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Discussion Starter · #1 · (Edited)
*** EDIT THE ERROR CODE CAME BACK, PLEASE READ ON AND ALSO MY OTHER THREAD IN THE TECHNICAL DISCUSSION FORUM ***

Hi boys! I think we might have found the answer to the SES light (0171 fuel sys lean b1) code appearing particularly on 2004 SpecVs...

A guy I know also owns a 2004 SpecV and was 100% stock until installing a CAI this week. As soon as he put it on and went for a stroll, BOOM, SES light.

The code was also fuel sys lean b1, so it's probably that as another friend suggested, there's an air turbulence created at the front of the filter that alters the normal airflow expected by the MAF and since it's a bit off, that and the fact that 2004 ECMs are so tightly tuned, it throws codes... Some have suggested putting a piece of tape just at the front of the filter, where the air comes in directly front the front air dam near the fog light... Has anyone ever tried this? It's supposedly to prevent the air from hitting DIRECTLY the front part of the CAI filter and not create a weird turbulence...

Because I also took out my S-AFC II completely, and the code still came back, so it wasn't the A'PEXis fault. We also had a idle air volume learning procedure done (after timing advance) and no code has come since. It's been 2 days without a SES light! YOUPI!
 

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before listening to the guy who just posted take a look at the install of you hi flow intake you probably have pirate air (an air leak) that can't be compensated for by the maf
 

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Ok I don't understand you here... you tell that the fault is the CAI but you still have yours and you said that you don't have the SES anymore :confused:

So why so many peoples here with 2004 and CAI never got that P0171 code???


As I said to you, even if the SAFC was removed, the ECM kept the learned parameters for a while and when you've removed the SAFC, he was expecting that "altered" MAF signal but indeed it was not there anymore and throw the SES.

Then, I've suggest you to have the IDLE AIR VOLUME LEARNING done and you've done it... guess what, no SES because the computer has now relearned the new MAF signal unchanged by the SAFC. Oh and after timing advance, you should have that learning done RIGHT AFTER, not some days after and that might be the problem too...


You'll see on the long run if the SES light come back and I hope you it will not ;)
 

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Discussion Starter · #4 ·
Well, the SES light came back on. You can read my thread about it in the technical discussion forum.

But just to let you know Angel, there is a difference in my system compared to most 2004 SpecV. It might sound stupid, but I'm one of the rare people who has a bypass valve with an AEM CAI. I just read the instructions manual for the AEM CAI and it's written that you can't use a bypass valve with an AEM CAI because of space restriction and also because of the MAF. So maybe the bypass valve alters the flow of air and the readings aren't as expected for the MAF.

Also, when I had my idle raised to 800 rpm and my timing advanced to 17 degrees, they did the idle air volume learning procedure right after, so I don't know why you said a couple of days later...

And a guy with a 2004 on the other board had a bone stock car, simply added a custom CAI and boom, P0171 error code (fuel sys lean b1). He removed the tube going into the wing to create a short ram intake and the code went away... This is starting to get on my nerves.
 

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so you hacked in a bypass valve? Where did you place the bypass filter on the tube? some air may be sucking in from the bypass valve if you placed it right in front of the MAF and causing turbulent airflow..if all else fails..get the nismo v2?
 

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El Burro
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I don't see how the bypass valve altered air flow. I've had it on my car for a while and I have and AEM just like OrangeVee does. As long as the screen on the MAF is there, the air shouldn't be getting turbulent.
 

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Discussion Starter · #10 ·
Heheh. That's a good one! I agree that OBD-II cars get freaky with those lights and throw them off at any given sign of faulty readings... I guess it's useful to protect our cars, but it's also stressful when you can't solve the problem.

Go to see my update in the other post (SES light nightmare) in the technical discussion and tell me what you think. Again, thanks for the support boys.
 
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