Header/ Exhaust Updates

[oregun]

So I’ve had my new exhaust for almost a month and, although I thought everything was peachy - I’ve had two CEL’s during that time. The first time was April 27th. It was a freezing day, litterally, and I was traveling on the highway, rather slowly due to the traffic. I was crusing along at 2100 RPMs, and it just popped up. This was quite a surprise, but I had just filled up with gas so I thought it might be a loose gas cap. Unfortuantely, it was a main catlyast effiency failure. I cleared it, and it didn’t come back for hundreds of miles.

May 3rd. Snow. Yes, it snowed in Chicago in May, dammit. Same deal, Crusing along at 45 MPH in 5th gear and another damn CEL.

So . . . What have I figured out. Well, I have always maintained, and posted a few times, that I think most of the CEL’s that we get after header installs and O2 sensor relocations are due to the CAT not being hot enough. In order to mitigate that problem, I had my header ceramic coated. Nevertheless, my cat is almost 50 inches of pipe away from the engine block, compared to the stock set up where it’s about 5 inches away. That is a lot of distance for the exhaust gasses to cool down. In addition, since there is practically no back pressure from my mandrel piping after the cat, the exhaust gas dosen’t spend as much “time” with in the CAT. So when the weather is cold, and you’re right around 2000-2300 RPMs, the engine is monitering the CAT, but it isn’t staying hot enough to operate efficiently enough. I assume rain and water splashing on the Cat might also cool it below ideal operating temperature.

(Educational rant about Catlyast monitering: Your car only moniters the cat (1) between 2000 and 4000? (not sure about the upper end) RPMs and (2) after the 2nd/downstream O2 sensor is over 700 degrees. You Cat is designed to operate between 700 and 1300 degrees. The hotter, the better. Your car makes the following “calculation”- it measures how much O2 is in the exhaust with the first sensor. Then, the second sensor should “see” less oxygen due to the catylast “using” some of the oxygen to do its thing (I’ll leave out the chemical formulas. )

What am I going to do? Header wrap. I bought some Thermo-Tec wrap and I’m going to skip the four primary pipes because after a little bit of expermentation because they are so contorted, it’s litterally impossible. However, I am going to wrap as far as I can go and hopefully wrap the CAT too.

So, anyone else who relocated their CAT and O2 sensor and still getting a CEL, you might want to give header wrap a try.

[mrhoaf]

Your theory makes perfect sense... Too bad you're going to have trouble finding out how well the wrap works until this fall/winter.....

[kylemorg]

You can always wrap the header tubes together rather than individually if they're too close to get the wrap easily between them. I used to use the fiberglass wrap stuff all the time when building small reactors (mostly heated stainless tubing) at work and that works. The air space between will warm up and the wrap will keep most of the heat in.

[getfuzzd]

very good to know...probably why everyone gets a CAT related cel if they didn't delete or disembowel it.

[oregun]

You can always wrap the header tubes together rather than individually if they're too close to get the wrap easily between them. I used to use the fiberglass wrap stuff all the time when building small reactors (mostly heated stainless tubing) at work and that works. The air space between will warm up and the wrap will keep most of the heat in.


I tried. Have you seen the pictures I posted up? It's not just that they are close together. The bends go all over and when you wrap them together the wrapping just gets all bunched up and falls off. However, there is an advantage to NOT wrapping my primarys, and that is they look so cool, I don't know if I want to cover them up.

I've finished wrapping the header back to the cat and man, what a pain in the a$$ if you don' t have a lift. I also spray painted all the wrapping with exhaust paint to keep it protected.

I think I might go puddle jumping during one of the thunderstorms to see if it worked. I hope there is no more snow for the year.

[KeWLKaT]

http://www.elantraxd.com/forums/images/smilies/iamwithstupid.gif

[kylemorg]

How about something like this for insulation:

http://www.speedwaymotors.com/product.ASP?wc=true&strBase_List=&hilt=&source=2191&base_no=70414001&str_base_no=000%2DCATALOG+RACE%2C70400%2C70411001% 2C70412001%2C70413001%2C70414001%2C750SP101%2C750S P121%2C750SP995%2C91044082%2C91080118%2C91080250%2 C&header_title=Race+Products%2DWrap+%26+Insulation&page_name=prod%5Flist%5Fdisplay%2Easp&search_type=L2%7E53&search_option=&deptsearch=&deptSearch_id=2&dept_id=L2%7E53&dept_id_p=&dept_name=&dept_name_p=Race+Products&ShowImages=yes&sq=0&cont=1&intPgNo=1&redirect=

[oregun]

Yeah, I called thermo-tec about that stuff. Apparently it works - but not nearly as well as header wrap, in terms of holding in heat. That stuff does more to protect you from the heat of the headers - yeah I know it's the same thing.

Like I said, the headers are already ceramic coated. And they look too cool to wrap them in a blanket.

[sed]

updates on the header issues doc?

shawn :)

[oregun]

Well, since the header wrapping, I have had no CEL's what so ever. I definately do not recommend using header wrap without a lift. I really crinked my neck.

50 feet was plenty to get from the second part of the header and wrap the entire cat. After a good coat of Exhaust paint and a 30 minute drive, the smell finally went away.

I guess I'll have to wait till November to see if it's good enough. Looks like summer is finally here in Chicago.

[OdessitPashka]

I had relocated my sensor behind the cat and get CEL every 300mi or so. Then for half a year I stopped getting it, now got it back again... weird car.

[900Z1]

I'm not a electronics guru but couldn't you put a resistor in the cat connection
to make the ECU think it was hotter than it acually was. I know you can buy a
O2 simulator for GM's
Just my 2cents

[oregun]

That is opposite of what you want to accomplish.
When the O2 sensor is "hot" it starts to moniter and the engine runs closed loop.

If it never thinks it's hot enough, it won't moniter the cat


OD- Buy 15 feet of Header wrap and wrap your CAT. See if that helps.

[OdessitPashka]

I have header wrap, maybe I'll try it.

The very weird thing is on my tibby I have exactly the same headers with test pipe and no CEL for the last 5k mi.... explain that!!!

[900Z1]

That is opposite of what you want to accomplish.
When the O2 sensor is "hot" it starts to moniter and the engine runs closed loop.

If it never thinks it's hot enough, it won't moniter the cat


OD- Buy 15 feet of Header wrap and wrap your CAT. See if that helps.

Sounds like you know a little about how the computer works, I wish there
were software for the Hyundai's. Check out www.hptuners.com
This is the software I use on my GM's