hydrocarbons too high
 

Hi i have a 1990 miata with a bp swap im running the stock s-code vaf. I am trying to pass DEQ in Oregon and my miata won't pass my hc were 513 the first time I tested then I changed the sparks and put 2 and 1/2 bottles of octane boost and changed the oil and checked the timing and now the best I can do is 362 and it has to be at 220 hc and my CO was high too both times. Is there anything else I could do to try and fix my HC and CO? I heard its cause I'm running too rich does it have anything to do with my vaf or ecu?

i had this issue at idle before i installed my ms. to pass i cleaned my air filter ran regular gas and bypassed my begi fpr.

not sure what allowed me to pass out of those things but im guessing it was mostly to the begi fpr bypass. i stayed out of boost while driving with these changes.

bandaids suck. sorry if that doesnt help but you you didnt give much detail on your setup

Well I'm not tubo'd I'm just running all stock so I'm not sure what it could be

stock egr?.... hows your o2 sensor. maybe clean it.... cat could be clogged...

One thing to try. Make sure they turn the headlights off. Even better is putting a box fan in front of the car to see if you can prevent the cooling fan from coming on.

I blame the fact the that the ignitor is on the fender while the coils are behind the plugs. Both my 90, when it was street legal, and my friends car had issues passing the idle test. Both cars had no problems at the "cruise" part of tailpipe test.

I bet your oxides of nitrogen were reading low, though. Am I right?

I have a new cat just but in a known good o2 and I don't know about the egr. I'm sorry I'm not sure what that is.

It doesn't say my NOx

What? They all passed emissions that way from the factory.

How would rearranging the deck chairs on the Titanic have kept it from sinking? You are missing the part about the iceberg.

I literally have no idea what that means.


EGR is Exhaust Gas Recirculation. '90-'93 engines didn't have it, whereas '94 and later did. So even though you probably do have it now, it's mostly likely not doing anything as your ECU (assuming you kept the stock '90 ECU and wiring harness) can't control it.

Doesn't matter anyway, as EGR is primarily effective in combating high NOx, which you don't have.


If you have high HC and CO, then either you're running too rich (which is probably due to a bad O2 sensor) or your catalytic converter is shot. I'm not 100% certain, but it sounds from the quote above that you're trying to say you have replaced both of these?

(I am, of course, presupposing that the engine isn't misfiring like crazy.)


I also have utterly no idea what this business is from mcfandango about the igniter being located on the passenger's side fender. It could be in the trunk for all I care, so long as the wiring between it and the ignition coils was in proper order and it was supplied with an adequate ground.

Ya I meant I replaced both stupid predictive text. The o2 is from my roommate who just passed deq and the cart is a magna flow I just bought on eBay.

shot in the dark... maf/afm sensor good? try cleaning it or borrowing another. if its not the o2 or cat... air filter or something to do with the mixture not sure what else it could be.

is your timing stock?

Ya timing is stock. I'll try another spare s code vaf I have laying around maybe that will help

New plugs, wires, new oil? Try to block the PCV and use a breather.

Only reason I see for why battery/alternator voltage seems to such a huge effect on emissions. The cruise speed test the voltage is usually over 14V, at idle I've seen ~13V. I'll have to go back and see if I can dig up the tail pipe test print outs, probably not at this point. Cruise speed was ~1500rpm if I remember. No issues with HC/CO there. Only with the idle test. I should have been a little clearer in my original post.

Cooling fan and headlights being on made a difference from pass/fail. That hasn't been an issue on the 94+ cars I know of. My car still barely passed the sniffer with a Link ECU and fresh wires/plugs. And wasn't running overly rich according to the wideband gauge during the test.

And if the ignitor is in such a great place for 90-93, why was it moved to internal to the coils in 94?

My point was that 90-93 cars all passed emissions when new so why would that matter now? And frankly, I would think they became integrated due to component cost or packaging costs related to additional harnessing, bracketry, and connectors on the 1.6 cars that they were able to do away with when they redesigned the system and not necessarily superior functionality. If it had cost significantly more to make them integrated it might not have been done at all.

/threadjack

There is no "free air calibration" for AEM sensors.

A misfire could also cause your AFRs to be that lean.

actually i remember what i did to pass last time. i turned my idle up. I passed fine at cruise and failed at idle so after i failed the 2nd time i said screw it and turned my idle up to 1500rpm. i know they are supposed to check but they didn't. that motor ended up having a cracked ring in #4 with tons of blowby. anyway. hopefully you dont have any other issues going on. You still never mentioned what hydrocarbs were too high, i just assumed idle. if you're emissions group is as lazy as they are here and you are in fact failing idle but passing at cruise then you can try adjusting your idle temporarly.

you should just get a turbo, cops, ms3, etc... and call it a day. boost the hydrocarbs out of it.

OK my 5th time testing and I failed again I have replaced the coil packs and cleaned the vaf got new plugs new wires an oil change I tried octain boosters to pass then this time tried rubbing alcohol and its been the closest at 282 HC I need 220 to pass in Oregon my CO was .49 which is passing. I'm out of ideas I've even changed the o2 sensor and cleaned my air filter.

damn bro you could have saved them all.

Tighten the spring on the afm? You just need to lean the car out.