Throwing P0171 and P1170 codes

[B-R-Z]

Some background: I've been running an OFT stage 2 91 tune for over a year now with no issues at all. Around 2 weeks ago I noticed a different sound coming from my engine bay when accelerating. In addition to the normal rush of air sound common with aftermarket headers, I also now get a light tapping sound at certain RPMs and only under acceleration. I also can smell exhaust under the engine bay or in the cabin if I sit idling. I assumed my header was cracked or I had a leak somewhere so I put it off to this weekend to investigate.

This morning I removed the skid plate to check for header cracks/leaks etc but it looks fine. The only thing I noticed is the gasket from the header to overpipe looks like it's deteriorating around the outside edges, but besides that it looks ok.

So after checking my car out, I go out to get coffee this morning and as I am leaving my CEL and traction control light comes on.

On the highway the traction control light turned off after a few minutes, came back on for a few minutes, then turned off for good. I do think my battery is going bad, do you guys think this can be voltage related? I have had no problems starting the car recently, but if I sit listening to music for a few minutes the starter has a hard time turning over.

Any help is appreciated

I just went out there and if I hover my head over where the flex pipes are I can smell exhaust, if I hover over where the overpipe and header connect I smell nothing.

You really can't tell by looking since they have the protective covering.

Edit: I think it's definitely the flex pipes. I was hovering my fingers directly outside the protective mesh trying to feel for leaks. I thought I felt air but I'm not 100% certain. Now, smelling my fingers, they stink so I think this is my leak.

Is this possible to fix, or am I buying a new header?

[JB86'd]

Well that's definitely an exhaust leak..no debate there. Could definitely be the cause of your codes.

[steve99]

Definitely appears to be a leak if you can smell exhaust


P0171 too lean
P0170 Fuel trim malfunction


Both codes would also point to exhaust or intake leak.


If its leaking at those flex joints it very close to 02 sensor. In between exhaust pulses it will suck in fresh air. 02 will see fresh air with lots of oxygen and ecu will assume engine is lean hence P0171, ecu will then add heaps of fuel using fuel trims which will likely max out and you get P0170.


Log with oft you will likely see very high positive LTFT and lean AFR readings compare to Commanded AFR at lower rpm to confirm


An exhaust shop may be able to weld in new flex joints. If it was a cheap header probably just replace it with a decent one.


dying battery can cause all sorts of weird issues.

[B-R-Z]

Thanks Steve. That also explains why I am seeing slightly worse fuel economy.

Is there any harm in driving it in the interim? I plan on swapping headers tomorrow and I need to find my laptop so I can flash either an OFT stage 1 or flash back to stock.

Is it safe to say that the traction control light is a result of the CEL?

Are leaking flex joints fixable?

[steve99]

Originally Posted by B-R-Z

Thanks Steve. That also explains why I am seeing slightly worse fuel economy.

Is there any harm in driving it in the interim? I plan on swapping headers tomorrow and I need to find my laptop so I can flash either an OFT stage 1 or flash back to stock.

Is it safe to say that the traction control light is a result of the CEL?

Are leaking flex joints fixable?

Traction light likely to be different problem might be due to dying battery or some other issue like wheel speed sensor, can be caused by staggered wheel setups


I doubt the flex joints would be fixable, they would have to cut them out and weld in new ones.


best not to drive it too far like it is

[B-R-Z]

Thanks, Steve.

I assume they sell these flex joints at pep boys/auto zone? My buddy said he is willing to replace these joints for me. Assuming doing one at a time will keep fitment/alignments the same.

[B-R-Z]

I think I was also leaking where the header connects to the block. One of the bolts was only hand tight--it was one of the bolts that was nearly inaccessible with a socket when I installed it. I noticed a bit of soot buildup on the block right in this vicinity earlier this morning. Based on the discoloration on the flange, I think I was leaking here, too.

On the right side


Not sure how to confirm if it's my flex connectors, but it looks like there is a little black coloration.

[B-R-Z]

Is there any way to confirm if my flex joints are bad?

Having that one loose nut on the flange and all of the soot build up on my block, I'm wondering if my issue was that loose bolt and not the flex joint. The flex joints while having a black coloration, there is no soot buildup. I'm now debating on reinstalling my UEL header and see if the sound goes away. If my leak was at the flex joints, wouldn't I have more gunk build up and not just a black coloration?

Is a little leakage at the flex joint normal?

[Wayno]

Only exhaust should come out the back of the car, flex joints or not

[B-R-Z]

Originally Posted by Wayno

Only exhaust should come out the back of the car, flex joints or not

Yea but some flex joints are 100% mesh...There's no way they are air tight

[HLHachiRoku]

Honestly you can have a shop cut the flex joints out and just weld a solid same diameter pipe in there. All the aftermarket headers are running without them now. Then you don't have to worry about any leaks there ever again. Also you can put new gaskets on ^.^ I made the mistake and reused mine this past weekend, and I believe its leaking now. I ordered some new ones and should be here this week. I'm not sure, but I haven't thrown any codes and recorded some driving on my oft that I finally was able to get =D LOVE the power increase haha.

[B-R-Z]

So there's no longer a chance of headers cracking or whatever the reason for flex joints are?

[HLHachiRoku]

My wife got me JDL header and over pipe for Christmas =D It is ceramic coated but has the flex joints. (finally able to install since i bought my OFT =D ) JDL makes headers now with no flex joints. When i asked they said there is no need as their test ones came back fine without the flex joints. They are flex joint free now. So JDL, Openflash don't have them either I have seen, I'm sure there are others. It also brings down the cost of the header as well, along with a component that won't fail over time as well. So its a win win for everyone =D

**edit* Also when I installed the header, honestly don't see how the flex joint would even move at all, if everything is bolted up tight, the exhaust is bolted as well to the tranny mount. The motor won't budge, I tried moving it. This is probably the reason most if not all have gone away with the flex joint. Maybe over time when the motor mounts get weak? Not sure time will tell lol.

[B-R-Z]

I snapped a few pics of where the header meets the block on the side that I had the 1 loose nut. I think this was more where or only where my header was leaking. What do you guys think?

Since it's already out, I'm going to have a friend replace the flex joints with straight pipes. Thinking of bolting the header flanges to a piece of wood to maintain fitment.