problems with running lean and need suggestions


Founding Member
Oct 20, 2001
I am having a hard time trying to figure out where to start with my problem. The basic setup is the same as last year but have added 1 5/8 long tubes and an 80 mm throttle along with a plx m300. Anyway, I set the basics along with maf transfer. The car idles around 14.5-15.0. It does this without any problems. I take the car for a drive and within 2 blocks after hitting 3500 or so it starts running choppy. At this point the A/F jumps to 19.0 - 20.0 then reads lean. At this point it will not run. I shut the car off then restart and it runs at 15.0 Where do I go from here? What do I check first?
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I have replaced both o2 senors. I have also tried using original mass air and I still have the same problem. Car idles fine til it goes closed loop or whichever after 120 seconds or so. At that point my datalogging shows the o2's bouncing from real low to high. The wideband shows it climbing to high 18-19's
I have the same WB meter...idles at 14.7 due to ECU in open loop..then once closed starts inching up to LEAN , then i shut the car off.

I sent you an email

any drivability problems (knock/ping) I have a feeling it has something to do with adding in a resistor to the ECU input to offset the missing heating element of the stock sensor. Let me know what happend with your setup- THANKS