Smog nazis and HC

[Craig 94 TA GT]

I tried to get the car smogged on Saturday and it failed as a gross polluter - literally 8x the limit for HC (2.5x gross polluter limits). CO% was borderline but failed as well. NOx was fine. It turns out, the motor just started to miss and was missing on the smog dyno. My question is, a slight miss going to cause this high HC count? The count is unbelievable - has anyone had a smog when it was missing (it not missing that bad but enough that it shakes under load). Here are the results:
15 mph
HC max: 83
HC gross polluter: 269
HC measured: 686
CO max: 0.48
CO gross polluter: 1.98
CO measured: .66
NO (PPM) max: 689
NO gross polluter: 1907
NO measured: 382

25 mph
HC max: 48
HC gross polluter: 219
HC measured: 526
CO max: 0.46
CO gross polluter: 1.96
CO measured: .53
NO (PPM) max: 706
NO gross polluter: 1707
NO measured: 335

The cause of the miss was a plug wire touching the header and the core arching on the header.

[FTA1995]

WOW thats high. Its probably from the misfire. You have stock everything im guessing? Is that a single cat m6? A4? Give us details!

If you have a high HC emission, its completely unburnt fuel. Your NOx is semi burnt fuel, and oviously the CO is the fully burnt.

I would check o see if your CAT(s) are good still if its been running like that for a while. they should b as the NOx levels are within testing range.

Odds are, you fix the miss, shouldn't be a problem. If it still is, run a scan, see what the O2's are reading.

What state are you in btw? I love it here in illinois, no more OBD1 smog!

I'll try to help ya out, but you'll probabl get better answers from a mod or someone whos older with more experience.

[Craig 94 TA GT]

Thanks - I'm almost certain that it's the misfire causing such high HC counts, but I was just curious to see if anyone else had it smogged while encountering a misfire.

The basic motor is in the signature. Advanced Induction heads/cam, forged pistons/rods, 355 CID, 39 lb injectors, 58mm TB, Carsound cat less than 5 years old, SLP 1 3/4 headers, etc. 3200 stall with a custom built 4L60E and 9" rear. Basically nothing is stock anymore. The cam is mild enough to smog, but I cannot list the specs here as AI requested to keep it private. All I can say is it's hotter than the hotcam, but not over 230*.

You are lucky in IL! I'm in CA where the smog police just want to get rid of your car because you have an American V8.

[ConElite]

Thanks - I'm almost certain that it's the misfire causing such high HC counts, but I was just curious to see if anyone else had it smogged while encountering a misfire.

The basic motor is in the signature. Advanced Induction heads/cam, forged pistons/rods, 355 CID, 39 lb injectors, 58mm TB, Carsound cat less than 5 years old, SLP 1 3/4 headers, etc. 3200 stall with a custom built 4L60E and 9" rear. Basically nothing is stock anymore. The cam is mild enough to smog, but I cannot list the specs here as AI requested to keep it private. All I can say is it's hotter than the hotcam, but not over 230*.

You are lucky in IL! I'm in CA where the smog police just want to get rid of your car because you have an American V8.

I feel your pain, your looking at $200 smogs every 2 years.

Where in California are you?

[Craig 94 TA GT]

Eddie, do you know any "special" treatment given to "gross polluter" vehicles? I have read a few things. One, that it must be repaired and pass in a test only or gold shield station, but must be smogged every year at a test only from now on. Another site said if I pass for 4 consecutive years, I'll be removed from the gross polluter list. A third site said that once I pass, everything will be back to normal. I'm not sure which is right - the DMV says nothing about this.

I'm in the bay area, CA - I'm not sure how similar to LA smog rules, but I think the bay area is trying to follow LA smog II "standards." The thing is, I could have gone another route and had it pass smog "no questions asked" but wanted to do it all legit. But now, the plan is backfiring all because of 1 wire!

[Injuneer]

Your CO and HC are a direct result of the misfire - no question about it. When the cylinder doesn't fire, raw fuel (= HC or "hydrocarbons") and unused air leave the cylinder into the exhaust. The HC component is obvious, but the unused air makes it even worse. The O2 sensor sees the extra air, tells the PCM its running lean, and the PCM adds extra fuel to the entire bank with the misfire. Now you have one cylinder pouring unburned fuel into the exhaust, and the other three running extremely rich, pouring even more unburned hydrocarbons into the exhaust. Throw in an exhaust leak before the O2 sensor, and it will run even richer.

[FTA1995]

Sorry didn't see the sig before,

Are you sure it was just that secondary wire grounding at the dyno?
I had an amazing experience before with a blown opti.
coolant got inside the cap side and blew the bottom terminal off causing a random miss at cyl #1. I think that was a bit of a unicorn problem, most opti damage is to the optical disk or sensor.
Snoop around a little and let us know!

[Joe 1320]

In one word,

Yes.

any miss will cause a failure.

[Craig 94 TA GT]

Thanks guys. I'm glad that the miss was causing the excessively high HC counts. The #5 wire wasn't burned too bad, but it was curved where it was burned, and kind of split, but exposed right to the header. So it was likely arching. What timing to have it do this right before the smog check.

I'll take it in for another smog soon - the good thing is that I talked to the smog shop and they said that once I pass, the gross polluter label will be remove and I will be under the standard "bi-annual" smog check. I'm glad, because that's an extra $70-$100 a year they would have charged.

[Craig 94 TA GT]

It failed again this morning
I think my only other option is to take it back to the dyno tuner and have them pull timing and run the mixture leaner at part throttle. That and replace the alternator (current one is going out at a constant 12.3 volts, and clean the air filter). I have a feeling an exhaust leak is present and screwing things up. I had enough with SLP junk headers - I wish I could just get long tubes and be done with SLPs, which I have had nothing but problems with since day 1. Here are the results:

15 mph (1768 RPM)
HC max: 83
HC ave: 21
HC measured: 64
CO max: 0.48
CO ave: 0.06
CO measured: .11
NO (PPM) max: 689
NO ave: 150
NO measured: 422

25 mph (1749 RPM)
HC max: 48
HC ave: 13
HC measured: 58
CO max: 0.46
CO ave: 0.05
CO measured: 0.12
NO (PPM) max: 706
NO ave: 136
NO measured: 366

[Injuneer]

Major improvement.

Did you clear the long term fuel corrections after you fixed the misfire? If not, how long did you drive it before retesting? It may not have had time to pull the long terms in the moderate load/RPM cells down if you didn't drive in those cells over a period of time.

[Craig 94 TA GT]

Thanks Fred - I didn't reset the PCM and only drove it for a day after the miss. I reset it this morning and initially, it was surging bad at idle - around 500-1000 RPM. After driving commuting to work it leveled out and is fine now. That was strange, but I guess it's ok now.

I also cleaned the air filter last night - which was embarrassingly dirty. There were clumps of caked on dirt, yet it's only been 1.5 years, 12000 miles. I also cleaned the MAF and put the new alternator on. A scan shows 1/2 volt higher at idle - and probably a higher differential as the RPMs go up. The last thing I'm going to do is use TunerCat or LT1Edit to put the fans back to stock. I've read on camaroz28 that the fans keeping the engine at 180-185 means more HC. If I bring it to stock just for smog, I'm thinking it will help the HC. The only thing is - I have never tuned using these programs. Do you know which is easier for simple things like this? I've read horror stories about people destroying their PCM with Tunercat (a disconnect when flashing), but I don't know about LT1edit.

I also noticed that after cleaning the filter, the MAF reading has gone down at idle. It's now 10.x at 850 idle, where it was 11.x to 12.x previously. I wonder if that means anything.

[Injuneer]

Do you have a washable gauze filter (e.g. - K&N)? Did you go a bit heavy on the oil? That will coat the sensing elements in the MAF sensor and throw the readings off.

[Craig 94 TA GT]

Yes, it's a Moroso CAI, and I was extra light on the oil this time. Maybe because I cleaned the MAF, the reading is different? I did 1 scan after the cleaning, so I'd better check again - could have been an off reading for some reason. I used electrical contact cleaner and a (very very slight) touch of TB cleaner. I heard that TB cleaner can harm it though - I hope it didn't. Well, it is running so much smoother and has tons more power. I have also reset the PCM since then, and the idle has not been surging right after anymore.

Carputing is getting me LT1Edit within 48 hours, so I can adjust the fans, then try to smog again. I hope this is the last time I have to worry about smog in the next 2 years.

[EDIT] Ok, scratch the lack of surging part. I reset the PCM this weekend and drove it for the first time this morning - it started surging at idle like crazy again. 400 RPM to 1000 RPM constantly surging. But it's fine now, after getting into closed loop and driving for a bit. It probably means nothing, but I find it very strange - I should scan it to see what it's actually doing, maybe the IAC value is going way up and down during this time.

[Craig 94 TA GT]

Looks like I have way more issues than described here. I have no idea what's wrong besides saying the tune is off, or guesing at other stuff. Oh and looks like the MAF readings are good now. Idle shows mid 12s now, so I think the readings were just weird circumstances that day.

This morning, however, it took about 5 minutes to start. It sat there cranking and cranking, once in a blue moom, it would catch for a very minute split second. Well eventually, I would then try to hit the throttle during this time - and that's how it got started. It seems to be driving rough in open loop, and here are stats from a scan:
- First part of my commute, IAC counts were 150-160 at 60 MPH. Second part was 110 at 60 MPH. IAC at idle is around 65-75. Does this sound right, or do I need to adjust the stop screw?
- BLMs are not looking good. They are 160/150ish for cells 2, 3, 16, 18. They are high 150/140s for cells 5, 6, 7, 9, 10, 11, 18 (sometimes 160, sometimes 150). The dyno tuner, using a wideband at the exhaust tip, said I was running to rich at part throttle so he leaned it out a bit. So it appears that this leaning out made the car raise the BLMs to add more fuel?
- Seeing tons of knock, but the tuner programmed knock retard to be minimum. I think the knock is sign of an exhaust leak?

I'm not sure what other value I should look at to further diagnose the issues. Thanks in advance for any help.