I had this new minor issue pop up while towing my 10Klb travel trailer this weekend. Whenever I am decelerating down a hill and the speed drops from over 40MPH to 35MPH the engine will stall right at 35MPH. Doesn't do this when not towing. If I blip the throttle right before 35MPH it will idle fine. Engine starts right back up. Truck is an almost stock early 99 with an automatic transmission. Any ideas?

 

Have you had it die on you or hesitate when you are turning a corner from a stop?I am thinking CPS(Cam Position Sensor)

 

Never stalled any other time. I considered the CPS and I have a spare so I might swap that out anyway. It is very predictable over a 300+ mile trip it happened 6 times and always right at 35MPH while decelerating down a hill from a faster speed. Once I figured this out I was able to prevent it by blipping the throttle before I reached 35MPH and then it would drop to an idle. Thanks for your input!

 

Keep us informed if you change anything or find the fix.Take care!

 

Fixed. I pulled the motor to replaced my #5 piston that had a hole burnt in it, and replaced the CPS. Not sure if it was a connection problem corrected during the engine removal/install or the CPS, but I just pulled my trailer 150 miles and had zero problems. Thanks guys.

 

Goahhlee...We normally do not pull the motor to change the CPS.
Glad you got it fixed.

 

Was it knowned then, with the stalling out, that the piston was bad, or developed since the "posting of stalling out"?

 

I put over 10K miles on the truck with a bad piston, (had no compression on #5) that didn't change. The stalling was a new problem. It was wierd because it only ever happened while pulling my camper, and it happened EVERYTIME I decelerated through ~37MPH with the camper attached. ~37MPH is where the transmission downshifts, but no longer stalls... I now pulled the camper a total of 400 miles and no issues, next trip is in a few weeks.

I didn't realize you could replace the CPS w/o removing the motor. Good to know for next time

edit: I just realized I never mentioned the no compression on #5 in my first post, sorry about that!