Obx Header leak

[Brandoe91]

Codes
P0171 bank 1 system too lean and misfire codes for cylinder 1 3 and 5 (all on bank 1).

I tested for vacuum leaks, fuel pressure ,change plugs, pvc , valve cover gaskets etc. Codes kept coming back.

Today I took a picture of the rear header and it seems l might have found an exhaust leak(black soot at the header). I think the leak might be throwing off bank 1 sensor 1 reading, thus causing bank one to run lean and randomly misfire. What do you guys think?


Don't mind leak and loose nut, I already replaced valve cover gasket just never cleaned back there.

[chullen1]

I HAVE SEEN THIS BEFORE ON MY SET, LOOK FOR THE EGR PIPE AND SEE IF THAT BROKE OFF SINCE THIS IS COMMON.

[1gSE]

did you replace the header gasket too?

[TRD_Sloara]

Wait, why is the top stud nut almost off of the stud? Shouldn't that be tightened down? It looks like that is where it is leaking.

The gasket looks new to me. I almost feel like captain obvious pointing out the nut, but assuming the car was driven like this, I'm about 98% sure that would be the culprit.

[Brandoe91]

Egr is fine. Where was yours leaking from and did you have any codes?

I HAVE SEEN THIS BEFORE ON MY SET, LOOK FOR THE EGR PIPE AND SEE IF THAT BROKE OFF SINCE THIS IS COMMON.

When I initial installed the headers couple months back, but since I've seen the leak no. I will fix it at the end of the week and hope it will fix my problems. Then BOOOST

did you replace the header gasket too?

Ye i stated it was loose but good eye all the same. I also think it's the culprit, as you can see the black soot (exhaust leak) in the same area.I just wanted to know if you guys think the leak is causing the lean code. I know an exhaust leak before 02 sensor can cause a lean condition but my leak seems small. So I am not sure.

Wait, why is the top stud nut almost off of the stud? Shouldn't that be tightened down? It looks like that is where it is leaking.

The gasket looks new to me. I almost feel like captain obvious pointing out the nut, but assuming the car was driven like this, I'm about 98% sure that would be the culprit.

[chullen1]

I HAD A EGR CODE WHEN MY HEADERS DID GO, I HAD THEM ON FOR ABOUT A YEAR IN EAST COAST CLIMATE AND THEY BROKE AT THE EGR PIPE ATTACHMENT AND THE FRONT HEADER CRACKED AT THE WELD.

[TheGreenDutch]

those OBX headers are too fragile.

[Brandoe91]

Tightened the nut but the same codes came back on after a couple miles . Do guys think I should replace the header gasket?

[1gSE]

I would. But before that, I would run a can of SeaFoam through it to pin the leak just in case its coming from somewhere else

[Brandoe91]

I gave it to a good mechanic friend of mine to look at, hopefully he finds the fault or faults . He is also going to smoke the engine to check for leaks.

I would. But before that, I would run a can of SeaFoam through it to pin the leak just in case its coming from somewhere else

[Eye8Pussies]

I would. But before that, I would run a can of SeaFoam through it to pin the leak just in case its coming from somewhere else

I agree.


having a BIG leak in the header area can throw codes. But with such a small leak (if as indicated by the soot, it is very doubtful that it will throw a code. Vacuum leaks are a lot more sensitive than exhaust leaks

[SirThomas88]

I would say a leak right there at the header could definitely suck in enough air to throw a code.

But try the Seafoam trick to find the leak. Also, the EGR pipes DO break off a lot (mine did) as was previously mentioned.

Replace that gasket ASAP!

[Brandoe91]

Mechanic fixed the exhaust leak and replace a header stud. After all that, codes P0171, P0300 P303 and P305 all came back. Last night I was reading how some injen intake can throw a P0171.So, this morning I decided to put back the stock intake. It worked, the CEL went away and fuel trims came back within spec. Thanks everyone for all the input. Fingers still crossed but hope I solved the issue.

[trd4life]

injen intake needs to be tuned on a dyno with a safc to work correctly

[Brandoe91]

So it seems. I saw that a few s/ced ppl got the too lean p0171 code but never saw any threads with N/A ppl having any trouble with the injen sri. What's crazy Gabe, Adam was just down here and was gonna do my s/c install but because of the codes we postponed it. Right after he left I fixed the the dam CEL.

injen intake needs to be tuned on a dyno with a safc to work correctly