New Member here. I have a 92 Camaro TPI 305, 5 speed. It failed recent emissions on idle. it runs rough at idle after warm up but seems responsive and smooth everwhere else.
There are no codes. I Just installed TunerPro on my laptop and got a usb ALDL cable and downloaded a sample. I am trying to establish the desired or known values that Ii should have such as o2 voltage, idle speed, timing ,etc to compare. I can't seem to find these. I thought I saw a chart with the parameters on the net. I get about 500-700mv on O2. I pulled and cleaned IAC, cleaned throttle body, and installed new O2 senser. The distributer and plugs were replaced last yr. It does seem to run smooth during warm up, or first starting. Will test fuel pressure, but I'm thinking a leaky pressure reg diaphram. thoughts? TunerPro experts?

thanks

 

I am no Tunepro expert, but as far as I know you don't need to be in order to know the right values for the sensor and timing. For timing you should have a sticker on the hood that will tell you what the timing needs to be. As far as the other sensors: TPS should be v0.54 with the TB closed and above v4 when wide open. O2 sensor values will varry between closed and open loop situations. The fuel pressure regulator can be test with a vacuume pump to see if it holds pressure, or you can check if there is fuel present in the lines connected to it. I would also recommend testing the EVAP system as it may cause you to fail emmisions as well, you might have a bad purge valve. Last but not least I would recommend a product called Cataclean, it helped me pass emmisions in my state, got the HC level from 300 to 210 just enuogh to pass, but I would go there only after testing everything.

 

Thanks for the input. Downloaded Datamaster and got a scan

o2 voltage 400-700, engine loping and smelling of raw fumes.
the a/f ratio is still 14.7 in closed loop
this with idle at 775-2500 rpm

IAC was at 20% these are some of the ##

I am going to look at the MAP and am thinking about a leaky pressure reg diaphram. i doubt it has ever been off the car,
thanks

 

What are the Smog Test numbers, Idle, 2500. CO, HC, CO2, O2, NOx

 

Idle HC 769 2570 HC 325
CO 1.64 CO 2.71
CO+co2 1.64 co+co22 12.51
O2% 5.4 O2% 5.8
Car only failed idle HC, the limit is 400 ppm. there are no NOX values yet (future)
I just tested the MAP and it is ok per the shop manual.
was going to hook up a fuel pressure gage, but with this TPI the tap is right under the plenum. is there another port to hook up a gage?

thanks

 

Wow your state limit HC is pretty high, you should try that stuff I told you, it will get you to pass for sure.