Eractic idle upon start up?
08-09-13, 08:37 AM
#1
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Thread Starter
Eractic idle upon start up?
Why is my car upon start up in the morning the idle goes up an down constantly on its own an when i put the car in drive the idle is high? An at the end of the day when i finish work the idle goes back to normal upon start i'm looking for answers please?
08-09-13, 12:05 PM
#2
Lexus Champion
have you done any work on the car recently? - a vacuum leak could cause this
however, LS400 has two areas that frequently fail and will cause it, so the following two items are probably 98% chance
1. Idle Air Control Valve (IACV) if your car is from 1997 or older
2. failing ECU capacitors (all years)
what year is the car?
however, LS400 has two areas that frequently fail and will cause it, so the following two items are probably 98% chance
1. Idle Air Control Valve (IACV) if your car is from 1997 or older
2. failing ECU capacitors (all years)
what year is the car?
Last edited by LScowboyLS; 08-09-13 at 12:18 PM.
08-09-13, 02:43 PM
#4
Lexus Champion
even a replacement ECU will still need it's capacitors replaced
many times the capacitor leakage is obvious once you look inside, and as for the Idle Control Valve, there is a series of tests you can do to verify its operation:
Attachment 499542
many times the capacitor leakage is obvious once you look inside, and as for the Idle Control Valve, there is a series of tests you can do to verify its operation:
Attachment 499542
08-09-13, 08:08 PM
#6
Lexus Champion
you can clean the IACV, but that is not usually how they fail, usually a bearing goes bad, and no amount of cleaning will fix that. They can also blow one of their coils, and no amount of cleaning will fix that either, but the test above will show a bad coil.
the easiest thing to check though if you want to do the least work is to probably to pull the ECU using the instructions in post #1 of my ECU thread (disconnect negative battery cable first) - then while barefoot and wearing all cotton clothing, carefully open and photograph ECU insides using a high resolution camera, and Yamae and I are experienced at spotting leaking ECU capacitors and we will examine your pics!
the pics need to be at least as sharp and clear as the pic below, so most cell phones are not going to cut it, you need to photograph all 8 brown Nichicon capacitors
the easiest thing to check though if you want to do the least work is to probably to pull the ECU using the instructions in post #1 of my ECU thread (disconnect negative battery cable first) - then while barefoot and wearing all cotton clothing, carefully open and photograph ECU insides using a high resolution camera, and Yamae and I are experienced at spotting leaking ECU capacitors and we will examine your pics!
the pics need to be at least as sharp and clear as the pic below, so most cell phones are not going to cut it, you need to photograph all 8 brown Nichicon capacitors
Last edited by LScowboyLS; 08-09-13 at 09:05 PM.
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08-10-13, 11:55 AM
#8
Pole Position
No, not your "coils". Your IAC valve. Test it first to make sure that's the problem. If you dont have an Ohm meter buy one. It's alot cheaper then buying (expensive) parts you might not need.
08-10-13, 02:39 PM
#9
Lexus Champion
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