QuickSilverGSX9
20+ Year Contributor
- 123
- 0
- Mar 9, 2003
-
Fairfax,
Virginia
Hey all, I just need some help understanding all of this. First off, my mods are: 3" exhaust from the o2 back, 2.5" UICP w/ TB elbow, 680cc injectors, walbro 255lph hp fuel pump, hallman MBC, BR/SX AFPR w/ gauge, and the ramchargers MAFT with a 3" MAF and universal K&N filter.
Okay, so my fuel trims are acting very strange, at this point, tuning is not working with my MAFT. I've called and talked to Mike from Ramchargers and the things he suggested aren't the problems. My fuel trims after resetting the ECU are obviously 100%, however, over the period of several hours they fall down to 81% for mid and high, and low seems to do something different everytime i reset the ECU. Sometimes its really lean (139%), and sometimes its great and sits right between 90-110%. Also, I'd like to point out that even though my low fuel trim was decent, it was between 93-104% all evening, and my high fuel trim was 81%, anytime I went WOT I started to knock at first, and then as the RPM's increased, the knock would decrease. However, I notcied at and above 5500 RPM's, the car would physically and audibly stutter. Any ideas?
Mike suggested an exhaust leak on the manifold, turbine section of the turbo, or the o2 sensor housing itself. Casuing my previous 139% low fuel trim. I removed both the lower and upper heat shields and inspected them by eye as best I could, and then turned the car on and felt all around that area and felt no leaks whatsoever.
The base setting for the MAFT is at 5, which is supposedly for 600cc injectors (or minus 20%, I believe). Turning the switches for idle, mid, and wot had no change whatsoever, my mid fuel trim would drop to the 80%'s before high would and so I tried to lean it out, I put it at D or C, whatever -20% fuel at MID is. Anyways, it certainly did not lean my mid fuel trim out whatsoever, and yes, this is over a period of time, I gradually leaned mid out until it was at -20% and over that period of time it continually fell until it was 81%. I also tried leaning out the high fuel trim, and it didn't have any effect either, it gradually fell to 81-83%.
If anyone has any suggestions as to why my fuel trims are so strange, please feel free to respond, anything is worth trying at this point. I've made sure my fuel pressure is where it's supposed to be, and I've checked for intake leaks, made a cold-air box for my air filter, and everything else that's been advised. Thanks for the help.
-Bill
Okay, so my fuel trims are acting very strange, at this point, tuning is not working with my MAFT. I've called and talked to Mike from Ramchargers and the things he suggested aren't the problems. My fuel trims after resetting the ECU are obviously 100%, however, over the period of several hours they fall down to 81% for mid and high, and low seems to do something different everytime i reset the ECU. Sometimes its really lean (139%), and sometimes its great and sits right between 90-110%. Also, I'd like to point out that even though my low fuel trim was decent, it was between 93-104% all evening, and my high fuel trim was 81%, anytime I went WOT I started to knock at first, and then as the RPM's increased, the knock would decrease. However, I notcied at and above 5500 RPM's, the car would physically and audibly stutter. Any ideas?
Mike suggested an exhaust leak on the manifold, turbine section of the turbo, or the o2 sensor housing itself. Casuing my previous 139% low fuel trim. I removed both the lower and upper heat shields and inspected them by eye as best I could, and then turned the car on and felt all around that area and felt no leaks whatsoever.
The base setting for the MAFT is at 5, which is supposedly for 600cc injectors (or minus 20%, I believe). Turning the switches for idle, mid, and wot had no change whatsoever, my mid fuel trim would drop to the 80%'s before high would and so I tried to lean it out, I put it at D or C, whatever -20% fuel at MID is. Anyways, it certainly did not lean my mid fuel trim out whatsoever, and yes, this is over a period of time, I gradually leaned mid out until it was at -20% and over that period of time it continually fell until it was 81%. I also tried leaning out the high fuel trim, and it didn't have any effect either, it gradually fell to 81-83%.
If anyone has any suggestions as to why my fuel trims are so strange, please feel free to respond, anything is worth trying at this point. I've made sure my fuel pressure is where it's supposed to be, and I've checked for intake leaks, made a cold-air box for my air filter, and everything else that's been advised. Thanks for the help.
-Bill
Although low has been at 81% lately too. I've also checked all the same stuff and have had no results 
My car runs fine and gets no knock though. I just keep getting fuel cut 
thank you finally someone who actually made some sense of all this stuff.
