My GT4 with a jap-spec 3sgte and euro ecu is showing typically 14-15 on my air/fuel gauge. Is this too lean? My mechanic said that i shouldnt use the jap-ecu on 95 octane... Im running 15 psi turbo pressure.

Going on a road trip tomorrow, and i dont want to mess up my car again.

This post has been edited by skogs: Apr 11, 2014 - 3:15 AM

The stoichiometric ratio is 14.7:1

so i will be safe with this ratio?

10:1 is very safe
12:1 is reasonably safe
14:1 is agressively lean (less than safe)
15:1 is dangerous (knock)

This post has been edited by playr158: Apr 11, 2014 - 9:46 AM

I get consistently 14-15 while cruising and at mild acceleration, is this critical? Or is it just at wot that it shouldnt be that high?
I dont understand why it would be a wrong ratio, i only have som common mods:

- 3" turbo back exhaust
- Cone air filter
- stock blowoff valve
- blitz boost controller set to 1 Bar
- jap 3sgte w/o egr
- euro ecu

I havent had the balls to stare at the a/f-gauge while at wot yet.

This post has been edited by skogs: Apr 11, 2014 - 10:37 AM

I grew a pair and did some runs while having an eye on the a/f-gauge. And the ratio drops to around 10 when flooring it. Very safe then:)

Yeah, was going to say especially being a turbo it'll go richer as your floor it. Sounds like everything is perfect. Was worried for nothing about nothing.

depends on what you are doing. 14-15 is just fine for cruising, if you are hammer down and full boost, you want to be in the low 11's

>


When at idle or cruising you want to be at 14.7 because there is not much load on the engine and the turbo is not really doing anything. Once you floor it and boost builds, you want that ratio to get richer to supply more fuel to the extra power you are making. Normally when people talk about what afr their car is running, they are referring to the afr under wide open throttle and at full boost.

Here is a good visual example of the type of look up table your ecu uses. The 100 load on the left is 0 psi, and the 200 load is about 15 psi.

http://www.miataturbo.net/attachments/mega...-afr_tablez-jpg

Thats exactly where mine is between 14-15 idle and cruising
under boost, down to aout 11 or 12