I just picked up a gsr a month ago, I swaped out the engine that had horid compression (110,130,110,150). get it all in, running good, do all the safety stuff, take it out for an e-test... fails misserably. I know the guy that tested it and he said when all the numbers are as ellevated as mine were its usually a cat. plus on the way home the check engine light comes on for the downstream o2.

thing is it burns a little bit of oil, a little more than I'd like if I give it... my boss is certain it won't pass even with 2 new 02s and a new cat. what do you guys think... here were my numbers:

40Km/h
HC ppm 147, limit 68
CO % .30, limit .38
NO ppm 2385, limit 0526

idle
HC ppm 199, limit 200
CO % .04, limit 1

I am currently trying to get the car tested with our new etest here in ontario... but the shop says only 98 and newer can be tested using the obd test (a joke, as long as all the system are listed as functioning when they plug in and no MIL light in the ECU... it passes)

I added some gunk stop smoke today to try and help it, I also did a seafoam treatment yesterday. also my compression numbers were 182 185 183 194

any help or advice is appreciated (its getting a rebuilt engine in April, so I really don't want to take it out again to re-ring it, just to take it out again in april)

 

when I looked at the cat... it wasn't plugged but it looked like it was at least half way there (when comparing it to a new cat)

 

bump for someone who knows if those high numbers could be caused by aq bad cat and 02 sensors.

 

Year and mileage?

I would start out checking your regular maintenance items: plugs, cap/rotor, oil change, valve adjustment, ignition timing... While you're at it, check the cam timing too.

Your compression numbers are alarmingly low but if that were your problem, your NOx would not be that high. If all the above checks out, it may be your cat. Do you have a known good cat you can swap and test with?

 

1997, engine has 300K+ (km). I thought 180-200 was good for a GSR? when I change the engine I did a new timing belt kit, plugs and wires... the only thing that hasn't been changed is the distributor. I do have a known good cat from a civic, roughly the same length, but I'll have to wait for my o2 sensor to get here (monday morning).

 

took the cat off today, held it up to the light, almost no light shining through, if you tilt it the right way you could see a TINY bit of light... hopefully the good cat wiil help me pass.

 

When you did the T-belt, were you sure the cam timing was correct? Might want to pull the VC and double check that.

 

the failed cat is only a result of a problem. a bad cat does not produce high emissions. something else is wrong. even pre-cat those numbers are bad.
with high NOx readings, i'd be inclined to suspect a timing issue.
what is your ignition timing set at?

not sure how good that seafoam and stop smoke are for the cat either. also, the low compression engine would have been bad for it as well.
regardless, something else is wrong

 

when I did the t-belt, I checked 3 times to make sure it was right on, timing is whatever the factory ecu sets? can you really adjust the timing on our engines, I thought it was ecu controlled?

a good cat would filter alot of that stuff out, wouldn't it?

 

no, and no.
cats are not filters. a 3 way catalyst breaks down your pollutants; HC, CO, and NOx. once these compounds are broken down into simple molecules, less harmful compounds are formed. H2O, CO2, N and O2. there are 2 stages in a 3 way cat. first stage is reduction. this is where NOx is broken down into nitrogen and oxygen. the oxygen is then passed to the second stage, oxidation, where it is combined with HC and CO to form H2O and CO2. the only component needed to perform this, aside from the catalyst, is heat. roughly 500*f to be exact.

that is a very, very basic crash course on the system. nothing is created. nothing is destroyed. only transferred. it's the simple law of the conservation of mass. that's how you need to see it.
a gas analyzer is the absolute best diagnostic tool available. it tells you how the engine is performing better than anything else.
so, even if your cat were completely missing, those NOx numbers would still be very high. as mentioned, the cat is not going to increase those numbers. so that tells you they were high to begin with. you can confirm cat failure by taking readings pre-cat, and then tailpipe. compare the numbers to confirm efficiency. your cat may be operating just fine. you don't know until you test.
the simple formula to confirm is (HC in + HC out divided by HC in) + (CO in + CO out divided by CO in). take that number and divide by 2. that's your cat efficiency.
installing a brand new cat on a poorly operating engine will always get you reduced emissions. that's why people always assume, ok, the cat was bad. that's not the case. the cat can still do it's job. but not for long. the failed cat is almost always a result of an underlying issue. they can last an extremely long time under the conditions they were meant.

as for the timing, i was speaking of ignition timing, not valve timing. you must set your base timing using a timing light. your ecu does have timing adjustment capabilities, of course, but it uses that for timing advance with raised load. it must have base timing set manually. those NOx numbers scream of too much timing. timing probably needs to retarded. use a light and set base timing. remember, when setting base timing, you must go into base timing mode. that is, at operating temp, jump the 2 pin service connector. this bypasses the ecm from interfering while you make your adjustments.

 

I'll set the timing tomorrow morning, and with a good cat, 2 new o2 sensors... it will hopefully pass, also when it was tested it wasn't full of coolant, so it may have been a bit warm (gauge didn't read overheating, but may have contributed to the high #s)

 

timing is now set properly, the engine is running better, but I am still not sure it'll pass...

I think the #4 injector is leaking around the oring in the manifold... my htoughts are that this could cause the o2 sensor to read lean for a split second and maybe over-compensate a little? not sure if it could do that, but nonetheless, I thought it was leaking but couldn't smell anything, today I started to smell gas a little, so I'll be investigating tomorrow. any help is appreciated.

 

fix the leak. it needs to be done regardless

 

yeah, that will be done in the next day or so... my local acura dealer wants $7 for 1 oring for the injectors.

another e-test today just to see:
40 Km/h
HC 16% decrease (124... limit 68)
CO 200% increase (.93... limit .38)
NOx 85% decrease (414... limit 526)

at idle:
HC 25% decrease (157... limit 200)
CO increase (but passed 29% of limit)

this is without the new 02 sensors, and with the fuel leak (other than when I smelled it yesterday for a few minutes... seems to be very small, but there nonetheless)

 

high CO is an indication of rich fuel mixture. fix that leak and go from there. if you could get pre cat numbers, that would be ideal

 

ok, I had set the timing wrong, and a quick look through alldata showed to aim for the middle notch, so thats set... 2 new o2 sensors installed... re-checked compression, engine at op temp, wot 4-5 cranks and got 210 accross the board... replaced all the injector seals, so no more fuel leak. taking it for another emissions test tomorrrow.

 

No way really

 

c'mon... every thread needs a captain obvious. jk

 

OK, another update
this test has the fuel leak fixed, 2 new 02 sensors, a new distributor rotor, and proper timing set.

40 Km/h
HC 44... limit 68
CO .58... limit .38
NOx 326... limit 526

at idle:
HC 84... limit 200
CO .33... limit 1

the service advisor at the drive clean facility says the 40km/h numbers are high enough accross the board to go with a new cat (the used one I put on may not have been in as good shape as I thought). I can get a universal cat for $90 (walker) and I'll have to find someone I know that has a welder, but other than that it shouldn't be too difficult to fit that universal in there, considering it has a civic cat in it now.

 

it's not the cat. as usual, the smog tech has no clue. you're running rich. what were your o2 readings? co2?
i'll explain something about the smog test here; it is extremely foregiving, granted the engine and its sensors are operating correctly. you could pretty much go through with no cat at all and pass. again, granted the engine were performing correctly. and, of course, they would allow it.

anyways, you're running rich @ cruising speeds. you need to solve for that. looking back at your readings before the cat replacement and timing adjustment, your co was good. leads me to believe the timing is suspect.
what is it set at?

 

sounds like common sense, yes. but you'd be surprised at how many people try and diagnose an issue over top of another issue

 

Cat temp should be 100 degrees hotter or 10% hotter inlet to outlet. This will show the cat is working correctly. If it's cooler goin out then coming in its not working and a new one is needed. Mine was like 160 for a universal one.

El craputan do you not know how to read he said timing is set properly holy crap

 

first off, he never said what timing was set at. just "correctly"
second, the temp trick is never conclusive. it's a bogus hack way of diagnosing. sounds right up your alley, actually
you clearly have no clue yourself on the harmonized functioning of it all, so really, just step off and stop making yourself foolish by doling out false info

 

the co readings went up, but every other reading has gone down drastically, originally set the timing at the first notch, which I believe is 18*, which caust the HC to drop a bit (makes sense) after the new cap and putting the timing at 16* (middle notch) the HC went down drastically (still high but dropped nonetheless). The smog tech said it could be lazy o2 sensors, but with 2 brand new sensors, and the numbers haven't really moved, I am guessing thats not the problem... which is when he suggested the cat. he also told me they have had cars with numbers close to what mine are, put a universal cat on and viola pass the etest (which is all I need, the engine only needs to last through the winter) I still don't understand how all the numbers go in the right direction with every change, but yet the co has went up (down a bit with the last test).

also the co didn't go up until I set the timing (at 18*) and used my cousins civic cat that passed an etest a year ago. I'm still leaning toward the cat giving me passing numbers.

 

The new cat is basically a freebie, there is a scrap yard close that pays $80 per cat... so I'll take my old one there with gas considered walk away with $70 which takes up a good chunk of the $105 I need for the new one, plus the one thats on the car currently can be scrapped once I confirm the cat was or was not the co problem