Open Loop fuel delay.

[torq455]

I seem to remember a short time ago, my open loop 02 reading jumped up to 850-1000 mV very soon after the engine started up. now, as you can see, it take several seconds of running before it slowly begins to add fuel. as it adds fuel, which is evident from the 02 reading, the target AFR is climbing. what am i missing here? why the delay?

[torq455]

i just remembered that this, and other small issues started right after i downloaded the full .5 xdf version. after doing some comparing with a stock bin and same xdf, several values are different. i didn't think changing the xdf file version would effect a bin file.

[robertisaar]

i'm gonna say its the sensor warming up and hasn't entered the range of temp where its gives an accurate reading?

and you take a look at the pulse width? seems a tad high... then again it isn't at 14.7:1 yet either...

do you have a log that shows the ECU transitioning from open loop to closed?

EDIT: i just reread the original question again, what exactly is confusing you? and 950mV is like a ~12.5 A:F Ratio, so i would say its the sensor not acting normally since its not at operating temp... or its bad.

[torq455]

here's another one with Ben's chip i had him burn several years ago. i put it in since i was having some probs with my Ostrich. notice the 02 right after she fires. the 02 is a Denso 4-wire conversion with about 12K miles. 12.5 AFR cold is fine.

[robertisaar]

that is not right. it shouldn't be in that range right after it fires...

and i know 12.5:1 cold is fine, but the ECM was commanding a lot leaner than that but it was still reading from the o2 that it was around there, which leads me to believe either the sensor/wiring is bad or the tune is WAY rich in that section of the VE table(not likely since the sensor reading stays pretty consistent even with a differing commanded A/F ratio). $A1? and is it determining idle fuel from "calculated airflow" or not? if so, it won't adjust fueling at idle, it will go off of the table for IAC counts VS airflow, or whatever its called...

[torq455]

function of airflow box is unchecked. yes A1.

[robertisaar]

function of airflow box is unchecked. yes A1.

so it actually cares about what the o2 thinks? yet its still stupid-rich(supposedly)? something is definitely wrong...

again, i want to see a datalog as its going from open to closed, that should clear things up...

[torq455]

no, it's stupid lean. 02 is right around .450 mV. some datalogs it stays there for 7-8 seconds, others it says there for 15 seconds. you can tell the engine needs more fuel. it runs a little rough until it gets it. why is it with Ben's chip it doesn't wait even a second. granted, the ECM won't use it to adjust fueling. the 02 will read simply due to the amount of oxygen atoms passing bye.

[robertisaar]

high voltage from the 02 means rich and if its actually running lean, i think we found the issue... and does A1 use a idle fuel table? i know 88 does, and i've played around with that a little with my wife's GP, it used to run rough, but i copied the corresponding values from the main fuel table into the idle for 600,800,1200,1600 and found a midpoint for 1000,1400.

[torq455]

i know that, but at .450 it's not rich, and for a cold start that's too lean, and it stays like that between 8-15 seconds. it didn't do that with the other chip at all. i still have a feeling it has something to do with this xdf flie. can't hurt to use a different version and see what happens. if there is no change, then i'll try a fresh bin.

[robertisaar]

i know that, but at .450 it's not rich, and for a cold start that's too lean, and it stays like that between 8-15 seconds. it didn't do that with the other chip at all. i still have a feeling it has something to do with this xdf flie. can't hurt to use a different version and see what happens. if there is no change, then i'll try a fresh bin.

right, but its commanding a lot leaner than the o2 sensor says it is, thats what bothers me. and changing the XDF shouldn't do that, unless the conversions for fuel were WAY off.

you know what, send me your latest bin and a datalog to go with it, i'll see if i can find anything funny. 2 heads are better than 1.

[torq455]

that why i posted. i uploaded an older bin and it ran great for the short time i had it running. had high 02 volts immediately. i've been wondering if my old lap top has a bad sector, which is causing some files to become corrupt or damaged. maybe this is what happened, causing some of the bin values to have the wrong or incomplete values. i'll use this bin for a while, and see what happens. thanks for your input. i'll update in a few days.

[robertisaar]

i'll be waiting....

[Superdave]

open loop

A control system that does not have a feedback loop and thus is not self-correcting.


o2 values don't mean anything in open loop. a single wire o2 takes 2.5-3 minutes to warm up enough to give an accurate reading.. a 4 wire takes just over a minute.

[robertisaar]

open loop

A control system that does not have a feedback loop and thus is not self-correcting.


o2 values don't mean anything in open loop. a single wire o2 takes 2.5-3 minutes to warm up enough to give an accurate reading.. a 4 wire takes just over a minute.

right, but i've never seen an o2 sensor go that high right after start-up.

i think torq455 is using a heated one...