Engine surges when trying to upshift

[Mike Graf]

My 2005 Monterey, C900, 400HP bucks/surges when trying to upshift. This happens in 2nd, but between 3rd and 4th is the worst. We had it looked at and the boost pressure sensor was not responding properly (p/n 161-1704), and they replaced it. Replaced filters too. Also had multiple codes which they cleared out: PID120FMI1, PID173FMI0, and PID173FMI11. Problem is much improved because now if I stand on the throttle it will upshift. They are now thinking something in the turbo. We have another appointment next week to have turbo checked out, does anyone have any suggestions?

[Dave Atherton]

Mike, is your engine being checked out at a Caterpillar Service Shop or private shop. There a few
things within troubleshooting your problem that is not adding up. In doing the simple things first
engine at idle boost pressure should read zero and the atmosphere pressure sensor reads 14.
Change out of the boost pressure sensor 162-1704 in most cases event code will surface and
102-4 or a 102-7 which will indicate boost pressure sensor. Except both these event codes are
What is called a mechanical problem. Your max boost pressure is 32 psi under load. The jerking
Should be started around 1300- 1400 rpms. It sounds your problem is a fuel related thinking it
Is boost related problem. Dave Atherton Retired Cat Mechanic

[Jim Nichols]

Before going back to the shop to have the turbo checked change out the secondary fuel filter first. When Dave said possible fuel related secondary fuel filter came to mind.

[Mike Graf]

Thanks for the replies. I'll let you know what we find out.