I have a '91 240sx fastback with the original KA24DE engine. The car has over 277,000 miles. For the past 6 years it has gotten more and more difficult to pass. This year I have a new exhaust, new cat, new plugs, new 02 sensor, even retarded the timing, and it still won't pass! I've been trying to clean it out with ATF in the crankshaft and Lucas in the gas tank, but it didn't seem to help. Any ideas? I just put some SeaFoam in it, but I haven't been back to retest yet.

Here's my results:

15mph --- 25mph
HC ppm 194 --- 213
CO% .40 --- .49
NO ppm 3023 --- 2927

You run the seafoam for a few minutes, then change the oil..
have you pulled the seafoam through vacuum hose yet?

set the timing per fsm to stock timing.

ps wrong section

Thanks for the response. I put a little seafoam in the gas tank and a little in the oil. Drove about 100 miles and very little smoke. Car runs great. Can't understand why it won't pass. Retarding the timing worked in the past.

Why is this the wrong forum? Emissions come from the engine right? Anyway, I'll repost in the general discussion section and see what I get.

Well..what are the limits?

And your HC seems quite high...

Here's a scanned image of my results.

Your NOx is extremely high, and so is your HC.

The CO should be around 0.5% before cat, and almost 0 after cat, what kind of cat are you using?

Test the EGR system, turn the car on and let it idle. While idling, push the EGR diaphram up, the engine should sputter and stall.

If it does not, the EGR passages are blocked.

If it does stall, remove the vacuum line that goes from the EGR to the BPT. Push the diaphragm back up and while holding it, put your finger on the vacuum port on the EGR. Release the diaphragm and it should hold there. If it goes back down, replace EGR valve.

There's also some BPT valve testing, just don't know the procedures on top of my head, check the FSM, should be there.

Thanks! I'll try that.

Thanks again. I just went out and stuck my finger under the EGR and pushed it up. The car died immediately.

I found a good EGR thread.

240sx-egr-tutorial-t427162.html

Moved to KA.

Vegeta wrote:Thanks for the response. I put a little seafoam in the gas tank and a little in the oil. Drove about 100 miles and very little smoke. Car runs great. Can't understand why it won't pass. Retarding the timing worked in the past.

Why is this the wrong forum? Emissions come from the engine right? Anyway, I'll repost in the general discussion section and see what I get.

because your questions are not kaT specific lol its more of a general ka thing..

You wont get the mad fogger from seafoaming the oil/fuel tank. You must draw the seafoam through vac and then drive it till the fog stops. This removes deposits from the intake manifold as well as the combustion chamber. On my sohc(had like 200k) this really helped

I passed today!!!!



Here's what I did:

Replace o2 Sensor (Part No. SG9) Cost = $26.83
Use 22mm wrench to remove o2 sensor.


Retard timing all the way down. Mark position or make sure existing mark is clear on distributor before turning it. Loosen distributor (top and bottom bolts) and turn all the way counter-clockwise (to the left). Use 10mm (3/8)
socket wrench for bolts.

Got a can of SeaFoam ($10). Put half in gas tank and half in oil.

Changed oil at Valvoline. Got 10W40 MaxLife. Valvoline Oil Filter VO33.

Got 32oz can of Denatured Alcohol from Home Depot. Put half can in gas tank.

Make sure gas gauge is down to 1/4 tank before adding alcohol.

Drive on highway before taking emissions test. Don't let it cool down.

Be sure to fill the tank with good gas and drive for a while after passing. Remember, you have all that alcohol in your car. Go home and put some alcohol in your tummy! (NOT the Denatured Alcohol!)

Nice!

However, it took a lot of stuff to get it to pass...

How is she running?

Yeah, after 277,000 it gets tougher every year. Car still runs great. Hoping to drive it another 10 years!

Thats great to hear. keep that beast running forever...

On a different topic I will be attemting to pass my bros new 91 shortly, hopefully it wont need as many additives, as its only has 170K.

Has anyone ever cracked the 500K mark?