E11V2, V1.89 build 32, 20b, 550 primary injector/1680 seconday.

The car had a bad part throttle hesitation problem. After lots of trial and error adjustments, I found that the on-throttle duty cycle of the idle control valve setting was too low (~25%). I bumped it up to 40% and the hesitation is gone and the car is rev happy.

For experimentation, I changed the on-throttle duty to 0%. I pressed down on the throttle a bit (part throttle) and the car died instantly. Changed it back to 40% and it works great.

Is this normal? So basically if the idle air control valve fails, my car will be very difficult to drive.

Additional info, it idles solidly at 900 rpm with the following parameters:
2.700 ms of fuel
10 degrees timing advance
13.2-13.7 A/F ratio (any closer to 14 and idle becomes unstable)

Thanks for the input guys.

 

No it's not normal. You should be able to have a 0% DC when on throttle.

 

ok, I had some time to play with it tonight and here's how it went.

I tuned idle control valve on-duty cycle to 0% and increased throttle dead time (in the main set up menu) to 4%, turned off throttle pump for the time being, and the hesitation is gone.

I theorize that the engine needed some extra air (from on throttle duty cycle or the 4% throttle movement) to get a good fuel mixture initially.

So the engine idles good and respond well to light to medium throttle jabs. No hesitation what so ever; AF is about 13-13.8. Hesitates on quick jabs to WOT.

Now I go to turn throttle pump back on, and the car revs like ***.
Light throttle is ok, but medium and quick jabs actually leans out to 18 AF ratio.

The car actually runs better without throttle pump engaged.
It doesn't make sense. I followed the instructions in the manual but it's the same no matter what parameters I adjusted.

Do you have a throttle pump map that runs well? I use the stock 20b TPS. It is calibrated.

Thanks so much.

 

i have the same issue but with a haltech tps? i watch the tps readings in data guage and it shows no % til i have atleast 5-10% throttle push in. then its smooth for like 10% more then around25ish it bounces down and around from 7-35%????? but i may try out some of the things you mentioned adn ill keep posted on what your doing