Ryan Zoltan

Rebuilt 22re with 500 miles, failed ca smog high nox. It is running lean, no vacuum leaks, egr and ports are clean and functional. Could it be the new bosch o2 sensor? Or could it be the location of o2 on #3 cyl on dt header? Should I try adjusting afm?

Ryan Zoltan

Wow, finally got it to post! Ok, 87 4runner 22re, afm, tps are good, coolant temp and the c. sender are new, rebuild injectors, haven't bothered to test #2 coolant temp since its only supposed to work in 4x4, right? To check vacuum leaks I shorted e1 and t, hooked up tach and probed with propane, only time it idled up was when near opening for air box. Egr tested and cleaned anyways, passages open. Lc efi pro cam, dt tri-y header, engnbldr street rv head. new bosch o2 sensor. I know the IACV is stuck but it idles at 750 (at least when the dashpot isn't sticking). When it is first started it idles around 500 and miss's until I blip the throttle, idles really rough compared to my 92 but my 92 was stock. cat is a yr old, ran better with more power before rebuild with rings so worn two pistons fell out. I'm thinking fuel pressure, denso o2 sensor or afm adjustment. ca smog results
15 mph co2-13.1 o2-2.5 hc-72 co-0.01 nox-1005-max 789 fail
25 mph co2-13.8 o2-1.5 hc-43 co-0.01 nox-2293-max 844 gross polluter

scope103

When the NOx is that high, it is almost certainly an EGR problem. Your NOx is through the roof (avg passing in CA is 37/53ppm at 15/25mph). Your HC is pretty high (you would have failed in most parts of California) but not so far as to indicate a failed O2 sensor, or excess fuel pressure, IMHO.

If it were mine, I'd repeat the EGR diagnosis in the manual. When you cleaned the EGR, did you go all the way into the plenum?

oldblue

not sure how you verified it is running "lean". i would use a volt meter on the o2 sensor and see what it reads. a faulty egr can cause high nox, but most dyno smog tests are done while the engine is under a load and egr is not going to activate then anyways. my truck just failed last month with a reading of like 1300ppm of nox, and a really high hc reading as well. put a bolt on magnaflow catalyst i bought on amazon for $70, passed with flying colors. my money is on the converter.

oldblue

just re-read your post, and those hc readings are pretty low. like i said, i'd use a volt meter on the o2 sensor to see what signal it's giving the computer. also i've never had good luck finding vacuum leaks with propane or brake cleaner. i much prefer using a smoke machine, however the average dude ain't got one of those at home.

Ryan Zoltan

Ended up being Cat was wrong one (smaller than factory) and had to relocate o2 to collector (factory o2 is between the 2 y's and reads all 4 cly's through little ports) and switch to denso 4 wire sensor.