MTXL showing normal afr's while running but rich when off
 

Hello,
I have had a innovative mtxl for the past 10 months. The first install was great, although the cable runs along the brake vacuum metal tube. I bought the 8ft cable one. It is wired with the radio 12v. All is good until it start turning on/off. I get a interference noise on the radio speakers. Soon after it dies, I panic, pull off the road and check. I find nothing.

When I get home I find that it had lost ground (twist connections got loose, in all honesty I was going to hard wire them, but was still playing around with where I was going to put it in. It was currently living in the glove box and I was opening/closing thus a small tug on the cables. I think it was fine. Then ..it blew a fuse. 12v to ground. Fuse was replaced and 12v wire was not ever tucked in to the under glove box support on the 99+'s.

Now it lives on the floor mat, twist ties were twisted with needle nose pliers to a tight knit.

My current problem/question: I have it on the stock front O2 bung. Stock ecu usually reads 14.3 and when off it used to read 21-22.4 which means super lean or exhaust is empty of anything. After this incident of wires undoing themselves, it still reads the 14.3, it just is displaying 19 (sorta normal) but the other day it displayed 16afr for at least 5 minutes. What gives????? (it did tune well on VEAL, so i dont think I'll replace the whole unit)

Also, why does the stock ecu gets stuck at 11.5-12.5 every 10 minutes for like a minute straight? (cooling the cat?)

Finally, what's an acceptable warm up AFR, currently running in the 16's and it warms up in 3minutes vs the stock 6. I prefer the 3, but wonder about engine longevity (most warm up is in the driveway).

halp

okay, I'm getting closer, but its not stock ecu good.

Warm-up about three points lower than you are currently. 16 is way too lean even for warm idle. I'm surprised your car even idles or warms up without sputtering and kicking.

Start running seq. injection and you too can idle at 16:1 without issues.

I like 15.0:1 warm idle and 13.5-14.0:1 below 150°F CLT.

Ooo the wonders of sequential that I didn't know :) ...my warm-up is ~13.1-13.5 and phased out at 160F...batch idles less good above 14.3.


To answer the primary question:
Search innovate grounding issues. Your 12V and ground sound unstable. Soldering connections and using a dedicated 12v and ecu ground significantly improve signal quality.