Pulled codes, need help w/ diagnosis (everybody has a "codes" thread) :)

[40BelowSummer]

Okay these were the codes I got:
==============================================
KOEO
-------
157 =MAF circuit below min. voltage
172 =HEGO indicates system lean (RH)
176 =HEGO indicates system lean (LH)
177 =HEGO indicates system rich (LH)
543 =Fuel pump seconday circuit failure


KOER
-------
172 =HEGO indicates system lean (RH)
136 =HEGO indicates system lean (LH)
================================================

Please help me diagnose what these could mean and what I should check on. Being a newb @ SHOS and engines in general it is difficult for me have any opinion on whats wrong.

How could it read lean & rich at the same time?

Please help me diagnose

THANKS!!!!!!!!!!!!!!!!!!!

 

[sdpatt]

Since both O2 sensors are reading lean, it looks like your engine has a sensor problem causing the engine control system to run lean. Since your MAF sensor showed to be out of range, I would start there. Cleaning the MAF sensor filaments won't change the current. You should check the connector and be prepared to swap electronics on the sensor body.

Why don't you try searching on the specific code numbers that you found. That would narrow down your results list substantially.

 

[40BelowSummer]

i searched the individual numbers but was hard to diagnose because other people had diff combos of codes than I did, but i did get some stuff out of searching:

clean MAF?
clean or replace o2 sensors

but about fuel circuit?

 

[musiccitysho]

How many miles are on your car, and did you happen to get any maint. records from the previous owner? The reason I ask is that I have a 93 ATX and certain sensors on mine started going like wildfire at around 100,000 miles, if you look at my sig most of the ones Ive had to replace are listed. If you are in that mileage range and none have been replaced get ready to research and learn how to replace them thru this site. I don't think anyone who has brought a SHO into the "blue oval" for service has not been burned at least once, and paid a high price for their incompetence.
Like mentioned previously start with your mass airflow sensor it begins the cycle of reading metered air and your O2's complete it. If you are going to go ahead and modify your exhaust you may want to look into a 73 mm MAF if you need to replace the stock one because its reading "out of range" and cant just be cleaned.

 

[musiccitysho]

I just saw your post at 1030 and real quick, since both O2's are reading lean they are probably correct. Your MAF meters the air and sends the info to the computer which takes that info and creates the corect air/fuel ratio for the motor, but since you already have a code for the MAF being out of range you pretty much can count on the info the MAF is sending to be incorrect and maybe causing a chain reaction of lean/rich codes. When mine was off I had lots of black carbon coming out of the exhaust when I floored it, and lowered performance...bogging out
The fuel pump code I am not familiar with.Sorry

 

[sdpatt]

Did I not type my words loudly enough?

 

[40BelowSummer]

sdpatt:
Did I not type my words loudly enough?

yes, the more posts the better

Hmm..so I will plan on getting a 73mm MAF, I will check out my 02 sensors.

I bought my car w/ 112,600 miles from a dealer. I have no idea who the previous owner is but I am trying to find out. The only thing I know is that theres a sticker by the engine that says the timing belt was replaced 10k ago. Hopefully they did other stuff.

 

[sdpatt]

I sold my 73mm MAF body since the OEM piece made more horsepower and torque across the rev range. The power shortage was due to an overly lean mixture with both the 24 lb/hr and 19 lb/hr sample tubes.

 

[musiccitysho]

I take it back SPDATT is probably right, he's always right on this stuff! Its been awhile since I've been on the forum and a year ago it seemed everyone was about the 73mm but there are a ton of posts bashing it now apparently after lots of bad experiences with them. I guess you will have to do some homework and decide if a bigger MAF is right for you and your car and which one. I'm running the stock 55...only because I got suckered in by the dealership and paid over 250.00 for a new one when most likely I could have cleaned my origional and been on my way if at the time I would gotten the great advice from people here who know they're SHO's.
Good Luck, and listen

 

[projectSHO89]

Ignore the 542/543 codes unless you are having severe fuel delivery problems.

Those codes are posted when the engine is stalled.

Steve

 

[40BelowSummer]

well after researching about MAF's I think:

I will get a pro-m 75mm MAF especially since I plan on upgrading my exhaust in the future.

So if I get new o2 sensors and a new MAF should this corrct my problem (if the codes are right)

what about the rich one (177)? or should i not even worry about it til i get these things replaced?

 

[musiccitysho]

You missed what was said. Once more yor O2's are probably functioning properly and most likely do not need to be replaced. The reason for the 176/172 code is more than likely related to the malfunctioning MAF. When you replace that, your problems w/ the lean condition which your oxygen sensors are reading should go away w/ it. The reason you were told that is because both are reading it not just one. It is highly unlikely that both would be displaying that same lean code if they were shot and if that was happening it would be the HEGO not switching code (I dont know the code # offhand) instead of reading lean.

 

[40BelowSummer]

Update: I am about ready to order a new MAF, but on a side note I just checked my gas mileage:

268 miles on a full tank (18.6 gallon tank), even with gas light on for a full day.

268/18.6 = 14.4 MPG

And 210 of those are freeway miles.

Mabe when I order the MAF I should get some plugs/wires too?