O2 sensors reading LEAN

[mustbastang]

ok here is the skinny, i had a blown head gasket so when i fix the head gaskets i made a few changes. i changed my performer intake to track heat and i installed BBK short but equal headers, now my O2s r reading lean. my LM-1 wide band is reading a A/F at PT between 13.5 and 15.2 now at WOT i am reading 10.7 and 11.4. now after 4000 rpm at WOT the car bogs down, i replaced the driver side O2 and the reading on my PMS tuner is still reading lean could the headers be causing this problem.


thanks for the help

 

[final5-0]

Why the small fuel pump on a blown car?

As for the part throttle ratio range

If your load is not too great, then your in closed loop and a ratio that jumps around like that is not that uncommon. It just depends on how far off the tune is which determines how much the adaptive strategy is working to + or - the ratio with its attempt to give you 14.7

I'm a bit confused about the last 25% of your post but if I understand correctly, it looks like your too fat in open loop or wot.

Whatever you do to adjust the ratio with your PMS, I'd do it in small steps and use your wb to verify those small changes are helping. Don't wanna go the wrong way but if you happen to do it, since the adjustment is small, it ain't gonna do no harm, lol.

btw, might wanna dial the spark back a bit to be safe or you might be in the market for some new head gaskets.

Later
Grady

 

[must b a stang]

final5-0 thanks for the response, i still have to change the fuel pump, i am going with a 255lph. as for the tune my car is giving me 2 codes 1 is bank 2 lean and the second is bank 1 lean.

 

[Zero Signal]

So, wait your post says lean, the numbers you put there say rich. 13.5 to 15 ish should be fine for part throttle. You want it aorund 14.7 so i'd say you're fine there. But the 10.7 and 11.4 are waay rich for an N/A motor.

Are you refering to commanded AFR?

 

[Mathulus]

his car is s/c not n/a

 

[mustbastang]

I believe i have found the problem, the lower intake right under the t-stat housing seams to be leaking oil, after i posted i noticed an oil puddle in that area. i ordered new gaskets and i will due repair on wenesday. i hope this solves the problem.

 

[AznStanger3v]

So, wait your post says lean, the numbers you put there say rich. 13.5 to 15 ish should be fine for part throttle. You want it aorund 14.7 so i'd say you're fine there. But the 10.7 and 11.4 are waay rich for an N/A motor.

Are you refering to commanded AFR?

10.7 to 11.4 on a blown car are good numbers. and even for peak performance, stoiciometry isnt ideal, na or not. 14.7 is a number for the most efficient, emission friendly burn.

 

[final5-0]

10.7 to 11.4 on a blown car are good numbers. and even for peak performance, stoiciometry isnt ideal, na or not. 14.7 is a number for the most efficient, emission friendly burn.

Allan

I don't have any issues with what you are saying.
Your post did make think of some additional things however

Some things are still not clear to me about this thread but ...........

It looks like to me and I'd have to say that, by what Zero Signal posted.......

mustbastang is talking about two separate conditions of closed & open loop.
He uses "PT" and I'm gonna believe that is part throttle. Here is what bothers me about that ...........................

Part throttle may or may not be in closed loop due to our cars are load driven from the pcm's perspective. The range of 13.5 to 15.2 he talks about .........

my concerns would be for when he is seeing those ratio values are:
closed or open loop
amount of boost
amount of load
if he is in open loop he just might be too lean

I do wanna point out that I've had no experience with forced tuning but I've thought about it a good bit. Still, general basics would apply and I'd wanna know the above stuff.

I sure his PMS can tell him that stuff.

I'm through thinkin out loud now

Later
Grady

 

[mustbastang]

i am assuming im in open loop because my O2 sensors are reading .04 on driver side and .20 on passenger side, i replaced the driver side but got the same reading. the PMS dose not tell me if im in open loop or closed loop. my LM-1 sensor is not near the stock O2 location, it is locaded apprx. 3" from where H-pipe bends up towards header and it reads fine.