maft idle cruise-- what afr for each?

[BrockLee GS-T]

Hey everyone, i just picked up a car that has a maf-t and stock 450's for now, but it needs to be tuned desperatly, hardly idles at 500 rpm.... trick is i only have a lm-1 wideband for checking fuel trims so i need to figure what what afr it should be at during idle and during 3k cruise.

 

[eclipsegsx1736]

During idle and cruise conditions the car should be at 14.7:1 at all times when at operating temperature. The ECU does everything it can to keep the AFR at 14.7, but the ECU can only do so much. If your trim is too far off, it won't be able to compensate enough and you'll run rich/lean depending on which way you're incorrectly tuned. Get or borrow a logger or DSMlink and get your idle and cruise trims as close to 0 as possible. You'll never get it perfect but +/- 5 is ok.

Double check the injector settings on the MAF-T. Also depending on your piping and MAFT location/orientation etc you might need to change your trims quite a bit.

 

[xveganxcowboyx]

I believe 0 on obdII loggers is 100 on obdI for fuel trim. Just to help clarify.