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Dc headers on ULEV engine?

10K views 25 replies 6 participants last post by  IronTemple 
#1 ·
Ok I was excited that my new dc headers HHC5018 arrived today. I opened it and the instruction says "this header is not intended to be used on any ULEV engine"
That means in screwed?? Can't install the header?
Or is it fine to install it?
I have 98 accord 4 cyl. F23a4 engine
 
#9 ·
Your computer runs the air/fuel mixture. The ULEV motors run lean, so it is pumping less gas into the motor, it allows cleaner emissions while saving on gas. When you increase the flow rate of the exhaust, the computer responds by running leaner, so you'll be running even less gas. Which could be harmful to the engine. So if you want to run the header, you will most likely need a tune to run the proper air/fuel ratio. You can probably pick up an A/F controller to handle this instead of a chip and tune.
 
#12 ·
It's not intended but that doesn't mean it can't. Fitment will be correct.

Other than the fact that you are going to get around 3-5 HP more power if that, you can install it and see what happens. Hopefully, there are oxygen sensors, a.k.a. O2 sensor, bungs (opening to screw a sensor into) in the header in similar locations as your OEM exhaust manifold and downpipe. If not, you will need to bring your header to an exhaust/muffler store and they can weld in the bungs for you.

Don't install a Vortec Cyclone (Tornado Air) air-intake funnel into your intake, you're going to hit 5,000 HP and that's going to hurt your header.
 
#13 ·
so I put the dc header on, it did come with an o2 sensor bung. but after 1 day my check engine light came on and it was a P1164 code which is bad primary o2 sensor? correct me if im wrong. I cleared the code and CEL hasn't come back on yet.
does that code says for sure that its a bad o2 sensor? or could it be because im running lean after the dc header was installed as you guys stated above?
also, can a bad cat. converter gives me that code as well? the reason im asking this is because I know my cat. converter is bad. its broken inside. I saw like a cube that got loose in the cat converter while putting on my header. its like a rock inside a coke can, when you shake it makes a rattle noise.
also, I replaced a new primary o2 sensor about 2 years ago.
 
#16 · (Edited)
i wouldn't even waste my time modding a ulev vehicle. defeats the whole purpose with no real gains unless you do a serious build. to do it right you're gonna have to get a quality header and a retune with proper software and tuning hardware all for 4-5 hp gain...if you're lucky. more cost effective with a turbo at 7-10 psi and actually make 215-230whp.

my girl has the same car....just swap in a f20b :p
 
#17 ·
too late now. i gotta start somewhere. it's my first time doing all these mods.
how does the new header sets of the CEL though? how do I fix it without putting back the stock one?
its been more than 2 days now since I cleared the code, and the CEL hasnt come back on yet.
if I decide to swap in an H22A from the 97-98 prelude type S. can I reuse all these mods?
right now I have a magnaflow cat-back, AEM short ram, and this dc sports header
 
#19 ·
If it isn't throwing a CEL anymore, forget about it.

I don't know what's up with your catalytic converter. Something clanking around shouldn't be the source of your problem. It's a non-mechanical part. The materials in the catalytic converter help with exhaust emissions cleaning. If you do want to replace it, it's going to be expensive to replace it with an OEM catalytic converter. Get an after-market free-flow catalytic converter. It will free up the exhaust gas flow but again, no torque increase, minute amount of HP increase.

Just to give you the down-low if you don't know, the header is a bit more free-flowing on the exhaust side of things. So at low to mid RPMs, there isn't going to be less restriction with your header than you had with your OEM exhaust manifold. So you won't get any HP increase and no torque increase. At high RPMs, there is going to be less restriction so your engine is going to be able to push out exhaust gases a little bit easier. So you are going to get about 3- 5 HP only at the top end. No torque increase.

If you get a different engine, the layout is usually different and you won't be able to re-use the aftermarket parts you have.
 
#20 ·
I installed the new AEM wideband air/fuel controller. I just removed the stock primary o2 sensor and installed the a/f controller there. so right now the stock primary o2 sensor is not plug in to anything. now i have CEL codes P1166 and P1167

P1166 HO2S11 Heater Circuit Fault (Bank 1 Sensor 1)
P1167 HO2S11 Heater Circuit (VS+) Fault (Bank 1 Sensor 1)

Is it because i'm not using the stock primary o2 sensor hence i have the CEL?
or something else is wrong?

I also installed a magnaflow catalytic converter at the same time. but those 2 CEL codes don't have anything to do with the catalytic converter right...
 
#26 ·
Thanks again! A few more annoying questions! (not many of us willing to do mods to this engine!) I have a similar setup to you minus the headers - what did you think of the difference? Also, did you have to extend the wires to reach the new location for the O2 sensor? If so, what did you use to do that?
 
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