Closed loop idle

[speeder]

Great information Tim and Jim!

My Z will be running in a week or so with an EGT gauge in addition to WBO2.

The correlation between EGT, timing , and AFR is just what I've been looking for.

[clint78z]

Yes alot of good information, I did have a chance to pull some datalogs this weekend.

 

For now I am getting the map sorted out under 1 bar or zero psi. I am using closed loop correction to indicate which cells need to be set higher or lower. I am tuning them all to stoich for now, it seems to be working fairly decent. It still doesn't want to idle smoothly when I try to idle too lean it has trouble under 1.34ms on my DFI. I took TimZ's suggestion and knocked back the timing at idle and opened up the idle bypass a little more. I am still not at stoich but closer. The throttle response off idle is not quite up to par, but decent. The O2 sensor is a real pain in the butt at light cruise, dialing fuel in and out. I haven't really touched the igntion maps yet, another friend says he uses a gmeter and tunes for max G force without knock.

 

Yes my cheap ass might have to go wideband if I can find an NTK anymore for cheap. Anyone have a secret source for a cheap NTK sensor ??

[BLKMGK]

Suggest you take a look at the new AEM W/B. It's CHEAP but has no display yet. It can output both 0-5volt linear and a 0-1volt that simulates an OEM O2. You could probably buy one of the DIY displays and reprogram the PIC for the new calibration. AEM is working on a display, this box was primarily for use with aftermarket ECUs but demand for a display have still been great by those users. It uses a cheap Bosch sensor Info at http://Http://forum.aempower.com/bbs/

[Owen]

FWIW, I don't believe you have to idle in closed loop, I don't with my FAST setup. What I've learned from some tuners is that you should give the engine what it wants, not to force it. Meaning, if your engine idles smoothly and it's rich, then so be it, maybe a certain setup doesn't like to idle at stoich (as the L6 mentioned above). As long as it's safe for you and the engine, you should be ok.

 

I've spent way too much time trying to smooth out my Actual AF ratio vs Target AF ratio curve. I'd think with a WBO2, it's almost impossible to get the EG to idle at 14.7 each and every millisecond (or whatever your time axis is on your tables).

 

Just my 2cents

Owen

[clint78z]

Agreed that you don't have to run in closed loop for idle, my car runs quite well in open loop. The thing is it takes more time to set up for closed loop, many don't bother. You have to massage the cells, didle with the timing and throttle plate. I am not sure if my DFI has enough control to make this happen.

 

My 0 to 1 bar fuel table is shaping up rather nicely, with mabey 2-3 percent correction in a few areas. The TPS and delta MAP enrichments are, fairly close. I can't set the O2 trim authority so every once and a while at high vacuum light cruise the O2 sensor keeps jerking. Once I get this map close to bang on, I will lean it out a little more and then turn closed loop right OFF !!!

 

Thanks BLKMGK for the link, it looks like a good way to go since they clamped down on NTK sales. I couldn't find a price on the AEM setup, wouldn't happen to know what it is worth ??

 

I will post some datalogs soon so everyone can have a look, and I will write a little bit on how I went about tuning it.

[BLKMGK]

One thing I wish I could do with th eAEM is turn off closed loop at idle and then turn it on higher. Instead I can only turn it off up higher if I want but down low it's always on. I guess I can just make my idle targets rich is all One thing to understand about A/F at idle is that exhaust flow is VERY slow and getting the W/B to read reliably can be more difficult since changes made take awhile to hit the sensor. I idle a bit rich, like 13.5:1, and it's MUCH more stable than if I go for Stoich. Part of that is granularity - when I'm down that low my map isn't granular enough. I can fix that but it requires doing a pile of math and work so I've not done it this time around - I plan to in the future. Watch the timing too - get too aggressive and the idle will surge. My OEM ECU on th eSupra supposedly only has 12 degrees of timing at idle, Im running as much as 20 but cannot quite get Stoich idle. <shrug>

 

As for the price of the AEM W/B I'd look someplace liek Horsepowerfreaks.com since Chris has good prices. However be aware that the AEM doesn't YET have an external display. One coudl certainly be made and if you're handy with electronics the DIY display could be modified to work but as of yet it's not been done. AEM intends to fix this but I have NO idea what their time table is. I hope to have an AEM W/B one of these days for either the Z or my Mustang - possibly both. I iwll not tune without one!