Shandlar

To anyone who is kind enough to respond to my first post, "Thank you".

Problem: My Camaro just had its Service Engine Soon light come on for the first time. I went to my local parts store, and checked the codes.

1. P0100: Mass Or Volume Air Flow A Circuit
2. P0135: Oxygen Sensor Heater Bank 1 Sensor 1 (Pending)

To begin, let me state an embarrassment; I don't know as much about my car as I should. I bought it already "built" and I was foolish enough to think I could learn along the way. It is a 1997 Z28 and the engine has 78,XXX miles on it. It is mostly top-end mods, and it is still the 5.7L block. It has been modded, and it does have a custom tune on it. It *DOES* have K&N filters on it that were recently re-oiled (but the errors started before this was performed)

The previous (first) owner of the car told me that the SES light came on for him on "occasion" but always went away

I have been prowling around the forum, and I have tried most of the suggestions I've seen. Here's what I've tried, and what I "think" I know:
1. The cats have been removed, and there should only be the front bank of O2 sensors.
2. I have already taken out the MAF unit, and used MAF cleaner. (CRC if anyone is curious)
3. I did check the voltage (key on/engine off) between the pink wire and the black/white wire and got about 11.7
4. The first time the light illuminated, it turned itself off after about a day.
5. While the engine was running, when the MAF was disconnected at the plug, the engine almost died from the idle dropping so drastically. (Wasn't performed by me.)
6. Did see some engine oil (yes the black stuff) on the actual electrical connection. So I did use some CRC electrical connection cleaner on both sides of the connector.

Does anyone have a known fix, or a suggestion to assist in this troubleshooting? I believe the MAF sensor is still stock, and I believe I can get a new one for around 100. Should I try to just clear the codes and see if they return? Should I just give-in and replace the MAF sensor? I've been told by "garage mechanics" that the throttle body could also be causing this.

Once again, if anyone kind enough to respond to this needs to know a specific part, please tell me what kind of markings to look for so I can accurately respond.

****EDIT****
Does anyone know where I can purchase a rubber boot for the sir filter side of my MAF unit? I've checked at local part stores and eBay, but I am unaware if I am possibly searching for the wrong "key words"

Injuneer

P0100 is telling you there is no change in the MAF sensor reading when there is supposed to be. Could be a faulty MAF sensor, could be a faulty pink wire to the harness connector for the sensor. Fairly common problem specific to the 97's, where the pink wire breaks somewhere in the harness. Since you have checked and found 12V, could be intermittent, in which case clearing the codes would allow you to check and see if and how soon the code returns. Pull the "PCM BAT" fuse for 30 seconds.

If you have 12V, and your multimeter has a frequency scale, hook the connector back up and start the engine. Probe the frequency between the yellow signal wire and the black/white ground wire. Look for a frequency of about 1,600Hz at idle. Move the throttle to increase engine RPM and the frequency should increase.

P0135 tells you that the driver's side pre-cat O2 sensor isn't heating up fast enough, and it's possible the heater circuit or the heater in the sensor has failed. Clear the codes as above, and see if it comes back. If it does, swap the pre-cat O2 sensors side to side. If the code stays on the driver's side, it's a wiring problem, if it follows the sensor to the passenger side (P0155) it's a faulty sensor.

Shandlar

I did take a few minutes before work this morning, and started the car. SES light was still illuminated, so I turned it off, and pulled the fuse as suggested. After the fuse was re-set, the error light was gone. I let the car warm up, and then took about a 20 minute ride around town. It has not yet come back on.


If the error does return and is still pointing to the MAF, can you recommend a good brand to buy? I've been told that going to a salvage yard to get an OEM would be better than buying something new/refurb from a parts store.

Also, any suggestions on a replacement boot/gasket to connect the air filter assembly to that side of the MAF?

Injuneer

I believe there is a new GM part number, possibly for the same unit use in the LS1. And I believe the cost is lower. I'd strongly suggest sticking with a GM part, used or new. There is no reason to buy an aftermarket unit.

Shoebox has some info on his parts list:

1993-1997 F-Body Part Number Collection

1994-1997 MAF
AC-Delco 213-353 (old AC-Delco # 213-252)
current 19207203
old 25179711 and 25008308

Shandlar

It's been a few weeks, and I have driven my Z maybe a half dozen times since then. I went up to the parts store, and checked for codes. There was nothing active and nothing pending.

Possibly a fluke? Possibly a very spastic failure? Possibly just the weather that day?

In either case, thank you for your suggestions, and should the problem return, I will have the information I need to effectively solve it again.