'04 Cayenne S p2177 p2179 codes help

[MrFlip]

Hey guys,

First and foremost I want to say thank you for all that you have helped me with by answering other people's questions that I needed an answer to as well. And a thank you in advance for helping me out here or even just taking the time to read it. This is one of my favorite websites and forums.

Here is my (hopefully temporary) problem: Recently my 2004 Cayenne S (115,XXX miles) has been lacking a little bit of power since I had bought it in 2014. I went through the check list of what it could be: Spark plugs, Coils, Air Filters, Throttle body, Throttle relearn, Fuel filters, Fuel injectors.
Then again with what I've done
Spark plugs (changed in January)
Coils (untouched)
Air Filters (Purchased K&N's)
Throttle body butterfly (remover Throttle and cleaned with carb cleaner)
Throttle relearn (done)
Fuel Filters (part of sending unit however I did remove driver side and clean it with carb cleaner back in July of '15)
Fuel injectors (Seafoam/lucas treatment dumped in tank several times)

After cleaning the K&N's(cleaned, oiled and left for 6-8 hours to dry) I was driving about 20 miles then the car started choking a little, --CEL LIGHT TURNS ON-- assuming right away that I over oiled the filters I got home and sprayed my MAF's with MAF cleaner hoping that would help. On the way to work as the road curves right slightly, I feel the car choking a little and my traction control flashes momentarily. When I got to work the next day (Autozone), I cleared the codes and started up my car only to have it run as if it is choking out again only worse and if I tried to accelerate in Park it would struggle and backfire. Once it idled out to normal, a few miles or minutes later the CEL would turn back on. Same codes. Thinking I fried the MAFs I bought a pair (stated in good working condition) on eBay. They came in, installed, code erased, same problems. CEL back on. Same codes. Cleaned "new" MAF'S, no luck. Now for the past few days it's been back firing when I try to gun it down the road or even worse from a stop. Yesterday and today however it didn't let me go past 25 mph and even decelerated to the point of dying a couple times. It's fine in the morning but after driving for a couple hours it get worse the more I drove. By the end of the day it's backfiring, choking out, smells like gunpowder (best description I can think of for the smell). I couldn't get it past 20mph on my way home then randomly run fine then back to horrible. Another thing is that it seems to run worse when I take turns.

Any and all help is greatly appreciated!!

[MrFlip]

Update:
Assumed fuel pumps so I pulled #13 fuse and it started and ran. Put it back and pulled #14 fuse and it started and ran fine. As it was running I pulled the #13 fuse so both 13 and 14 were out and it was still running. Any idea what it might be? Does that mean both fuel pumps are bad?

[Casey at Pelican Parts]

This definitely seems like a lean running issue. What are the fuses 13 and 14 for? Sorry I don't have a fuse layout in front of me. Most of the time on these cars the lean running issue is due to an intake leak, or cracked crankcase vent hoses. Although the fuel pumps are not out of the question. Best thing to do is check the basics...fuel pressure, intake system for leaks with smoke tester, check charging system for proper voltage and make sure that you have no more than .050 Volts of AC voltage present at the battery, and of course the maintenance items which it seems like you already have air filters, fuel filter, spark plugs etc...

HERE is an article which will show you how to replace the pumps should they be the cause of your issue.

HERE is an article which shows you the breather hoses...

HERE is an article which shows you common vacuum leaks...

Let us know how it goes!

[MrFlip]

Casey
Thank you so much for the information!! I just recently purchased a pair of new MAF's and put them in, cleared the code and now all that pops up is a p0112 Intake Air Temperature Sensor 1 Circuit Low and the car ran like junk all day yesterday and all day today.

[MrFlip]

*Update*

After installing 2 new MAF's (Previous ones were off brand ones and showed the P2177 and P2179 code shortly after installing them) I am still with the same issue. To add icing to the cake I am now getting 7-9 MPG when I was previously getting 12-14 MPG, and I am hearing a small, vacuum leak like, noise from the PCV Diaphragm. I changed the diaphragm itself out about 5 months ago, could it have gone bad already?

[Casey at Pelican Parts]

I'm not sure which diaphragm you used, but there could be some under engineered replacements out there...it's worth having a look.

[kennethg]

IAT codes usually only set with a bad MAF as they're built into them. If you can get a live data reading at idle the MAF's should be in the 4.5-6.5 g/s. Most cases lean codes are vacuum leaks or low fuel pressure. Fuel pressure should be around 56-62psi. Have had a couple lines fail inside the tanks(not common) Vacuum line to the brake booster fails here and there(more common) along with the crankcase breather diaphragm. If the fuel pressure is in spec its going to be a vacuum leak. I would put the original MAF's back in and use paper air filters and start at the beginning.

[Mary1]

Thank you all for your informative posts. They help me so much.

[solo25]

I'm having a similar problem with my 2009 Cayenne GTS, but not as bad. I have some minor engine "missing" problems that just started happening, and I'd like to fix it before it gets worse. I have a Durametric device, and when I hooked it up, I got a lot of codes, but the ones that seemed pertinent were 1094 (air mass ahead of throttle valve, implausible, Value below lower limit value; 0174 System too lean bank 2 upper limit value exceeded, and 0171 System too lean bank 1 upper limit value exceeded. Any ideas on where to start before I go in and really screw things up?