Thread: How do I add fuel to just the decel and idle fuel cells?

I just started my tune after installing my heads. I replaced my 22# injectors with 60# to go with the turbo but now my idle and decel fuel cells go very lean, 17+ on the WB, actually dies on occasion. I know I can correct fuel as I modify my MAF table but this doesn't add fuel in lean condition. Is there a way to add fuel into just those two cells?

TIA,
Slim

If you enter DFCO if will spike lean and make it seem like an issue as the motor just becomes an air pump. You can shut off DFCO if you wanted and it will never do that.


And it sounds like you need to maybe get the right data for the injectors in the PCM if you are running 17 at idle, if your stoich is still set at 14.68.

I'm sorry, let me restate the issue. Once I let off the gas it temporarily spikes lean for no more than a second or so. During idle, it will bounce into and out of lean.

As for my injector fuel rate: the stock injectors were 22# (right for an L36?) at an 367 flow rate, the Siemans Deka injectors are rated at 65# per the ZZP site. My math was 22/65=.3385, 367*.3385=124.23

Isn't that correct?

Slim

Also, what is DFCO?

I couldn't tell you if the data is correct.

But what you are seeing on the wideband for the afr when you let off the gas is 100% normal, there really isnt anything you can do. It's not hurting anything because it can't. You let off the gas, injectors cut back to near nothing and the plate allows air in still for a short time, so the extra air just goes through with little to no fuel in a non load situation thus the WB showing lean. Sure thats not a super duper correct answer, but it's pretty much what happens.

Cool. I appreciate your time. So I shouldn't worry about those two cells too much? The main reason this came up is the car occasionally dies while driving when I let off during boost. Could that be part of the issue or should I look else where?

I recently dealt with the same issue. like said it normally isn't not going to hurt anything. me being top swapped i wanted it perfect, so i dove in deeper. I started lowering timing in the areas where the WB was lean. it corrected the problem. lowering timing is not going to hurt performance as this is not a cruse or wot or part throttle area. you are logging your wide band right? just watch where in relation to your timing table the AF goes lean and correct it.

I found out by trial and error that the 2bar MAP (even with the files swapped) was a no go for my car and was likely why my LTFT were so screwed up. Changed the MAP back to stock and no problems since.