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Discussion Starter #1
Hey,

I'm having some trouble with my 2003 is300 with 180K miles and was hoping someone on this forum would have some insight or information regarding my issue. I was driving on the freeway when all of a sudden the car shutoff going 65mph. When I brought it home, I tried to start it, but it would only start rarely and would stall immediately. Sometimes I can catch the car before it shuts off and it'll run if you gas it. So, after some attempts to fix it, I'm pretty much stumped. The car has had a long history of problems with the security system. Alarm would go off randomly when driving, doors would shut when attempting to open with key alarm, and we had a long history of problems with the immobilizer, but I had that fixed a few months back at a shop. I also noticed that when replacing the spark plugs, there was a decent amount of fuel and oil pooled on top of them. The longest I got it to run was after replacing the spark plugs and it went about 10 minutes. If anyone has any idea of what to test and things to look out for I would really appreciate it.

A list of other things I have done:
Verifying battery is good and alternator is good
Replacing the spark plugs
Cleaning the idle air valve
Checking coil packs
Checking the fuel pump wiring for power
Hearing the fuel pump running
Checking the relays
Checking the fuses
Making sure all wires and harnesses are not damaged and in place in the engine bay

OBDII data:
IAT Celsius -40
MAF (G/S) 0.40
TP% 0.0
SparkADV 8
RPM 865
VSS 9
Fuel Sys1 CL
Fuel Sys2 CL
DTC_CNT 5
ETC Celsius 66
LOAD PCT% 1.6
 

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So after you changed the spark plugs, then it ran for 10 minutes, did you go back and check them?

Reviewing spark plugs can tell you a lot about how your combustion cycle is performing, here's a generic chart to show you what I mean:

135304
 

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Discussion Starter #3
No, I haven’t tried that. I’ll go back and pull them in the morning and take a look at the condition they’re in now. Thanks for the suggestions and picture.
 

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Discussion Starter #4
I pulled the spark plugs again today, they looked good. My brother accidently started the car while the throttle body was removed and the car started up and was running relatively good other than the fluctuating idle. This leads me to believe that I have either an issue with the throttle body or one of the accessories that controls it. Any thoughts?
 

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could be one of the sensors, APS, TPS, stepper motor, MAF. By taking the throttle body off its disconnecting all of those, and all tell the ECU how much fuels needed.

Maybe try putting it all back together and see if it starts again, then troubleshoot the MAF as that is a common part to replace and then the others.
 

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Discussion Starter #6
I’ve tried disconnecting only the MAF sensor to see if the car at least runs, but it exhibits the same symptoms even with it not connected.
 

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Discussion Starter #7
Does anyone know generally how many volts the IAC motor is supposed to get? I'm getting 1v when I test it. Isn't it supposed to be 12v?
 
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