Lean at idle and crazy fuel trims!

[BudUMfan]

The last two days I have been getting a lean at idle code. Cleared it, but it comes back. Idle AFR is around 15.8 to 16 and some change, when it was a steady 14.5 or so. Then I check my fuel trims on my DH and they were going ******* bananas! No log as I was hauling the wife and kids, but did get some iphone pics. At idle my STFT was at like 25% and when cruising my LTFT were off the charts. This JUST started yesterday. Cold weather? Checked all BPV hoses, boost gauge was tight, TIP was tight. Maybe clean the MAF? I obviously am still a noob, but learning. Thoughts?

 

[bykeryder4life]

vacuum leak. pulling in unmetered air somewhere making high trims and lean codes. whats your vac at idle?

 

[BudUMfan]

-20 to -22. Looks normal, but still will try and hunt down the leak and really check to make sure everything is tight. I did remove part of my MS CAI when I put on mt TIP and did remove my MAF. I'll start there. Thanks.

 

[Wurf]

Agree about air getting around the MAF. It's the only thing that makes sense. PCV connection or recirc connection would be my guesses. One of them might not be tight enough and is leaking somehow but anything behind / after the MAF sensor would be suspect.

 

[BudUMfan]

Thanks guys. It has been brought to my attention that there are vacuum lines by the A/C unit for the intake manifold. Mazda just replaced my compressor and idler tensioner. Maybe something came loose. I check the usual culprits, BPV, inlet, boost gauge line etc. nothing. My MAF is completely covered in crud though. Taking it to the dealer Thurs.

 

[bykeryder4life]

clean off the maf yourself dont have the dealer do something so easy. that could easily be your problem

 

[ReNaToMS3]

Im having similar problems.

To clean the maf, do you unscrew it from the top of your intake, disconnect the wire coming to it, then invert it and spray the IAT and MAF right?

Im just a bit confused about the MAF location, as i never done this. Is it inside a housing right by the IAT? Do i just spray the inside then?

I know youre not supposed to spray from too close and to be careful with the little wires.

 

[matsuda]

Im having similar problems.

To clean the maf, do you unscrew it from the top of your intake, disconnect the wire coming to it, then invert it and spray the IAT and MAF right?

Im just a bit confused about the MAF location, as i never done this. Is it inside a housing right by the IAT? Do i just spray the inside then?

Yes, just spray inside.
CRC MAF cleaner is highly recommended.

 

[ReNaToMS3]

Did you find out what was the problem Bud?

Cleaned my MAF (sprayed and let it dry 3x), put it back on and 2 miles later my LTFT is around +18% at idle and around +13% cruising.

AFR is at a steady 14.58 at idle.

I disconnected the battery so should i wait 100 more miles to see how things are? I dont have my hopes up though.

I plan on taking my SRI and TIP apart and putting back together to see if it helps this weekend. Any other ideas is appreciated.

 

[BudUMfan]

Haven't yet. Same here on the trims (same as yours). I cleaned my crusty MAF to no avail. Getting ready to drop off at the dealership. I do have an aftermarket TIP, but confident it isn't the problem. Will post later on what they find, maybe it can help.

 

[BudUMfan]

Well, found out what was the deal. My purge solenoid valve was stuck open. Replaced free of charge, Thank You Mazda warranty!

 

[Wurf]

My purge solenoid valve will stick open sometimes when I've had too many beers. I hate it when that happens.

Glad you found it

 

[MSMS3]

Same thing happens to me when I eat too much sausage.

 

[ReNaToMS3]

Well, glad you found it. I guess i gotta check that as well.

Is that something easy to check? Im at 37k and im afraid powertrain warranty wont cover this. ):

 

[BudUMfan]

The tech said he manually operated it. Read on another forum it costs like $90 bucks. They did what I did, checked for vacuum leak with smoke then propane. I banged on the valve, you know, hit it with a hammer mentality. Glad they found it. Now trims are perfect

 

[Speed3Rookie]

The tech said he manually operated it. Read on another forum it costs like $90 bucks. They did what I did, checked for vacuum leak with smoke then propane. I banged on the valve, you know, hit it with a hammer mentality. Glad they found it. Now trims are perfect

where is this valve located?

 

[BudUMfan]

Look under your hood, there is a vacuum hose diagram. It should be pointed out there. Remove your intercooler shroud. You will see it.

 

[Speed3Rookie]

ok...thanks