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Running lean throwing a "Too Rich" Code?

sdavis11b

sdavis11b

New member
Hello Forum,

GP is throwing codes again. It all started with a bad gas cap that wouldnt close, bought a new one, gas cap is good.

The Codes:
P0172 System Too Rich(Bank 1)
P0401 Insufficient EGR Flow
P1811 Max Adapt and Long Shift

I have cleaned the MAF, inspected for vacuum leaks with Carb Cleaner, cleared the codes and now I get P0172 again.

Any suggestions?
 
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Re: Running too rich!

A vacuum leak usually causes a lean code (p0171).

EGR may be pooped out and stuck open, killing the good air in the engine and causing the fuel to not burn as well.
 
Re: Running too rich!

Rich = more fuel than air.
Check your air filter & PCV valve. Sometimes the boost bypass valve will stick. Clean that up with some throttle body cleaner. Check the vacuum lines going to the map sensor too.
 
Re: Running too rich!

Checked all vacuum lines with brake cleaner. No surging or anything after application. Vacuum is inbetween 18-20 where it should be. Where is the PCV valve? and the motor has 130k miles on it. Does the EGR go bad that quick? If so, do you think i could just blast it with some cleaner and get it working again?
 
Re: Running too rich!

It is not the vacuum lines or else it would be lean. You can try to clean the valve with brake cleaner and see if it frees it up. Might end up either replacing the valve or removing it and tuning it out.
 


Re: Running too rich!

Not really.

It's not the vacuum lines.

Delete the EGR with two cents and replace the PCV. It's in that black thing on he blower labeled: PCV.
 
Re: Running too rich!

Is there any way I could isolate the problem to verify the EGR is bad, as in unplug it? I hate just throwing money at a problem without knowing exactly whats wrong.
 
Re: Running too rich!

basically the only thing that cause too lean conditions is a failed maf sensor or a broken fuel pressure regulator.
 
Re: Running too rich!

darkhorizon said:
basically the only thing that cause too lean conditions is a failed maf sensor or a broken fuel pressure regulator.
Click to expand...

He's not running too lean, he's running too rich which means his car isn't getting enough air flow.

The P0172 is a classic code when it comes to a bad O2 sensor. Bank 1 is the sensor in the exhaust manifold. I just replaced the one in my wife's Grand AM and it's a totally new car now. Remember, that O2 sensor is the "nose" of your vehicle. I would start there.
 


Re: Running too rich!

Ive been through 3 O2 sensors since ive owned the vehicle. Back onto the EGR, is there a way to figure out if that is a problem without tuning software? I have a couple Aeroforce gauges.
 
Re: Running too rich!

sdavis11b said:
Ive been through 3 O2 sensors since ive owned the vehicle. Back onto the EGR, is there a way to figure out if that is a problem without tuning software? I have a couple Aeroforce gauges.
Click to expand...

Fab up a block off plate either between the EGR and it's mounting bracket, or on the LIM. It'll still probably have an egr code, but when you block that off, you won't have to worry about exhaust gasses getting into the intake charge.
 
Re: Running too rich!

The EGR can stick after getting clogged with carbon. There are 3 valves that open and close. I've had success cleaning the valves by removing the EGR and using a toothbrush with a combination of brake fluid first, then seafoam. Spray the toothbrush, not the EGR. If that doesn't work then you will need to delete the EGR (if it will still pass emissions) or replace it.
 
Re: Running too rich!

Took the EGR off, cleaned it up real nice, valve seems to be moving freely. Cleaned the PCV as well. Still running rich, A/F still inbetweeen 15.5-16.1. Does this mean the EGR is done?

Another couple questions regarding the issue:
What are the repercussions of running this rich besides horrible MPG
And when an EGR fails, does it stick open or stay closed?

Trying to prolong purchasing an EGR, they arent the cheapest replacement part.
 
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Re: Running too rich!

Um, 15.5 to 16.1 is lean.

Stoich is 14.7.

An EGR can fail open or closed, a scan tool could tell it's position from 0-100% open or closed.
 
Re: Running too rich!

15.5+ is definitely lean, not rich.

Anyways, don't replace your EGR (Unless you NEED it for emissions).

EGR's are stupid. Delete it. You can buy two block plates from ZZP for $5 each. Then all you need is some RTV and two bolts. $20 and some of your time and it's gone. Even if it's not the EGR, and you can delete it, do it anyways. $20 isn't much at all.

Also, I wouldn't even bother spending my time into cleaning an PCV valve. It's only $3 from a parts store for a brand new one. Just replace it.
 
Re: Running too rich!

Understood.

Then why am I throwing a "too rich" code running lean?
I will block the EGR here in the coming weeks. This will throw an EGR code until tuned out correct?
 
Re: Running too rich!

it will set a code. and the light.

you can make your own block off plates by ripping the egr tube end plates off and then rtv ing a coin in the holes. use the old egr tabs with their bolts to hold the coins in.
 
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