2003 Baja manual transmission, 111000 miles, recently replaced timing belt, water pump, idlers, etc, and it runs great once you get it started. This has been an issue for quite some time, and is now happening quite often. When you start the engine, as soon as it catches and you release the key, RPM's drop and it stalls in a matter of a second or two. If you just slightly depress the accelerator when starting, and then let off second or two after the engine starts, it remains running and settles into a nice idle.  I have cleaned the IACV, and also swapped it with a known good one from an Outback of the same year. The problem remained, and the IACV removed from the Baja and installed on the Outback is working fine. No codes displayed via OBDII. Could this be a TPS issue, or might a slight adjustment of it or the throttle body stop screw resolve it? Any suggestions appreciated.

 

Also, why does a normally aspirated Baja have a boost pressure sensor mounted atop the throttle body? 

 

Thanks!

Edited November 24, 201510 yr by ebbsspeed

Its a MAP sensor. It's measuring manifold absolute pressure, which is any pressure above perfect vacuum (0 pressure). In your case it's only measuring manifold vacuum, which is still higher pressure than perfect vacuum.

 

 

You could just have a vacuum leak. Check all of the breather and PCV hoses, and check the other small vacuum hoses for any splits or loose fit. There should be a diagram on the bottom of the hood, follow that to get an idea of where the hoses go.

 

Another thing that causes rough starting, rough idling, or stalling is carbon buildup in the throttle body and intake manifold. Seafoam works great to clean that out.

 

Don't touch the throttle body stop screw. That will just cause more problems.

Its a MAP sensor. It's measuring manifold absolute pressure, which is any pressure above perfect vacuum (0 pressure). In your case it's only measuring manifold vacuum, which is still higher pressure than perfect vacuum.

 

 

You could just have a vacuum leak. Check all of the breather and PCV hoses, and check the other small vacuum hoses for any splits or loose fit. There should be a diagram on the bottom of the hood, follow that to get an idea of where the hoses go.

 

Another thing that causes rough starting, rough idling, or stalling is carbon buildup in the throttle body and intake manifold. Seafoam works great to clean that out.

 

Don't touch the throttle body stop screw. That will just cause more problems.

Are you saying the MAP sensor could be causing this issue, or just pointing out that the module labeled "boost pressure sensor" is the MAP sensor? Thanks for the reply.

JUst an update on what fixed this. A few degree adjustment on the position of the TPS has resolved the issue. Not sure if there was a bad spot somewhere within the TPS, but it hasn't stalled out after starting for the past month now.