ThePass

iTrader: (3)

So in preperation for the smog ref I converted everything back to greddy spec (I have the carb sticker) and put the stock ECU back in.

The only thing he said I needed to change for the visual inspection to pass is to remove the wideband. Fine, I can pull that out for now.

My problem is that I passed everything on the emissions test except for HC (Hydro Carbons) at idle. Max is 120 and I measured 135. Interesting because for the 2500 rpm test the max is 140 and I measured 57. The guy told me this means at idle I am not burning enough fuel - there is a bit too much raw fuel coming out the exhaust - as in could possibly have a misfire or bad plugs etc.

The ref was pretty vague about what could be causing it but suggested I "Check the compression and if that is good, do a tune up and then last check the cat." which pretty much means "it could be anything and it's not my job to diagnose it."

So.. I'm going to check the compression this weekend but this sounds like maybe plugs? What should I check/how do I check it??

Any info/suggestions are realllly appreciated!

The cat is the same one from when I bought the car (3 yrs ago) but this doesn't sound like a problem with the cat...

-Ryan

patsmx5

iTrader: (16)

Well, first and foremost let me say this: We here in Mississippi don't do no emmisions testing and all that BS. So I really have no experience whatsoever.

Being pretty ignorant, I can't really tell you WHAT is causing the hydrocarbons to be too high. However, I can tell you a few tricks that will help you pass a test.

New plugs. Clean the O2 sensors w/carb spray. New sparkplug wires. Unbolt cat and empty a can of carb. spray through the engine after getting it fully warmed up. To do this you have to keep the engine revd way up. Spray carb stuff till it tries to dye, then stop, and as it catches and begins to race to redline again hose'er down. Gets all kinds of buildup out of the engine.

***guaranteed to work. Run a bottle of nitrous through it.

Also try searching around here as there have been a few threads here recently about failing emmisions.

ThePass

iTrader: (3)

Thanks for the suggestions.

Would I spray this directly into the throttle body and is that why I have to keep the revs way up so it doesn't die b/c the AFM is out of the equation? Or do I remove the filter and spray in right there and let it go through the turbo? Actually that second one sounds like a bad idea...

I just thought of something and maybe someone could tell me if this sounds like a possible cause of a problem:
I have the BKR7E NGK plugs (one step colder) in the car because of the turbo. Without my records I keep of work on the car next to me, I can't recall what I gapped them at but I gapped them according to what everyone on here was saying was a very good general spec for gapping these for a turbo application.
Now, could these 'colder' plugs or the gap on them that is intended for a turbo be a problem perhaps because it is out of 'stock' spec???

For the record, my wideband was reading between 14.8-15.2 when it was idling during the test so this whole 'too much raw fuel in the emissions' thing sounds like nonsense but whatever. I gotta play by the rules at least until I get it passed.

-Ryan

patsmx5

iTrader: (16)

Well, the way I always did it (on other cars) was to just take the pipe off the throttle body and spray the carb spray in there, holding the throttle pretty much wide open the whole time. But I dunno if you can do that cause stock you have a maf sensor. Hmm. I 'think' if you jump the fuel pump it will run without the MAF sensor. If so, that's enough you can do the cleaning.

Definately put a new set of proper heat range plugs in the motor. Personally, I'd run less gap. I run .020" for the last 30K miles and I suffer no ill effects. But if you're afraid to run too little gap, run whatever stock says for the test.

Savington

iTrader: (31)

Ryan, get a fresh set of plugs and wires and try again.

Also, I think removing the wideband is bullshit. Ask to see the law that says that it's illegal.

M-Tuned

iTrader: (6)

Install a new set of stock plugs not 7s and you should be fine!

jmnight

iTrader: (6)

what is your timing set to?

BenR

iTrader: (2)

New plugs exactly factory stock with factory gap
New wires
New oil and filter
190* thermostat
Drive the **** out of the car and get it nice and warm before taking it in
Retard the timing 2 degrees if you can get away with it

I wouldn't do the carb cleaner thing, but if I did, I would make note that Pat said to remove the cat.

Joe Perez

iTrader: (8)

Since the OP has a 1.6, he can spray through the AFM without too much risk of damaging anything. Another, more direct option would be to disconnect the rubber hose which connects the IAC inlet pipe to the plastic intake tube just before the throttle body, seal both ends with tape, and penetrate the tape on the plastic intake tube with the attachment from the spray can. This temporarily defeats idle control, so do it with a warm engine.

ThePass

iTrader: (3)

I'm going to get some NGK BKR6E's for the test and gap them to factory specs. The NGK wires on there have at least 3 years on them as they were on when I bought the car so I will replace those too.
As to the wideband, the ref pulled up the .pdf for the AEM UEGO instruction manual off the internet and right smack in the middle of the front page it says "not for highway use". He was going to try to get permission from the main office for my wideband since it uses a completely seperate o2 sensor and just runs to the gauge without affecting the car in any way but after he saw that on the manual there was no chance.

To be honest he's being fair enough... I have the intercooler still in there with duct tape over the ends lol. I doubt he's dumb enough to think I don't plan to swap everything back in later... but he's not giving me crap about it.
-Ryan

ThePass

iTrader: (3)

I set the timing to 10* before I went over. Can anyone confirm that retarding 1 or 2 degrees would help?

Changed the oil and filter before I went too.

180* thermostat but I will drive the crap outa the car before I go in next time. Last time it was barely at operating temp when I came in.

240_to_miata

iTrader: (2)

retarding the timing ALOT will help....

my friends 87 monte carlo was about 2.5 times the limit with his crate motor and we retarded it to the point where it would BARELY run, passed with flying colors.


I assume the same will work on a fuel injected 4 cyl

Joe Perez

iTrader: (8)

There is some anecdotal evidence which suggests that the various fuel additives on the shelf at the auto parts store which claim to help you pass an emissions test actually do work. I've never bothered researching any of them so I have no idea what magic snake oil they contain, just a FWIW.

With regard to timing- you can't get too carried away, as verifying the ignition timing is part of an emissions inspection in CA. However, the instructions for the Greddy kit specify that ignition timing is to be set to 6°BTDC, and there's some leeway called for in the test procedure (it's like +/- 2° or thereabouts) so you could run as low as 4° if you had it.

ThePass

iTrader: (3)

Joe - thanks for the info on the Greddy's instructions for timing being 6* - If I'm not mistaken the stock specs for a miata are 10* so that's what I have it at right now. Only problem is unless I have the instructions to show the ref, he won't pass me at 6* I'm sure... and I bought the kit used. Anyone know if the greddy miata instructions are available as like a pdf anywhere?? I would need that to get him to approve the difference in timing...

-Ryan

Joe Perez

iTrader: (8)

(must resist urge to be a wiseass.)

The Greddy install manual is the second sticky thread in the "Useful Saved Posts" forum: Useful Saved Posts - Miata Turbo Forum - Home of the turbo Mazda Miata.

The CARB document is sticky #4 in the same folder.

ThePass

iTrader: (3)

Thanks a million. Sorry to not have thought to search first. That Greddy install manual is priceless for my situation.

I checked my plugs a little while ago and the tips are whitish indicating running a bit lean so I call bullsh*t on "excessive raw fuel in emissions" but whatever. They are gapped to 0.30 which off the top of my head I cannot recall how close to stock that is 9can't remember stock specs will have to look that up.)

I'm ordering NGK BKR6E plugs and new NGK wires from my buddy at cost. $36 for it all.
Will gap the plugs to factory spec and retard timing to 6 degrees.
Plus will drive a bunch before going to the ref... too bad I can't hold a blowtorch to the cat while they run the test
We'll see what happens!

-Ryan