solved? was: [16v] hard start, bucking/bogging off idle

[treed2 at wsu.edu (T. Reed)]

My car really pissed me off today.. it did the "cut out in the middle of 
busy intersection" thing, then it ran like crap all the way back home. I 
felt like I should drive it really hard to teach it a lesson, but it would 
just buck and slow down whenever I hit the gas.

So... despite 28 F, darkness, several inches of snow deposited on several 
inches of ice, and a 10 mph wind, I decided I was going to go out and find 
out what the hell was making it do this.

Popped the hood, began looking around. Discovered that the coolant 
temperature sensor wire insulation was cracked and the wire had bent at a 
90 degree angle because of the lost strength. It was all nasty and 
corroded. Decided that it would be good to replace, so I got my inverter, 
soldering iron, and a desk lamp (had to improvise since I'm away from all 
my tools), and soldered a new tail on the wire. Only after reconnecting 
it did it occur to me that this was the sensor for the GAUGE!! Ugh, I need 
to work on my car as often as I used to so I'll start thinking these 
things through...

The one for the F.I. has an interlocking 2 wire connector. Oh well, I 
guess having accurate engine temps in the cluster is important too.

Frustrated but numb from the cold, I realized it had been a while since I 
checked/set the dpr current at idle. I think it was April or May.. so I 
hooked up the ammeter, dpr harness, and got my 3mm hex key.

Checked the current. It was something like 17 mA, then 15 mA, then 10 mA, 
then 6 mA, then 2 mA, then 17 mA, and it kept repeating this cycle. The 
low battery indicator was flashing on the meter so I replaced it and tried 
again. This time I got a steady 5-6-5-4-5-6-5-4-5-6-5-4 fluctuation.

Decided to try setting it to the stock 10 mA +/- 1 mA. After doing so, 
unhooked everything and went for a spin.

Wow, lots of low end torque now. I could spin the tires (on snow/ice of 
course) in 1st through 4th just by giving it a little gas. The car feels 
distinctly different, so I proceed out of the parking lot with caution. 
Drove around the neighborhood, stopping about 10 times... no problems with 
stalling or bucking when coming off idle! Now my biggest problem is 
throwing snow in 1st or 2nd even if I start out easy..

Did I fix it? I hope so! I won't know for sure until it doesn't do it for 
like a week straight..

The current theory is.. some things have changed since I last set the dpr 
current:
- the cat plugged up and had to be gutted to put it out of its misery
- added an autotech fuel module (disconnected for past few days)
- new battery cables and grounds
- car sat for 3 months
- the temperature dropped (20 - 30 F  vs.  45 - 65 F)

Somehow, these factors made the idle mixture rich enough to cause the car 
to run like crap.

Cold enrichment would make an already rich motor richer, which could 
explain why this problem didn't set in until after I put the snow tires on 
(it's been consistently 10 - 15 F colder since I put them on). The sudden 
disappearance of the cat could throw things out of tune too (particularly 
if I last set the dpr current when the cat was still semi-plugged).

The other corroborating evidence is that despite bucking and bogging 
seemingly at random, the car ran amazing above about 3500 rpm.. all kinds 
of torque. It ran right up to the rev limiter..

So apparently this craptacular hesitation is what a 2L 16V with CIS-E will 
do when there is proper fueling at the top end, but too much fuel around 
idle.

Now, with the 10 +/- 1 mA current setting, its going to peter out at 5000 
rpm or so, but be very strong down low..

Anyway, just thought I'd share the latest development in my quest to make 
this damn car run properly.

-Toby