Ive got an '88 C4(L98, 4+3) that Ive been keeping in storage and starting once a week. Well she was running fine up until a few weeks back when I went to start her and she wouldn't idle. If I give her any amount of gas she'll stay running though as soon as I take my foot off of the gas pedal she stalls out. I just checked my codes and all I'm getting besides the normal 12 is a code 13-which is for the oxygen sensor circuit. Btw the car has a new Bosch/Delco Maf sensor. And I can smell that she's running on the rich side.
The haynes manual(just took a glance-yes I have the GM service manual) says to replace the oxygen sensor and check the wiring/connectors from the o2 sensor.
Does this sound like it could be the problem?

 

I'd clean the throttle body and IAC/housing. If the engine will run at partial open throttle but will not idle ...the IAC is suspect. When the diagnostic connector is grounded as in pulling codes, you can feel the IAC connector for ticks.

With it thowing a code 13, you may want to ohm and leak test the injectors.

Thank AGENT 86: http://members.shaw.ca/corvette86/Code%2013.pdf

 

NO! When you start the engine the O2 sensor does nothing. It has to warm up and the ECM go into closed loop before the O2 sensor affects how the engine runs. Burn the Haynes and start trouble shooting from your FSM based on your symptoms.

The code tells you that the ECM received a reading from the O2 that isn't correct for the conditions. Before you replace the O2 sensor, you have to determine if the bad reading came from a defective sensor or if the sensor correctly sent a reading that shouldn't exist, and what caused that bad info to be generated. You say it smells rich? The code is likely because the ECM received a report of a too rich mixture. You are going to have to trouble shoot and diagnose the problem(s) to save throwing money (unneeded parts) at it.

RACE ON!!!

 

Do I just start troubleshooting from the chart under code 13 in the fsm?
In that case-how do I tell if it goes into closed loop vs open loop?
I have a 10megohms multimeter-Is this enough for for testing things on a car?
Where exactly do I touch the connectors on the multimeters to test the 02 sensor and the injectors? Do I need a special tool to remove the 02 sensor and the iac?

 

1. In the FSM it will tell you to use a scan tool. You can use a volt meter at the connector at the O2 sensor instead. The code could also indicate a bad connection at the O2 sensor or ECM, grounded wire, bad O2 sensor, or bad ECM.
2. The exhaust has to get >600*F for the O2 sensor to be active and the ECM closed loop. This happens usually around 140*-150* coolant temp. With the engine running you can ground the ALDL, like pulling code, and this will put the ECM in field service mode. The check engine light will start blinking. Slower blinks indicate a lean mixture and faster or constant light indicated a rich mixture.
3. Should be good as long as it has a volt setting.
4. Touch the purple wire connector with the O2 sensor connected in closed loop to view O2 sensor voltages. The voltage should move quickly. To ohm the injectors you will need to set the multimeter to ohms. Remove the injector connectors and touch each terminal on the injector with the two leads on the mulitmeter. They should ohm close to each other (~16 ohms).
5. There is a special O2 sensor tool/socket, that has a cutout for the wire. I use a wrench after disconneting the wire and with the exhaust a little wire...use WD-40. IIRC, I used a 3/4" wrench to remove the O2 sensor and IAC. I might be wrong with the sizes but try and see.