Running lean

[Fos]

Hy, I own a 95 talon fwd, and ther's a problem... while boosting, the a/f mixture gets really lean. It chokes on about 1bar boost.Feels like a fuel cut, but its not.

I'm using
stock t25
stock fuel pump and injectors, only rewired the pump.
different intercooler, but it has NO boost leaks.

I did the boost leak test... the intake system holds fine. I checked all the connectors and vacum lines, checked the plugs (totally white = running lean)

My fuel pressure hits 60 psi while starting the boost and stays there... shouldn'i it constantly rize?? Does anybody know, whats the normal fuel pressure on idle and on boost, while using stock equiptment.

Thank you.

 

[talontsi9095]

I am having the same exact problem with my car and i just got done fixing a boost leak. I have an upgraded fuel system and a small 16g i was running 1.4 bar of boost but it feels like at 1 bar of boost it hits a fuel cut. So if i figure it out ill post back up.

 

[Jingx284]

how do you know its running lean? If its just cutting out like that, it could be something as simple as your spark plugs. Start from the easiest and work your way up...

 

[alex]

The stock base fuel pressure for a 2g whether its m/t or a/t is 43.7 PSI.

 

[talontsi9095]

Well im going to replace my plug wires and my plugs first and make sure that isnt it my car doesnt start choking until 4000 rpms.

 

[steve]

My fuel pressure hits 60 psi while starting the boost and stays there... shouldn'i it constantly rize?? Does anybody know, whats the normal fuel pressure on idle and on boost, while using stock equiptment.

Base fuel pressure with the reference hose off on a 2G is 43 psi. The vacuum or pressure from the reference hose modifies the base 1:1 so engine vacuum lowers the fuel pressure and boost raises it. At idle with normal 18 in hg vacuum the fuel pressure should be about = 43 - 8.84 = 34 psi and at 0 in hg vacuum/0 psi boost it should be 43 psi. Each psi of boost should increase the fuel pressure one psi. You shouldn't see 60 psi fuel pressure until 17 psi boost.

Steve

 

[alex]

Make sure the fuel pump is actually pumping out gas. Make sure you can hear it when starting the car.

 

[Fos]

I know it is lean, because the spark plugs are white. The fuel pressure is OK and no boost leaks exist. I did some datalogging and while the throttle was max, the air flow kept rizing and suddenly the a/f fell like 50%. It only does so, when I get boost, when I just floor it with the 5 gear and low speed, It starts to accelerate and the A/f shows rich... normal.

I allso checked the air flow rates that ECU gets and they are ok, so are timing, fuel trims, o2 and so on and so on... Cant understand, WTF is wrong. The lean mixture hits dramatically.

 

[a1320eclipse]

mine is doin the exact same thing to a "T", well, according to the a/f gauge. and the plugs are white, just rolling into the throttle it runs rich, and then all of the sudden it backs way into a lean condition. Ive got a 90 tsi with rewire fuel pump, k&n, and bc.

 

[Fos]

Make sure the fuel pump is actually pumping out gas. Make sure you can hear it when starting the car.

It should be quite impossible for the pump to pump out anything other than gas, because It runs smooth, no studdering and no fluctuation in the fuel pressure. If it would pump out something else, it shouldn't choose between boost and normal coast, the pump allways pumps 100%. And my FP is 60 psi while boosting.

I even swapt my MAF and the results are 100% the same..
When I disconnected my O2 , It still ran lean ... no master differences. Although, with the disconnected o2 the ECU Should use the fuel map and I should run a bit rich mixture.
(even checked the ECU visually, it all shiny and no burned tracks or anything, clean pins and all.)

Once again ... what the hell is goin' onWTF


If anybody out there has found a solution to the similar problem, please let me know...

 

[Fos]

http://www.dsmtalk.com/forums/showthread.php?p=1388840#post1388840

I allso described my problem there....

Please help... I'm out of ideas right now...

 

[b15turbo]

I have the same problem on my car, Anytime i add fuel into my car it goes lean, I was using the logger to see what it was running and any time i add fuel threw my safc or just raising my fuel pressure the car goes lean I’m in process right now of putting a new turbo on my car with new manifold and o2 housing and i did notice that my old o2 housing had a little crack in it and one of the sides was not bolted at all so i don’t know if that caused it or not so ones i install all the new parts with my new o2 housing we will see if that fixed it or not.

 

[b15turbo]

I just remembered this too, when i ran .85v on the logger i had 0 knock and then i add fuel and it went leaner like .80 but i would get like 5 knock. And i did check my fpr everything is set right and the fuel does goes up when i hit boost and it holds fine. Some people told me it could cause because of my o2 housing being cracked and not bolted tight enough so you might want to check that too.

 

[steve]

It's not uncommon for the plugs of a DSM to be white. The stock plugs run on the high end of their heat range. The fact that the car spends a lot of time in closed loop where the A/F is 14.7:1 contributes to the plugs burning off any deposits.

Power loss could just be due to knock. If your getting -10 degrees (negative) there is no question your knocking. Even if your getting 10 degrees (positive) your still having the timing retarded because of knock.

Steve

 

[Fos]

thanks steve, I try to replace my old Denso plugs for some NGK's, and do some more dataloging and post it here. I dont have the old ones left...

 

[Fos]

I thought about what you said Steve and I still think that I'm having some kinde of a kinky problem. Its totally unnormal for the A/F to get SO lean when I hit the gas pedal. My narrowband displays me the first light, allthough it should be like 7'th or 8'th.

The logger allso shows me rich when starting to accelerate and then fall way lean.
I replaced my sparks allso... still the same.

I allso cant explain how the hell it runs lean (no black smoke from the exhaust) when I disconnect my o2? Shouldnt it run on the map and automatically turn me rich?

Edit: did some testing today (datalogging again in next week) and I noticed that my A/F was rich just until the turbo started to spin, no matter what gear.

 

[Fos]

update... my timing advance is 30 when not accelerating hard and while accelerating, it drops to 16-17 degrees. I guess that eliminates the detonation question huh?

try to post a log tomorrow...

(just in case canged the fuel filter allso... thank god thees mitsubishi engineres for finding the Perfect location for the filter )