Just failed emissions

[dwh4784]

I just brought home a bone stock 84 Daytona turbo and it failed emissions, yippie. It passed everything except HC(hydrocarbons) at idle and it didn't fail by much. The little pamphlet they gave me said it's most likely fuel system related so what should I check/replace first? No codes BTW.

[87glhs232]

Where are you located? I know Spokane, but City...rural? If your county requires you to run a cat, a new one will clean up 90% of an engines emissions problems (or so a wise man once told me). I know on my car my HC went from 211ppm to something like 30ppm. The big one on mine was NOx 2272ppm down to a couple hundred.

[GLHSKEN]

Yep stock cat is morre than likely Kaputtt... O2 sensor could clean it up as well..

[87glhs232]

Yep stock cat is morre than likely Kaputtt... O2 sensor could clean it up as well..

+1 on the O2...always a good choice.

[dwh4784]

Spokane Valley, we're our own city technically but nobody cares. We do have e-check though.

I looked under it when I was checking it out and what is sitting in the cat spot really doesn't look like a cat to me...more like a little resonator. I was trying not to fall down in the snow though so I didn't look too hard. I'm not going to have much of a chance to look at it until next week, dumb time of year to buy a car I guess.

The o2 sensor doesn't plug in the same as the one on my 85 either, it looks like it plugs in right at the sensor? The wire is stretched tight too. When I bought the one for my 85 it had a cord coming off of it so you could plug it in and have some slack.

[turbovanman²]

Usually the ox fails you get a CO failure. What are your readings and whats the limit?

[dwh4784]

HC Idle Limit 220, Read 402: FAIL
HC Cruise Limit 160, Read 160: PASS
CO Idle Limit 1.2, Read .83: PASS
CO Cruise Limit 1.2, Read .74: PASS

[turbovanman²]

what about CO, can you list all readings and specs please.

Any good running TD without a cat should be able to easily be under 200 HC's. HC's are caused by bad compression, bad tune-up items, timing cam or ignition being out, the the engine is just plain wore out.

[dwh4784]

It just got dark but so far I replaced the o2 sensor and spark plugs(someone had put bosche platinums in there). They were all a little on the white side but looked pretty good. If I get a chance this weekend I'll check cam and ignition timing. If those check out I'll check the compression. The guy I bought it from said he checked it and it was fine, he had a turbo supra and a turbo civic and seemed like he knew what he was talking about. He hasn't driven it much, he bought it to play around with but never got around to it and is moving to Oregon now.

One thing I forgot to mention is that it always wants to die when you're coming to a stop. Sometimes it does, but usually it just stumbles and then catches. Other than that it starts/runs/drives really well.

[turbovanman²]

One thing I forgot to mention is that it always wants to die when you're coming to a stop. Sometimes it does, but usually it just stumbles and then catches. Other than that it starts/runs/drives really well.

Double check the carbon button is still in the cap or not worn away.

I bet the throttle body and motor is coked up, that would also cause it to fail at idle. You need to remove the AIS, get a toothbrush and carb cleaner, scrub the bore and throttle blade till there spotless. Clean off the AIS pintle, and disconnect the battery. It should be fine now, if not, knock out the little tin cap and open the blade a bit more.

[85_600]

One thing I forgot to mention is that it always wants to die when you're coming to a stop. Sometimes it does, but usually it just stumbles and then catches. Other than that it starts/runs/drives really well.

Same here except on a 85 600 A-413 T1. I've cleaned my TB and AIS and TPS as best as I could ( removed the TB and AIS and cleaned with carb cleaner ). Everything was pretty much clean. Even though I did this I still have that stumble coming to a stop, mainly from a slower speed, like residential driving or parking lot speeds. I'm thinking it may be either the Speed Distance Sensor or my MAP.

Just thought I'd post on the stumble due to someone else going through it as well. Good Luck!

[Rampage16V]

I would also check for vacuum leaks to the MAP sensor if it is just rich at idle.
might help to use gas with 10% ethanol too.

[omnivore]

The stumbling at approach to a stop sounds like TPS to me. My car did that before, and a TPS solved it.

As for the HC, my own car failed the idle test as well. I retarded the timing 3 or 4 degrees and it cleaned it up

[Rampage16V]

As for the dieing coming to a stop . The speed sensor not working will do this. The computer is supposed to keep the revs up til you reach 3-5 mph or so. So if the sensor doesn't work the idle will just come down til it almost stalls and the ais motor has to try and keep up.

[GLHSKEN]

Yep, the speed sensor is a code 15. It will cause this. TPS is a different animal... I had a situation where even new speed sensors would throw the code after a short while. The tps rarely sets a code and is ofter the culprit.

[Tony Hanna]

might help to use gas with 10% ethanol too.

I seem to remember reading this somewhere else too.
HC's are just fuel that hasn't been burned completely (overly rich mixture) right?
If so, then adding a little bit of an oxygenated fuel should help lean it out a tad.
Makes sense to me.

[mech1nxh]

HC Idle Limit 220, Read 402: FAIL
HC Cruise Limit 160, Read 160: PASS
CO Idle Limit 1.2, Read .83: PASS
CO Cruise Limit 1.2, Read .74: PASS

on your print out are there readings for

O/2 ? (oxygen)
C/O2 ? (carbon dioxide)
NOX ? (oxides of nitrogen)

if the analyser is 5 gas could you list all please,(HC, CO, CO2, O2, NOX)
if the analyser is 4 gas no NOX reading will be present(HC,CO, CO2, O2)

that will help in diag greatly......thx mech1nxh

[dwh4784]

After the basic tuneup items and a little cleaning of the AIS it seems to be better, it still bogs a bit coming to a stop but hasn't wanted to die. Hopefully after work tomorrow I can check the timing and possibly Sea Foam it. I'm also going to get a better look under it and see if that's a cat or not.

[dwh4784]

Checked timing today, cam looks dead on but ignition was advanced quite a bit...out of the window actually. So I got that set to 12*. I also bought some Sea Foam and treated it with that, afterwards it was running really good and no stumbling. But I let it cool down and drove it again and it's back, still no codes. Also upon further inspection it does have a cat, it just looks newer than the rest of the exhaust system.
So I guess Friday I'll go test it again.

[Lee'sdaytona]

hmm....do you think its possible that someone removed the cat, gutted it and put the shell back on for visual inspection? If this is the case, you probably would not pass with no cat at all! Maybe if it isn't welded and only has exhaust clamps on it, you could take it down and have a look. Just a thought
-Lee