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Ls400 Code 25 Lean !


k_tieu

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Hey guys i have a 1990 LS400

i recently cleaned out the egr port and the PCV port. and a day later the car shakes when it drives. code 25 comes up for air fuel device lean, feels like a miss fire but it is not miss firing at all i checked all vacuum hoses there fine so far have not found a intake leak i only have an exhaust leak before the main cat, thats about it.

and yes this kills the power too u have to step a bit farther for it to go. i am so puzzled i even cleaned the AMF. im starting to think that i should take the intake runners apart n clean it out. but yea every time u go into reverse it studders/ shakes. and same when u drive.

some say it could be the o2 sensor but i dont know at the moment.

thanks for your responses

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If you have an exhaust leak before the O2 sensors then there will be oxygen added to the exhaust stream. The O2's see that oxygen as lean - excess oxygen means insufficient fuel as far as the ECU is concerned. It then adds fuel to correct it. You'll have to repair the exhaust leaks. The ECU has only a limited range of adjustment, and a big leak will exceed it's ability to trim the mixture. That has probably produced the code.

Check all of your previous work again as well.

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