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Only runs with TPS disconnected
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Mark_Le_Rouret
New User
Jun 16, 2020, 1:55 AM
Post #1 of 7
(2013 views)
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Only runs with TPS disconnected
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Hi,
My car will only start with the Throttle Position Sensor disconnected.
I changed the throttle body (with TPS integrated) but car will still not start unless TPS is disconnected.
I am completely stumped by this so if f anyone has any ideas I would be eternally grateful.
The car is a Nissan Micra.
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Hammer Time
Ultimate Carjunky
/ Moderator
Jun 16, 2020, 4:29 AM
Post #2 of 7
(2003 views)
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Re: Only runs with TPS disconnected
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We don't have that car here in the US so we don't have any specific info on it but obviously you need to troubleshoot the TPS circuit to see what the PCM is seeing when the TPS is plugged in. You may have a wiring problem. It appears it is seeing wide open throttle when the TPS is plugged in causing it to go into clear flood mode.
You will likely need a professional scan tool to do this.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Mark_Le_Rouret
New User
Jun 16, 2020, 11:11 PM
Post #3 of 7
(1970 views)
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Re: Only runs with TPS disconnected
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Hi Hammer and thanks for your response.
In the end it was the TPS relearn procedure that fixed it.
After changing the throttle body I understood that the engine would still run without this, albeit not well, but apparently not.
I think disconnecting the TPS made it revert to limp home mode enabling it to run.
I had to do a number of attempts at the relearn, driving the car inbetween. It got better and better until the revs became settled and even at 900 rpm.
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Mark_Le_Rouret
New User
Jun 16, 2020, 11:36 PM
Post #4 of 7
(1965 views)
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Re: Only runs with TPS disconnected
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Hmm.... it was really reluctant to start this morning. It's like it has forgotten the relearn thing, but not completely.
I did the relearn again and now seems fine again, but of course it's warm and easier to start...
Any ideas?
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Hammer Time
Ultimate Carjunky
/ Moderator
Jun 17, 2020, 4:26 AM
Post #5 of 7
(1955 views)
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Re: Only runs with TPS disconnected
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Like I said, we have no specific info on that car so I can't tell you if you are doing the relearn correctly.
I still revert back to the scan tool for more info and possibly the correct way to do the relearn.
There still may be a problem in the circuit. I never heard of a TPS causing a no start simply due to a relearn procedure. If it is an electronic throttle, it will have dual TPS and if they both fail it will disable the throttle
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Mark_Le_Rouret
New User
Jun 19, 2020, 5:56 AM
Post #6 of 7
(1891 views)
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Re: Only runs with TPS disconnected
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Yesterday morning after day of normal running and starting, failed to start at all!!!
Got to thinking it must be temperature related, so opened the bonnet/hood and left the car in the sun all morning.
Sure enough it started!! and the idle speed was good so the relearn was saved!!
Not that it's cold at night. Got down to about 18 C/ 65 F last night.
Any ideas what that could be?
Doesnt have to be the throttle body thing... maybe another unrelated fault.
I previously changed cam position, crankshaft position, MAF sensors and battery is in good condition.
ECU is throwing no error codes at all when it fails to start.
I already took it to the Nissan dealer. they charged me 180€ for a diagnostic procedure.
They told me there is a catestrophic mechanical fault inside the engine that could only be fixed by replacing the engine!!!
I nearly scrapped it at that point... then thought it just didn't sound right.
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Hammer Time
Ultimate Carjunky
/ Moderator
Jun 19, 2020, 6:23 AM
Post #7 of 7
(1889 views)
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Re: Only runs with TPS disconnected
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Like I stated in my first response, you need a professional scan tool to diagnose this problem.
The crystal ball isn't working today.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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