A couple of Gtir questions

Discussions concerning the M7790 cpu

Moderator: Matt

Post Reply
Fast Guy
 

Posts: 27
Joined: Sat May 12, 2012 3:25 am

A couple of Gtir questions

Post by Fast Guy »

How do you lean out the cruise afr? as you can't turn the o2 flag off and go leaner than 14.7.

Also are there anymore enrichment maps not discovered as from cold it likes abit of throttle to start easily and when I blip the throttle from idle it bogs down because fuelling goes to over 8ms but I can't see anywhere near that looking at the maps. It seems to be OK after 50degs.



My full throttle fuelling is into the 10s is that way too rich? Is mid/low 11s better?
CoZZm0
 

Posts: 133
Joined: Fri May 21, 2010 8:07 pm
Location: Sydney, Australia

Re: A couple of Gtir questions

Post by CoZZm0 »

You should be able to turn the O2 flags off ?
Fast Guy
 

Posts: 27
Joined: Sat May 12, 2012 3:25 am

Re: A couple of Gtir questions

Post by Fast Guy »

Fast Guy wrote: you can't turn the o2 flag off and go leaner than 14.7.
You can turn them off, but you can't adjust the value in the box to leaner than 14.7 with the flag off.
Fast Guy
 

Posts: 27
Joined: Sat May 12, 2012 3:25 am

Re: A couple of Gtir questions

Post by Fast Guy »

Well I tried running with the O2 feedback switch off and if anything it ran slightly richer (14.5s) than with the O2 on and nowhere near the 15.5ish I wanted to try.
Fusion Ed
 

Posts: 281
Joined: Fri May 04, 2007 4:13 am
Location: Chertsey Surrey
Contact:

Re: A couple of Gtir questions

Post by Fusion Ed »

You should keep an eye on EGT if your going to do this.
Fast Guy
 

Posts: 27
Joined: Sat May 12, 2012 3:25 am

Re: A couple of Gtir questions

Post by Fast Guy »

I can't do it anyway as it doesn't seem to be possible to run lean in the low load areas with the o2 feedback off it still seems to ignore the figures in the map cells and runs around 14.5s.


What are reasonable egts?
Eric
 

Posts: 227
Joined: Mon Jan 14, 2008 7:59 pm
Location: Holland
Contact:

Re: A couple of Gtir questions

Post by Eric »

I can't do it anyway as it doesn't seem to be possible to run lean in the low load areas
it is possible if you really want to by adjusting the K-value and disable O2 feedback completely, although it's not a recommended method, because all values in the fuelmaps will be off by an x-percent.

you will have to add fuel in all the non-cruise/load areas of the fuelmaps or you will melt a piston in seconds....


and, as recommended, keep a good eye on the EGT's

I'm not sure what safe EGT's are for a SR20, but usually it's best to keep it below 800C
Fast Guy
 

Posts: 27
Joined: Sat May 12, 2012 3:25 am

Re: A couple of Gtir questions

Post by Fast Guy »

Is that pre or post turbo? My EGT sensor is in the collector for the manifold pre turbo and it goes over 800c regularly.
It runs hotter on cruise than fulll throttle, but I guess the amount of fuel going in at wot is the reason for that and that it's cruisingat 14.7 which I read somewhere is where it runs hottest.
Fusion Ed
 

Posts: 281
Joined: Fri May 04, 2007 4:13 am
Location: Chertsey Surrey
Contact:

Re: A couple of Gtir questions

Post by Fusion Ed »

Pre turbo. Post turbo it will be much cooler.
Post Reply