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Discussion Starter · #1 ·
I have a 4 cylinder 2005 Accord with a high STFT of 45%. The problem reports as a P0171. Despite the high STFT, the car starts and performs normally. The car has been of the road for 4 months now.
I hope someone can give me some guidance.
I have done the following without making the STFT go away:
1 I have replaced the fuel pump and fuel filter and had the injectors professionally cleaned. Fuel pressure is 50 psi.
2 I've replaced both O2 sensors.
3 I have swapped the MAF sensor with a known good one.
4 I found one vacuum leak in the Front Engine mount and replaced it.
5 I've blocked off/ plugged all the vacuum lines, ie the brake booster line, the purge line, the PCV hose line.
6 The MAP sensor reads 4.5 psi at idle and 3.6 psi at 3000 rpm. Is that correct?
7 I don't think there any intake manifold gasket leaks. I've used starting fluid in the area. There are no fuel injector seal vacuum leaks, which happened to me on another car.
Can someone give me guidance on what to check next?
Thank you in advance
Respectfully
AJW2W11E
 

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Discussion Starter · #3 ·
I measure 20 psi vacuum with a gauge and I've plugged all my vacuum lines (one at a time) and the STFT reading won't go away. There's about seven vacuum ports/ Tomorrow I'll post a diagram of where they are.
I will take another look.
 

· Turbo lag
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When you had the injectors cleaned, did they flow test it? Or did they just threw it in the wash and got it back to you?
 
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What are the values of the STFT and LTFT ?

What information is in the freeze frame data?

Check the tube from the airbox to the throttle body and make sure it does not have cracks in it.

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· Cruising in Montana
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^^^ greg1c beat me to it. Check the big hose from the air filter box to the throttle body. It must be removed from the vehicle to be checked. A 5.5mm deep-well socket is needed for the two clamps, or a JIS screwdriver. (A Phillips will strip the screw heads.)
 

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Discussion Starter · #11 ·
What are the values of the STFT and LTFT ?

What information is in the freeze frame data?

Check the tube from the airbox to the throttle body and make sure it does not have cracks in it.

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STFT 42% LTFT 3%
Freeze Frame Data- Unfortunately I cleared the last PO171 back in the summer. .I haven't had another one since I don't drive it because I don't want to damage the car. It's is in a constant state of testing as I replace and test sensors etc.
I'm using Live Data
 

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Block off the air shrouding vacuum hose from the thermo-switch to the intake. IIRC, the '05 should have this.

Having 20" of vacuum measured at the intake, isn't an accurate way to test for vacuum leaks. Is there ANY exhaust leaks just prior to the first air fuel sensor? It can draw in false air and skew its readings. Sometimes you may not hear the leak. You should use carb cleaner to check for vacuum leaks, not ether. Does it idle normally? A huge vacuum leak at idle should cause a very low idle on a MAF equipped car. What's the MAP voltage, cold start, and as it warms to operating temp?

Is the 45% positive trim at idle only? If you rev it to 2500, what's the short term and long term trims?
 
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