2003 DMax... do I have a Cat or not?

**AlanL** · 06-05-2003, 07:49

My truck is a 2003 DMax purchased in NH.

I was looking at the exhaust while doing an oil change. I have what looks like a resonator or something up near the turbo.

I was surfing around looking at 4 inch exhausts to go with my new predator and I noticed that none of the exhausts that I've seen seem to have this part.

Is this the dreaded catalytic converter that some trucks have been coming with? If it is, does that mean that I have to get a custom exhaust that includes a cat to stay legal?

If my truck has a cat, I guess I expected it to be down a little farther from the turbo and heat shielded like on a gas vehicle... this big can that I'm seeing is definitely right up near the turbo at the end of the "down pipe".

Thanks for any info you can offer.
-Al

**GMCTRUCK** · 06-05-2003, 08:48

Yup, that's the cat. Which most likely means you're truck has the egr also. I didn't think NH required that emissions package. Maybe the truck was to be shipped to MA originally. Or it was just ordered with MA emissions. Check the window sticker.

**Kent Tuttle** · 06-05-2003, 08:55

The CAT on my truck was back almost even with the rear of the trans, near the flange connecting to the rest of the exhaust.

**AlanL** · 06-05-2003, 09:25

They're probably shipping MA spec vehicles to NH because lots of Mass residents (note that I didn't say M*******s

oops [img]smile.gif[/img] ) come to NH to buy. The same is true in reverse, as well, so I think that the dealers in NE order the least common denominator spec vehicles to cover this situation.

So, given this realization that I have a cat on my truck... is there an aftermarket exhaust out there that includes a cat?

If not, is there any harm to replacing with a catless exhaust? I've done this on my race car, but that now has a permanent "Check engine light" FWIW, every time I hit the loud pedal, the engine seems to be there and working, regardless of the light

I'm assuming that since the truck came with the cat, that I'm required to have one, even though my state doesn't require it.

-Al

**a64pilot** · 06-05-2003, 11:13

Alan L,

For your race car it is a simple thing to plug in a 02 simulator in the wiring harness where the factory 02 sensor was mounted either in or after the cat. For the 96 and newer OBDII cars a second 02 sensor was added to monitor the Cat's performance, it can be replaced with a simulator thereby returning the check engine light to a functional item.

**DMAX Daddy** · 06-05-2003, 11:52

Picture of Catalytic Beer Keg

This is on the passenger side, maybe even with the front passengers door.

**AlanL** · 06-05-2003, 12:37

RE: Picture

Yes, that's exactly what I have.

RE: Race Car advice

Actually, I have the parts for an OBD I conversion, and after that, the light will be out. I'm converting to OBD I on the car because the computer will more readily do exactly what its told to do... it won't try to adapt to anything.

The OBD I conversion and a set of M3 cams and I'll gain about 40 HP. This isn't much, or difficult to do in a Dmax, but in my 2.8 liter 6 banger gas engine, its a big deal.

-Al

**GMCTRUCK** · 06-05-2003, 14:57

Alan L, If it were my truck and I were putting an exhaust on it I would lose the cat. Let those M*******s

run them if they want. It's not gonna set off any lights either. I know Banks has a system for trucks with or without cat and I assume Kennedy and the others have systems for both also.

**lbrown** · 06-05-2003, 18:05

I just put JK's 4" exhaust on yesterday. I took off the cat, didnt really know what it was. Truck runs fine without it. Sure does sound alot better, not that loud at all. Why is there a cat on my truck in Ga? Gotta go check my sticker. I though this wasnt going to happen until 04's.

**DMAX Daddy** · 06-05-2003, 18:37

Mine will have the CAT until its out of warranty at least. They are getting serious against diesels now in CA. Lord knows what they ae going to try to get rid of all oil fired beasts.

I sure wish running around holding hands singing "Kum-by-a" would propel my vehicle, but I dont see it happening. The EPA Nazis are going to try though...

**VWLURE** · 06-05-2003, 19:15

I just put on the Banks exhaust and I went without the cat. even though mine had one. I live in Cali. so I saved the cat. and if I ever need to put it back on, just bolt it up! It took about 2 hours to do the exhaust.

**lbrown** · 06-05-2003, 19:28

OK, my sticker says Federal Emissions n/c Ha!
Also found a sticker that said not for full time use in Ca. Complies with VT and NY emissions. Thats a long way from GA!
I guess my concern is would this have made a difference in what I ordered from JK.
Hey John, do you have a different exhaust system for a cat vehicle?

patrick m. · 06-05-2003, 19:42

That's the liberal "left" coast. after all the liberals decide whats best for us, because we are unable to.

**DURAMONSTER** · 06-05-2003, 21:35

I just went through this. the 03 Kali trucks have cats but there will be no inspections on a 03 diesel ever It is just a start. You can take it off with no reprocusions.

**Kent Tuttle** · 06-05-2003, 22:22

This is why I went with the JK system on my '02, no cat. I thought I saw somewhere that in '06 diesels in CA were going to be tested?? I have the cat just in case [img]tongue.gif[/img]

**DMAX Daddy** · 06-05-2003, 22:30

Thanks Monster. Maybe Ill get the rest of the system and save the Cat just in case....

**RWTD** · 06-05-2003, 23:27

Originally posted by a64pilot:
For your race car it is a simple thing to plug in a 02 simulator in the wiring harness where the factory 02 sensor was mounted either in or after the cat. For the 96 and newer OBDII cars a second 02 sensor was added to monitor the Cat's performance, it can be replaced with a simulator thereby returning the check engine light to a functional item.

Alan, is your race car the Beemer, or??? Depending on who you have your programming with, the DTC's for the rear O2's can be permanently disabled in the tuning. I tune this out of the GM Gas cars/trucks all the time, as well as the EGR, and AIR DTC's.

Otherwise, do as a64pilot stated, and buy you some SIMS.

Edit: I just saw it was for your 328. You really want to convert to OBD-1, 'eh? Uhhhg, I hate OBD-1 now that I've dealt with OBD-2 long enough. But you're right, OBD-1 is easiest to work with, but OBD-2 offers many more adjustments to get perfect driveability for almost any combination.

**AlanL** · 06-06-2003, 08:23

OBD I is the hot ticket in these BMWs. There have been a ton of people making mods to these with real gains. The success with OBD II mods has been far less.

Regardless of which system is actually better overall, I can get more power from the off the shelf parts with OBD I, so hassle and money wise, that's the system to go with.

I have all of the parts, I just need to get them installed.

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