Head Scratching!

[michaellatini]

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

[Bruce.m]

Idle control?

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

[michaellatini]

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

[Steve Arndt]

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

[wreck]

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 ?

[Bruce.m]

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?

[wreck]

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

[michaellatini]

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!

[wreck]

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 .

[Piledriver]

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....