Throttle Position Sensor problems
Thread Starter
Safety Car
Joined: Nov 2009
Posts: 3,973
Likes: 341
From: Adelaide South Australia
Throttle Position Sensor problems
I was doing the IAC and throttle position sensor reset, chasing an idle problem.
When I tested the TPS thru its range when I got to just over half throttle and the meter was reading 1.99 volts, It suddenly went to 1. on the readout and didnt change all the way to full throttle.
I removed the TPS and checked it again, same result.
It is not showing any codes.
This would tie in with an issue i had recently at hillclimb, where the engine wouldnt run at 3/4 or more throttle, the engine would nose over and the knock sensor code would come on.
Has anyone experienced this ?
Is it a TPS problem, or a wiring problem ?
When I tested the TPS thru its range when I got to just over half throttle and the meter was reading 1.99 volts, It suddenly went to 1. on the readout and didnt change all the way to full throttle.
I removed the TPS and checked it again, same result.
It is not showing any codes.
This would tie in with an issue i had recently at hillclimb, where the engine wouldnt run at 3/4 or more throttle, the engine would nose over and the knock sensor code would come on.
Has anyone experienced this ?
Is it a TPS problem, or a wiring problem ?
Le Mans Master
Joined: Feb 2005
Posts: 6,479
Likes: 565
From: Clearwater Florida
..... You should have 5.00 volts on the reference wire from the ECU ... If you have that , it would rule out the wiring ... make sure you check it between the A and C wires on the connector ... the ground feeds back to the ECU for TPS ......
Thread Starter
Safety Car
Joined: Nov 2009
Posts: 3,973
Likes: 341
From: Adelaide South Australia
if the wiring is ok, then it must be the TPS.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
It definitely sounds like your TPS is bad, though it could be a bad connection or wiring problem.
The ECM has a puilldown resistor inside it that makes the ECM think the TPS is at zero percent if it goes open. When you hit a dead spot in the TPS it will act as if you shut off the ignition.
The ECM has a puilldown resistor inside it that makes the ECM think the TPS is at zero percent if it goes open. When you hit a dead spot in the TPS it will act as if you shut off the ignition.
Thread Starter
Safety Car
Joined: Nov 2009
Posts: 3,973
Likes: 341
From: Adelaide South Australia
i checked everything again, I have 5 volts at the sensor connection, and now the TPS is reading from .54 up to 4.5 volts at full throttle.
I have to confess I think I didnt have the correct setting on the test meter,
Looks like fuel surge is my problem, but will worry about that in the new year.
We had a cruise night Saturday, the idle is a bit better now, especially after lowering the fuel pressure and putting the vacuum line back on. Its also interesting to compare the reading on the dash tacho compared to the Autometer tacho, sometimes the same, sometimes quite different !
I have to confess I think I didnt have the correct setting on the test meter,
Looks like fuel surge is my problem, but will worry about that in the new year.
We had a cruise night Saturday, the idle is a bit better now, especially after lowering the fuel pressure and putting the vacuum line back on. Its also interesting to compare the reading on the dash tacho compared to the Autometer tacho, sometimes the same, sometimes quite different !
Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 412
From: WV
i checked everything again, I have 5 volts at the sensor connection, and now the TPS is reading from .54 up to 4.5 volts at full throttle.
I have to confess I think I didnt have the correct setting on the test meter,Looks like fuel surge is my problem, but will worry about that in the new year.
We had a cruise night Saturday, the idle is a bit better now, especially after lowering the fuel pressure and putting the vacuum line back on. Its also interesting to compare the reading on the dash tacho compared to the Autometer tacho, sometimes the same, sometimes quite different !
I have to confess I think I didnt have the correct setting on the test meter,Looks like fuel surge is my problem, but will worry about that in the new year.
We had a cruise night Saturday, the idle is a bit better now, especially after lowering the fuel pressure and putting the vacuum line back on. Its also interesting to compare the reading on the dash tacho compared to the Autometer tacho, sometimes the same, sometimes quite different !
Le Mans Master
Joined: Feb 2005
Posts: 6,479
Likes: 565
From: Clearwater Florida
..... You might want to tape a fuel pressure gauge to the windshield ... another thing to consider is quantity of fuel in the tank ... C4's are notorious for fuel slosh issues when running less than 1/2 tank ... this would be compounded by running uphill ...........
Thread Starter
Safety Car
Joined: Nov 2009
Posts: 3,973
Likes: 341
From: Adelaide South Australia
The regulator Im using has the gauge screwed into it, I would have to remove it and put a schraeder valve in to test, but that will have to wait, Im moving house right now.
at the hillclimb I started with 3/4 tank, and then a full tank, it actually ran its quickest time with the full tank, but I dont want to be dragging that much weight up the hill. There are no more meetings till next April, its now the summer cruising season here in Aus.
I will make a shroud for the fuel pump assembly and see how that goes in the new year.
at the hillclimb I started with 3/4 tank, and then a full tank, it actually ran its quickest time with the full tank, but I dont want to be dragging that much weight up the hill. There are no more meetings till next April, its now the summer cruising season here in Aus.
I will make a shroud for the fuel pump assembly and see how that goes in the new year.
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