DT Long Tube Headers and Y-Pipe CEL issues.
 

Well my saga continues with my DT long tube headers and y-pipe install on my 06 v8. Here is a series of events, looking for advice on what to try next:

1) Installed DT headers and DT y-pipe last Sunday (5/12) with an experienced mechanic. Removed all the cats. Took 10 hours, no real install issues. Started up the truck afterwards and drove it around the block, no CEL and ran well.

2) Went out later that night and got it up to highway speeds and it threw a CEL for the O2 sensors (P0420 and P0430). Took it home disconnected the battery then drove it around again, CEL came back on for a O2 sensor error. Called Jason Burtman who I bought them from and he said I needed CEL eliminators (basically metal 02 spacers), and he sent me 4 of them.

3) Went to install the spacers yesterday morning using the original O2 sensors, and after I got done, I started it up and got a CEL for code P0057 which is bad downstream O2 sensor.

4) So now I go and order 2 new downstream Denso O2 sensors (part number 2344261) from the local Advance Auto Parts. They came in the morning, and when I went to install them they were longer than the ones that were in there originally, see photo.

https://ibb.co/596ptfv

Passenger side fit ok on top of the spacer, but the drivers side would not fit without loosening the y-pipe, screwing in the sensor then retightening the y-pipe to the headers. That being said the wires coming out of the 02 sensor were rubbing on the frame with zero gap. Got it all back together and decided to disconnect the battery for 30 mins again just to give it a full reset. Started it back up and it threw 5 codes this time:

P0037 B1-S2 HEATER ISSUES O2
P0057 B2-S2 HEATER ISSUES O2

P0102 MAS AIR FLOW SENSOR

1440& 1443 0AIR INJECTION SYSTEM

Super frustrated at this point, I took the truck out and tried to drive it. It stalled at the first stop sign. Was able to get it back to my house and decided to remove all the spacers and go back to what I started with. Jason suggested I remove the front 2 spacers first , so I tried that, no luck truck shuts off. Removed all the spacers disconnect the battery for another 30 mins and fire it back up and immediately get all 5 codes again but seems to drive ok.

4) Drove it to the shop to buy some MAF cleaner and it seemed to be running ok but still had the CEL.

Note: I am running the Slyfox air injection bypass but didn't get a code on that till today when I added the new 02 sensors.

So now I am stuck and looking for help. I have my mechanic friend coming by on Sunday but Jason suggested I see if anyone else could help troubleshoot. My questions are:

1) What are the chances I get 2 bad O2 sensors out of the box? And why is the new one so much larger? I thought Denso was OEM?

2) Why am I now getting and MAF code? I got some cleaner but haven't pulled it out yet to check it. Going to do that when I have some time tonight.

3) I called Doug Thorley and they said the O2 spacers should keep the CEL off, but weren't much help beyond that. They said if I was getting the air injection code that there was a leak somewhere, so I went and retightened everything but still getting the code.

Looking for any advice on how to move forward besides taking it to a shop, thanks.

The p0420 and p0430 are 100% expected with upper catalyst removal and nothing to modify the O2 sensor signal but seems like you've already got that figured out. The only reason they logged after a drive is because you need to get up to certain conditions for that drive monitor to complete it's cycle. Spacers may or may not work to prevent these fault codes.

P0037 B1-S2 HEATER ISSUES O2
P0057 B2-S2 HEATER ISSUES O2

These are most likely related to either plugging in the sensors connector not fully seated, damaged wires, or bad sensors. If it's a damaged common ground to the heater on one of the O2 sensors it could cause the other sensor fault to log too without being bad at all. I would carefully do continuity and pin to pin short checks in the sensor harnesses and from the sensors connector to ECM connector. You have the right part number sensor and the ones I ordered from amazon recently looked exactly like the stock sensors so they shouldn't be longer? You can measure the heater circuit of the sensors to see if there is any resistance like a heater should have, or an open or a short indicating a bad sensor.


P0102 MAS AIR FLOW SENSOR

1440& 1443 0AIR INJECTION SYSTEM

These are all related to your slyfox bypass, check the wire spliced into the MAF plug, I had mine come unhooked once and cause a 102 but I didn't log 1440 and 1443 because somehow my AIP and valve is still operational! These faults can cause limp mode. Fix this first then go back to the O2 sensor issue separately.


My personal saga with a similar setup is that with 3 stacked spacers I still got a P0430 after I installed the DT ypipe. I ended up going with a URD O2 simulator and recently posted a thread about issues with install but we figured it out (tan wire must be wired to GROUND not signal reference). The signal simulator eliminates the need to spacer O2 sensors in the ypipe making it a less tight fit between sensor and the bottom of the body. The O2 sensor wire on the passenger side still needed to be unclipped from the first holder to be long enough.

EDIT: I don't think DT knows much about the exact application, they told another member to put spacers on the UPSTREAM air/fuel ratio sensors. So I wouldn't listen to them. I'm sure they have a good general knowledge of this stuff but spacer on the upstream would cause poor running issues. Only ever put spacers on the y pipe sensors.

Thank you for this post. I will be going with DT long tubes soon. Very helpful.

OP please let us know how this gets resolved. You may want to get in touch with Gadget at URD

Updates? Got this sorted? If yes what was the solution?

Very cool. Seems like an easy solution.

Thanks!

No luck yet, have another shop looking at it today. That min cat seems interesting. I bought some of these bc they were recommended on a FB forum, but I haven't tried them yet:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

My main issue is I am getting a MAF code and secondary air codes even thought I have the slyfox secondary air bypass. I am wondering if the relay went bad on the bypass coincidentally.

Yeah this helps, thanks. My problem is I DID install the spacers on the upstream 02s at first bc they sent me 4, so maybe that threw everything out of wack?

YES, NEVER install spacers on the upstream sensors. They are air/fuel ratio sensors controlling how the engine runs and are not related to catalyst efficiency - they are located BEFORE the catalysts in the factory header. Any fault codes return with spacers only on the downstream? You might need to stack 2 or 3 on each side.

As blackoutt said, for the love of god don't have spacers in the upstream 02 sensors. Downstream is strictly for cat efficiency checking while upstream 02 is for Air/Fuel mixture.
As an aside, can you give us your impressions of the DT Longtubes? Any noise difference? Are you running an otherwise stock exhaust (with all cats deleted?)

Thanks!

Lesson learned, I was just going by what Jason Burtman and Doug Thorley said to do, I am just having trouble undoing the issues that caused. When the truck ran well for a the first few days, overall impressions were great. Felt like more power throughout the range, but I didn't push it too hard since I had a CEL still coming on after it heated up. I have a K&N CAI and a Gibson catback exhaust and it definitely made it louder, almost too loud for my tastes. Here is a video but it doesn't do it justice:

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Idle is slightly louder at a cold start, but dies down once it heats up and is not really any louder than before. I'd say its the loudest drone is at about 30-40 mph. I haven't run the new setup for long enough to determine anything about mpg gains yet. One thing I don't like about running catless is the smell, but that could be bc it is running rich. Hoping to get it fixed soon so I can enjoy it again.

How does the story end? I have longtubes & the Y pipe ordered. Was planning to add a single cat after the Y to kill the fumes

Also curious, was thinking about doing the same thing.

I believe this is the same guy that the shop found a blown ECU fuse from reading on a FB post.

Just a heads up. I still have the factory Y Pipe with HFC cats welded on my DT header and Gibson setup and the fumes are pretty heavy, especially on cold start. So don't expect too much of the smell to be cutdown. If anything it were me I would just put in a resonator to cut out any drone depending on which exhaust setup you go with, just a thought. :shrug:

Just an FYI - I manufacture the mini cats which are made to solve this exact problem forever. The problem is that if you install spacers, your wires smash against the frame, so how do you get correct operation without anything sticking out and without using spacers? The solution is to machine a mini-cat that goes inside the exhaust that does not protrude at all AND contains legit carb compliant material. PM me for details.