Manifold pressure issues / sensor issue?

I got up early to fly Saturday, did a very complete preflight as I have not flow in 10 days. Aircraft started up without an issue and I allowed it to warm up very well as it was cold day in North Texas.

Run up was normal no issues... then things got strange.

Normal take off making full power nothing out of the normal, during climb I went to pull the power back to 25inches 2500 RPM my climb setting. I noticed that as in pulled the throttle back the manifold pressure was not coming down as expected. I flew the aircraft out of the pattern to try and diagnose the issue. The airplane was flying normally no other indication of a problem.

Now this is my first constant speed propeller and I don?t want to hard the engine so I was very uncomfortable pulling that prop back and having a high manifold pressure even though the engine was acting normally I have not idea what that real MP was.

Throttle to idle 27.7 inches m
3/4 throttle 28+

I landed with no issues.

I have GRT HXr with a GRT EIS 4000 both were displaying the same info as the EIS feeds the HXr.

I am guessing I have a bad sensor? I would love some guidance on what to do next. Replace the sensor. Do I have one? Air leak. I really have no idea.

Thanks for your help, Sean

Most likely- the hose at the cylinder or the sensor slipped off the fitting.

You are seeing ambient pressure from an operable sensor.

Aft side of cyl #3 back right or your sensor

moosepileit said:

Most likely- the hose at the cylinder or the sensor slipped off the fitting.

You are seeing ambient pressure from an operable sensor.

Aft side of cyl #3 back right or your sensor

Click to expand...

+1. Start at the aft starboard cylinder. Look for a flexible tube (it may be covered with steel braid) attached to the intake manifold. Follow the tube, it probably is attached to a firewall feed-thru. Go inside the airplane to the firewall feed-thru, follow the rubber tube to the sensor box. Look for a leak or disconnection in one of those tubes.