Hello fellas, just a quick question..
just bought a 91 camaro rs, with a rebuilt 305 V8.. i'm not too up to date with emissions numbers, just wondering if anyone's seen these numbers before...

Reading Allowable
HC - 157 117 FAIL (25mph test)
CO - 0.03 0.65 PASS (25mph test)
NO - 1261 0821 FAIL (25mph test)
RPM- 1200 0-2500 PASS (25mph test)
NO - 1648 0907 FAIL (15mph test)

everything else in 15mph test passed.. Just hoping someone might have a tip...I have a new muffler on, but I suspect the problem is the Cat.
thanks for your time,
Robb

 

GA has emissions?!?!?!!

 

welcome to the thirggen boards.
we really need to see all the numbers, both pass & fail.
if i had to guess from what you posted, i would say
your EGR isn't working & your running a little lean.

check to see if it has any codes stored. if it does, post them too.

 

thanks for the reply...

Reading / Allowable
HC - 157 / 117 FAIL (25mph test)
CO - 0.03 / 0.65 PASS (25mph test)
NO - 1261 / 0821 FAIL (25mph test)
RPM- 1200 / 0-2500 PASS (25mph test)
CO+CO2% - 13.3 / 6.0 min PASS (25mph test)

HC - 119 / 120 PASS (15mph test)
CO - 0.02 / 0.67 PASS (15mph test)
NO - 1648 / 0907 FAIL (15mph test)
RPM - 1258 / 0-2500 PASS (15mph test)
CO+CO2% - 13.5 / 6.0 min PASS (15mph test)

CAT CON> - present
fuel cap test PASS

does this look familiar??

 

much better

with your CO being as low as it is on both parts of the test, you either have a killer cat or your running lean, with out knowing what kind of temp difference there is between the inlet & the outlet of the cat or what your pre cat gases are, i would say you are lean.
running lean causes a lean misfire which causes the HC levels to climb, i would almost be willing to bet your O2 levels are on the high side too, maybe around 2~3%

your CO2 production looks a little low, but still ok. it shows a cat thats probably working fine.

the TBI injectors normally don't have much of a problem with getting clogged, but it does happen, so you may have dirty injectors.

the first things to check are, codes, fuel pressure, O2 sensor, both coolant & air temp sensors, spark plugs, timing & make sure the motor is getting up to operating temp.


running lean will cause higher than normal NOx, but the levels of NO you have show the EGR system does have some problems. a bad EGR valve, a bad EGR valve solenoid, no vacuum signal to the solenoid, or clogged EGR ports.
the cat also takes care of NOx, but even the best working cat can only do so much, the EGR system is the first line on NOx reduction.

if you find the EGR valve is bad & replace it, replace the solenoid too. use Delco parts, they work much better than the aftermarket parts do.

 

The timing maybe a little over-advanced as well. That will increase both NOx and HC!

 

Fast355 is absolutely right, i should have mentioned checking the timing also

 

Hey, thanks alot for the reply, fellas.. I tried to check the codes, but when I inserted the jump wire into "B" and "A" in the ECM, the ecm/ignition fuse blew..
we'll see...

thanks again