Just failed emissions twice

[Matt Timion]

Originally Posted by MetroMPG

Also, is it running hot because it's lean, or is it lean because it's running hot? If you know what I mean.

I know exactly what you mean. Tomorrow I'll swap the o2 sensor. I tried to do it tonight but it started getting dark, and in my "old age" I'm developing the inability to see very well at nighttime. I also realized I'm going to have to solder the wire for the o2 sensor if I want to use the spare I have.

[DirtyOldTown]

Fix the overheating first. NOx increases with the temperature in the combustion chamber, and overheating will cause an increase in NOx. It's also possible that your EGR valve is not working, but I bet it's the overheating. You said it was worse the second time around when the car was warmer, right? To test your EGR valve, apply vacuum to it while the the engine is idling with no load. The engine should sputter or stall. If the idle doesn't change, then the EGR system isn't working. Could be a bad EGR valve or a clogged passage. Check for coolant leaks as the cause of the over heating. Also, make sure the fan(s) is/are working. I agree with Ryland about the NGKs - It's all I put in Hondas, and it's what the come with from the factory (those and Densos). If it's overheated pretty bad you may want to check that the head gasket didn't blow - Civics will do that when they get hot. Does it smoke?

[Matt Timion]

No smoke.

Just checked parts sites and the 87 CRX Si doesn't have an EGR.

Just a bit of info I didn't mention before. The PGMFI light would come on every once in a while. I checked the code on the ECU and it said the problem was either the spark plugs or the O2 sensor. This is why I think replacing the o2 sensor will help.

There are no coolant leaks that I know of, but I'll double check anyway. Oil is always clean so odds of a headgasket being blown are low.

I'll get some NGK plugs and put them in. Any idea where I can buy them? Pepboys? Napa? Honda?

[95metro]

NAPA seems to prefer NGK in my area. At least that's what they gave me for my Toyota a few years ago.

[Matt Timion]

Originally Posted by 95metro

NAPA seems to prefer NGK in my area. At least that's what they gave me for my Toyota a few years ago.

[Mr. Burns]Excelllent[/Mr. Burns]

I'll putter on over there today and get some new plugs for my n600 and the CRX.

[JanGeo]

arg lost the post ended up in advance -

cut out the fuel additives there is a theory that acetone interacts with the O2 sensor and makes it run lean - retard your timing and cold air instead of hot air intake.

[Matt Timion]

Originally Posted by JanGeo

arg lost the post ended up in advance -

cut out the fuel additives there is a theory that acetone interacts with the O2 sensor and makes it run lean - retard your timing and cold air instead of hot air intake.

This car doesn't have any fuel saving mods.

[JanGeo]

Just the high temp ... humm you would think that the ethanol would help it but as we all know the difference is not oxygenating the fuel as expected . . . maybe time for some carbon rich fuel additives then!!! And lower thermostat to run cooler - come to think of it if you are lean it will run HOT and make more NOx right??

[DirtyOldTown]

Usually when head gaskets blow on these things, the oil never gets contaminated. The gasket will allow coolant into the comb. chamber and it will smoke (steam) out the tailpipe - this is just from my experience with Hondas, not other brands. Since you have no smoke, the head gasket is probably okay. If your old plugs look unusually clean, that's a sign of a blown gasket as well. How's your thermostat and EGR valve? How does your radiator look?

[Matt Timion]

Originally Posted by DirtyOldTown

How's your thermostat and EGR valve? How does your radiator look?

Once again, no EGR Valve on this car.

I'm assuming the t-stat is fine, but I have no plans on replacing it unless it's stuck open or shut. Both rad hoses heat up, so I'm assuming it's fine.