P0172 & P0175, running reach, black pipes, high idle...

[briskspirit]

Hi all!

I was reading the forum to find something similar to my problem and nothing...

So I have bought 2006 Mustang GT through auction after a small accident. It is 107K miles with X-pipe, catless with Magnaflow mufflers, maybe was with CAI(air filter with MAF was removed by previous owner or insurance as car was hit to the left front). Stock or tuned - unknown.

So I've bought cheap eBay CAI(just to mount MAF and test everything). Engine was running veeery bad, missfiring, very reach but without mechanical issues/noises. Replaced spark plugs, COPs, fuel filter, TPS(was faulty), cleaned TB. Now car runs much better but I still getting 171 and 175 codes, running rich with black pipes and annoying raw fuel smell.

Coolant temp sensor = ok
Long term fuel trim(both) = -25% !
Fuel pressure idle/WOT = ~39psi +- 3
All four O2 sensors working fine, giving healthy sinus wave on output
MAF was bought used/cleaned, tried a new one from AutoZone - didn't helped.
MAF reading on idle 10-12 g/sec
Idle most time ~950rpm , sometimes bumping to 1200 and going down.

So by codes, fuel trims and O2 readings I understand that there should be some unmetered air flowing in or to much fuel going in. Readings are same for both banks, so that shouldn't be injectors. fuel rail pressure by OBD2 is ~39psi, so fuel pump and pressure sensor seems to work fine too.

Help please, now I am lost... I am over my budget already...

Thank you all!

 

[stkjock]

sounds like without knowing what/if the tune is in the car, you'll need to get a handheld tuner and get a tune in there

 

[briskspirit]

sounds like without knowing what/if the tune is in the car, you'll need to get a handheld tuner and get a tune in there

That will eat $400... Or minimum $200-220 if I would take used tuner from eBay... Maybe other ideas to try out before I throw a lot of money for a tuner?...

 

[Juice]

Sounds like the CAI is not calibrated to the car. So, if the CAI is a "no tune required" part and you have a tune for a "tune required" CAI, that would explain the rich condition. A Ford dealer should be able to reflash to stock for less $ vs tuner. Around here, it is 1hr labor for an IDS hookup. $129.99 But now you will have cat conv codes.

 

[stkjock]

without knowing the tune in the car you'll be chasing your tail with parts swaps IMO

the car is catless, usually needs a tune adjustment for that, you have no idea what CAI/Intake was on the car, tune adjustment usually needed for that, you already replaced the COPs - likely that wasn't needed, you replaced the plugs, if the car was well maintained prior, also likely not needed..... so I'll say good luck and maybe someone else will have a better suggestion for you.

Sounds like the CAI is not calibrated to the car. So, if the CAI is a "no tune required" part and you have a tune for a "tune required" CAI, that would explain the rich condition. A Ford dealer should be able to reflash to stock for less $ vs tuner. Around here, it is 1hr labor for an IDS hookup. $129.99

flash to stock w/o a stock intake or cats, not sure that will work well?

 

[Mustang Mark]

Its the aftermarket CAI causing it. Spend the money on a new tune. The ECM thinks there is more air going into the engine than there actually is because the diameter of the MAF is wrong for the tune in the car. The only way to correct it is a retune, or find out what was on the car before and purchase that.

 

[Juice]

without knowing the tune in the car you'll be chasing your tail with parts swaps IMO

the car is catless, usually needs a tune adjustment for that, you have no idea what CAI/Intake was on the car, tune adjustment usually needed for that, you already replaced the COPs - likely that wasn't needed, you replaced the plugs, if the car was well maintained prior, also likely not needed..... so I'll say good luck and maybe someone else will have a better suggestion for you.




flash to stock w/o a stock intake or cats, not sure that will work well?

If it is truely a "no tune required" CAI, yes. But then he is stuck with cat codes.

 

[briskspirit]

What tuner can you advise? Used one is preferred... Maybe SCT X3? That will be suitable for my case. Thank you!

 

[46addict]

Assuming it's a no tune required CAI, I would start doing some checks. Make sure the front o2 sensor harnesses are not criss crossed. Not sure if the wires are long enough to make this mistake, but it's worth checking. Then pull the vacuum line going into the fuel rail pressure sensor and make sure there is no gas pooled up in the line. If there is gas, your pressure sensor needs replaced. Another thing to look for in the datalogs is o2 sensor voltage. If the car is trying to correct a rich mixture, sensor voltage will be greater than .5v with STFT values less than .90. If the numbers don't follow this pattern, you may have bad front o2 sensors.

 

[Lime1Gt]

You might want to try checking the evap system.

 

[briskspirit]

You might want to try checking the evap system.

As I see by OBD2 EVAP works fine..

Bought SCT BDX tuner, will check if switching to stock air filter will help

 

[briskspirit]

Assuming it's a no tune required CAI, I would start doing some checks. Make sure the front o2 sensor harnesses are not criss crossed. Not sure if the wires are long enough to make this mistake, but it's worth checking. Then pull the vacuum line going into the fuel rail pressure sensor and make sure there is no gas pooled up in the line. If there is gas, your pressure sensor needs replaced. Another thing to look for in the datalogs is o2 sensor voltage. If the car is trying to correct a rich mixture, sensor voltage will be greater than .5v with STFT values less than .90. If the numbers don't follow this pattern, you may have bad front o2 sensors.

My PCM "sees" 11-12g/sec of air at ~900RPM (And on stock air filter should see 4.6-6g/sec). So that could be my problem.

O2 sensors are ok, getting healthy sinus wave from 0.1 to 0.9 V, getting lean by O2 when driving on gear with closed throttle.

 

[briskspirit]

So I hooked up SCT BDX , chose stock air, 93 octane, o2 off, idle 740, diff 3.55 and everything else - stock.

Now my mustang is reading short/long term trims ~ +1% and idle is stable! So my problem should be solved for now! (99%...)

 

[stkjock]

You’re welcome

 

[briskspirit]

You’re welcome

Thank you!

 

[briskspirit]

Nah, nothing changed...

Got a wrench sign few times yesterday with "limp mode". (TB cleaned, TPS new). MAF is reading 10g/sec. Fuel trims both banks -25% and not enough. Rich as hell... Next step is to get a normal CAI or stock air box, eBay Chinese crap is messing with MAF readings(tried 2 MAFs). And TB motor could be dying?

 

[briskspirit]

Anybody please?.. I've checked virtually everything...

 

[stkjock]

the issue IMHO, is that you don't know the mods on the car and cannot get a properly set up tune for it.

 

[01yellerCobra]

As has been mentioned multiple times, get it flashed back to stock. Then go from there. Maybe even track down a stock mid pipe to throw in.

 

[nbk13nw]

Have you cleaned the TB since you bought the car? Mine ran rough, lack smoke burning gas, idled badly. Cleaned the TB and ran fine afterwards