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2000 Corolla - P0171 Too Lean System :(



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Corollan8085

Hello everyone,

So I believe the code P0171 (Too Lean system) for 8th Gen. Corolla is popular, I see many people posting this issue over the internet EVERYWHERE. I am proud to be became part of them now LOL

The code actually did came out once about a year ago, when I just bought this car. But after let the Pepboys clean the fuel injectors, it went away for long time till now. But this time, its little different than before.

- Pepboys checked any leaks in intake system, None found.

- Cleaned the fuel injector again but did not fix the problem.

- Cleaned MAF sensor with MAF sensor cleaner, the light was on again. Pepboys recommanded to replace MAF sensor so I did. However, did not fix problem.

- Replaced Air filter, did not fix problem.

- Replaced PCV valve myself, Did not fix problem.

- Pepboys recommands to replace VSV, asking $240 including labor.. Thinking about it.

- Thinking about the intake manifold gasket, do they go bad usually?

Is there anything else I should look for?

Little bit info. of my car:

2000 Corolla CE, has 211,400 miles, Code P0171 comes again after about 20~30 miles since reset.

* I do hear some 'air' noise around where the engine oil dipstick is, thought its normal engine intake sound, but is it?

* Experiencing lack of power in the morning. As I pedal the accelerator, the speed goes up but rarely the speed decreased in short period of time.

Looking forward to see any solution that I could try something that fix the problem.

Thanks..!!

 

dom

If all vacuum, brake booster, and PCV hoses are good and snug, you likely have a vacuum leak at the intake manifold gasket, if your welded metal intake manifold itself isn't leaking... You should be able to see oily dark residue beside the gasket on engine head where it's leaking, as the intake vacuum pressure pulses blow out some of the vented crankcase aerated oil.

NILLINOIS

Check out this video to diagnose if you have an intake leak..too easy...but remember..COLD ENGINE.

( the video uses vacuum leak, but this will also work if you have manifold leak, just spray by intake manifold edge)

 

( I'm have the same problem on 00 and did all you listed too. It even stumped my usual mechanic )

the current diagnosis is 1) bad spark plugs ( brand new NGK V-Power ) and bad cat converter, which causes computer to

run long term fuel trim levels too high.

dom

( I'm have the same problem on 00 and did all you listed too. It even stumped my usual mechanic )

the current diagnosis is 1) bad spark plugs ( brand new NGK V-Power ) and bad cat converter, which causes computer to

run long term fuel trim levels too high.

Are you getting lean code P0171 at all? As stated in your thread, if your problem is excess fuel trim added because of spark plugs, cat, or other, you're running too rich and not too lean.