Hondata

I drive a 2000 turbo ITR just Hondata tuned, we made 295whp on a Mustang MD dyno. Everything is wonderful, except so far in a week I have gotten code 43 twice, cruising at 60mph at about 3200rpm. I notice that the ECU goes into open loop as soon as I get the code. Today, no code all day. Any ideas? I know it is a fuel system fault, but does anyone know exactly what criteria in terms of inputs the ECU gets when it puts out code 43. Thanks in advance.

your high vac/low load area of the fuel maps are out to lunch (once the o2 trims over a set % into or out of the map it mils assuming that something must be wrong for the map values to need that much correction)...bet you dollars to donuts.

I'm discovering some more issues, maybe related to the reason I'm getting the code 43 occasionally (3 times in a week)

1.)stalled once at idle - hard to start afterwards
2.)this morning EGT climbed to 1400 at 65mph 3200 rpm cruising
3.)surging while cold and warming up
4.)will be in closed loop and running fine, then goes into open loop for no reason
5.)occasional stumble at around 3000rpm low load

Can all of this be tuned out by changing the low load high vacuum map?

None of this was happening prior to Hondata

If you continue having hard starts, try unplugging your evap purge solenoid.

I only had one hard start, that was after the car was warmed up, I pulled into a gas station, left the car idling for about 10 seconds, then it died, when I attempted to start it it just cranked and cranked, I eventually got it going by holding the throttle fully open.

I've been thinking about this now for a while, and I'm starting to think that maybe I should reconnect the coolant lines back onto the throttle body, I have it bypassed. I'm going to try that and see if this still happens. I have had it bypassed for a couple of years, no issues, until I got Hondata...that's why I was suspecting the programming.

1400F is not uncommon at cruising speeds, though sometimes adding a little advance at that point can drop 50F or so.

What is unusual about it is that it has never happened before. It was like a fluke thing. I'm wondering how it just decided to go lean..

Well after taking my tuner for a drive on the highway, based on what he saw, he suggested that my O2 might be bad. I came home, threw in my secondary O2 that I had sitting in my toolbox....

Everything is back to normal, EGTs at cruise are back to where I expect them to be, and the closed loop issue seems to be fixed...

I haven't gotten another code 43 since.

open or closed O2 or no O2 shouldn't have had anything to do with your bad starts at least. Your in Open until you hit 5% throttle to 790bar intake vac.
I believe Your 1400 problem was the O2 . But your starts shouldn't have improved over an O2 swap.>?!. heh? Am I wrong?

The car is in fact in closed loop at idle normally, if the O2 sensor is defective and the car is therefore in open loop at idle it will run rich as hell, so after running rich the car is shut off, it would make sense that it would then be hard to start with the plugs covered in soot. Once the O2 sensor is operating properly, the plugs would stay clean therefore enabling an easier start....my opinion anyways.

What injectors are you using?

me?

rc 440s