Lean cruise on an 03 Workhorse motorhome

[98ls1blackbird]

Can someone please guide me through setting up the lean cruise on my 8.1L motorhome? You can assume I know nothing, so spoon feed me. I wanted to do the AutoVE procedure, but the pcm does not contain the proper PID's. GM.AFR for one. So my only way to get additional mileage is the lean cruise. If I cannot get this to work, this license is worthless. Thanks for any help.
John

[98ls1blackbird]

Nobody??????????? Come on someone has to know how to do this. Help a guy out. Thanks.

[joecar]

Which PCM and which OS do you have...?

[98ls1blackbird]

OK, here is all the info I can get from the info page on the tune tool.
99+ gen III
Engine: 8.1L
O.S.: 12579405
Transmission: Allison LCT
OS ID: AR
BCC: YCTJ

Hope this helps, I really need some help on this one. We are leaving tomorrow to go to Florida from Michigan. A little extra mileage would be great. I have an LM-1 wideband already hooked up and calibrated to EFILive on this motorhome. So I will be able to monitor the A/F ratio. Thanks.

[GMPX]

Sorry, it's not possible, only on Holden platforms.
Besides, lean cruise is not really ideal for something that will always be under load like your motorhome.
To get a few more MPG try getting severe on the DFCO (Decel fuel cut off) settings so as soon as you are off the throttle it kicks in.

Cheers,
Ross

[98ls1blackbird]

Actually lean cruise is available in this pcm it just has all the values zeroed out. I dont know enough about what I'm doing to massage the DFCO settings. I dont know if that would save that much because most of the time its going down the highway with the cruise on, in od with the tcc locked. I kind of wanted to know how to set the values in lean cruise because my son has an 04 GTO M6 as a daily driver and he has talked about it. Thanks for any help.

[zrx1200]

Actually lean cruise is available in this pcm it just has all the values zeroed out. I dont know enough about what I'm doing to massage the DFCO settings. I dont know if that would save that much because most of the time its going down the highway with the cruise on, in od with the tcc locked. I kind of wanted to know how to set the values in lean cruise because my son has an 04 GTO M6 as a daily driver and he has talked about it. Thanks for any help.
ok i have just driven 4000+k in last 2 weeks with wideband ect.first half with lean cruise.second half without.difference .5 of a litre per hundred k's..small price to pay for a happy engine..wish i had 8.1 litre's though....

[Chevy366]

Actually lean cruise is available in this pcm it just has all the values zeroed out. I dont know enough about what I'm doing to massage the DFCO settings. I dont know if that would save that much because most of the time its going down the highway with the cruise on, in od with the tcc locked. I kind of wanted to know how to set the values in lean cruise because my son has an 04 GTO M6 as a daily driver and he has talked about it. Thanks for any help.
Lean Cruise is in almost all American PCMs but it don't work (thank the EPA for that) , you can put what ever numbers you want there but the PCM will ignore the values .
Do a search here on the forum and you will come up with a good write up about why it can't be done .
Lean Cruise , the real story :http://forum.efilive.com/showthread.php?t=833&highlight=lean+cruise

[98ls1blackbird]

OK, thanks guys.. I thought it was worth a try.

[N0DIH]

For those who have lean cruise on Holden cars/trucks, is there a significant difference in mpg?

In reality, does it REALLY hurt emissions that bad for the gains in mpg?

With this economy, if we can gather some hard core data, we can start to push some of the politicians to lax up on the emissions laws and give the paying taxpayers a break.

Just a warped thought....

[ElusiveR]

Good luck. Emissions change very rapidly as you change AFR. NOx levels go very high at lean ratios - so much so that the catalysts can't keep up. And if you think emissions levels will go anywhere but down....

Ryan

[joecar]

I agree... even running slightly lean will increase NOx levels a great deal...

Your fuel economy will improve by upto 5+ MPG, but your NOx levels will go 2x or 3x the allowed limit... if you're getting this smogged, it will be the failing item (HC and CO will be ridiculously low, almost zero, the smog technician will say "that's weird")).

My understanding is that it's the NOx which causes the dirty brown inversion layer smog thingy you see in the Los Angeles basin on a hot day... altho you don't really see it anymore.

If you're pulling a square (air resistant) load, the engine will be under load even at cruise, and running lean may not be good for the combustion chambers (even if there's no ping, combustion chamber temperatures will go very high).

[N0DIH]

But don't CO and HC levels drop in the 15-15.3 despite NOx climbing?

[joecar]

Yes, HC and CO levels drop as NOx levels climb.

[N0DIH]

Seems we need a cat converter that works leaner than what we have.... Promote higher compression, leaner mixtures, better mpg, and let the cat scrub the exhaust for NOx....