DIY_EFI Digest Sunday, April 9 2000 Volume 05 : Number 142 In this issue: RE: C/L WB/WOT OEM ECUs... See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- Date: Sun, 09 Apr 2000 04:59:17 -0700 From: Carl Summers Subject: RE: C/L WB/WOT OEM ECUs... Absolutely, The probs I have run across with closed loop control isn't always the sensor, but more likely, the software doesn't know what to do with the "crazies".......the guy's that "know" don't listen to the guy's that "do" or have "seen it"....(grumpy knows what I mean)......It's pretty easy to take an output and change it to an AFR, and then have the controller take over what it does from there......but if they(the controller..hehe) doesn't know or anticipate what to do next.....guess what.......anyway....ttyl - -Carl Summers - -----Original Message----- From: owner-diy_efi@xxx.org]On Behalf Of Garfield Willis Sent: Saturday, April 08, 2000 10:40 PM To: diy_efi@xxx.org Subject: Re: C/L WB/WOT OEM ECUs... On Sat, 08 Apr 2000 18:28:45 -0700, Doug Dayson wrote: >Is WB O2 closed loop control at WOT actually safe? > >I was just thinking that any fouling and/or other malfunction of the O2 sensor >etc could result in you going way lean under load with catastrophic results... then On Sat, 8 Apr 2000 21:50:54 -0400, "Kendall Frederick" wrote: >There have been a couple of stories of Fel-pro users having just that >problem...I think I'd use the w/b to set my WOT fuel map, then run it from >the tables most of the time. That's what several FelPro users I know do. Yup, in the face of additional failure modes (more electrics), you might very well decide that O/L is a more conservative/safer approach. The problem has often been that in an atttempt to get those O/L tables just right, sometimes you err on the lean side, with disasterous results too. Hence the interest in using C/L WB sensing to prevent that from happening. That risk has to be weighted against the likelyhood of sensor/electrics failure, for sure. But everyone's assuming that the major role of precision O2 sensing WILL be in the tuning/cal work that's needed for dialing in better O/L maps. This thread is just for those intrepid souls who insist on going one step further and pushing the envelop of C/L control. Using this sensing technology to cheaply open that up to some who want to experiment, is kinda like a "second-order effect". Not the main thrust of the technology, but an interesting and alluring one. So don't misunderstand the motivation; nobody is thinking (I hope) that C/L WOT control is always safer than O/L. You're trading the possibility of more *precise* mixture control, for the perhaps increased possibility of failure in the system, especially in it's infancy. This is often the case; I'm sure FelPro has heard from it's share of clients who blew engines, and blamed it on the C/L controller, rightly or wrongly. Realistically, a failsafe/fallback mode "if the WB O2 sensor suffers sudden catastrophic failure during WOT" is probably dreaming. Where it really matters, you likely just don't have time to decide, "oh, the O2 sensor isn't responding, let's transition to O/L". We're talkin fractions of a second. Altho the OEM ECUs do have just that sort of fallback, I really wonder if it's capable of responding fast enough, should you be under *heavy* load and suffer a lean transient due to sensor failure. OTOH, certainly wise to consider such "what-ifs", and decide if there's anything that can be done to mitigate. I'd say it's a sage and appropriate observation to bring up at this point. There be some wee dragons here. :) Gar - ---------------------------------------------------------------------------- To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes) in the body of a message (not the subject) to majordomo@xxx.org - ---------------------------------------------------------------------------- To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes) in the body of a message (not the subject) to majordomo@xxx.org ------------------------------ End of DIY_EFI Digest V5 #142 ***************************** To subscribe to DIY_EFI-Digest, send the command: subscribe diy_efi-digest in the body of a message to "Majordomo@xxx. A non-digest (direct mail) version of this list is also available; to subscribe to that instead, replace "diy_efi-digest" in the command above with "diy_efi".