hey guys

I have a 1990 z24 with an exhaust problem I have failed two e-tests but the results
are just outrageous. I have done a complete tune up and I replaced the o2 sensor and the muffler before doing the emmision tests but I keep getting a grey smoke from the exhaust followed by a rather harsh smell after giving it some gas. but all in all the car runs great.

can anyone help me with this problem?

could a faulty idle air control valve cause this type of issue with my exhaust system?

did you replace the cat?

No I did not replace the cat this time cause I had whole system replaced six months ago.

I replaced the iac valve today and the car seems to be alot better but the exhaust is still to harsh.

Is the smoke blue-ish? You might just be burning oil. If the smoke is white, you might have a head issue. Dunno about gray smoke. The harsh smell, is it like sulfur or more like concentrated exhaust smell (like a really old car)?

Is the smoke blue-ish? You might just be burning oil. If the smoke is white, you might have a head issue. Dunno about gray smoke. The harsh smell, is it like sulfur or more like concentrated exhaust smell (like a really old car)?

the problem is just concentrated unburnt exhaust i hope or rather thats what i have been told by friend of mine. he thinks it's the egr or my cat.

You said the results on the emissions test were outreageous. So...what were the results? High in hydrocarbons or what?

You said the results on the emissions test were outreageous. So...what were the results? High in hydrocarbons or what?
here are the readings

test 1 May,5

hc- limit 66 reading 101 fail
co%- limit 0.37 reading 0.56 fail
no-limit 757 reading 1310 fail

test 2 May,16

hc- limit 66 reading 40 pass
co%- limit 0.37 reading 0.58 fail
no- limit 757 reading 4438 fail

curb idle test for both tests was below normal each time the No content is what gets me???
My cat is more than likely dead now due to this.

Replace your cat and remember to make sure your car is nice and warm next time you go in.