radeonboy

So I have a JDM D15B VTEC in an EH2 automatic (93 Honda Civic DX Hatch) and up here in Canada I failed emissions testing two times already. I would like your guys help in diagnosing what is going on. I'm leaning towards bad catalytic converter + oxygen sensor (and possibly bad ignition timing) but here is what was done up to this point. BTW: The car was kept in the garage for about a year and a half sitting doing nothing. But I want opinions first before shelling out $$ for both parts.

3 years back Pass.



Test 1: Did nothing but went to emissions test, failed only CO%.



Test 2: Cleaned PCV valve, changed oil/filter, seafoam, high octane, ran the car hot until test. Failed, much worse this time. Almost failed NO ppm as well. Three things failed and forth almost failed. The seafoam must have facked up the O2 sensor which facked up the cat. But then again the cat is probably too old. Thats why I smell something bad when the car is idling.



THANKS IN ADVANCE

Sleepy_Red_hatch

carbon monoxide is a by-product of combustion. typically on a older honda it is due to a deteriorating cat. but again e-tests are very hard to diag over the internet. how's your air filter? plugs? timing? what kind of oil did you use?

also seafoam is not usually a good idea before an e-test because it washes the cylinder walls and lowers your compression for a lil while afterwards (piston rings always need a tiny bit of oil on the cylinder walls)

did you just buy the car? if not (probably not) you can ask them to diag your car and there is a max they can charge you for repairs.

most shops are borederline retarded and will say you need a cat, if you request honda parts only, thats way over the conditional pass limit and voila, you have your sticker.....did that a few years back with my D15B which was burning oil

radeonboy

Ya I seafoamed then drove it around for a few days until I changed oil 10w30. Air filter is some CAI and the filter seems clean. Plugs look good. Timing is something Im not sure about. The guys who did the swap couple of years back may have done it but Im not sure if its done correctly since the swap looked kind of shady.

I'll inquire about that conditional pass. I totally forgot about that. I skimmed something that said $450 repair or something. But I guess they will charge to diagnose and its too expensive, they give the conditional pass? Don't know how it works

Sleepy_Red_hatch

basically, they diag it (100$) then they recommend the repair. if the repair is higher then 350$ you get a pass without doing it, if they try various things (like plugs, wires, filters) and still doesn't pass, just yell at them and say it wasn't necessary and they will revert it to stock (because the were wrong) and usually they call something too expensive (engine damage or cat) and pass it conditionally. i used canadian tire personally, they are kinda retarded imho

that's my 0.02$

btw if you need some work done, check my sig, im in ottawa too

Former User

Any CEL codes?

I start by doing a basic ignition system tune up - plugs, wires, cap, rotor, ignition timing.

canadaek

it barely pass 3 years ago did you run a couple of tanks of fresh gas through it ? i would look at the oxygen sensor first . unless you have a dead miss plugs,wire's,cap,rotors don't usually make that big of a difference and it usually makes stuff worse for the first couple of days as deposits are burned off of the combustion chamber . but when all 3 gas are high a failed converter is a possibility .a bad cat or over advanced ignition timing or lean a/f ratio are the normal causes of high nox as most Honda's don't have an egr valve (your car is running rich though hi HC and not burning all the fuel high CO)

Former User

This^ is just plain wrong.

canadaek

well Ron i have been test's and fixing cars for drive clean for like 10 years i'm certified inspector and repair technician my drive clean id # is 20182 and plugs and wires NEVER make a 80ppm difference in HC so please show me your proof .if there's a spark it won't change the readings very much and i have seen lots of cars fail get a tune up then fail worse .

Former User

You know as well as I do that engine misfire (of varying severity) due to one or more ignition system problems is the most common cause of high HC for our cars (92-00 Civics/Del Sols). Think about it. The ignition system is most prone to wear and neglect and will greatly affect HC emissions. Therefore, the first thing to look at in a case like this is the ignition system - plugs, wires, cap, rotor, ignition timing - as I stated. If the ignition system is proven fine, then look at other possibilities, assuming that there are no obvious CEL codes to guide troubleshooting.

canadaek

worn ignition usually results in high CO readings (incomplete combustion )HC are raw fuel i'v also seen lots of lazy oxygen sensors that never trip the cel and they are even more ignored then the ignition cat can only clean up so much A/f ratio has more of an effect then worn plugs on emmisions in my experience the 25/25 test we use here 25% load at 25mph doesn't put much stress on an engine so if you don't notice a misfire in normal driving it probably won't show up on the dyno i'm not saying to ignore the basics just that # that high are usually a bigger problem . still waiting to be proved wrong i'm not fleabag telling him to clean his grounds and pcv valve i do this for a living

Former User

The car failed for high CO levels twice and, in the latest test, also for high HC.

Clearly, a bad O2 sensor can make the engine run rich. So can a bunch of other things, including fuel system issues, a stuck open thermostat, etc. However, ignition components require much more frequent replacement than do OEM O2 sensors, which can easily function properly beyond 100K miles. My point is that you would check the ignition system and timing before the O2 sensor in a case like this, unless there was direct evidence that the O2 sensor is bad. In addition, inspection and testing of the ignition system are so easy and basic.

A poorly maintained ignition system that causes misfires and releases unburnt fuel into the exhaust system is also the most common cause of cat destruction.

How do you know the engine isn't misfiring enough to raise HC in the exhaust?

So why not just tell the OP to start with the basics by checking the basic ignition system components? It's the logical first step. If the ignition system is fine, then go from there (coil, igniter unit, fuel pressure, FPR, O2 sensor, thermostat...).

Are you saying that professionals are always right? In reality, neither of us know what is causing the OP's problem. However, making a pan statement in this thread telling the OP to ignore the plugs, wires, cap, and rotor when emissions tests show high HC is not only wrong but ridiculous. Also, have you considered that high HC in this case might have more than one cause?

canadaek

i didn't tell him not to i said in my experiance it almost never makes that large of a differance on the emmisions


no there not always right but experiance does count for a lot and us argueing isn't helping the op so i'm done hopefully he will post the fix and any work he does dosn't count towards a conditinal pass .

Former User

I hope our interchange was more debate than argument. Debating differences of opinion is fine in tech forums if the discussion remains civil. I hope my comments didn't cross that line.

canadaek

no your comments where ok i just don't like being told i'm wrong. hopefully something we said helps to op