LS - 1st and 2nd Gen (1990-2000) Discussion topics related to the 1990 - 2000 Lexus LS400

running rich and misfire

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Old 07-15-24, 06:22 PM
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yungnano
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Default running rich and misfire

I recently purchased a 95 LS400 with 240k miles and it started misfiring, with smoke coming out the exhaust and it would reek like gas. The codes I get are for misfires in cylinder 2, 3, 4, 6, and 8 as well as P0170. I replaced the fuel injectors with junkyard ones (cleaned them while tapping them with power) thinking it was that and didn't solve the issue. Then I put a new fuel regulator and it gave it a bit more power and way less fuel was burning into the exhaust. The regulator was toast I could hear the spring move around when you shake it. I put new plug wires, checked for spark to see if all the coils where good and they all got spark. I haven't done plugs yet but that was my next guess was either plugs, O2 sensors, or the fuel dampener or fuel filter. At some point oil change maybe as well since fuel might have thinned out my oil but does anyone else have an idea to what it could be? It is running very rich and smells like fuel into the cabin still but not as bad as it was before I swapped out the regulator.
Old 07-15-24, 07:07 PM
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400fanboy
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Has the ECU been repaired?

https://www.clublexus.com/forums/ls-...capacitor.html
Old 07-15-24, 08:09 PM
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yungnano
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No it has not but, it doesn't have symptoms of a bad ECU. A friend was telling me it could be the vacuum switch valve could be bad causing the regulator to go bad.
Old 07-15-24, 11:04 PM
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CLLEXUSS
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Actually 400fanboy is correct, the P0170 code is a possible symptom of an issue with an ecu. But you need proper diagnostics, or continue on with process of elimination, entirely up to you.
Old 07-16-24, 12:11 AM
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Yamae
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Originally Posted by yungnano
No it has not but, it doesn't have symptoms of a bad ECU. A friend was telling me it could be the vacuum switch valve could be bad causing the regulator to go bad.
Why don't you ask or support your friend to fix the problem before asking LS400 people here?
Old 07-16-24, 08:28 AM
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400fanboy
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Did someone delete my post?
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