EternalHour

Hi guys. I am new here, just registered, and I am hoping one of you can help me out because I have been dealing with this issue for years. Some history first. The last several years (I believe since the timing belt was replaced) my car will not pass the emissions test (high HC at idle). I took it somewhere else this year but previous years I took it to the same shop, they would make a repair and it would pass. I believe what they were doing is using a different vehicle to pass it. So, this year it is not passing. Last year the shop said the cat was bad so I replaced it. This year the cat was bad again so I had it warrantied. After replacing the cat the results were better but still two hundred and something for HC at idle. It seems to me that the engine is running rich and killing the catalytic converter. I have an oem o2 sensor on order which I am going to replace, but I believe the root issue is ignition timing. The car runs normally, but barely rough idle. When I check the timing at 0 degrees, the red mark lines up. When I check the timing at 16 degrees, the white tdc mark is around 3/4" off. Should they not coincide? Sorry for the long post just wanted to make sure everything is explained properly. Right now I am on a temporary registration.

EternalHour

Here is the work I have done over the last several years:

Timing belt, distributor, cap & rotor, oem wires, plugs, pcv valve, valve lash adjustment, battery, master/slave clutch cylinder, front/rear brake pads, radiator, fuel filter, checked all vacuum lines, thermostat. That's about all I can think of.

Hondaguy83

Do another valve adjustment. I bet exaust clearance is tight causing to run rich that's causing high hc. Ill replace cap and rotor too since u haven't had it some in a year. Might as well change all ignition components.

fcm

If your running rich you need to check the ECT sensor.

Also, as mentioned insure valve adjustment is correct. 94

EternalHour

I will test the ECT sensor, but I'm not able to test the valve clearances because I don't have any feeler gauges. The dealership adjusted them. I will try to get some though.

To build upon what I asked, should the white tdc mark on the crank pulley line up with the timing gun set at 16 degrees?

fcm

No, the white mark is TDC, you need to be at 16 degrees btdc, the middle mark, [if you have a non adjustable timing light]. 94

mikelusmc12

Fcm is correct, if you timing marks are lining up where you say they are, then your timing is way off, that's why it had a rough idle.


Posted from Honda-tech.com App for Android

EternalHour

Hi fcm. I am aware that the white mark is tdc and the red mark is 16 btdc. But, since I do have an adjustable timing light, by adjusting the gun to 16 degrees shouldn't it bring the white mark back to 0 degrees? Or am I missing something?

wunfstgsr

deff sounds like timing is off.

If the dealer did the valve lash i doubt its off.
Id always change oil, air filter and maybe o2 sensor and check/clear all codes and timing and drive it for at least 30 mins before i smog. Those right there will run the motor allot better and give better results.

Most smog test shops/programs will make the smog tester check timing and if timing is off the smog is stoped/failed until timing is corrected then the test resumes. The timing adjustment will usually cost an additional fee of about $50.

fcm

Are you jumping the service connector, is engine warmed up to normal running temp.?

Do you know for sure your timing light adjustment is working properly? 94

EternalHour

Sorry for the delay, been really busy. Yep, I jump the service connector prior to checking the timing and make sure the engine is warmed up. Here are the most recent things I have done prior to retesting and failing today.

Checked resistance to ECT sensor: passed (230 ohms).
Checked MAP sensor: No visible problems.
Checked timing once again: Ignition timing is 16 btdc, cam timing (TDC) appears to be 1 or 2 degrees retarded (-1 or -2 degrees from TDC).
Replaced o2 sensor with OEM.
Catalytic converter tested as bad, had shop warranty it.
Replaced spark plugs. The existing were autolight and looked fine, put in nkg iridium.
While replacing the spark plugs, the connector inside wire #4 broke off. Replaced the wires with some aftermarkets at autozone since I couldn't get OEM's soon enough.

The HC at idle reading is now 508 ppm, where as before it was 336 ppm. I don't understand how it could have gotten worse by doing this maintenance but the engine idles better and came down from 850 to 750. I am at a loss of what else to do.

fcm

What do you mean, "cam timing (TDC) appears to be 1 or 2 degrees retarded (-1 or -2 degrees from TDC)"???

Are you sure timing belt is not off by one tooth? 94

EternalHour

No I am not sure, but I am no mechanic. But, I let a local shop change the timing belt and I think they may not have set TDC properly. But at this point, I am thinking if I want something done properly I may need to do it myself even though I am not really comfortable with it. That is the only indication of the issue so far.

fcm

It's not that hard to do, checking it is easy enough. 94

EternalHour

So I opened up the valve cover and checked the cam timing, it was right on the money. I also did a compression test and every cylinder was at 180 psi. Next thing I will be doing is a leak down test but I suspect that something may be going on with the injectors.

el crapitan

High Speed
HC=121
CO=1.06
CO2=13.9

Idle
HC=508
CO=1.12
CO2=13.9

these were your readings. you are not running rich. running rich is a result of excess fuel to air ratio. it will yield a much higher CO relative to HC. high HC is a result of not burning the air fuel mixture efficiently. that is what you have here.
the main causes of high HC are ignition timing, ignition components, low compression due to multiple possibilities, and the number one cause-misfires. you see the pattern? anything that is keeping the air fuel mixture you already have, to burn.

just so you know, generally, sensors will cause a rich condition. that's ect, o2, map...since they are what define the air fuel mixture. it would result in a high CO reading, with slightly higher than average HC.

TBH, when looking at emissions readings, your priority emissions are not HC or CO. they're CO2 first, then O2. those 2 will tell you everything you need to know.
you want your CO2 to be as high as possible. around 14.5-15 is an indication of a properly functioning system. since CO2 is a combination of CO and O2 (and some of the carbon from HC). if you have a low CO2 reading, we know it lacks either CO or O2. so, next we would look at O2. the O2 is going to seal the deal here. low O2 will indicate a rich condition. point blank. done. low CO2 and low O2 = rich. without even looking at HC or CO. we don't need to. we know CO will be high (rich) because it's missing from CO2. if we had low CO2 and high O2 we would be running lean and have very low CO.

it's actually super simple stuff. when dealing with emissions we're only dealing with a few very simple gases that enter the combustion chamber and exit as reformed gases that the converter reforms into other, less harmful, and still simple molecules. nothings created or destroyed. just rearranged.


for starters, you need to stop replacing the cat before figuring the underlying problem. it will just burn out again. and the cheaper it is, the faster it will.
couple things i'm noticing here. you say you have a rough idle. is it lopey? or is it more of a misfire? like the engine stutters? if so, the misfiring is likely the cause of your high HC. misfires will shoot your HC through the roof.

another thing; 180psi across on a b18c? pretty low. are you sure you performed the test correctly?
engine at operating temp, all spark plugs removed, WOT, crank until the gauge stops moving.
if ALL of those conditions were met, then try running a wet test.
if you perform the test again under those conditions and you get a reading like 210psi across, there's no need to run a leakdown test, as this is only performed to find where compression is escaping. and 210 wouldn't indicate a loss in compression

EternalHour

Thanks for all the great info el crapitan! So if I am interpreting your emissions analysis correctly, you suspect an ignition or combustion issue? Do you believe it is worthwhile to get the injectors tested? The idle is a bit various. It isn't rough to the point that the whole car shakes, but I can feel the shake/vibration slightly in the steering wheel at a dead stop. I also notice that when the engine drops from a higher rpm, to idle rpm, the engine/car shakes and then stabilizes (idle dipping and possibly missing?). When doing the compression test I went by this article and the engine was at operating temp. The psi definitely peaked at 180, but, I did it just prior to doing an oil change and the crankcase still had seafoam in it and probably thinned the oil (which was also a quart low). Maybe I should test it again. When trying to take the map sensor off to clean it the screw stripped so I haven't been able to do that yet. Do you think the piston rings may be shot?

el crapitan

alright. sounds like the comp test was performed correctly. try a wet test. see if that yields better numbers.
i mean, the injectors COULD be causing problems, ie, lean misfires. but let's first look at the problems we know exist that could contribute to your high hc. we know your comp numbers are a bit low. it also sounds like you're misfiring at idle. let's start with the wet test. then we'll try and solve for the misfires

EternalHour

Ran another dry and wet compression test, here are the results:


Dry Wet

Cylinder #4 180 220
Cylinder #3 180 195
Cylinder #2 180 195
Cylinder #1 180 215

I've read that on a b18c1 engine the compression numbers should be 230-240 psi, is that correct? Thanks so much for the help.

el crapitan

yea, i think on average, you should see about 220. know what? try and get ahold of another tester. just to confirm it's not off. a lot of times, the readings vary from tester to tester

EternalHour

Ok I will do that. What is the worst case scenario with these numbers, piston ring replacement? I am actually really surprised that the numbers are low, car only has 136k miles and I baby it.

el crapitan

wow. i just looked back at your compression test results. do you see the pattern there? it's beautiful. your 1 and 4 are nearly identical in both dry and wet. while 2 and 3 are as well. look back at the instructional link you'd posted. do you see his pattern? 1 and 4 identical. 2 and 3 as well. do you know why that is? cylinder 1 and 4 are paired, as are 2 and 3. when you turn your key to shut the engine off, what actually stops the engine is its lack of momentum. a 4 cylinder engine will stop in the same cylinder position every time. it develops this stopped cylinder position from the factory. the cause is extremely minor differences in bearing and/or ring clearances. once that position is determined, it always stops there. always. that means it always starts there as well. so, if you have paired cylinders that start let's say 3/4 of the way to TDC, those paired cylinders will be starved for oil for 1.25 full strokes, since they both won't pick up oil until they reach the bottom of the cylinder. that's some pretty cool **** right there. engine wear isn't really about how many miles have acquired, but how many times the engine is shut off. since something like 95% of engine wear is attributed to start up. that's why highway miles aren't seen as such a bad thing.

but anyways, i think your next move here should be a leakdown test. not so much for cylinders 1 and 4, as it's obvious that the problem there is rings, but more for 2 and 3. but of course, run the test on all cylinders anyways

EternalHour

That is some pretty cool ****, thanks for the explanation. There is actually another similarity I noticed after going back and looking at that article, the test I rented is exactly the same. Hmmmm....Maybe you are onto something with using a different tester. When I take the compression tester back I will rent a leakdown.

I also forgot to mention, I noticed something odd after taking out the spark plugs and looking down into the cylinder. It looked like there was some sort of deposit in there, tan or brownish. Maybe they were just reflections but I swear there was some sort of buildup.

el crapitan

yeah, there's gonna be carbon deposits in there. i wouldn't worry about that

Hondaguy83

Inspect plugs and do leak down test. Could be mechanical issue like valve springs or valves.