COS 3 Lean Cruise

[5.7ute]

With a quick look it is the same problem I had. Up to frame 2790 it all looks O.K. Once you have hit 90kpa map things have got screwy from there. Try remove all enrichment from B3647 and use only the PE modifier and see what happens. Once lean cruise locks on that "rich" cruise only dropping the speed below B3637 disables it.
A clue to it being locked in a rich mode is your commanded EQ under decel in the log.

[vbhero]

With a quick look it is the same problem I had. Up to frame 2790 it all looks O.K. Once you have hit 90kpa map things have got screwy from there. Try remove all enrichment from B3647 and use only the PE modifier and see what happens. Once lean cruise locks on that "rich" cruise only dropping the speed below B3637 disables it.
A clue to it being locked in a rich mode is your commanded EQ under decel in the log.

Interesting, that sort of gels with a gut feel I had when I noted it as I was driving.

I will remove all enrichment in B3647 and log again. Watch this space

[vbhero]

Sorry for the delay with updates.

I did the above and all appears to be okay. What I did find in the intervening time was that when running OL the default setting for the Purge Canister solenoid was disabled, this resulted in the canister saturating and bulk fuel fumes. I since enabled it, which now results in my AFRs going rich (as you would expect) because I tuned it with the solenoid disabled, so I need to adjust my VE etc again.

I'll keep an eye on the lean cruise for a while and report back if I have further issues.

[joecar]

Sorry for the delay with updates.

I did the above and all appears to be okay. What I did find in the intervening time was that when running OL the default setting for the Purge Canister solenoid was disabled, this resulted in the canister saturating and bulk fuel fumes. I since enabled it, which now results in my AFRs going rich (as you would expect) because I tuned it with the solenoid disabled, so I need to adjust my VE etc again.

I'll keep an eye on the lean cruise for a while and report back if I have further issues.

Thanks for posting back...


interesting, so should keep EVAP enabled.

[vbhero]

Thanks for posting back...


interesting, so should keep EVAP enabled.

It would seem that way. I disconnected the electrical plug on the solenoid to confirm, and my AFRs returned to normal, plugged it in and rich it went.
I'm going to do it a few more times just to make sure that it wasn't fluke / timing before I say 100% that would be the case. The theory would fit, that despite the rich AFRs, my actual fuel consumption does not seem to be affected thus indicating that it may be the fuel vapours being fed to the throttle body artificially raising the AFRs?

[Chevy366]

Will the vapor eventually stabilize (over saturation, versus normal operation) or will it continue to effect the AFRs?
I ran COS 3 for the longest and never saw any difference but I left everything as it was and used PE for enrichment.
Lean Cruise I have found, at least in my area, does nothing for me, due to the terrain it goes in and out too often to be of any use, I actually disabled it and picked up mileage, go figure.
Before the Lean Cruise patch I played with making a pseudo lean cruise cell area in B3647 in the cruise cell areas, again as long as it stayed in that area it worked.

[vbhero]

Will the vapor eventually stabilize (over saturation, versus normal operation) or will it continue to effect the AFRs?
I ran COS 3 for the longest and never saw any difference but I left everything as it was and used PE for enrichment.
Lean Cruise I have found, at least in my area, does nothing for me, due to the terrain it goes in and out too often to be of any use, I actually disabled it and picked up mileage, go figure.
Before the Lean Cruise patch I played with making a pseudo lean cruise cell area in B3647 in the cruise cell areas, again as long as it stayed in that area it worked.

I am not sure about the stabilisation of the vapour levels. This is what I expected to happen as the car "consumed" what was in the canister, but a mate of mine who is a mechanic seems to think that the charcoal would now be stuffed and the canister would be U/S. I need to find out more about this.
The thing that has me thinking twice about what to do next, is my AFRs are okay initially, but once the conditions are met to actuate the solenoid you see the AFRs richen up. At their worst it will go from 1.01lambda to 0.79 then recover to approx 0.88 lambda. Keep in mind that I am full open loop.
The other thing is, my consumption figures seem normal which if the car is going as rich as it indicates, I would expect increased consumption, which is why I mention above that it would logically be a function of the vapour purge?
So do I re-do my Auto VE? If so, then I would have to re-do it once the EVAP is active? What then happens to the AFRs when EVAP isn't active? Or is this why we wait until car is up to operating temp before starting AutoVE? Obviously EVAP isn't a consideration that people think about when doing their AutoVE when in SOL or CL.
If indeed my canister is stuffed, then that could be doing all sorts of weird things.

I was using B3647 for pseudo Lean Cruise, but I didn't like the idea of transient lean spikes as it passed through those cells during part throttle accel.

Where to from here? I am going to disconnect the solenoid to make 100% certain that the AFR change is a result of it. If it is, then I'll have to decide whether I should re-do AutoVe.

Sorry for the ramble, I find it helps sometimes to put everything down in text to make sense of my thought process. That plus, I am still pretty raw at tuning so input from others always helps the learning process.