I have been trying to pass smog for weeks with my new to me iroc. I have replaced cat, 02 sensor, plugs, wires, rebuilt and flow matched injectors, pcv, ignition module, coil, map sensor, all new vacuum lines, egr valve, air filters you name it I probably changed it. I cleaned the plenum, the runners, the egr passages, and I seafoamed it like 3 times. Set timing at 4 btdc (you get up to 3 degrees from stock in CA) So my last attempt it came within 30ppm of passing on the 15 and 25 mph tests for CA everything else passed. I am now out of bullets so to speak, but as a last resort I checked the ecm and found it has a hypertech chip in it. I am sure this is causing my fail.

So I guess 2 things:

1. Where can i get a stock chip 1989 305 F code federal car

2. What is your opinion on the chip causing this?

Thanks guys.

 

I used to do smogs and repairs in Ca. What are you failing on? HC's? CO?

 

failing HC's nox is high too but just enough to pass

HC's about 30 ppm too high, nox is just under passing.

 

Is your air pump functioning properly? I'd also put the timing back to the stock spec. Even though its only 3 degrees from the stock setting and even though its computer controlled advancing the timing affects HC and CO emissions, leans out the A/F which will raise the combustion temps which can increase NOx emissions. Also with that chip it may have a cooler thermostat than the stock 195* stat...

I hated doing cars that barely failed. Sometimes I would shut the car off during the test and restart it and would pass with flying colors.

 

I replaced it with a stock thermostat, air pump appears to be working no squealing or evidence of air leaks or anything.

Techs are very helpful at the smog shop I think they feel bad for me.

 

if anyone can help with my chip issue:

ecm 16198259 service replacement (i am assuming for a 1227165)

it sounds like it should have a 9298anyh memcal??

 

Just failed my smog. Has new wires, plugs, cat. I failed because my NOX was too high. It is a 5.7 Z28. The tech suggested the egr... any thoughts?

 

take off the plenum and remove the egr valve, clean out egr ports and valve, check egr valve for operation as well. Check vacuum lines make sure none are cracked or broken and also check the rest of the egr system like the vacuum module and the egr temp switch high nox usually due to that stuff.

 

Passed! The throttle body ports were all coked up and no vacuum was getting to the EGR valve. Cleaned it out, the valve started working, although not all the way- probably seized up a bit from lack of use- but enough to reduce the NOX to very low levels and I just picked up my tags from the DMV(actually AAA- took 10 minutes)! Thanks for the help!