I have a 1998 Dodge Ram Van B1500 with 105K miles driven- great van. I am running into a problem when I am driving usually at about 40mph, but can be in the 50's and 30's, where when I start to climb a hill and so am naturally loosing speed, and before the van shifts into a lower gear to get more power, I get some hesitations where it feels like a super-brief loss of power. It most notably happens then, but can happen when I am not on a grade as well. I will feel it about 4 times in about 10 seconds before the shift to a lower gear takes place (if going up a grade). It doesn't happen every time either, just most times when I try to take it easy on the car when climbing a grade (vs. aggressively climbing a hill by stomping on the gas and shifting it into a lower gear where there is no power issue). It also happens when I very slowly and gently push the accelerator while the car is not under high torque and on relatively flat ground. I have also got check engine lights (non blinking) recently: P1494 - Leak Detection Pump Switch or Mechanical Fault- which may or may not be related. As a summary, this hesitation problem is happening when I slowly push the accelerator while “undergunning” the engine/autotransmission (low rpm for the gear).
I have kept this van fully serviced and in top notch running condition. Just checked plugs and wires- they look flawless.

Any ideas? Huge thanks.

 

P1494 Leak Detect Pumps SW or mechanical fault
Leak Detection Pump (LDP) switch operation is monitored immediately after a cold start, with ambient temperature 40-90 degrees F and engine coolant temperature within 10 degrees F of ambient temperature. DTC will set in Powertrain Control Module (PCM) memory when PCM does not sense a change in switch state when LDP solenoid is energized.
Possible causes are:

• Leak or obstruction in LDP vacuum supply.
• Defective LDP.
• LDP switch senses circuit open, shorted, corroded or defective PCM. The switch connector is a very common problem.

So it seems the code is set at startup, when certain temperature parameters are met - which may be why the dealership said it's ok to drive.

Also, there's a really good article about it HERE.-
http://autorepair.about.com/library/faqs/bl010h.htm

 

For sure check the LPD.

"If" the LPD is fine, take you fist and bang on the CAT. If it rattles like marbles it could be clogged or going bad. About 100K miles, these tend to go bad.

 

Thanks a lot you guys... do you think the check engine light 1494 and the hesitation are related?? Is the possibly faulty switch or catalytic the cause of my tiny hesitations?

 

CE Light.... small puncture in an LDP hose.

Power loss... turns out the plug wires fell onto the manifold and burned through one on the underside (couldn't see it unless wires totally removed).
Misfire DTC's were not coming through PCM and turning on the CE Light (but Dodge was able to find them and they were registering apparently).


Thanks for your help folks... you were on the right track.


Does anyone know where Dodge would have found the misfire DTC's? My OBDII scanner didn't pick up any of them, CE light or not. I'm totally curious where Dodge found them. Does it require a DRB III?