Check engine light came on.... high idle @ 2000rpm!! - ClubLexus - Lexus Forum Discussion


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Check engine light came on.... high idle @ 2000rpm!!

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Old 10-23-17, 11:36 PM   #1
OMAHA
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Default Check engine light came on.... high idle @ 2000rpm!!

took me about 3 times to start my car, wouldn't keep a idle. Then once it kept a idle, it revved up to 2000rpms and i had poor or no acceleration. It seems that it is burning LEAN now. It seems the car is in "limp home mode"..... it's at 250k and has not done this too me before.... bought the car at 200k. ANY IDEAS?
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Old 10-23-17, 11:40 PM   #2
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Traction control light came on also....it is OFF
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Old 10-23-17, 11:57 PM   #3
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I've also noticed the pipe between the manifold and catalytic converter is RED HOT!
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Old 10-24-17, 12:25 AM   #4
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Any rough idle before this? If the cat is red it is failing or has already melted
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Old 10-24-17, 01:03 AM   #5
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Any rough idle before this? If the cat is red it is failing or has already melted
No rough idle before this happened..... ran great all day. A bad cat would cause this?
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Old 10-24-17, 03:03 AM   #6
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You will need to try pull the codes. A bad cat can cause all kinds of running issues, however a cat rarely just goes bad. There will be an underlying issue.
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Old 10-24-17, 06:50 AM   #7
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it helps to know your year model??? your ECM could have leaking CAP's
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Old 10-24-17, 08:36 AM   #8
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it helps to know your year model??? Your ecm could have leaking cap's
1994 ls400
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Old 10-24-17, 09:54 AM   #9
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1994 ls400
Check the Air Flow Meter (AFM). They're know to go bad without warning. Try unplugging it to see if the idle goes back to normal. Mine did on my 93. Sometimes it doesn't throw a code to show it's bad. This thread shows the resistance it's supposed to be at. https://www.clublexus.com/forums/per...on-issues.html
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Old 10-24-17, 10:06 AM   #10
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Ok, i took it to o'reillys and they could not get any codes to register.... they suggested a clogged catalytic converter, but i digress..... getting it towed to a Lexus/Toyota specialist auto shop.

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Old 10-24-17, 10:41 AM   #11
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The absence of codes has me suspecting the ECU. Lots of potential issues that interconnect so you'll have to step through and eliminate one by one, the ECU is worth the check to verify if there is leakage. Then onto the next one.
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Old 10-24-17, 12:03 PM   #12
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The absence of codes has me suspecting the ECU. Lots of potential issues that interconnect so you'll have to step through and eliminate one by one, the ECU is worth the check to verify if there is leakage. Then onto the next one.
a leaky ecu was my strongest guess at this point....lol....i read cowboys post, miss ol cowboy!
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Old 10-24-17, 12:40 PM   #13
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His helpful posts on the forum continue on. I was reviewing a much older thread but to comment on one of his reply's would be mute since he isn't active. In that time span we've learned different approaches to diagnose-fix. I mentally debate some threads in the FAQ for updates to reflect what we do now.
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Old 10-25-17, 10:50 AM   #14
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Found out today that the auto shop suggests starting with a rebuilt computer, $650 parts and labor. The Toyota/Lexus shop told me that no codes came up on the diagnostics. They think that is because the computer has gone bad.
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Old 10-25-17, 11:32 AM   #15
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I found a rebuilt computer $300 with core.....also, i found a 1993 LS400 at the junkyard, so would a computer from a '93 work on a '94 ?
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