What would cause a lean condition??
Safety Car
Joined: Feb 2002
Posts: 4,212
Likes: 10
From: Sun City West Az
A vacuum leak ahead of the O2 sensor(s) will fool it into thinking the mixture is lean. (O2 mainly below 450mv)....the ECM will then fatten up the fuel mixture (BLM's above 128) in an attempt to correct the 'false lean". The bigger the vacuum leak, the richer the fuel / air ratio to correct it.
Thread Starter
Racer
Joined: May 2001
Posts: 472
Likes: 0
From: Tampa Bay Area
So a vacuum leak in the intake will result in a rich condition?
I have just replaced my fuel pump and blown a wad of whatever out of my return line and now the car is running insanely lean. I have tried adjusting the FP but to no avail.
Can anyone tell me about where the adjustment screw (how far in or out) should be set for an Accel AFPR? I had the screw about all the way out before I cleaned out the return line, I have screwed it in considerably so far and it hasn't made much difference. I have an FP guage but it is reading bizzare readings. It reads 55 psi on my stock Jeep that should read about 35 and it reads about 62 on the vette. It read about 55 or so before the pump change. So I really think that the guage readings should be thrown out of consideration due to inconsistancy.
I have just replaced my fuel pump and blown a wad of whatever out of my return line and now the car is running insanely lean. I have tried adjusting the FP but to no avail.
Can anyone tell me about where the adjustment screw (how far in or out) should be set for an Accel AFPR? I had the screw about all the way out before I cleaned out the return line, I have screwed it in considerably so far and it hasn't made much difference. I have an FP guage but it is reading bizzare readings. It reads 55 psi on my stock Jeep that should read about 35 and it reads about 62 on the vette. It read about 55 or so before the pump change. So I really think that the guage readings should be thrown out of consideration due to inconsistancy.
Pro
Joined: Sep 2001
Posts: 743
Likes: 4
From: Guyton GA
You should dump the computer memory after you adjust the fuel pressure, by disconnecting the battery cable for a minute. You may have also gotten some trash down to the injectors which could restrict flow. Oxygen sensors are cheap to replace and do wear out. FYI, if you use silicone lubes on o-rings, it can foul out the oxygen sensor.
Team Owner
Joined: Jan 2003
Posts: 20,304
Likes: 240
From: Summerland B.C. Canada
I can say from experience that a clogged fuel filter can cause a lean condition. My GF's Hyundai started running like crap. I pulled the plugs and it was running so lean that it was cooking the plugs. Replaced the fuel filter and plugs and away she goes. I opened the filter up 
Looked like it was coated in tar. We've been together for 7 years and not once did I change the filter 
I guess I hate that car 
Looked like it was coated in tar. We've been together for 7 years and not once did I change the filter I guess I hate that car
Thread Starter
Racer
Joined: May 2001
Posts: 472
Likes: 0
From: Tampa Bay Area
On a MAF car a intake air leak will cause a lean condition, right? Because it reduces the vacuum signal to the MAF and it thinks that less air is coming through than really is. I thought that I read that somewhere.
I know that I have an intake vacuum leak and I bought the runner gaskets to replace them. I will do that tommorrow, while I am doing that I will check the O2 sensor, any way to tell if it is fouled out?? Fuel filter is relatively new the motor only has 1200 mi on it. I will also check the injectors.
Thanks for all your help.
I know that I have an intake vacuum leak and I bought the runner gaskets to replace them. I will do that tommorrow, while I am doing that I will check the O2 sensor, any way to tell if it is fouled out?? Fuel filter is relatively new the motor only has 1200 mi on it. I will also check the injectors.
Thanks for all your help.
