PLEASE HELP! Another Failed Cali Smog. Super High Nox

ASSISTANCE Stock Engine-Bay Components
1

Hey there Fellas,

I know, I know. Another smog issue. Yes I searched everywhere here and on the web.
Anyway, here goes:

I knew the car was gonna fail so I put on a brand new cat. Carsound Cat, I believe. It still failed.
Passed on the HC and CO but measured around 2300 on the Nox. Smog tech said timing was far too advanced. So, my buddy retarded timing all the way, tested again, still failed. Same results. For the third time, I eyeballed the timing to the middle and also put on a new O2 sensor. Nox went down to about 1800 so it still failed. I believe the max in cali is around 700.

Everything is new on this car:
Plugs, Oil, O2 sensor, Catalytic Converter, Wires, Cap and Rotor, etc…
I have a new Air Filter that I just came in the mail yesterday but I don’t know if that helps to pass.
The car is a '93 GSR with a '94 GSR motor. It has a CAI, AEBS IM, DC header and running a chipped (Xenocron) p28 ECU.

I’m just about to give on this piece. Does anyone out there have any ideas?
Thanks for even reading all this. Seriously.

2

Wouldn’t a stock ECU help it pass? I could be wrong but out of the things you listed that is the one thing that stands out to me.

3

First of all, I would time your car properly with a timing light and not just ‘eyeball’ it.

Second, I would do a little research about combustion. In the 30 seconds of research I did, I found that you could be running too lean, that your EGR system may not be working properly and that what KIND of cat you actually bought will all make a difference in your NOx emissions.

What basemap are you running? Saying you have a “chipped p28 ECU” is like saying “I have a intel chip in my computer and have a problem with my OS”. One thing has absolutely nothing to do with the other as far as diagnosing the problem. (if that is over your head, keep in mind that Linux, Windows, OSX (as well as other OSs) can all run on Intel chips)

4

in order to make any sort of analysis, your detailed results would be necessary

5

[QUOTE=buymysoul;2157545]First of all, I would time your car properly with a timing light and not just ‘eyeball’ it.

Second, I would do a little research about combustion. In the 30 seconds of research I did, I found that you could be running too lean, that your EGR system may not be working properly and that what KIND of cat you actually bought will all make a difference in your NOx emissions.

What basemap are you running? Saying you have a “chipped p28 ECU” is like saying “I have a intel chip in my computer and have a problem with my OS”. One thing has absolutely nothing to do with the other as far as diagnosing the problem. (if that is over your head, keep in mind that Linux, Windows, OSX (as well as other OSs) can all run on Intel chips)[/QUOTE]

You’ve got a great point about the timing light. That is next on my list of tools to buy, actually.

Yes, I did do a bunch of searches on combustion. Yes, I understand that the car may be running lean, which is what the smog tech said. But I’m not really sure how to correct lean conditions. Is this where the timing light comes in?
Also, on the EGR topic, the motor is from a 94 which from what I understand does not have an EGR system. Correct me if I’m wrong.
The cat is a Carsound. Brand new, installed 4 weeks ago. My sorta mechanic looked at the cat and said that it may be too small for what I need. He suggested that I put on an OBDII cat on there but will that guarantee a pass??? I don’t have $300 plus to blow on another new cat just to pray that it helps.
As far as the ECU, pardon my ignorance. When I blew my stock motor 3 years ago and had a 94 gsr put in (not by me), it ran like $hit. Hesitation, bogging, low power, etc… Did a tiny bit of asking around and I was told to get a chipped p28. So I found one, sent it to Xenocron, told him my mods, CAI, AEBS IM, and DC Header. I got my new ECU back, plugged it in, and the car ran like a champ! That’s the extent of my ECU knowledge as I hadn’t had to the need to know more.
Anyway, when the time came for a smog check, it failed. And I never had the money or time to diagnose it then. But now I’m trying again and I am still clueless, so thanks for your time.

As far as the actual results, this is pretty close to actual numbers (paper not in front of me):

CO: both 15 and 25 MPH passed very low reading
HC: both 15 and 25 MPH passed very low reading
NOX: 15 MPH 2300 ppm 25 MPH 2200 ppm

Thanks again for those that have helped!!!

6

You’re the second person that have told me this. The first person told me to go with an LS ECU.
Can anyone else comment on this? Like I said earlier, my knowledge of ECUs is super limited. Yes, I can spend hours on end here searching and researching, but I am in a jam and yes, I do need quick answers. My association wants to tow my car for expired tags.

Thanks!!

7

when you have very low hc readings combined with high nox readings it indicates that you are running lean.
start with the basics and time the engine correctly. the richer you run, the lower your nox reading will be, but hc readings will rise in relation. you need to find a happy medium. what i would do is check timing and if it is retarded significantly, that’s probably where your problem is
a vacuum leak could also cause a lean condition

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I would maybe email xenocron and ask him about the chip. He may be able to mail you one with a stock 94 GSR basemap if that isn’t what you already have. I don’t know really know anything useful (to you) about tuning and all that business so I’m not sure what he does (or what anyone would do) for the mods you listed but that engine in decent shape should be able to pass smog assuming the carsound cat you bought is california spec and not some ‘high flow’ 49 state cat. I would suspect your fuel and ignition isn’t right; the ECU is what controls it. The cheapest way for you to possibly get that under control is to get a different chip for it and change it yourself. The other thing you could do is to have it dyno tuned and make sure that they don’t just do WOT tuning. Do you happen to know what ECU was in it when it ran like shit?

I do not think an LS ecu would do you any good.

As far as your (homeowners? renters?) association is concerned, I assume you are not driving the car currently and that there is some sticker of some sort that identifies the expiration date. As long as you aren’t driving the car, I would just photoshop ‘current’ tags and tape it in place to get them off your back as you figure this out. :wink:

Sorry I can’t give you any more specific help. Good luck.

9

if it were the cat, he’d have high hc as well, as the catalyst actually helps burn the hc.
this can be solved with timing, i’m sure of it

10

Thank you Fellas for all your help.
I will start with the easiest and that’s to buy a timing light and learn how to use it.
If that doesn’t help, I’ll turn to the ECU.
Thanks again. Will keep you posted. Hopefully by Monday.

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The reason why I mentioned ECU is that is where all the fuel/ignition/timing maps are at… So if the guy programmed the chip and it was slightly off from what you needed, it could be running lean/rich. The map is just a ‘guesstimate’ as to where your car should be at, its by no means an exact fit to your ride.

So I say either timing is off, like the guys here already mentioned, or the map isnt close enough to yield a pass with emissions.

12

yea, but timing could be tweaked enough at the distributor to get a pass

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I disagree, the OP said that the timing was fully retarded for the 2nd test and it still failed. The more you retard the timing, the less NOx. However, you are only changing base timing at the distributor, so the ECU could be advancing the timing too much. I agree with previous posters that since the ecu is chipped thats the best place to start. Remember NOx is caused by high combustion chamber temeprature/pressure. Advanced ignition timing and lean air/fuel ratio are the most common causes. Besides the Ecu fuel/timing maps being off other causes could be a build up of carbon in the combustion chamber, or vacuum leak. It’s also possible that the converter isn’t high enough quality but with readings that high theres likely something besides the converter.[/

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didn’t see that he’d tried retarding timing. my bad. wouldn’t he have to reset the pcm when adjusting though?

15

Passed my smog!!!

So, thanks to your input in just over the last couple of days, I finally passed.
Had my ECU rechipped back to the stock 94 GSR basemap. And had my timing checked at just shy of 16 TDC. Apparently I have good Distributor Eye-Balling skills lol

first test:
15MPH 25MPH
HC MEAS 7 MAX 89 MEAS 3 MAX 54
CO MEAS 0.0 MAX .37 MEAS 0.0 MAX .36
NOX MEAS 2314 MAX 495 MEAS 2218 MAX 746

After new plugs, o2 sensor, oil change, and going back to stock basemap…
15MPH 25PMH
HC MEAS 25 MAX 89 MEAS 13 MAX 89
CO MEAS .02 MAX .37 MEAS .01 MAX .36
NOX MEAS 475 MAX 495 MEAS 243 MAX 746

I suppose I could’ve saved some money by going straight to the ECU but the learning process was fun. I actually know what ignition timing means now lol
and at least now I have new plugs and an o2 sensor.
Also I noticed the I barely passed the NOX on 15MPH
I wonder if that’s because the car sat for a bit before the test. Had it running, though.

Thanks again for everyone’s help.

ps, the car feels slower now, but smoother. kinda bittersweet really :confused:

16

Unified and 90da9 :high five:

Glad you passed. :slight_smile:

You know, to pass and have more power, you could always, I dunno, have it actually tuned! :slight_smile:

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[QUOTE=buymysoul;2158150]Unified and 90da9 :high five:

Glad you passed. :slight_smile:

You know, to pass and have more power, you could always, I dunno, have it actually tuned! :)[/QUOTE]

X2… a tune will get you all set. But remember, the buttt dyno isn’t always accurate… you might not be far off from the basemap you were running.

Glad you got it passed though, its frustrating to get emissioned sometimes lol

18

Shit. These folks in Indiana can’t even spell emissions. When I first moved to this state I called the BMV about where I was supposed to take the car to get inspected. They had no idea what I was talking about. Yeah. There is such a thing as too much leniency. I’ll take my redneck trucks with at least a hint of catalytic converter, thank you very much!

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Glad you passed man, emissions testing sucks.