ZLT195

'95 dual cat Z28

I just replaced the air pump had DTC 29. I had replaced it about a year and a half ago but the car sat for a year while I was over seas and must have rusted on the inside. Anyway, Scanmaster is now showing p/s O2 sensor sometimes not cycling normal, it will hang then cycles and is not consistant and somtimes cycles fine. I also noticed that its pulling timing sometimes upto 5. Egr I think read like 50 under about 3/8-1/2 throttle.

How can I check the o2 to see if its bad? I'm sure I have to change that sensor car runs a little rich so I will replace both sides.

Also can I check the check valves on the air tubes to make sure they are OK. They are about 3 years old and have maybe 10,000 miles on them.

It's been awhile since I've messed witht the car much less drove it so, anyone with suggestions or had the same situation?

Z~

Injuneer

You are aware that the 95 and up cars had a problem with the AIR pump wiring, bad enough that they were recalled?

What value does the O2 sensor "hang" at? If its about 450mV, that may indicate a wiring problem. Swap the O2 sensors side to side and see if the problem follows the sensor (sensor problem), or stays on the passenger side (wiring problem).

To check the AIR check valves, remove the rubber hose closest to the check valve, and see if there is exhaust flowing out of the hard line. That would indicate the check valve is leaking.

ZLT195

Thanks

I thought there was only a recall to replace the air pump. I never heard of a wiring problem. What exactly is the wire problem?

I'll swap the O2 sensor and see if the p/s O2 is going south.

killpro

yea, i just went to the dealer a couple months ago, apparently the wiring for the air pump was the wrong size. they said that the wiring is .8 mm, and is suppose to be 1.00 mm. and the fuse was the wrong size, but they only did a recall on the 95-97. i have a 94 Z28, and those bastards were gonna charge me like 300 bucks to do the job, so i said F that, and simply unplugged the damn air pump, haha.

ZLT195

UPDATE

I did not swap the 02 sensors yet. My SUV gave me a SES light this morning and I drive 100 miles to work one way right now so I took the camaro.

Both 02 sensors are acting up now. Scanmaster reads about .800 while driving sometimes and when I let off the gas goes down to like .100 most times it is cycling correctly though. I was doing about 80mph while noticing those readings. I also noticed that it is pulling timing about 1.5 to 3.0 on scanmaster and does not do it all the time and is 0.0 most of the time.

Thoughts?

edit: The car runs fine and does not stutter or anything. If I punch it, it screams like always. No Codes.

Injuneer

The O2 sensors will typically read 800+mV when the PCM goes into power enrichment (PE) mode. That can happen as low as 20% throttle at 5,600RPM or at 66% throttle under 2,800RPM (stock programming).

When the throttle closes, the PCM shuts down the injectors, in most cases, so seeing 100mV at closed throttle decel isn't unusual either.

http://members.aol.com/InjuneerZZ/ScanMast.htm