The Corvette Doctor

A week ago, the battery was near nothing in my 1998 Camaro Z28 LS1 auto with 253,xxx miles and wouldn't start. I can't complain, the battery was 6 years old. I charged it before I replaced it, and the car ran terrible. High idle, surging, and so on, along it very unpredictable starting (sometimes very slow cranking, other times more normal). So I replaced the battery on Thursday instead of fooling with it and worrying if it would quit.

Put a few hundred miles on it, everything was normal, and on Monday out to lunch, the Service Engine Soon light came on. Yesterday, I was able to get the codes checked at AutoZone and Advance Auto. The codes were:


• P0137 02 Sensor Circuit Low Voltage (Bank I Sensor 2)
• P0171 System too Lean (Bank 1)
• P0174 System too Lean (Bank 2)
• P0507 Idle Control System RPM Higher Than Expected


Information I have found or have been told is:

- Fuel Injection Idle Air Control Valve needs replaced
- Left and Right Bank O2 sensors need replaced
- MAF may need to be replaced
- Injectors may be dirty
- May have a bad injector
- Vacuum leak in intake
- Use CRC Mass Air flow cleaner
- Use Seafoam cleaner

Basic look over of the engine, I can find no hoses loose or leaking. No connectors loose or wires broken or worn. Plug wires are only 25,000 miles and are on and secure.

So what does the forum recommend?

Thanks

Fry_

I'd start by cleaning the MAF with q-tips and rubbing alcohol, you only need to clean the "hot wires" in the MAF just be gentle if you damage them you'll be buying a new one. You can also remove and clean your IAC valve is may be slightly clogged.

Paul Bell

iTrader: (9)

This'll do better in this section.

JakeFusion

iTrader: (7)

As said, clean the MAF and IAC. It's possible your O2s are going out as well given the age.

Paul Bell

iTrader: (9)

Have a good look at the battery connections-at the battery and the engine block & starter.

Pull the boots over the battery terminals and look for corrosion where the wire is crimped into the connector.

JakeFusion

iTrader: (7)

My car wouldn't idle when I had my old battery in there. It was a flaming POS. So I replaced it and the car ran fine.

So, Paul makes a valid point. Especially if the old battery failed and boiled over and corroded stuff.

The Corvette Doctor

Thanks everyone.

The funny running cleared as soon as I put the new battery in, and the cables and connections were all clean. The SES was on Monday after the battery on Thursday.

Since many pointed to a dirty MAF or IAC, I figured that would set everything off so the O2 sensors would read wrong, and make them look like they were failing.


Based on a combination of replies everywhere, I figured the best and cheapest place to start was a good cleaning. I got a can of Sea Foam and a can of CRC MAF cleaner, filled the tank and dumped the Sea Foam in. Drove 60 miles home Thursday night.

I then sprayed the MAF and IAC with the CRC cleaner and let it sit overnight. Drove 60 miles to work and 60 back, the Service engine Soon light was still on. I went to pick up a friend for dinner and the SES light went out, after about 170 miles from the Sea Foam.

It hasn't come back.


When the SES goes out, have the codes cleared, or does the light just eventually time out? Do I need to get the codes read again, or will they be gone?

The car only did a bit of stumbling after cleaning the MAF and IAC but that stopped after about a half mile.

The idle is a bit up on cold start now, but that goes away after about a half mile, too.




Thanks for the move.

Paul Bell

iTrader: (9)

Some codes may still still be in there, not all codes illuminate the SES light.

Have it scanned, note the codes, if any and have them cleared.

Fingers crossed!

2xLS1

iTrader: (25)

Light will go out then the diagnostic runs for that code and does not see the fault. Codes will show in history until a certain number of key cycles without detecting the fault clears them from history. The number of key cycles can vary depending on the particular code. You can clear them from history with a code reader or by disconnecting the battery or pulling the PCB BAT and PCM IGN fuses for a short time. Since 2 of your codes were fuel trim related codes (171, 174), I would would do the battery disconnect or fuse pull so the fuel trims get reset.

1FastBrick

iTrader: (16)

Look at the Throttle body. I bet it is dirty.

With that kind of milage it probably needs new intake gaskets as well. The O-ring style gaskets shrink over time from the heat cycles.

If you ever disconnect the battery again, Start it up cold and let the car Idle for 10 minutes to relearn the base idle.

The car has a basic set of parameters to get it running and keep it running if everything is properly maintained. It learns over time and makes small adjustments as needed. every time you disconnect the battery you set it back to basic and it has to relearn. The parameters are set up for a new/fresh stock engine. Normal wear over the life of the engine, older plugs, wires, sensors and so on will affect how it learns and runs. After disconnecting the power, By firing it up and letting it idle to warm up, its going to compensate early on.

The base parameters also tell the Throttle Body how much it should be open. When it's dirty, it has to compensate. Sometimes the mismatch can cause the idle to be off. If you just get in and drive after pulling the power, the car will warm up fast and the idle will do the same thing because it never gets a chance to learn. Un-metered air from leaky intake gaskets can also cause similar issues and effect the idle as well.

If those cars have a serviceable fuel filter, I would do that as well.