the_egg

Any help appreciated as I have about 2 days before my reg expires.

I posted before about my 92 Civic lx and some overheating issues that have popped up in the last few months. I took it in yesterday for a smog test, And it failed the first run due to timing problems (running at 10, should be 16). I took it into my local Honda dealer and they spent about an hour adjusting the timing, but it was reported to be running at the required 16 after the adjustment.

By this time, it was starting to run hot again (temp gauge spiking at a stop light, drops back down after moving again). The smog guy ran the check again, and the timing ran perfect but all 3 CA emissions were almost double the legal amount. I've been thinking for a while that it might have been a clogged radiator (downpipe from the therm to tbe base of the radiator was dry when I changed out the thermostat last month), so I put in some radiator flush, ran for a short while, parked overnight, and ran it for another hour + today without any overheating.

What I'm wondering is this: if the radiator had been blocked and caused coolant to leak into the block, could that be the cause for the second smog fail? I'm amazed that the emissions got so bad after a simple timing adjustment, so I'm hoping this radiator flush might've done the trick.

Again, any help is welcome...I've got a pretty short amount of time to get this figured out.

Welshwizard

My 92 DX has just failed 2 times. First time it passed at 15 mph but failed at 25 mph. Tuned, replaced dist cap and rotor, oil/filter change change, replaced cat converter. Now fails at 15 mph and passes at 25 mph. All fails are on NOx reading. Another log on this site (92 CRX) has talked about timing and having the engine at correct running temperature - cold engine runs a little rich and this makes more NOx. Same chat had a response that only adjustment on a dyno (at a SMOG fixer) got a similar problem fixed (and running better than some new cars). I'm just as confused. BTW - my engine was also overheating and the radiator running dry - not yet fixed.

vansxskater

Thats the most *** backwards thing i read all day. A rich cool mixture reduces NOx levels. NOx is produced when nitrogen and oxygen bond under high pressure and high combustion temperatures (over 2500) degrees. NOx emissions are at its highest just lean of stochiometric.

vansxskater

If your leaking coolant into your cylinders then yea there's no way your going to pass smog.

Welshwizard

You are correct, but the comment is not as half assed as you might think. Just lean of stoichiometric is indeed the highest NOx point. I have assumed that the cylinder stiochiometry is set by the ECU at a leaner point than that highest point in order to cool the flame and minimize NOx for a target power output. But if the engine is running with 'cool' water in the block, won't that cause the EMU to add a little extra fuel to compensate for loss in power causing the mixture to move towards a richer stoichiometry and NOx to increase? Cooler cylinder walls could cause slightly cooler air in the cylinder and lead to slightly higher running cylinder pressures (cool air is more dense and compresses to a higher pressure) and this would lead to higher NOx as you point out. I confess to not knowing the ins and outs of IC engine controls so I am just working from basic chemistry.