lean lean lean HELP!!!
5th Gear Member
Joined: Sep 2003
Posts: 3,105
From: Phoenix, AZ
RE: lean lean lean HELP!!!
Every site I quickly looked up said that 91 is right bank is lean and 41 is system lean. Remember, always fix the lower numbered code first as it may rid the lower priority codes. Now, what makes a car run lean or a computer think it's lean is a vaccum leak, low fuel pressure, an exhaust leak, a dirty or faulty MAF sensor, or a faulty BAP sensor.
15inHG of vaccuum is on the low side. Should be around 17-21 on a fairly stock engine. This sort of suggests to me that you have an intake or vaccum leak.
Low fuel pressure is obvious, and you checked that.
If there's an exhasut leak before the O2 sensor then it will measure more oxygen in the exhaust and think its leaner than it is.
A dirty or unresponsive MAF sensor will give false signals to the computer thinking there's less air flow going through the engine and the ECU will lessen the pulse width on the injectors.
The Baro sensor is what goes out in the newer Fords, but is included in the MAF sensor. Your BAP is in the middle of the firewall and measures atmospheric pressure. If it's faulty and giving the computer a signal of 133Hz when it needs to be more in the neighborhood of 149-153Hz it will go lean because the ECU thinks its at a higher elevation. The BAP can also be checked with a DMM.
Hope this helps.
15inHG of vaccuum is on the low side. Should be around 17-21 on a fairly stock engine. This sort of suggests to me that you have an intake or vaccum leak.
Low fuel pressure is obvious, and you checked that.
If there's an exhasut leak before the O2 sensor then it will measure more oxygen in the exhaust and think its leaner than it is.
A dirty or unresponsive MAF sensor will give false signals to the computer thinking there's less air flow going through the engine and the ECU will lessen the pulse width on the injectors.
The Baro sensor is what goes out in the newer Fords, but is included in the MAF sensor. Your BAP is in the middle of the firewall and measures atmospheric pressure. If it's faulty and giving the computer a signal of 133Hz when it needs to be more in the neighborhood of 149-153Hz it will go lean because the ECU thinks its at a higher elevation. The BAP can also be checked with a DMM.
Hope this helps.
Thread Starter
1st Gear Member
Joined: Nov 2005
Posts: 149
From:
RE: lean lean lean HELP!!!
hey thanks alot for that alot of good info, i found a good leak at the egr valve at idle, im guessing the dirphram has a rip of somthing could this be it??? i frickin hope so im about to loose it, haha
2nd Gear Member
Joined: Nov 2005
Posts: 202
RE: lean lean lean HELP!!!
ORIGINAL: zex92mustang
the car is lean not rich.
the car is lean not rich.
