Why is it that....
Thread Starter
TECH Resident
iTrader: (3)
Joined: Nov 2001
Posts: 979
Likes: 0
From: Richmond, VA Where fast cars, well......are hard to come by.
Why is it that.... ...when I first start the car after it's been sitting (read:engine cold), it runs so much better than when it warms up, part throttle-wise? It's in open loop until the o2 sensors heat up right, then goes to closed loop? But still reads off the maf the whole time? Runs just perfect, then the o2's start swinging around trying to get that 14.7:1 afr, and I can feel slight sputters here and there even with constant tps, and every so often a little 'buck' on shifting. Any ideas?
Re: Why is it that.... The mixture loop doesn't maintain a constant
0.500V O2 sensor. It lets it bounce, I think
it dithers the mixture on purpose and looks
for an -average- 0.500 (or whatever). So if
you look at the sensor voltage it's all over
the road. When it gets into the outlying
areas the road gets a little rough. My car
popped at idle since new.
At cold, I believe there is some built-in
enrichment in the open-loop settings. You
miss lean; you would have to be stankin'
rich to have a misfire stumble.
0.500V O2 sensor. It lets it bounce, I think
it dithers the mixture on purpose and looks
for an -average- 0.500 (or whatever). So if
you look at the sensor voltage it's all over
the road. When it gets into the outlying
areas the road gets a little rough. My car
popped at idle since new.
At cold, I believe there is some built-in
enrichment in the open-loop settings. You
miss lean; you would have to be stankin'
rich to have a misfire stumble.
TECH Addict
Joined: Nov 2001
Posts: 2,207
Likes: 0
From: College Station, Tx
Re: Why is it that.... It's running a bit richer until you reach a certain temp threshold - and typically you will achieve a better/more stable idle to the rich side of stoich (it just won't be as fuel efficient/good on emissions).
Chris
Chris
