General Help with fuel trims, low stuck at 140%

[BlackbirdOfPrey]

I ran MMCD lately and it says my low fuel trims are 140%. I don't know why this could be considering I have a walbro255 w/o an AFPR. Shouldn't my trims be a lot lower? My medium and high are 100 solid. Anyone know why this would be?

 

[Reese92tsi]

Did you remove any honeycombs from the MAF? Any major boost leaks? Has the fuel filter been changed?

 

[BlackbirdOfPrey]

lower honeycomb was removed as per free mods, fuel filter has been on for less than 10k miles, and boost leaks not that i know of, if it warms up ill check again...

 

[spyderturbo007]

It could be the result of a couple of things. PCV valve age, O2 sensor or even running a 255lph FP with no AFPR. It's hard to narrow it down anymore without more information.

Leak check?

 

[Reese92tsi]

Putting the lower honeycomb back in will probably restore idle quality and get your low trim back to normal but it will put you alot closer to fuel cut.

 

[dsm-onster]

It could be the result of a couple of things. PCV valve age, O2 sensor or even running a 255lph FP with no AFPR. It's hard to narrow it down anymore without more information.

Leak check?

I agree. I would definately look at the pcv valve. It could be letting air get sucked in but pushing closed like it should for a boost leak test and "fall under the radar". Do you have your valve cover vent open? on the valve cover? You can't just cap the intake pipe off ank keep the pcv valve on the car. the air will be sucked in from the valve cover vent and into the valve cover then into a properly functioning pcv valve. add this to a lower honeycomb removal and it would explain alot.

If you have a walbro 255 hp pum and stock fpr then your low trim should be pegged rich (under 80) not pegged lean as you are reporting. This means that, even though you are overruning you fuel pressure regulator with the fuel pump, you're still running lean at idle !!!

 

[power=dsm]

what is your safc setting at ?

 

[BlackbirdOfPrey]

I have no SAFC. Breather on valve cover is open. I will do a leak test tomarrow when I install my EPROM, hopefully have some more info after that.

 

[spyderturbo007]

If you have a walbro 255 hp pum and stock fpr then your low trim should be pegged rich (under 80) not pegged lean as you are reporting. This means that, even though you are overruning you fuel pressure regulator with the fuel pump, you're still running lean at idle !!!

Thanks for catching my screw up.

Apparently my brain was functioning backwards yesterday.

You get a rep point.

 

[dsm-onster]

Thanks for catching my screw up.

Apparently my brain was functioning backwards yesterday.

You get a rep point.

Thanx. I hope I wasn't implying that I thought you didn't know this. Just clearing it up for future researchers. My functioned has brain backwards many times. I figured I wasn't alone in my affliction .

 

[BlackbirdOfPrey]

Installed ECU, found one good sized boost leak so far, have to wait to fix it because I don't know what part this is (doesn't say in manual, and most parts stores didn't know either).

 

[spyderturbo007]

Thanx. I hope I wasn't implying that I thought you didn't know this. Just clearing it up for future researchers. My functioned has brain backwards many times. I figured I wasn't alone in my affliction .

Nope, not at all. I appreciate you catching my early morning mistake.

 

[jepherz]

o2 sensor? If it's a leak, its more than likely after the TB somewhere.

 

[DSMcamaro]

I also had a 140% FTRL reading after I installed my warblo 190 with no AFPR. But now I have a translator to get it back closer to the 100% range.