wolfdogg

hi all,
i need a bit of help on ideas to fix HC emission at idle.

honda civic 94 ex, 202,000 miles, stock engine. air cleaner clean, oil due for a change only slightly dirty. will change in the days following. female driver for 99% of its life, until i get ahold of it, then i shake the cob webs out of it by hitting WOT regularly.


heres the tested emissions specs
at 732RPM (at idle)
CO2 MEAS-15.00%
O2 0.00%
HC MAX-100 AVE-17 MEAS-170 (FAIL)
CO max-1.00 ave-0.00 MEAS-0.09

at 2492rpm
CO2 MEAS-14.90
O2 MEAS-0.00
HC MAX-130 AVE-12 MEAS-35
CO MAX-1.00 AVE-0.10 MEAS-0.20

car runs good, idle is smooth, doesnt seem to be any miss, very fast at stock. in the tank now is some lucas fuel cleaner (the one that claims to reduce NOX emissions) through there on 97 octane chevron currently. this cleaner was NOT in there during the test, its my attempt to clean the injectors incase they are dumping too much gas.

a bit of history
i smogged it 2 years ago, it didnt pass. so i changed the plugs, re-adjusted the valves for the first time, changed oil, put a new header on there and new O2 sensor (see below), possibly fuel filter (not sure on this one, i think i will do that now), changed air cleaner, possibly rotor
then it FAILED. so i replaced CAT, and it PASSED.

since then the car maily sat in driveway for 2 years, i think we put about 5000 miles on it max, in last 2 years since last smog. now its FAILING.

THE PLUGS,
bosch platinum +2 (4301's)
my first suspect is the plugs,
i looked at the plugs they are all clean, had a bit of ash deposits, or maybe sugar speckles, was light brown, and clean looking, i interpreted this as clean, but the rim on the plug was built up with carbon deposits. so i wonder if this is the indicator of runnign too rich, because these plugs have some sort of self-cleaning mechanism due to the type of metals used, and the air-gap technology so that might explain why the tips were clean, but the rim was carbon built up.

the factory gap, which i can FIND NO WHERE using google is about .023 thousandths on both ground electrodes. in the end i decided to stretch them to .030 thousandts despite the manufacturers recommendation that they dont need adjusting. the car ran better, but im not sure if that gap help clean off the idle HC's in the end or not. the next smog will tell.

could the plugs be the problem? should i get a hotter plug?

Plug wires
havent been changed at all to my knowledge, but we bought the car at just over 100k, so maybe before this they were... they look ok, and are seperated nicely, except in a couple spots they touch.

Rotor
not sure, ill open teh cap and inspect, but i think i filed the corrosion off the cap terminals last time, and prob cleaned up the rotor as well.

FUEL DELIVERY
im wondering if the stock fuel pressure regulator is adjustable, i thought of backing it off a tad to slow some fuel down at idle. would this help to pass smog? i DONT have a pressure guage, do they rent them at Auto Zone?

I do have a Mity-Vac that is good for gauging the vacuum, can i use this?

i was considering replacing the Injectors, i found them for $25 a piece refurbished. please try not to recommend me against the re-furbs unelss totally necessary, because im on a very tight budget right now. but should i be worrying about my injectors at all right now in the first place?

I need to change the fuel filter because im not sure if i did this last smog or not.

Exhaust
the one thing i replaced to performance was i put a Pace Setter header on there (was the cheapest i could find other than stock) and i put a new O2 sensor on there. i did this just before last smog 2 years ago.

One thing im concerned about on thsi one is the location of the O2 sensor, seems to be in an area of turbulence, rather than in a smooth flow area.

links to header images
http://www.jcwhitney.com/jcwhitney/s...49296_CL_1.jpg
http://www.jcwhitney.com/performance...stid=16663111#


so what is the first line of action here?
hotter plugs?
new injectors?
turn down the fuel pressure?
change the plug wires, cap rotor?

Former User

Plugs, wires, cap, rotor and ignition timing is where I would start.

Measuring the fuel pressure would tell you whether the FPR is acting up.

pityocamptes

How long has the gas been sitting in the tank?

wolfdogg

yeah, i cant measure the FPR at all, wish i could. dont have a guage. my dad does, he lives 1hr drive.

as far as plugs, wires, cap, rotor, thats about as expensive as a complete diagnostic and i always shy away from replacing something simply because im not sure. If there is any definitive way to test the plug wires i would prefer that first. as far as the cap and rotor, do you think filing clean is ok, or will that cause too much a gap for the spark to leap reducing the spark?

the gas is clean, i ran out the old tank, atleast 95% of it, then filled to over a half tank of new 97 chevron.

Former User

Measure resistance of the plug wires and check for any cracking in the insulation. If either is bad, replace them. Inspect the contact points of the cap and rotor and look for cracks or breaks. Just replace the plugs if they are fouled.

wolfdogg

i will check the resistance of the plug wires, thanks.

update
-i replaced the cap today it was old, and worn out, and changed the oil. i cleaned the rotor with a file, it looked mostly clean, but now looks really clean.
-the compression is 88psi on all cylinders

i didnt suspect 88 psi was bad, since all were the same, but the ****** mechanic at the smog shop informed me today that that amount is still low. and he mentioned that this will affect primarily the idle HC output, if im not mistaken.

he also pointed out, correct me if hes wrong, that if it was the FPR then it would also would cause high CO2, (or CO forgot which one he said) if it was the FPR.

ddd4114

High CO readings are caused by rich mixtures, and high HC readings are caused by unburnt fuel passing through the exhaust.

It sounds like you have a slight misfiring issue, so I agree that you should check the ignition components.

FYI, based on your emissions, you were running slightly richer than stoich at idle (when it failed), and you were running a stoich mixture at 2500 rpm.

88 psi is pretty low for a compression test, even if all cylinders are reading closely. Did you test with a warm engine and an open throttle? How many times did you crank the engine over for each cylinder?

wolfdogg

ahh, engine was NOT warm if i recall correctly, and forgotten about WOT if i ever knew. i cranked it just for a couple seconds each. but i had my dad watch the guage, and we tested that if i cranked it more, the guage didnt rise .

how long should i crank it, and does it need to be warm, and should i hold throttle open when cranking?

ddd4114

The engine should be fully warm, and the throttle should be wide open. You can stop cranking whenever the needle stops moving, as you did before.

wolfdogg

(EDIT, replaced CAP last week, and changed oil and filter. havent gotten re-smogged yet)
RonJ@HT, plugs were only slightly carbon fouled around rim only, so i just cleaned them up and gapped them as mentioned above to .030.

ok, i checked the compression WOT after warming up.

assuming from left to right is cylinders 1-4,
cyl 1 106psi
cyl2 101 psi
cyl 3 106 psi
cyl4 106-109 psi

plug wires
1 - 5.3 Kilo ohm
2 - 6.x K ohm (forgot exactly what, but was in 6 range)
3 - 7.x K ohm (forgot exactly what but was low 7's)
4 - 7.9 K ohm
the general trend was the shorter the wire the less resistance. but i think i got solid readings on them. i didnt realize they would be over .1 ohm.

can somebody please comment on these specs for the compression and plug wires, then refer back to the original question please.

thanks.

93egSLEEPER

Those are some pretty low compression numbers. Could be part of the problem. As a "rule of thumb" it takes 90-100psi for combustion to take place. For it to take place properly and efficiently 110psi is a basic starting number. Every motor is different, but low compression will cause inefficient burning of the fuel, rich conditions, causing you to be high in HC.

ddd4114

If I was to take a guess, your valves (particularly the exhaust) aren't seating properly. Even though the readings are about even, they're pretty low.

Try doing a wet compression test by putting a few drops of oil into the cylinder before installing the gauge. If the readings increase significantly, that would indicate the rings.

Former User

The plug gap should be 0.043 in.

The plug wire resistance is fine. They just need to be less than 25K Ohms.

Cylinder compressions seem low, but it depends on how you are doing the test. Provide some details.

wolfdogg

ok, i pulled all 4 plugs, put the compression tester into cyl 1 (on the right), tightened by hand, it has a rubber o-ring at base, and no real great way to get a wrench at all (unless i had a socket like used for O2 sensor, are those the same size? if so i could have used that, but i thought that socket was a bit bigger like 3/4 or something) , so i tightened by hand until the o-ring seated. its all i could do given the type of tester and no slotted socket to fit. then to test it, i pushed throttle to floor wide open, then cranked while the engine turned over a dozen or so times. about 5 seconds possibly, then i took the reading, and did it once more to make sure i got the same thing. then i removed the tester, hand threaded it into the next cylinder, and did it again.

there is a bit more but i didnt want to open a can of worms on this one, here it goes.

i changed the oil the other day, but i placed too much oil in there. i poured about 75% of the oil jog in there, putting 10-40w castrol. i noticed i may have put too much oil in, the dipstick confirmed this. do they make 6 qt jugs? i thought it wasd only 5 qts, and i estimated pouring 4 qts in. anyway, its about 1/3rd qt too much. when i took it for a drive it was smoking a bit the other day. i drove it slightly hard until it stopped smoking. today when i warmed the car up for the compression test, and pulled the plugs, they were slightly oil fouled. i knew right away why. the oil was only visible on the outside thread area, and maybe a bit shiny on the center platimum electrode.

ok, so what does this mean, it means i did do a wet compression test. so the readings are as high as they will ever be.

im guessing the compression being a bit low might cause this to fail HC's at idle on the smog test. is this the culprit?

ddd4114, does that rule out the rings? or point to them? i suspected the valve guides, before i did the test, but i asked the manager at autozone for his opinion and he thought the compression was ok, i beleived him until you guys mentioned its a bit low.

can someone predict the rings over the valve quides, or valves , or vice versa, with this info?

RonJ@HT the plugs are the non-adjustable type, being bosch platinum x2, silly as it seems to me. im regretting buying them because of this. so since they are non-adjustable i alredy broke the manu's specs by adjusting them in the first place. i confirmed they were an even .023 straight from the manu, with their air gap technology, .. blah blah. so i thought i was already pushing it by stretching them to .030. i know standard plugs are supposed to be set to .043 +-, but for these non-adjustable type too?

Former User

1) What color was the smoke from the exhaust (blue = oil; white = coolant; black = fuel)? Drain the excess oil from the crankcase. Did you also replace the oil filter?

2) Discard the Bosch plugs and buy four NGK ZFR5J-11 spark plugs. They should be pre-gapped (0.043 in) at the factory, but still double check them prior to installation.

3) Check whether the ignition timing is set to spec. There's a diagram for this in the FAQs sticky.

4) Redo the emissions test.

wolfdogg

the smoke was bluish white, im almost positive it was oil. so you think just the plugs might be the problem? HC was 170, where max allowed was 100, ppm i believe. i think i liek the idea of discarding the plugs.

i think the tech said is was 10 deg BTDC, if i recall. maybe i should adjust it a few points? ill look into it. thanks for the advice, its much appreciated.