Well I'm sure many have seen my endless posts about running lean etc.

My car as of yesterday, almost 60 out drove great. Mid 12's at redline with my vortech sc at 7 psi.
Then last night was upper 40's or so and ran really lean to low 14's.
Even below vtec would floor it and would jump right to mid 13's.

Then today again. Just under 60 degrees was mid 12's at redline again.

My question is, can 10-15 degrees really make that much of a difference on afr's?
Definitely is because of the cold or happens at night at least.
The last few weeks it has worked great at night and day but now being colder out at night goes lean.

Never would have though probably 12 degrees cooler last night would make that much of a difference to run super lean...


Forgot to mention. I am running just the vortech FMU with stock injectors and a Blox MAP block. No ems.
Please don't just say buy AEM EMS cause I really don't think this should happen.
I do want to buy stand alone soon though but just want to make sure it is no something else first.

 

colder air is denser, and that means more air in your combusiton chamber for the same amount of fuel.

this is exactly why its nice to have stand alone for FI setups. all this can be tuned. for you, i would just crank that stupid fmu more to richen up the mixture. if it wont, then rewire the fuel pump and then hopefully you will gain some more. if that doesnt work either, its time for a stand alone!

 

Normal with your setup, I'm afraid.

 

But really normal for 10-15 degrees? I could understand like a 30-40 degree difference causing 1.5-2 point on the afr but 10-15 degrees seems nuts.

 

My SOS setup with their piggyback (i.e. FVM) and RRFPR doesn't do this at all. I was actually expecting it to have big swings in the AFR when cold like that but it doesn't seem to.

 

Yeah I haven't heard anyone else having this issue. Maybe from like summer at 90's to winter at 20's but 60-45/50 seems crazy.

 

An FMU is garbage and cannot add any correction for FI to account for the change in density. You really need to get a piggy back or EMS.

 

I agree, I can't believe your motor hasn't grenaded itself yet, get an EMS and bring it to Evans brotha

 

The SOS FVM seems to be a step-up from the Vortech FMU.

 

Must be! All I know is that I'm very happy with my SOS kit, even the Base kit.

Moddiction, perhaps you can buy the FVM from SOS if you don't want to shell out the money for a standalone?

I believe they originally sold it as an upgrade when their kits were first released, but it's now included. I'd give them a call to see if it's even possible to buy separately, and/or see how it would work with your Vortech. You may have to get their RRFPR as well.