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DMS1

92 Sc400 Cranks Ok, No Start

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I have a 1992 SC400. It cranks over but doesnt start. I have spark and fuel, seems like too much fuel. Also, when I turn the key to on, NO Check Engine Light. That makes me think it is the engine ecu. Any input would be appreciated. Also, where is the ecu located? Thanks guys.

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A bad crank position sensor on my 92 sc400 allowed the car to start and if you kept your foot on the accelerator and applied gas it would run. The car wouldn’t idle without stalling. A mechanic found it via a code but I don’t know what that code was.

BTW the computer on my 87 Vette died but the car still ran in a “limp” mode. I don’t know if the Lexus has a similar type of design.

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I have a 1992 SC400. It cranks over but doesnt start. I have spark and fuel, seems like too much fuel. Also, when I turn the key to on, NO Check Engine Light. That makes me think it is the engine ecu. Any input would be appreciated. Also, where is the ecu located? Thanks guys.

if the car is parked outdoors and it has rained then the problem is moisture.

my 96 sc400 has a tough time starting when i get heavy rain. so i try to

start the thing before i go to sleep or else i wait for a day or so to start it.

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the car ran great, then one day it wouldnt start again. it is in my garage and dry. with my snap-on scanner, i can get rpm reference, it has spark and fuel. seems like too much fuel. the injector pulse is 17.0 m/s when i turn the key on and 19.6 when cranked. seems way too high. maybe the quad driver in the ecu? any comments are appreciated. thanks guys

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are you perhaps using the valet key? on my old SC300 i was using the valet key after the alarm went off, the car would crank and turn like it was about to start but it never would. if you are using the master key then i don't know what it could be

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the car floods when cranked, but has good spark and fuel pressure.

i'm thinking crank sensor, cam sensor or ecu.

what do you guys think?

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I think that you should clear all the fuel out of the cylinders/crankcase because your ECU might be in flood "fail safe" mode right now.

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I think that you should clear all the fuel out of the cylinders/crankcase because your ECU might be in flood "fail safe" mode right now.

I pulled all the plugs and changed the oil, tomorrow i'm putting in a set of new plugs and see what happens. If it doesnt start, I think it needs cam sensors. I read that the cam sensors regulate the injector pulse and it seems too high.

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Don't "shotgun" it. Replace only what you have to. There are a few sensors that regulate injector pulse width. Don't throw parts at it...unless you have money to burn.

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i have changed the plugs and the crank sensor.

still same problem, cranks over, has compression, spark and fuel.

seems to immediately flood.

ecu has no codes.

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the right side cam sensor wire looks worn, the 2 inner wires are fine, but the ground around them is worn thru.

could this be the problem?

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I have a 1992 SC400. It cranks over but doesnt start. I have spark and fuel, seems like too much fuel. Also, when I turn the key to on, NO Check Engine Light. That makes me think it is the engine ecu. Any input would be appreciated. Also, where is the ecu located? Thanks guys.

ECU is on the passenger side under the rug you need a 10mm socket to get to it, its under a black cover, Im currently having the same problem with mine when it does start is really rich when it doesnt start its because there is no check engine light, ive been trying to figure out if the ECU has a fail safe where if it lacks a needed signal it shuts down power to the ECU, I have no spark though when this happens, and when it does start it runs like crap but that could also be the overly rich condition... ive been trying to figure this out for almost a week and its annoying me because I cant figure out whats shutting down the ecu

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the right side cam sensor wire looks worn, the 2 inner wires are fine, but the ground around them is worn thru.

could this be the problem?

possibly but it would start with a bad cam sensor if you have no check engine light check the main EFI relay in the engine bay I just had the same issues and it turned out to be when my motor would get to operating temp the relay would not meet the connections a quick check is to turn your ignition key on remove the efi relay and bridge the 2 bottom relay connectors if the ecu turns on you know you have a problem with power or ground to the relay... WTB your snap on scanner would be lovely to figure out which one of my sensors are not working right im too lazy to do it the right way.

Hope this helped good luck man

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If it worked fine before and then suddenly stopped working, it might be the ECU. Did you ck for spark, fuel is good so that isnt the issue. The ECU would prevent spark. It did on mine and when I replaced it, the car started up right away, make sure you do all the trouble shooting bfore you jump on a used ECU.

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After driving about 30 miles I shut the car off, visit friends for about 2 hours.  When I try to start the car it turns over but does not start.  The next day it starts as if nothing happened.  This has happened three times at the same location at three month intervals.  Car has 150,000 miles, fuel pump and fuel filter has been changed (no help).  I'm thinking ecu has to be changed but not sure.  Any thoughts?

Edited by Timtom
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