94 Protege 1.8L SOHC wont pass emissions test. High NO PPM reading was 1055 limit is 550. car runs great replaced the O2 sensor still the same reading. what could this be? one of the causes is to far advanced timing. i tryed to retard it but was haveing a really hard time getting a consistant reading. where to line it up to. all i see is a T and 10the haynes say 4 degrees BTDC. so do i line it up with the marks before the T or After the T on the 10 side. i will try and show and example. it goes. llllTlllll10ll
any help on this would be great. the car is nice and just put a new clutch in a month ago so i would be dissapointing to waste all that hassle putting the tranny back in lol

 

Go to Autozone and buy a large bottle of Techron and put it in the gas tank. Drive that tank of gas out and change your oil. Check your spark plugs and make sure the are NGK plugs. If it has more than 100k miles it may need a new coil also.

 

ok here is what iv done. Plugs, wires, cap, rotor, got my buddys tool from honda and use some cb40 stuff to clean the injectors like they do at the dealers. checked the fuel pressuer new air filter. tryed 94 octane still the same. high NOX so thats why i leaning toward the timing one of the causes of high NOX is to far advanced timing. but again i had a really hard time getting a consistant reading could that be a bad coil issuse not strong enough to make my timing light work right?

 

Bump.^^

 

Her's a direct quote from CatalyticConverter.org website:-

"What causes High NOX Emissions
Thousands of technicians have faced the challenge of bringing a particularly stubborn application into compliance for NOx emissions. High NOx readings are a clear sign of performance issues somewhere in the system. The question is, where?

Among the potential causes of non-compliant NOx readings are:
Misfire condition
Malfunctioning or improperly adjusted EGR valve
Failed oxygen sensor
Leak in exhaust tubing upstream of converter
Excessive carbon deposits in combustion chamber
Improper spark advance
Blocked coolant passage
Overly lean air-fuel mixture
Damaged cold air duct
Failed or malfunctioning catalytic converter
Corroded or damaged engine sensor electrical connections
Please note that while a failed catalytic converter will contribute to high NOx readings, the failure in itself may have been caused by some other upstream performance problem. In all cases, it is crucial to identify the root cause of the problem before blaming the converter."


Additionally, I read on a Mazda forum somewhere that prolonged use of fuel having a greater than 87 Octane rating is detremental to the O2 sensors and/or catalytic converter. Best bet follow the rules, multiply the cost of repair x the probability of the failure and list the results in ascending order, then get to work starting with the lowest number and working up. Good luck, and don't forget, unlike the case study on the site I quoted, the Protege DOES have an EGR .

 

I just another thought re your NOX fail.
You recently did major work on the power train, so things got pretty well shaken up.
Now, you didn't mention anything about a check engine light or a P1071 code, so this implies the engine idle conditions are OK, yet you still get high NOX.
I've had plenty of issues with CEL and engine air duct in the idle regime, but if you're getting high NOX and no CEL, and if it's excess air, it would seem unlikely that it's the air intake duct EXCEPT, if a duct split doesn't leak at idle, it doesn't necessarily follow that it won't open up with the power train loaded, because under load, the engine is reaction torqued against its mounts, so a split can open under loaded conditions and then reseal when the engine tilts back to its rest position when unloaded.
It's a long shot, but at least its not hard to check out, and doesn't cost $$$.
See also my reply on topic "Too Lean" 2000 Mazda Protege"

 

i honestly think its the timing. but i will try your idea. do you know how to read the timing marks. lllTlllll10llll thats what they look like. where is 4* btdc? would it be the second line before the T or the second line after the T right now its set on the second line before the T and the car doesnt run that well. feels like it wants to go but somthing is holding it back on acceleration. car ran good before i started messing with the timing. also in that list you got acouple posts up. i see it says Exhaust leak upstream of cat. how would this affect the NOX.? i have a little leak right before it joins to the flex pipe..? hopfully its as simple as putting a bead of weld on mu pipe. lol

 

she passed runs like crap but she passed. still unsure of the timing im sure its wrong. anyone know how to read the marks? theres an example of what they look like in the upper post. has a hesitation on acceleration

 

OK. Engines normally operate over a wider span of BTDC than ATDC, so the side with the biggest span is BEFORE TDC.
Looking at your "bar code" in your post, BEFORE is to the right of T. You can verify this by looking at the crank pulley. Mine turns clockwise, so BEFORE, i.e. earlier spark, occurs in the firewall direction, retarding the spark would move the firing point in the direction of the rad.
From your description, you've timed your spark on the WRONG side of the T.
Try setting your spark to midway between the T and the 10 mark, giving you 5 degrees advance. A degree off shouldn't make much difference; right now you're off by 8 degrees, not great !
If this gets you in the right ballpark, you can then tweak the spark back a smidgeon toward the T if it makes you sleep better at night !
If you've been running for any amount of time with the spark this far retarded, your engine would be running below design temperature, so you might have sooted up the plugs. Get it right then take the car out for a half hour spin at autoroute speeds and that should clean them up.

 

Sorry, I overlooked your question re high NOX. Here's the answer. The O2 sensor doesn't sense NOX. It assumes all of the O2 in the exhaust stream came from combustion in the engine, and "looks" for residual O2. If it sees too much, it assumes it came from the engine, and an engine emitting too much O2 is running too lean. A lean mixture causes a higher than optimum flame temperature in the cylinder which will result in atmospheric nitrogen being oxidized to NOX, a smog promoter.
Near the engine end of an exhaust system, the plumbing behaves as a resonant pipe, so the high pressure exhaust pulse actually creates a wake, a partial vacuum, behind it as it heads for the tailpipe. This partial vacuum sucks air through leaks in the front part of the exhaust system which the O2 sensor interprets as having come out of a too lean engine, hence it interprets "unused" oxygen as implying a too lean i.e. too hot exhaust gas, whose elevated temperature is conducive to NOX formation. So the NOX issue is IMPLIED, not actually measured.