tomczaksdiesel

Hi guys, have a 88 22re that just failed smog. I am in Cali, and it is a Cali truck. The only thing that failed on the truck was the NO PPM readings at 15&25mph. They read 1977 for 15mph, and 1773 at 25mph.

Wondering what you guys would think could cause this? No exhaust leaks are present, has a newer cat (maybe bad?), runs good when driving just gets terrible gas mileage, but does have a slight backfire\miss at idle.

Could it be the egr being stuck or gunked up? Or injectors clogged? Need input. Tomorrow I'll be setting valve lash and checking vacuum lines as well as pulling cat off to check if.

Thanks guys

tomczaksdiesel

Also my co2 number read 14.4 while 02 measured 0.4

C0 measured .12&.10 when max was 1.04&1.32.

Max for the NO PPM were 795& 855. So it was over twice the allowed amount

KBAM

High NO is suspect of a malfunctioning egr. I'd check that first.

Post the entire results if you can. Partial information doesn't give the whole picture of what your truck is doing.

tomczaksdiesel

Okay I'll graph it as best as I can

15mph 14xx rpm- c02 14.4, 02 0.4, hc ppm meas 72 max 140, C0 meas .12 max 1.04, NO ppm meas 1977 max 795.

25mph 1655 rpm- c02 14.4, 02 0.4, hc ppm meas 66 max 116, C0 meas .10 max 1.32, NO ppm meas 1773 max 855.

KBAM

I'd check the egr first. Other quick suspects: 02 sensor, cat. Did they tag you as a gross polluter with those numbers?

tomczaksdiesel

Brand new 02, I will clean egr if I can find out how to. And yes on my tag is says high polluter. Thanks for the insight hope to hear others chime in too! Hoping to get this fixed asap

KBAM

Check out the FSM On top of the forum. You'll be able to go thru it step by step. Shouldn't take you much time at all.

Also jumping forward to your cat, is it welded or bolted on? If bolted, you could take it off and do the daylight test, you also shouldn't hear anything rattling around inside.

tomczaksdiesel

Its welded on, I will cut it off and check inside

KBAM

Well if it's welded I wouldn't cut it off until you've exhausted your other options, just for the sake of keeping your sanity. Lol

tomczaksdiesel

All good I weld often so its just more practice for me if I have to weld it back on thanks for the help I'll report back tomorrow

scope103

KBAM is on the right track. The EGR is there to get NOx under control. That's what it does. That's ALL it does.

Your other numbers are pretty good; I don't think it's the catalytic converter.

The manual is here so you don't need to guess. http://personal.utulsa.edu/~nathan-b...ne/19egrsy.pdf

tomczaksdiesel

Thank you very much I will clean it tomorrow

bswarm

The EGR also helps prevent pinging. Easy EGR test: Take the vacuum hose off the EGR valve, use a vacuum pump or a manifold vacuum hose connected to EGR valve, engine should stumble or even die if EGR is good and unblocked. You should be able to watch the EGR stem move when applying vacuum to it. If EGR works then it's a vacuum hose problem or bad EGR modulator or EGR solenoid.

tomczaksdiesel

Well did vacuum test on egr valve, it does kill the engine when running. Did apply power to vsv and it does open the solenoid. Im not sure what else to check or if I just need to clean the system? What do you guys think?

bswarm

Do you have a vacuum gauge? If so connect it to the hose for the EGR valve and watch for vacuum when you open the throttle. You may have to use a long vacuum line and actually drive it to see vacuum. Check your timing also. Other causes of NoX: Lean mixture, overheating, high compression and/or carbon buildup, bad cat (but your other emissions look ok so probably not the cat)