Z28Camaro30Ann

iTrader: (15)

I converted my 97 SS over to OBD1 while I lived in Wyoming...no emissions there at ALL. I recently moved to Colorado...STRICT emissions. They are going to do a test on my car and I have to convert my PCM back over to OBD2. The only things I changed was I removed my rear O2 Sensors, and I added in a 94 LT1 Knock Sensor and installed the 94 PCM. Everything is great EXCEPT for the fact that "reverse engineering" my car is illegal in...say....50 states. Oops.

SO, now I need to pass emissions...which means I need to install the OBD2 PCM, Rear O2 Sensors, 2 Catalytic Converters, an actual exhaust system (Previously it was LT Headers to an LPP ORY to an SLP LM1 dumped at the axle), mock up my A.I.R. system and I need to tune the OBD2 PCM.

Now don't get me wrong...I HATE the LT1 OBD2 and I DO NOT plan on keeping it...therefore I am copying one of our esteemed member's exhaust threads almost to the letter...the ONLY change I am making is instead of 2.5" QTP Cutouts, I am doing 3" QTP Cutouts and I will have 3" to 2.5" reducers that will take it down to the 2.5" pipe AFTER the QTP's...the cutouts can be taken off and the reducers can be used BEFORE the CATs since the CATs will be 2.5". Here is the link: https://ls1tech.com/forums/lt1-lt4-m...cs-inside.html

My question is...when I do this, do I absolutely HAVE to change that Knock Sensor??? If I don't what will happen exactly?

Basically what I will be doing is throwing my ALL of my emissions stuff onto the car and having my tuner set up a VERY conservative "emissions" tune on the OBD2 PCM. Once that is done, I will take it back out and re-install the OBD1 PCM to rive it to the emissions shop. Once I get to the shop, I will remove the OBD1 PCM and install the pre-tuned OBD2 PCM. I will do my emissions test, and upon passing I will stop in the lot and remove the OBD2 PCM, re-install my OBD1 PCM and head back to my shop where I will remove all of the emissions crap, throw it into storage, re-install the QTP Cutouts and I am good for 2 years.

Thoughts, questions, concerns? Anything that I missed or am overlooking? Thanks in advance!

gregrob

iTrader: (8)

Dude, you really need to find a "friendly" shop, end of story.

You really think a healthy stroker is going to pass anyway?

Z28Camaro30Ann

iTrader: (15)

I don't have a lot of choice man. I have to take the "Enhanced Colorado Emissions" and they are done by "Air Care of Colorado" only. There are only 2 other shops in Denver besides Air Care that are authorized to do Enhanced Emissions and neither of them are "Friendly". I talked to them already. If I were doing a "Basic Emissions Test" then yes I could find one, but I don't fall under a county that does those.

And yes, I believe I CAN get a healthy 383 to pass. As long as I can get the visual **** taken care of, it is all about air to fuel ratio after that. I talked to a guy today that helps run the program. He is as muscle car friendly as he CAN be without getting in a lot of trouble. He gave me a few hints on how to squeak by and how the system works. Fuel control is the key. He said there was a stroked and supercharged 9 second mustang that came through a couple of weeks ago and he passed after he took this guys advice. So I am taking his advice. I need exhaust regardless, so I am going to make a system that can accomadate CAT's at emissions time. The AIR system will only be mocked up but won't be functional. He said they don't look for EGR or EVAP, and they don't dig too far into the PCM. He said all they look for are 2 CAT's NEAR the stock location, 4 O2's, AIR and no engine codes. If all that passes, they run the sniffer and if my A/F is set up right and the CAT's are working, I should pass. If not he said to call him and tell him what the results were and he would give me a few more pointers.

I don't have the option of a "Friendly" shop at the moment so I need to go this route. At least for the first registration in Co.

gregrob

iTrader: (8)

Find a way around it...

Its not all about AF ratio either. You have a cam that has overlap and you will have high nox.

You might be able to do an emissions only tune and run it lean as hell, but I guarantee you will have to keep stacking cats on there to get it to pass.

**** emissions. I would find a way around it.

Z28Camaro30Ann

iTrader: (15)

I have been trying for 2 weeks. This IS a way around it...if I did it like they wanted, I would have to install my EVAP, EGR, AIR, and make it all fully functional again...which means I would need emissions headers and everything...Then they would dig into my PCM and check to make sure everything s functioning properly and all that jazz...no thanks.

If I do this, I can set up a nice exhaust system that I like, and just make 1 piece on each side interchangeable for CAT's. The tune will be set up for emissions specifically and nothing else. I will do whatever it takes to get it to pass this one time. Once I get past this one, I have 2 years and I don't have to worry about it as much.

The reason this one is so hard is because I can't just do the "drive-by" vans or get leniency because I am a new resident and the car is coming from another state. He said there is no real way around it for the first one. Once I get past this one I will have it MUCH easier. The OBD2 PCM will only be in the car for about 10 minutes...however long it takes for me to get the car through emissions. As soon as I get out of the bay, I will pull it out and put the OBD1 back in it and head straight back to Trent's to remove the CAT's and AIR and put mu cutouts back on. Then I am free for 2 years.

I am gonna talk with Trent some more tomorrow and see if he knows any tricks.

Lgoldtop

If u decide to sell your dumped exhaust shoot me a pm.

Lgoldtop

If you* decide to sell your dumped exhaust shoot me a pm.

esoteric18

My truck was straight piped and failed.horribly. i put half a tank of e85 in and it got within .o3 on the hydrocarbons and passed the other 2. That's with straight pipes. i eventually had to add a cat. The truck ran like **** but it got close. I'm not saying a 383 should do it but just giving my experience on what works. After this one it shouldn't be too hard to find a "friendly" shop.

95mysticta

iTrader: (4)

I dont know how strict Colorado is for emissions but up here its all the same bs had to build my motor around to make sure it passes. Problem as stated by gregrob is that AI and LE make most of there cams on a 110 or lower lsa which is what kills your nox levels. If you had your cam ground on a 112 you would be fine. A local guy up here passed his 383 with a le custom 230/236 112lsa cam.

shbox

To answer the knock sensor question, the knock sensor must match the OBD computer type or there will be a trouble code and your timing will be automatically retarded by differing degrees and performance will be impacted.

jaycenk

iTrader: (1)

I think you may be better off getting a front K member and bolting in a junk yard stock engine to it and swap it and pass lol.
Your gonna get close and have a **** load invested and may still not be able to pass. I see post like this so often with LT headers here and I have yet to see someone who passed with out "some help".
If you do attempt it, I would say put a set of shorties on it and get the cats in the stock location and run alcohol mix fuel and tune to get those damn things nice and hot and then switch back to LT's after. Still not sure that would even pass. LT's make it tuff to get the cats hot enough to work. Most guys actually use them just to quiet down the exhaust.