Code 25 lean condition running ~12psi

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Code 25 lean condition running ~12psi

Postby EvilStig » Thu Nov 28, 2019 3:27 am

Hi folks,

so the wideband I installed is a PoS and doesn't work, so I can't get an accurate reading... with the stock o2 sensor, the ECU throws a code 25 after ~60 miles of driving. I'm running ~12psi on a CT27 (stock turbo with upgraded turbine and compressor impellers) using a greddy profec EBC. My boost gauge is also apparently shit though so I don't really know how accurate that is either...

Anyway, shop tells me vacuum leak which I know it's not, since the manifold holds pressure. Too much venting from BoV would read rich, I would assume, so that leaves... the injectors? Is it possible I just need to upgrade my injectors to support the extra boost? Has anyone else run into this?

Thanks.
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Re: Code 25 lean condition running ~12psi

Postby underscore » Thu Nov 28, 2019 3:39 am

If it's at the same-ish distance every time maybe the O2 sensor is just crapping out when things fully heat up? Or alternatively something is leaking when fully heated up. Is the code coming up under boost or when cruising?
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Re: Code 25 lean condition running ~12psi

Postby EvilStig » Thu Nov 28, 2019 3:51 am

underscore wrote:If it's at the same-ish distance every time maybe the O2 sensor is just crapping out when things fully heat up? Or alternatively something is leaking when fully heated up. Is the code coming up under boost or when cruising?


milage before it throws code seems to vary. It usually seems to throw it while cruising at or around freeway speeds.

I've already replaced the o2 sensor so I doubt that's it unless I was sold a bad one.
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Re: Code 25 lean condition running ~12psi

Postby Gert » Thu Nov 28, 2019 7:12 pm

EvilStig wrote:Has anyone else run into this?

Probably. But you are very brave that you try to tackle a problem without knowing the most important data like: A/F ratio and boost level.
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Re: Code 25 lean condition running ~12psi

Postby EvilStig » Thu Nov 28, 2019 7:38 pm

Gert wrote:
EvilStig wrote:Has anyone else run into this?

Probably. But you are very brave that you try to tackle a problem without knowing the most important data like: A/F ratio and boost level.


hey not my fault everything is shit. Gotta start somewhere to get this shit working again.
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Re: Code 25 lean condition running ~12psi

Postby underscore » Thu Nov 28, 2019 7:47 pm

If it's happening while cruising you should be under vacuum so a leaky BOV would make it run lean. Definitely get a known good boost gauge on there along with a wideband should cut the potential causes in half, since you'll know whether the problem is that you're actually running lean or it's an error in the engine management somewhere.
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Re: Code 25 lean condition running ~12psi

Postby silverarrow » Fri Nov 29, 2019 6:54 am

Can you dial down the boost or is the wastegate set at 12 psi? Clogged cats if you still have them both?
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Re: Code 25 lean condition running ~12psi

Postby EvilStig » Fri Nov 29, 2019 5:15 pm

silverarrow wrote:Can you dial down the boost or is the wastegate set at 12 psi? Clogged cats if you still have them both?


Using a pro-fec EBC, have to reprogram it anyway after leaving the battery unplugged overnight to clear the codes, I'll dial it down a bit to around 10 and see what that does. Although the pro-fec isn't smart enough to meter boost by MAP, I still trust its boost reading a lot more than the stock or aftermarket boost gauges I have installed. I've only ever seen the glowshift gauge hit 8 PSI when I know it's been up around 14, and it consistently reads a vacuum with the engine off or even under moderate boost (so did the Bosch gauge it was a replacement for).

underscore wrote:a leaky BOV would make it run lean


I don't believe it's leaking under vacuum, my concern was if it was dumping too much to atmo when letting off under boost (It's a partially recirculating system). But that would cause a rich condition.

It took me half a week to run the current boost gauge and wideband into the cabin, and the manufacturers have been less than helpful in supporting their products. I'd have to start from scratch with new, different branded equipment to install trustworthy gauges, and that's time consuming and expensive... plus I have only one upstream o2 port so I'd need to find another all in one gauge and sensor kit that includes a narrow band emulator to plug into the ecu.
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Re: Code 25 lean condition running ~12psi

Postby underscore » Fri Nov 29, 2019 10:33 pm

Don't get fancy with the gauge, just run a piece of vacuum tube out the hood near the windshield and back in the window and put a mechanical gauge on the end of it. Borrow one you know is good off a buddy or grab a cheap one, it doesn't even have to be made for a car. If it's something new test if against a known good gauge to see how off it is.
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Re: Code 25 lean condition running ~12psi

Postby silverarrow » Sat Nov 30, 2019 2:02 am

Curious...what wideband are you using and I'm guessing you're putting the o2 sensor in the stock o2 location? As for the boost gauge issue, bum one off a buddy to test. Reading off your ebc should be quite close or as accurate as a boost gauge too though. I've never been a fan of the Greddy boost controllers...had boost spikes and boost creep often with them. I'm a fanboy of the APexi AVCR if I had to have a boost controller.
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