gLudeous

First off, thanks for looking at a posting with a mundane, no fun topic.

I just got my emissions test, and barely passed the hydrocarbon part at 25mph (limit is 86 ppm, it had 86 ppm). The others were well within the acceptable range. I asked the tech who did the test and he said it's either the cat getting fouled up or the EGR.

I have 57,000 miles, the car burns a quart to a quart and a half every 3000 miles. I bought it a year ago so I don't know how it did last year. The only engine mod I have is an AEM intake.

Has anyone else run into problems this early? Is this a sign of those "bad rings" that was mentioned earlier? If it's the cat, I'm hoping that would solve things for a bit, or am I wrong? Would it foul up within a year? Needing new rings would be a great excuse to put in Type S pistons or something, or would it be more involved (i.e. resleeving or something, I don't know much about bottom end rebuilding). What do you suggest?

Thanks for the help.

gLudeous

Oh, the tech also said it might be running rich, or is he full of it?

smoothludey

I'm assuming you have a 5gen...I have a 98 base 5spd and I have the same oil consumption problem...it's about 1 quart/1000miles and according to the honda mechanics this is completely normal, especially if you like to hit vtec, which i do. The explanation i got was that the preludes run very rich, that's no bunk, check your tailpipe to see if you have black carbon build up (tell-tale sign of richness). Ok, becuz these cars run so rich, the extra fuel is somehow helping to leach the oil between the pistons and sleeves resulting in the higher than usual oil consumption. I have also heard some rumors going around about bad piston rings on preludes, dont' know if they pertain to 5gens or not. At the dealership i also asked to see if there were any service bulletins out for my car using the VIN, and there weren't any. So if you're concerned, go and ask the service manager to run your VIN thru his computer...chances are there wont' be anything, but you never know.

ThatPreludeGuy

I'll check what the specs are here in NJ but I just went through it and I made it by a ton. I have a I/H/E but never had to do the rolling dyno test. In NJ we have a override if the car is too low I'll try and get the paper tomorrow and let you know what the specs where.

baked

I just "blew" 12ppm the other day. In NC they test at idle.

gLudeous

I thought of a possibility, tell me if this sounds ridiculous. They did an oil change first, and of course got oil all over the header which has now been burning off. Might some of the burning oil skewed the reading?

marcucci

The burning oil would NOT have skewed the reading. They sniff from up in the pipe and not outside of it.

I haven't seen or heard of a Prelude blowing that high for the HC test. I'd suspect you are far from stoich, though I'm not sure if running rich=more HC.

I would suggest a basic tuneup. The plugs may tell you a story as well- look for buildup on them. The intake would likely alter the emissions as it alters the fuel map, though I wouldn't suspect it to be by that much. Worst case, you might try going back to stock.

If your plugs are hideously fouled you may have fouled the O2 sensors. Use a lot of injector cleaner or NOS Octane Boost? These will f**k up your O2 sensors and cat if you use them regularly. Best case, you may need new plugs, worst case, it could be the O2 sensors and cat and intake and... a lot of things.

I'd try the plugs, cap, and rotor if you haven't done them- you may just not be getting a very clean burn. From there, it's a crapshoot, though my next step would be to go back to a stock intake, unless you have an AFC or some other way to change the fuel map.

gLudeous

I looked at the plugs a month or so ago, they looked fine, no carbon buildup, just grayish with hints of darkness closer to the threads.

I'm still not sure the burning oil wouldn't have caused a problem, they just clip the thing to the tailpipe and I'm sure burning oil fumes have HUGE HC content, so even if just a hint got to the sensor it might have popped it up.

VeeTec

I am going today to see if my car passes.

I am a bit concerned.

------------------
Warren

93 Prelude VTEC N/A (lots of mods) 13.79@100.7

00 Honda Accord SE (stock)

marcucci

What about the gap or the electrode shape? If they open up you won't be burning very clean.

I'm sure, though. You've got exhaust flying out the tailpipe at somewhere around 70 or 80 CFM, there's no way anything ambient could "sneak" back up to the sensor head, at least 2-4 inches into the taipipe. The exhaust, even at idle, would have enough pressure to keep anything ambient from diluting the real thing.

Check the cap and rotor as well- I don't think those are normal maintenence until 60k mile or more. Under hard (high RPM) driving, they wear that much faster and will lead to that much less spark. Not as complete a burn, it should leave the exhaust rich. With your readings I don't think you've cooked the cat, but I wouldn't be surprised if you just needed a new cap and rotor to get you back where you need to be (might as well throw in new plugs, too).

BTW, that's a pretty severe limit on emissions- here in the Dallas/Fort Worth area, it's 220ppm. Haven't had to do my 'lude yet, it's still too new.

gLudeous

220! Well, maybe it's not so bad as I thought. VA is evil. but they have a deal where if you show you spent at least $250 trying to fix it and it still fails then you get a Pass ("E" for Effort).