Smog problem

[Bill]

Good thought Scott, unfortunately the '90 does not have EGR, so no joy. any other thoughts?

Thats good info ittlfly It sounds like what I'm seeing is close to normal. The cross counts are constantly changing and intergrator (both l&r) varies between 120 and 130

[FULLPWR]

Hi, I just wanted to share some info of what i had happen to me just recently with trying to pass emissions here in tx.

when mine failed:
I had a bad coil, bad sec vac leak, fouled plugs, and tried to pass my
(i didnt know all that was bad when i desired a sticker badly)
the report readings were:
HC (ppm) 334 low speed 403 high speed
CO (%) .51 low speed .56 hi
O2 (%) 1.1 lo 1.2 hi
Nox (ppm) 1239 lo 1726 hi


when it passed after i found out both my cats were hollow empty
i put it new cats then readings were:

HC (ppm) 67 low speed 80 hi speed
CO (%) 0.03 lo 0.03 hi
O2 (%) .30 lo .3 hi
Nox (ppm) 6 lo 13 hi


Luis

oh, when it passed it passed with new cats and it was also before i fix the bad stuff.....go figure huh.

[Bill]

Thanks Louis,
Thats good, passing with all that bad stuff. I think my major problem was a vacuum leak where the PCV line go into the throttle block. I've fixed that and I hope all else is well. Enjoy driving your beast!

[ittlfly]

you might check your readings on your long term fuel trims (BLM"S) on both banks to be sure they aren't to far scewed on either side of 128. You should be checking at low RPM (idle) in cell 16 if your scanner shows your cell #'s. One bank that is 'out of wack'' will at least point you in direction. If you have an exhaust leak (lean condition), I would suspect that the BLM(s) will be headed way north of 128 and would be locked in. The fact that the PCM is not throwing a code shows that it is in control and the need to fatten up A/F is within the abilty of the PCM.

[scottfab]

Originally Posted by Bill

Thats good info ittlfly It sounds like what I'm seeing is close to normal. The cross counts are constantly changing and intergrator (both l&r) varies between 120 and 130

The O2 sensors sometimes fail in a way where they swing back and forth faster than normal. (about 2x faster)
However when mine did this it caused a rich condition and hi HC only.
Do they put the sensor in both exhaust pipes?
If your lean and getting hi NX then you should see some sort of asymmetry on L or R with Block/Integrator values.
One trick I have heard of is unplugging the battery just before going in.
When in learn mode the car runs richer than normal which should get lower NX.
Keep us posted.
Could be you have some thing not seen before.
Are the HC reading ok?

[Bill]

I should have posted this in the first place

15 mph - 1504 RPM - HC-max 77--meas 44 - CO-max .5 --meas .03 -NO max 540 -- meas 752

25 mph - 1788 RPM - HC-max 59--meas 52 - CO- max .59--meas .09 -NO max 498 -- meas 345

Since then I have corrected a significant vacuum leak Idle has dropped from 1400 to 800 RPM