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Rough Idle - Check Engine Light

Tiny
UPMM019
  • MEMBER
  • 2001 CHEVROLET SUBURBAN
  • 204,000 MILES
I recently bought a 2001 Chevy Suburban 1500 LT 4WD with 204K miles on it.

the check engine light is on and had one of the auto parts store check the codes.

The first is Cyl 2 Misfires, EGR Cont Circut Perf, o2 sensor bank 2 sens 1 - that is what I was given. Not sure if that is short hand or not.

That said, what can I do as a layperson to look into troubleshoot these issues.

Regarding the codes they were reset and tripped again.

the other thing that is noticeable is that the exhaust is really black as if it is running really rich.
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Wednesday, October 9th, 2013 AT 3:12 PM

27 Replies

Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
If you haven't given it a tune-up recently, give it a tune-up. 02 sensors are part of a tune-up. As far as cylinder number 2, check fuel--spark and compression on that cylinder.
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Wednesday, October 9th, 2013 AT 3:28 PM
Tiny
JDL
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Just to add, can you give us the actual code #? What is the engine litre size? For cylinder #2 misfire, it should be p0302. Our database doesn't even list that code?
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Wednesday, October 9th, 2013 AT 3:46 PM
Tiny
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I actually didn't get the code myself. I had a buddy bring it to a car part place and they read the code.

Like I said I just bought it so I have no clue if and when if it ever had a tune up.

If a tune up is step one what should that all entail?

Plugs, and what else? Is this something a layperson can do or does it need to be done by a shop with the diagnostics?
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Wednesday, October 9th, 2013 AT 4:40 PM
Tiny
JDL
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Spark plugs--spark plug wires--dis. Cap and rotor where applicable. Check or change filters, air and fuel. With the fuel filter make sure no pressure on the system before taking any fuel lines loose. Check all fluids. Like I said 02 sensors are part of a tune-up. Use a gage and check fuel pressure. I'm sure I'm leaving something out.

Make sure all the lites work front and rear/ turn signals--brake lites--tail lamps--tag lite. Make sure the horn works. Check the air in the tires.

What's engine litre size?
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Wednesday, October 9th, 2013 AT 4:54 PM
Tiny
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Do these vehicle even have a rotor? I think they are all electronic ignition.

Why replace all o2 sensors? Or is there only one. Not sure.
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Wednesday, October 9th, 2013 AT 5:51 PM
Tiny
JDL
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I asked about engine litre size. The v8 shows coil near plug, no distributor. My info shows 4 oxygen sensors. I'd replace the front two for a start.
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Thursday, October 10th, 2013 AT 7:21 AM
Tiny
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Shouldn't I just replace the one that is bad?
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Thursday, October 10th, 2013 AT 7:53 AM
Tiny
JDL
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With a tune-up, I'd replace the front two. It's your vehicle, do what ever you want. I doubt if replacing all four would hurt, anything.

If money is an issue, replace only one, that's up to you.
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Thursday, October 10th, 2013 AT 9:40 AM
Tiny
UPMM019
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For now I did just the one throwing the error code.

I pulled and replaced all spark plugs with OEM plugs and replaced the wires.

I also changed the air filter and the fuel filter.

After I did all of this I drove it for about 5-6 miles. Check Engine light still on but only solid not blinking.

I just drove it again and within the first few blocks the check engine light went off and stayed off for that drive.

I have an reader coming tomorrow so I will scan it again for codes.

The plugs were really really bad. Some didn't even have tips and the gaps were huge.
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Thursday, October 10th, 2013 AT 8:11 PM
Tiny
JDL
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Sounds like your headed in the right direction. Keep us posted.
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Friday, October 11th, 2013 AT 6:43 AM
Tiny
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Too good to be true. The suburban is now throwing the following codes:

Most recent read:
p 0171 system too lean bank 1

p0 300 random multiple cylinder misfire detected

prior read:
p 0131 02 sense or circuit low voltage bank 1 sensor 1

p 0171 system too lean bank 1

p 1153 manufacturer control

prior read:
p 0171 system too lean bank 1

What is the solution to these codes?
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+1
Sunday, October 13th, 2013 AT 10:56 AM
Tiny
JDL
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Have you changed the 02 sensor? Also, check the 02 sensor wiring circuit.
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Sunday, October 13th, 2013 AT 12:19 PM
Tiny
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I changed bank 2

not sure about how to check the circuit.
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Sunday, October 13th, 2013 AT 12:40 PM
Tiny
JDL
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Just to add, the most common causes for po171 are, miscalibrated maf sensor--- exhaust or intake vacuum leaks---low fuel pressure/volume.
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Sunday, October 13th, 2013 AT 12:44 PM
Tiny
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How does one correct a miscalibrated MAF sensor?

Not sure how I find the exhaust/vacuum leak

Fuel pressure, not sure how that is checked either but I did change the fuel filter.
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Sunday, October 13th, 2013 AT 6:50 PM
Tiny
JDL
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With the engine idling, you could tap on the maf sensor, see if any effect on the idle. As far as exhaust leak, get under the vehicle and check it out.
As far as intake, you could spray some wd40 or something around the gasket areas, if the rpms take off, you found a leak.
As far as fuel pressure, use a gage and check fuel pressure. Some of the national brand autostores will loan out a fuel pressure gage. You may have to put up a deposit, but, you get it back when you bring the tool back.
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Monday, October 14th, 2013 AT 7:44 AM
Tiny
JDL
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Just wanted to add, anytime you use a flammable spray of any king, you have to be careful about starting a fire or anything. Safety is your responsibility.
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Monday, October 14th, 2013 AT 7:47 AM
Tiny
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Where do I find the maf sensor? I am not familar with it?

Is it something that can be easily replaced to solve these error codes?
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Monday, October 14th, 2013 AT 10:45 AM
Tiny
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Ok. I am going to look at the Mass Air Flow now that I know what it is. Had to look it up.

I am going spray some cleaner in it. But not sure that will solve the issue.

Don't these just need to be replaced over time?

Can you visually look at the MAF and know it is bad or dirty, etc?
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Monday, October 14th, 2013 AT 12:15 PM
Tiny
JDL
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My info says to not spray anything on it. The code doesn't tell you what to replace just that the system thinks there is problem on that circuit somewhere.

Forget the codes for a minute. Are there any driveability issues, still, after what you've done? If no driveability issues and no check engine lite, sounds like your good to go.
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Monday, October 14th, 2013 AT 12:51 PM

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