Hi guys,

I’ll describe the symptoms and hopefully some bright spark will enlighten me on where I’m going wrong:

Firstly- specs. S/C Miata, with intercooler. IAT bung is just before the intake mani, and I do not believe the sensor itself is subject to heat soak.

I USED to find that my car would run much leaner in cold/winter weather and I’d always have to re-tune my ve table.

I’ve since totally changed coolant corrected air density from the DIYPNP basemap.

I’ve changed it to IAT corrected:

(deg c)

13 103
16 105
19 107
22 112
25 115
30 120
40 125

This ends at 3k rpm on the assumption that there’s sufficient airflow to not be affected by heatsoak of the intake tubing.

Map seems much better now. I’ve been tuning in the mornings when ambient is about 8 deg c.

WOT is tuned for 11.8AFR.

I went for a long drive over the weekend and WOT was now 12.5WOT. most disconcerting. Ambient was much higher about 15 deg.

This was on the motorway at about 4k rpm.

So it seems the ECU is over correcting for the warmer, less dense air and removing too much fuel.

Where can I play with parameters? It can’t be IAT corrected air density, because that ends @ 3k rpm.


Stumped.

 

Assuming this is an MS2 becaused you mentioned the DIYPNP. In which case the IAT related corrections do NOT end at 3K rpm.

 

Thanks for the reply.

Yes, it is a MS1.

In coolant corrected air density, you can change it to IAT corrected air density. That has parameters for the rpm range it ends at. which is 3k rpm in the basemap.

However, if it really doesn't end there, then i know i've probably been too onservative in my correction

 

MS1 is a different story and if you've set it up to end at 3000rpm, then it should. Watch the gair correction in a datalog to verify.

 

ok- i'll check it out.

if it is, then i'm thinking i need to extend it to redline.

 

Appreciate your support here.

I’ve taken a log this morning.

MAT was 2.8 deg c this morning and Gair was 109

After Motorway journey and heatsoaking traffic, MAT rose to 15deg c. Gair 107.

Both times rpm is around 1500. Is this right?

As expected the taper works, and when I hit highway rpm over 3k rpm Gair drops off to 105.


Can someone comment on whether this is correct?

 

Yeah that's correct.

 

Cheers again.

Any idea why i'm 11.8AFR in cold weather and 12.5 in warm WOT?


is Gair removing too much?

 

Rather obviously I would say.

 

Cheers.

I'll increase the IAT corrections all the way to redline.

Wanted to get this sorted before I start playing with the timing map!