Working smog pump system

[sixt9x33rs]

I have a smog pump system on the Silver Z that I recently bought. I am told the smog system was removed years ago when the car was fairly new. Now the smog system seems to be working well as installed. When I compare the exhaust smell of this car against non smog cars I have or cars with smog where the pump has been "devaned" there is a big difference. The Silver car just does not "stink" like the others. However, the car does have an exhaust "pop" when you let off the gas at medium or high RPM. Any ideas on how to solve the exhaust popping noise?

Lawrence

[JKZ27]

I think the popping is a characteristic of the AIR(smog) system pumping air into the exhaust to continue burning any unburnt fuel. Thus, the different exhaust smell. Kind of cool yours is working.

[JohnZ]

However, the car does have an exhaust "pop" when you let off the gas at medium or high RPM. Any ideas on how to solve the exhaust popping noise?

Lawrence

That "popping" on over-run is the classic symptom of a failed diverter valve diaphragm - when it's working properly, on over-run, the high vacuum level to the diaphragm closes the diverter valve and dumps the air pump output to atmosphere instead of sending it to the exhaust manifolds. When the diaphragm fails, the valve defaults to "open", and sends air pump output to the exhaust manifolds 100% of the time; air pumped into the manifolds on over-run causes the "popping" in the exhaust system.

[JKZ27]

Yeah...what JohnZ said is quite a bit more accurate. Sorry.

[sixt9x33rs]

However, the car does have an exhaust "pop" when you let off the gas at medium or high RPM. Any ideas on how to solve the exhaust popping noise?

Lawrence

John, other than the "pop" is this damaging anything?

That "popping" on over-run is the classic symptom of a failed diverter valve diaphragm - when it's working properly, on over-run, the high vacuum level to the diaphragm closes the diverter valve and dumps the air pump output to atmosphere instead of sending it to the exhaust manifolds. When the diaphragm fails, the valve defaults to "open", and sends air pump output to the exhaust manifolds 100% of the time; air pumped into the manifolds on over-run causes the "popping" in the exhaust system.

[JohnZ]

<< John, other than the "pop" is this damaging anything? >>

No, not really - it's more of an annoyance than anything else.