OK, my daily driver isnt driving no more. I got a P0174 set for system lean bank 2, The car bucks and jerks at low rpms and the exhaust is way hotter on the passenger side then the drivers side. Ive tried spraying the intake but I cant find the leak, I have 9" of vacuum at idle but i do have pretty big cams, The afm n42 cams. Im also hearing like a whistle around 3000rpm, it almost sounds like a vacuum leak but could it be the accufab throttle body? Ive been pulling my hair out over this any help would be appreciated, Thanks
Need Help ASAP/Vacuum leak maybe??
- Thread starter sleepin89
- Start date
it's probally a misfire and not a actual lean condition if it bucks and jerks.
what can happen is a misfire will dump unburned oxygen in the exhaust, the 02 sensor picks this xoygen up, since it can't sense the unburned fuel in the exhaust it only sees the oxygen, thats how you get a lean code in one bank.
to verify this look at the long term fuel trims for bank 1 and 2
if bank 2 is adding 20 percent or so to the misture and bank 1 is adding under 10 percent then you know this is ytour problem.
many many times you can have a misfire and not set the mifire codes.
this may or may not be your problem, but it is somthing you should test for.
what can happen is a misfire will dump unburned oxygen in the exhaust, the 02 sensor picks this xoygen up, since it can't sense the unburned fuel in the exhaust it only sees the oxygen, thats how you get a lean code in one bank.
to verify this look at the long term fuel trims for bank 1 and 2
if bank 2 is adding 20 percent or so to the misture and bank 1 is adding under 10 percent then you know this is ytour problem.
many many times you can have a misfire and not set the mifire codes.
this may or may not be your problem, but it is somthing you should test for.
what could be causing the misfire?, Ive changed the plugs, the old ones had a brownish tint to them, and I checked the injectors with a noid light and also tried changing them, is there anything im missing?
do you have access to live data from the pcm?
if you do get the values for the maf voltage lt fuel trims for banks 1+2 and baro.
if you do get the values for the maf voltage lt fuel trims for banks 1+2 and baro.
well you have a vacumm leak then, becuase you are maxing out the fuel trims or close to it on both banks
check all the hoses and spray the base of the intake and plenum with carb cleaner..
also check all the intake hose connections after the maf and make sure they are tight
check all the hoses and spray the base of the intake and plenum with carb cleaner..
also check all the intake hose connections after the maf and make sure they are tight
BlackGT4.6
New Member
I had the same code. befor i bought the car someone put a cheap maf housing on it. I replaced it with a buddies c&l housing no more code. Just my 2 cents. good luck.
should I get a new sensor?, The problem is the car had a big nitrous backfire, it blew so bad that it broke the valveguides in the heads, so in went the 5.0 stroker motor, but I replaced the MAF housing with the MAC stright shot kit. I never replaced the sensor I just cleaned it with QD electronics cleaner. Could it be just the sensor? and wouldnt it set a code if it was bad?,what voltage value am I looking for on the scan tool for the MAF? I need help cause this is my only transportation right now, thanks
Ok, just replaced the MAF sensor and it still does the same thing. It seems to run lean only under 3000rpm according to my scan tool. the long term fuel trim is 24-25 on both banks until I hit 3000rpm and then it clears up and hauls a*#, and the fuel trim is like 2-3 on both banks. So whatever it is I got narrowed down to only happen under 3000rpm. Any advice? Thanks:SNSign:
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