After a full gasket replacement, it starts and revs to 4,000 RPMs until the engine is turned off?

CJCHRISTENSEN8

MEMBER
2004 CHRYSLER PACIFICA
3.5L
V6
2WD
AUTOMATIC
144,000 MILES

After a full gasket replacement, including head gaskets, we have the engine back together and started. It immediately revs to 4,000 RPMs and stays there until we turn it off. The spark plugs are new, the MAP sensor is new, the EGR valve is new, and the oil was replaced. The MAF has been cleaned, and tests the correct voltage, the TPS test for the correct voltage, and the IAC valve was cleaned and visually verified as working. The dealership said we don't need to update the PCM. We have codes p068, which is non-correlation between TPS, MAP, and MAF, but they all seem to be okay. We also have p0123, which is high voltage output from TPS. That specifically tested at.9V before startup and went to 3.6V when I manually opened the throttle with engine running. Hope you have some ideas, and thanks in advance!

1 Reply

JACOBANDNICKOLAS

MECHANIC
108,289 POSTS

Hi,

When you turn the key to run, engine off, does the throttle plate fully close? Also, if I recall, this has a plastic intake. Are you certain it isn't cracked or leaking?

As far as the TPS, are you sure it is properly installed? The throttle shaft end of the throttle body slides into a socket in the TPS. The socket has two tabs inside it. The throttle shaft rests against the tabs. When indexed correctly, the TPS can rotate clockwise a few degrees to line up the mounting screw holes with the screw holes in the throttle body. The TPS has slight tension when rotated into position. If it is difficult to rotate the TPS into position, install the sensor with the throttle shaft on the other side of the tabs in the socket.

Let me know.

Joe

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