mx5cartalk.com

hey guys,

Who knows what rpm an na6 ecu open loops and what sensors it still runs in closed loop regardless?

Thanks,
Dann

Dann, I think it's the same code as the NA8 which goes open at 4608rpm. I'm basing that theory on the NA8 fuel table (load vs rpm) which seems to say that below 1/2 throttle (load <= 9) it will stay at closed loop until 4608.



Also, the NA8 still uses MAF, IAT, ECT and TPS in open loop.

edit: sorry, question was about closed loop sensors. I'd guess the same set plus O2. Idle also depends on clutch switch, gearbox neutral switch , TPS closure switches

I bloody KNEW you would be the bloke who would know.

OK, I have a dodgy CLT sensor, are you reffering to ECT as CLT?

Coolant that is.

Also dont forget the cam angle sensor...

Dann

yh, ECT = engine coolant temp. They usually fail open, so signalling very cold. I think if they fail closed the ecu recognises that and plays safe and assumes it's somewhat cold too.

Test is

NA8 and NA6 AFM and MAF are quite different, and the 1.6 doesn't have a linear TPS. So the fuel maps will look totally different. You're testing my memory here (used to have an AFR gauge on my NA6...)

Open loop isn't purely done on rpm. Under the right conditions at low RPM it can go open. But typically only if the engine is cold, or also if it's too hot (used to get open loop at idle when it was really hot!). I think it could also go closed loop at higher RPM if the full-throttle switch wasn't activated.

but that's trying to recall from about 6 years ago...

From what I recall reading a few years ago the NA8 code was pretty much just ported across from the NA6 with an update to the logic for the different sensors: variable TPS, reversed output curve from the MAF and the different idle control.

The Load column (the leftmost one in the table) is a calculation derived from MAF and TPS values in the NA8. I'd assume it was just AFM in the NA6. The table sort of indicates that no matter what the Load value is it always seems to point towards going out of closed loop above 4608. I've logged my AFRs at all sorts of throttle settings. There's never been a sign of closed loop cycling above 4500 and you an get open loop going right down to 1000 if you just put your foot down.

Someone with an NA6 and an AFR logger can test it out. Try accelerating at various steady throttle positions from around 1500 to 5000+ and see where the closed loop cycling pattern cuts out.

manga_blue wrote:Someone with an NA6 and an AFR logger can test it out. Try accelerating at various steady throttle positions from around 1500 to 5000+ and see where the closed loop cycling pattern cuts out.

Would you be able to tell this from a Dyno graph?

ie: the graph printout from the dyno AFR sniffer in the exhaust.


I'm pretty sure it's revs vs AFR

You can do it on a dyno or on the road with a logger. Makes no difference except that it's a helluva lot cheaper to log part throttle values on the road rather than burn up dyno time.

Just so you know what we're talking about, here's a sample of closed loop running on the road. The purple line is AFR cycling between around 14.3 and 15.5 on a steady cruise. Black line is RPM, red line is throttle position.

manga_blue wrote:You can do it on a dyno or on the road with a logger. Makes no difference except that it's a helluva lot cheaper to log part throttle values on the road rather than burn up dyno time.

True.

Just thinking I've got a dyno sheet here at home from Pam's car (NA6 stock ecu)

It has a printout of AFR/Revs

If it's of any use I can happily scan it, if not, I won't bother.