Extremely lean LTFT's
02-12-2014, 05:23 PM
#1
Extremely lean LTFT's I need some help from the fueling experts here. I have a 2000 ws6 fully stock auto car. I installed an ls6 intake and removed but did not take off the egr pipe that went into the ls1 intake. I simply unplugged the connector to power the egr motor until my Lt's get here. I also removed the air injection hoses and capped them off near the mani's. The car has an SLP ram air kit with a smooth bellows and a k&n filter. Stock car other than that. I was logging LTFT's and they are around +19+22% while crusing and go to 25% when WOT. It starts right up and runs good with no hesitation at all. Motor sounds beautiful and I am not getting any KR that I can remember. I replaced the fuel filter 100 miles ago, replaced the plugs with NGK v-power plugs that are stock heat range and run a can of seafoam through the tank at the same time. Why is my car's LTFT's in the +19+22 range? Is the egr unplugged and the addition of an LS6 intake capable of causing this alone or is there something else I should be looking for? Thanks for any help.
Last edited by JRENIGAR; 02-12-2014 at 09:21 PM.
02-15-2014, 11:16 AM
#2
An update: I logged my STFT's and they are +5 to-3% on both banks while crusing down the highway in OD and running 1800 RPM or so. I also logged my o2 sensor voltage to make sure they are good and they were back and fourth between 0.78v to 0.11v on both banks consistently so no problem there that I can tell. I did a 2nd gear WOT run through 3rd and no KR whatsoever and the car runs absolutely great for a stock car. On the WOT run the LTFT's went straight to +25% and didnt budge at all. I also noticed that when I come to a stop in gear at idle the RPM is about 550-600 and the STFT's go to like +19 to +22% and at the same time the o2 voltage drops to around 0.05v or so. WTF? I have had the battery cable off for quite a bit while replacing the rear cover seal due to a leak so the memory should have been reset. I installed new intake manifold gaskets and am pretty sure there is no vaccum leak.
Last edited by JRENIGAR; 02-15-2014 at 06:38 PM.
02-17-2014, 07:14 AM
#5
Your tune is obviously lean or there is a leak somewhere in the exhaust. STFT isn't really important as they simply drive your LTFT's. If you are off 20% in the VE table and your LTFT are 18% your STFT will be 2%. You want LTFT under 5% each.
I'd go through the exhaust first. Check to make sure the EGR valve isn't open. A leak in the intake could be at fault as well. What are your IAC counts at hot idle?
I'd go through the exhaust first. Check to make sure the EGR valve isn't open. A leak in the intake could be at fault as well. What are your IAC counts at hot idle?
02-17-2014, 02:14 PM
#7
Not too sure one the EGR position but IAC is your Idle Air Control.....The valve that controls airflow at idle. If you have a leak it will be at Zero. If the motor needs too much air it maxed in the 300's. The later is usually remedied by drilling a bigger hole in the TB blade but that's not your issue here.
I guess with the EGR take it off and see if you can pass air through it.
I guess with the EGR take it off and see if you can pass air through it.
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02-19-2014, 08:28 AM
#10
Well I cant see IAC counts with this predator Im using to datalog. I did look at the cyl misfires and all of them have misfired a different # of times from each other. I am not getting the multiple cyl misfire code or any other misfire codes either. I can faintly hear a thud in the exhaust evry once in a while when its just idling. Stock crap is too quiet to really hear a good exhaust note through. Im almost positive that I cleaned the maf when I first got the car but I will try it again just to be sure.
02-19-2014, 12:37 PM
#11
Cleaned the maf and no difference. I also unplugged it while running and no difference exept when I first do it and the car stumbles just a sec then goes back to normal. Headers came in so I guess next Ill do a compression check before mm's and headers go on. I think the comp check would be done the easiest with no manis or headers on the car.
03-01-2014, 11:18 AM
#12
Got a can of carb cleaner and sprayed it all around the intake where it meets the heads and where the injector orings are while car was running with no change in idle. This leads me to believe there is no intake leak. I also installed new intake gaskets last week when the LS6 intake was installed. Done comp check and all 8 were 133-135psi. Installed poly mm;s, headers, and oryp with new gaskets and reinstalled factory catback. New plugs, wires, and Bosch o2 sensors also just to be sure. Its still doing the same thing. No codes this time exept the p1637 code that says"Can link ECM/ABS control module circuit network" on the predator tuner. I drove the car and its showing +25% LTFT when ideling and o2 voltage is 0.00v to 0.10v. Just crusing its showing +19% to +22% and the o2 sensor voltage is 0.11v to 0.87v constantly sweeping back and fourth. Whats going on? I have never had a mechanical issue I couldnt figure out on these cars but this has me stumpped. Im gonna take it to a tuner to have the tune and computer checked but wanna make sure I have the basics done beforehand and try to avoid silly B.S. problems that I could have fixed before paying someone else to fix it. Any Ideas? I ahve a friend with HP Tuners and a laptop thats gonna come over tomorrow and help try to diagnose it but honestly he's not very good on it just able to copy n paste crap from one file to the next and datalog a bit with it. if there are any specific paramaters we should be looking at with his computer that this diablo predator wont monitor let me know. Feel free to P.M. me if you want. Thanks to anyone who can help try to figure this crap out.
Last edited by JRENIGAR; 03-01-2014 at 11:28 AM.
03-01-2014, 12:41 PM
#13
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if the fuel trims are lean at idle only then you are looking for a vacuum leak most likely. if fuel trims are lean at all times you are looking at poor sensor performance, poor fuel delivery or quality, outside air entering the exhaust stream near the o2 sensor (bank specific). or lastly, calibration needs edited. good luck!
03-01-2014, 01:06 PM
#14
if the fuel trims are lean at idle only then you are looking for a vacuum leak most likely. if fuel trims are lean at all times you are looking at poor sensor performance, poor fuel delivery or quality, outside air entering the exhaust stream near the o2 sensor (bank specific). or lastly, calibration needs edited. good luck!
03-01-2014, 08:14 PM
#16
