Setting 650cc Trims with MAFT

mattdev · 05-08-2008, 09:05 PM

I just installed my FIC 650's and am having a hell of a time with my fuel trims. I am tuning w/ MAF-T.

Of course, you can't just set the MAF-T to 650cc, you have to richen it up. The MAF-T is set ALLL the way down to 470cc injectors ans will still read 7%!! I have heard of people setting 580cc settings for 650's, but 470 just seems way too low. I have worked my way down from the 650cc setting down to 470cc settings! From about 520cc setting and up and up my trims were pegged at 18% (leaned out to the max)

Any ideas? I will check for pre-o2 exhaust leaks in the A.M. I am running stock re-wired fuel pump, but shouldn't be a problem... What else could cause such a lean condition?!

EDIT: I brought the trims down to 0 and the Translator is set for 460cc injectors. My o2 voltage reads .78 and my wideband is reading a perfect 14.7 at cruise and a little more lean at idle (still 0% idle trim).

EDIT: More details that may help. My T-25 is days from going out, occasionaly blows oil and whines like a siren (don't worry I have a new 18g sitting in my apt.)

JayRolla · 05-09-2008, 08:39 PM

You are looking at the trims all wrong. If you add fuel the trim goes down, if you take away fuel it goes up. So when you have it set for 470cc injectors its dumping lots of fuel and the trim is going to peg rich which is 70%.

Switch it back to 650cc injectors and adjust accordingly but remember if you add fuel it goes down and when you take fuel away the trim goes up.

mattdev · 05-09-2008, 10:27 PM

I understand that adding fuel sends the trim down and subtracting fuel brings it up. And the problem is that I am adding gobs of fuel just to achieve a level trim.

Again, right now I can 0 out the trims, but the settings are abnormally rich to achieve the 0 trim. Would a lack of Fuel Pressure cause this perhaps. Maybe due to the stock fuel pump or an old fuel filter. I checked my fuel pump voltage and I easily get 12v (thought maybe I messed up on the rewire) however the filter has not been changed. I don't have any vacuum or boost leaks either...

JayRolla · 05-10-2008, 10:02 AM

To get my low trims inine I have to add a lot at lower rpms, how you know your rich, do you have a wbo2 or are you just guessing from the fuel you have to add.

mattdev · 05-10-2008, 06:37 PM

I have a wideband and with the fuel trims at zero, I run a 14.7. I am just wondering if something is wrong since I am adding a ton of fuel to get the 14.7/0% Trim. Unless the MAF-T is completely off (by 200cc). Again I have heard that you must richen it up some (set to maybe 580cc) but set at 580 I am still ridiculously lean. It just makes me wonder...

I must have been running super lean with my stock injectors, as I had it set to the same setting I do now, with 650's. It WAS throwing a P0170 (Fuel Trim), so I'm sure I was.

JayRolla · 05-10-2008, 08:21 PM

Hmm thats wierd, if your afr's are fine and you have low IDC's I would not worry about it. Dont a boost leak test lately?

Talek · 05-11-2008, 11:45 PM

I have FIC 650's and am running GMAFT and I'm having an issue with overly lean conditions as well. I've got my mid and wot dials set for 6, which is what, 35% more fuel? and I still get small amounts of knock. My o2 usually reads around .91-.93 under boost, I don't have a wideband only a palm logger.

mattdev · 05-15-2008, 11:06 PM

As stated before, would a blown turbo count as a boost leak, or be causing this? I install my new 18g next week, I guess I'll find out for myself.