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Greg
Greg, Technician
Category: Car
Satisfied Customers: 7124
Experience:  17 years Shop Owner /Technician. 27 years experience,
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my rpms jump while driving and in park or N .... ls400 93

Customer Question

my rpm's jump while driving and in park or "N".... ls400 93 lexus
Submitted: 7 years ago.
Category: Car
Expert:  Greg replied 7 years ago.
Hi and welcome to JA.com
Is your check engine light on ,
Customer: replied 7 years ago.
NO and I have replaced my tps my self... mass air flow my self... ecu my self... fuel felter... spark plugs and wires... all my self
Expert:  Greg replied 7 years ago.
Why did you change all these parts did you have a code read out before changing these parts ,been working on the lexus many years and i've never had to replavce a ECM .
Regards Greg.
Customer: replied 7 years ago.
Took the car to lexus dealer and they said the the ecm was bad... everything else i did befor i took the car... I was hoping it wasn't the ecm but then after I bought a new one I had hoped it was.... just to be done with it...
Expert:  Greg replied 7 years ago.
But after replacing you still had the same problem?
Customer: replied 7 years ago.
At first my car wasn't doing this... it wouldn't get up and go at all.... I had to ease into the gas to go.... so then I thought it was the fuel filter... then the mass air flow... then the spark plugs and wires... then the tps... then took it in and they said it was the ecm... then it worked just fine after replacing the ecm.... then it just started doing this... its like when i am just giving it a little bit of gas just to stay at a speed like 40 or 60 or 10 or in park or "N", it does the jumping... and when I'm driving it does it and its like 1500 rpms that in jumps... thought it might be the tranmission but I can't pay to have it replaced... don't know
Customer: replied 7 years ago.
I had my old mass air flow and put that back on it.... then this morning it did just fine... then when I got it to go home it started to do it again..
Expert:  Greg replied 7 years ago.
I'm going to show you how to diagnose this yourself.
retrieve codes
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Data link fig 1
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Data link fig 2
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Let me know if you need more help
Regards Greg
Customer: replied 7 years ago.
I'm at a lost for words... I have no idea what you are asking me to do... I am sorry but I know how to replace parts not find the problem... I really don't where to go with this info....
Customer: replied 7 years ago.
I'm at a lost for words... I have no idea what you are asking me to do... I am sorry but I know how to replace parts not find the problem... I really don't where to go with this info....
And there is no check engine light on
Expert:  Greg replied 7 years ago.
Hi
You will have to find a approved lexus Garage with the right diagnostic ability to diagnose this problem ,
Its no good just throwing parts at your car in the hope you replace a part you need , as it might not be a part but a wiring issue, which is the case on older cars , the ls400 and other Lexus, have problems with engine wiring harness after 10 years old due to engine heat harness wiring get brittle and break and contacts get corrosion .
Kind regards Greg
Customer: replied 7 years ago.
Okay...
Expert:  Greg replied 7 years ago.
OK
Let me know if you need more info .Happy Motoring
Regards Greg