Right cylinder banks lean, 160 blm on right side and I believe 118 left. Wasn't running right today and threw the code. Fuel pump checked out fine a few weeks ago, new filter too. Any ideas?

 

Not likely that its the pump or the filter, since that would affect both banks of the engine. Exhaust leak on that side, misfires on that side, faulty O2 sensor or wiring, plugged injector. What cells are those numbers from?

 

I am having a similar probem, the right BLM is much higher than the left at cell 16 (idle). The rest of the cells are more in line. I also have fuel coming out the tail pipe at startup.

I have checked and can not find any exhaust leaks, I switched the O2's and get the same result, the opti plugs are new, have not checked wires in depth. The engine does not appear to have any mis-fire. WOT is strong but I am still chasing some minor KR. The only potential exhaust leak I can see would be the #1 slip fit primary on the left side, of course the left side appears to be the best side according to the BLM's.

Here is a summary of my fuel cells from Datamaster:
Cell LBLM RBLM
2 135 148
3 130 138
6 127 127
7 121 118
10 128 121
11 126 123
15 128 128
16 135 160
17 130 150
18 130 145

One other wierd thing. On my old staock engine the O2's at atartup stayed at 450mv for a few minutes till things warmed up and got going. Now on this engine the O2's st startup are bouncing in the 800's and 900's. Once in closed loop they bounce way up and way down like the old motor.

I have also been told that this is an anomaly with the cam that can be fixed with the right tune.

 

could possibly be a clogged fuel rail...dont forget that after a hundred thousand miles or so of one way passaging, things tend to settle in the bends. the vortech v-6 is notorious for this at 65k miles.

 

No chance, it was pressure cleaned when the engine was rebuilt plus the cross section is well over a 1/4" or so that would be hard to clog up.

 

Erased the code let it sit for about 8 hours. Runs perfectly fine, and no check engine light came back on after a half hour ride. Could todays extreme heat/humidity played a role?

 

Could leaving the PCM fuse out for a minute be any different than leaving it out for 8 hours?

 

yes, and yes, carbon and dirt can build up on the fuel rail...even if the rail is 1/4".

the difference is the codes are not reset, but when the problem fixes itself and goes away, the bulb goes out. the codes are still stored for information later, which is why when you have a light problem, you should always delete the codes, run it until the light comes back on and THEN diagnose the codes.

pulling the PCM fuse will do many things that are undesirable. firstly, you lose your radio settings. not detrimental, but annoying, and can be very bad if you lost your theft-loc code. second, you lose your idle. then, you lose your driver settings. your fuel trim levels, ox counts, and many other numbers will have to be reset. sometimes this takes several tanks of gas, and all the while you'll be getting less economy than before.

 

A clogged fuel rail would produce exactly the opposite results of what his data log shows. His problem only exists at idle and VERY low engine loads = very low fuel demand. As engine loads (and fuel demand) go up, the problem goes away.

How does carbon build up in a fuel rail...... precipitating out of the fuel ?

The code sets when the BLM's max out.... you may not have driven it enough. Clearing the codes clears the BLM's and they have to start building up all over again. Heat and humidity will not cause the problem you experienced. Its something that is affecting ONLY one bank of the engine, at low loads and idle. Have you checked for vacuum leaks, particularly around the injectors?

No - removing the power to the PCM clears any stored codes, the long term fuel corrections (BLM's) and the learned IAC setting. 30 seconds is all it takes.

Where do you come up with this stuff…… ? Pulling the PCM fuse does not affect the radio power. You lose the learned IAC position, which the PCM relearns immediately on startup – not even necessary to go through the “learn” procedure. What are “driver settings – please define? What are “ox counts”….. please define? What are the “many other number” that have to be reset – please explain?

 

I have looked one more time for exhaust and vacuum leaks, none found.
Its funny how this only happens at idle or when the TB blades are closed. The rests of the BLM's are very much in line and consistent. Someone mentioned "cam reversion".

Also how long does it take spark plugs to turn brown, assuming A/F was correct. I have 400 miles on my new plugs and they are still very white on the insulators. Also the O2 millivolt readings never make it any higher than the 700's.
Does this sound like a real lean condition?

 

When did this problem start? Was something done to the car around the time the light came on?

 

I am not getting the light on mine. I just installed brand new motor (see sig).

 

Try this for split BLMs

 

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