Help getting GReddy Kit to pass smog - Lean AFR problem
 

I live here in sunny California so I've got to deal with SMOG.:loser:

Well, my numbers up so I stopped messing with the car and put the stock intake peices from the kit back on with the intention of going to the local SMOG test shop to get it through the 2 year ordeal. I've got a SMOG sticker for it so I should be OK as long as they don't look too hard at my ARTech downtube and exhaust. I do have a CA legal CAT in place.

Car is a 91, currently has the stock GReddy manifold, intake piping (OE cross over tube) but the down pipe is a 3" stainless devorced tube from ARTech along with 3" CA Cat and exhaust.

The problem:
Someone told me I should look at my timing before I brought the car to be tested so I checked it and I was set at about 6 degrees (I had set it to whatever the stock GReddy kit was supposed to be set at when I first installed it).

The same person told me I should set the timing to stock (without turbo) to pass smog so I advanced the timing until it was at 9 degrees figuring it was at the low end of stock but a little low to avoid knock. (I'm running premium gas - 91 octane)

I was driving the car on the freeway and I noticed that my Wideband was showing an AFR around 14.8-15.6 and my Check Engine Light was coming on. Then after a few minutes the CEL would go out and and my AFR would be around 12.3 (I belive that is where it should be)

I am running the stock ECU and currently fuel managment is using the stock Vortec rising rate fuel pressure regulator that comes with the GReddy kit (stock injectors etc).

The last time I checked the CEL flashes it came back with a code 17 so basically its saying the narrow band O2 is out of range. I changed the O2 a few years ago so I'm thinking that it should be OK.

When I first set up the kit my AFRs were fine. Since then I was working on putting in an intercooler and other things to get ready for some track days (eventually I'll add mega squirt, injectors, etc)

So, I've put it back to the stock kit but the only other changes are advancing the timing and installing the custom 3" ARTech devorced gasses down pipe and exhaust.

1) Should I set the timing back down to 6 degrees (Is that the stock GReddy kit setting)?
2) Do you suspect a vacuum leak? (why would it go lean then back to 12.3)
3) Do you suspect the narrow band O2? (Its not very old)
4) What else could I be missing?

I'm already passed my SMOG date by a 2 days but if I can get it to pass before the 20th I only have to pay the extra $21 after that I think they tack on another $10 every 10 days.

Any help would be greatly appreciated.

The ECU should control to 14.7 at low and mid-throttle.

It's possible that the VE gain from the free flowing exhaust is taking you pretty far off the stock fueling map -- so far off that the feedback loop can't compensate.

I would put the stock exhaust back on for the test. Hopefully you still have it.

Also, this is an excellent example of why bandaids can be hazardous to your engine.

I hear what you are saying but I'd like to avoid putting back the stock exhaust if I can (It means taking the whole thing off including manifold)

When I first set up the kit I had a 2.5" downpipe (not seperated gasses) and exhaust with a Flying Miata CAT. I didn't have any problems with the AFRs getting out of wack.

My boost seems limited to about 3psi

I don't plan to run it this way other than to get it through SMOG. If I can find a way to get it to pass without removing the DP life would be so much easier since the switch from Intercooler to stock cross pipe is pretty quick.

Look up the actual text for the CARB EO# for the GReddy kit. If the EO says "base timing changed to 6°" then you CAN'T pass unless it's set to 6° simply from a visual standpoint.

Database: Aftermarket Parts Database of Executive Orders :bigtu:

I'll reset my timing and see if that helps the AFRs as well. I'm not sure why Andrew had said to set to 10deg.

However I'm wondering if will really cure the lean state issue. Does your engine pump more fuel with retarded timing?

Can't wait to get this thing through SMOG so I can switch over to MS.

By the way, did you ever find that info that states adding an intercooler is CARB legal?

I looked at it but couldn't actually find a hard reference for it. I think there is a section in the CARB EO database for "Intercooler Modification" or somesuch, so that kinda points to a fat "NO!"

Its been a while, but with an OBD1 vehicle, do you get rollered? IIRC the testing protocol is sniff at idle, and sniff at "cruse RPM" on a set of rollers. The test should be right around 2k RPM with like, no load so I wouldn't imagine it will see boost. No boost = no lean condition? Can you somehow set your wastegate full open and just let the stock ECU handle things with no boost?

I'm just grabbing at straws here, feel free to tell me to piss up a rope. Hell, I had to go back to full stock before anyone would even test mine. That iron boat anchor and pre-cat is no fun at all :(

An intercooler isn't listed as part of the turbo kit according to the EO here:
http://arb.ca.gov/msprog/aftermkt/devices/eo/D-397.pdf
So it's theoretically illegal to add to your Greddy kit.
If you look at the BEGI turbo kit EO, an optional intercooler is mentioned.

Reset the timing and disconnected the battery to clear the codes and took off down the freeway to get it smogged and just before I got there the CL came on again!

Instead of going to the smog shop I went to the parts store and picked up a new O2 sensor thinking that it must be my problem. Got back home and popped the hood and smelled something odd.

I checked the codes and it seemed to flash out 17 and 18 (I remembered 17 was an O2 sensor code)

As I dug around I found out that my O2 wires had slipped down and sat on that huge 3" downpipe and when I pulled the mess out I could see bare wires.

I put a single wire O2 back in and carefully routed the wire way around the DP and got it all hooked up again.

I drove it last night and no CL but AFRs at cruz were still in the mid 14s. Later I realized that is stoike (sp?) and it would drop under boost into the 11s-12s and even 10s under hard acceleration. I'm think that's OK?

Anyway, its currently sitting at the "Star Certified" shop as required by my DMV renewel form. Don't know why I keep getting hit with "Test Only" or now this new "Star Certified" because I've never failed a smog. It's a real pain to find one that is open on a Sunday.

Wish me luck!!

PASSED!!!!

Numbers weren't great but under the Max. Worst was NOX. I'll post the numbers later.

Now I can finish putting in the intercooler and start on the MS install so I can get a proper tune. (For use off road on the race track only of course!)

Grats man! :party: :party: :party:

I think the word you are looking for is "stoichiometric" or "stoich" and yeah, its 14.7:1. 10-12 under boost sounds safe-ish.

Can't comment on the STAR thing, did they roller the car? I think this may be the new oppression for OBD1 and earlier vehicles. My car (OBDII) didn't get roller'd, but the shop had a set.

Anyway, glad to hear it worked out for the best! Sounds like its time to invest in a thermal solution for your wiring ;)

Yes, had to go on the rollers (that's always been required in SJ) it's also why our tests cost so damn much! $58.20

Seems like I do better at the higher speed test. NO is high for both which means I'll probably get subjected to special treatment again next time:loser:

I parted out all my turbo parts because of the STAR program. Smog techs online are all complaining about it because their customers are getting forced to a small number of stations.

AFAIK, older cars stand a higher chance of getting sent to a star station, but my parent's 05 g35 also got sent- so it might be random as well.

So what exactly is STAR then?

LOL, I should post my numbers with the stock twin cat setup :loser:

STAR is when the government sends cars that are "likely to fail" to special stations.
Directed Vehicles
Similar idea to "test only" smog stations/requirements.