Shoptalkforums.com

Hello All,

New question. What would cause the engine to run differently on a cold start, Closed Loop vs. Open Loop? In open loop cold start, 35-40* outside it starts in 1 or 2 second and idles smooth at 1250rpm. The IAC valve jumps to around 60 steps and the AFR is around 12:5 then drives off smooth! Closed loop it is hard to start, seems like it is flooding because I have to hold the pedal to the floor for flood clearing. The IAC jumps to around 60 steps and it is running fouling rich at 10:1 or lower.

Isn't it supposed to run off of the Open Loop until it hits the warmup temp setting in, AFR/O2??? I have it set to 147*

I cannot figure this out.

Thank you for any advice you may have to offer.

M

Idle control?

Are you using “…. Closed+Open loop”? (Stepper or PWM versions).
Or just closed loop?

Thank you, Bruce. I should have said, it's Closed + open loop and IAC vavle not pwm

Don't run closed loop until it is warmed up.

My guess is that you are getting two lots of enrichment , one from the warm up enrichment and another from the closed loop . what happens if you raise the temperature for the closed loop to start ?

I’m a bit lost.

If you are running “open+closed stepper” idle control, then that uses a baseline stepper count vs coolant temp profile and tweaks that using closed loop to chase a target idle rpm.

That is all about the air control at idle.

Fuelling is a separate control system. So AFR is not part of idle control input.

Are you using TPS or Map driven fuel table?

I'm using MAP for light throttle and it changes to TPS over 82kpa , I don't have any idle control .

wreck wrote: ↑Tue Dec 05, 2023 1:38 pm My guess is that you are getting two lots of enrichment , one from the warm up enrichment and another from the closed loop . what happens if you raise the temperature for the closed loop to start ?

Wreck, you had it. I switched from Open Loop to CL+OL and changed the temp at the same time due to much colder weather, not getting to CL around town so, when I changed the active above coolant temp in the AFR/O2 I must have missed the last digit intending to set it to 140, it was at 14* Hammer head mistake. When you want to hit yourself in the head with a hammer!

glad I could help . once I somehow changed the duty cycle from 80% to around 20% .I spent a while trying to work out why it was suddenly leaning out , checking fuel pressure etc .

wreck wrote: ↑Thu Dec 07, 2023 1:00 pm glad I could help . once I somehow changed the duty cycle from 80% to around 20% .I spent a while trying to work out why it was suddenly leaning out , checking fuel pressure etc .

...DIY EMS setups are excellent at helping you learn....