Help with NOX emissions (CA)

[89Red240]

Ok, here's the story. Bought my '89 240 hb about 2 months ago. The 87 year-old man who I bought the car from (Hell of a car for an old man! said the car had been smogged. Well it hadn't. He was responsible for smogging it before I bought it and I will pursue sending him the bill after all is said and done. Right now I just want to get it passed so I can drive the thing!

HC and CO have been in spec in every test. It has failed NOX at 15 and 25mph dyno test every time. 15 has always failed worse so I'll just give those specs to keep it simple. Car had new shiny AIV valve when I bought it. Timit is dead on at 15btdc.

NOX limit for my car = 800ppm

1st test:-NOx = +-2500 ppm

2nd test:-Found and replaced broken vacuum line going from BPT valve to EGR valve.-Checked all Vacuum lines and replaced any that were questionable.-Tested EGR valve and BPT valve according to Chilton's manual. Everything checked out.-Replaced O2 sensor and changed oil.-Sent injectors off to be flow tested, rebuilt, and flow tested again. No difference after rebuild. All are in within stock spec.-NOx now at +- 1200

3rd test:-Replaced Cat.-NOx now at +-1300

The car is completely stock (except KN filter in stock box) and runs fine and I have am out of ideas as to where the problem could be. Engine has 125k miles. Like I said an old man owned it before me and probably never took it above 3500 rpm. It even blew a fair amout of carbon out the exhaust when I redlined it the first few times. I have it scheduled for diagnostics at a local shop in a few days. I have never had a car in the shop before and would like to avoid it. Any ideas?

Thanks

[Nismo_Freak]

Seafoam time!

Buy 2 cans.

Run 1 through the fuel tank (put in about 10 gallons of 93)

Bump timing to 17 deg. while you run this blend (aids in heating up the piston crowns to unlodge the carbon)

Run 1 through the brake boost vacuum line.

KA24E's are carbon monsters, especially if you don't clean them up by reving the piss out of it every so often.

Also, clean the MAF with some brake cleaner ... you could be running slightly lean as a result of build-up on the MAF wire.

Clean out the throttle body w/ some brake cleaner, just makes the car run smoother.

Could always spray a bunch of Windex on the muffler tip right before you smog it... you think I'm joking I'm not. The ammonia in windex will react with N0x emissions in the presence of oxygen. It's commonly used in boiler's and other industrial size combustions.

[pacman88]

PLACERVILLE!!! I'm livin here too!! And my 240 has the same problems, its a small world...