler method of adding fuel, not really based on O2 sensors. (It uses MAF, taking into account IAT etc.)

If you want non-WOT LTFTs, they're standard OBD data.

If trims changed with the plugs be worried in case they're causing misfires. Sure won't help 1/4 mile times if so!!

Or if the plugs are slowing the way the burn occurs, that would likely be bad too.

 

The plugs were fine when I changed them. And according to the only fuel trims o can see on torque its within spec. The highest I I've seen it is 1.6 and .08 at the lowest. But I have no idea if its the short term or long term.

 

It's not related to any O2 sensor, so you're quoting a bogus value. You want to look at the true LTFTs. Get an app that works if torque doesn't.

 

Ok I now have the correct fuel trims. I can hear what sounds like a leak from the PVC valve but it might be a normal noise. Does these long term fuel trims indicate a leak.
Idle
Ltft1 10.2
Ltft2 8.6
2500rpm
Ltft1 3.3
Ltft2 2.3

 

Yes! Nothing huge - it sets lean codes at 25% and you're well away from there.

You can spray a little burnable gas (propane, carb cleaner or whatever) cautiously where you think the leak may be and the trims (plus revs, but you may not hear them) should react instantly. Well, they will if you can get the gas right to where the leak is - can be impractical in a full engine bay.