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93 LS 400 cuts out at 2000 rpm

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Old 05-07-11, 07:50 PM   #1
radiohound
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Default 93 LS 400 cuts out at 2000 rpm

hello friends ... my 93 just stared acting up ... uphill or underload, it justs cuts out completely at 1500-2000 rpm ... and it cuts out when floored also ...
I can ease up and it catches back on ... but very puzzling ...

idles fine and revs clean in neutral ... just under load ...

new plugs, dist caps, rotors, timing belt, crank position and cam sensor changed within 3K ... car has 160K on it ... no problems before this

any thoughts or advice ... right now, can't go anywhere because car is dicey ...

thanks

frank
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Old 05-07-11, 08:46 PM   #2
deanshark
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Does it do it mainly when the car warms up? Do you hear pinging under load? My car was doing the same thing last year until I read this. http://www.clublexus.com/forums/ls40...nging-too.html As it says in the link, remove ECU fuse, unplug the AFM, replace fuse. Doing this will put the ECU in "fail safe" mode. If that is the problem don't drive for too long with the AFM unplugged. Mine is and it runs very rich, bad mileage, and I don't know for sure but I think it messed up my ECU. I can't retrieve codes from the CEL anymore, it just flashes like there are no codes stored even though I know there should be.
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Old 05-08-11, 03:36 PM   #3
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another thing to consider would be the coil packs but usually if one goes out the rpms are reall low have u checked for codes
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Old 05-13-11, 10:22 PM   #4
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Default progress, sort off..

well, thanks for the replies and guidance ...this is driving me crazy ..

I replaced the Coolant temperture sensor and cleaned the Throttle body and plenum.. a pita ..with all the hoses needing replacement ,, but it runs better but is still doing it under hard throttle.

I changed the plugs and wires and rotors and caps about 3K ago with non-lexus parts and am ready to take the factory plunge ..

I will check out your suggestions this weekend ...

thanks and keep 'em coming ...
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Old 05-15-11, 01:03 PM   #5
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Default problem solved,I hope

so I changed out the Main Computer with one from a traction controlled car. Mine is not Traction Controlled.

Anyway, the hesitation I've been experiencing immediately disappeared. Hmmm. I ran it for a while but it seems to be all good, so far. I am a bit leery of declaring success. Anyway, here is the list of things I changed without making a difference:

Wires and plugs
rotors and caps
Fuel pump relay
Mass air sensor
Fuel filter (major PITA)
Engine coolant sensor ( mild PITA)

Cleaned Throttle Body of a 1/4 inch of scum build-up.
Changed associated vaccum and coolant hoses

Changed ECU unit ... and it cleared the hesitation and stumble at 1700 rpm ...

Plan to crack the old ECU and check out the capacitors ...there is a thread on the forums about the ones that can be replaced ...
Thanks for the help and hope this helps someone else

frank
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Old 05-16-11, 06:17 AM   #6
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I'm sure it's the caps in your ecu. I had the same problem. Bought a replacement ecu off ebay for $250 since I could not find one in my local junkyard at the time. Since then I have found 2 more good 93-94 ecu's in my local j/y for $24 each. I keep a spare in the glovebox for an emergency since I take my Lex on long family trips. I keep the other in my closet at home.

I see that DriftMotion offers ls400 ecu repairs. I just plan to take one of my extra ecu's to a local electronics repair shop to replace the caps before they go bad.

I plan to get a ucf20 next year and sell my ucf11.
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Old 05-17-11, 11:48 AM   #7
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Default sound like my problem

Quote:
Originally Posted by radiohound View Post
so I changed out the Main Computer with one from a traction controlled car. Mine is not Traction Controlled.

Anyway, the hesitation I've been experiencing immediately disappeared. Hmmm. I ran it for a while but it seems to be all good, so far. I am a bit leery of declaring success. Anyway, here is the list of things I changed without making a difference:

Wires and plugs
rotors and caps
Fuel pump relay
Mass air sensor
Fuel filter (major PITA)
Engine coolant sensor ( mild PITA)

Cleaned Throttle Body of a 1/4 inch of scum build-up.
Changed associated vaccum and coolant hoses

Changed ECU unit ... and it cleared the hesitation and stumble at 1700 rpm ...

Plan to crack the old ECU and check out the capacitors ...there is a thread on the forums about the ones that can be replaced ...
Thanks for the help and hope this helps someone else

frank
I have a problem some what like that .my car kills at 1700 rpm starts up fine I'm waiting on the junk yard to let me know when a 93-94 w/trac come in and go from there.
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Old 08-11-11, 11:46 PM   #8
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any update?
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Old 09-11-12, 06:21 PM   #9
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same issue, but not rpm related, more of an underload issue. thread is here


http://www.clublexus.com/forums/ls40...ng-nuts-5.html
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Old 09-11-12, 06:21 PM
 
 
 
 
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2000rpm, 400, 93, 93ls, 98, bad, cuts, ecu, filter, fuel, lexus, ls, ls400, pump, put, replace, start

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