The engine of my 1996 Dodge 3500 Ram Van, 60000 miles, sometimes “races” under a load, and even once in a while while idling. It’s not a sticking accelerator - it doesn’t pick up speed, just increases rpm for a minute or so, then returns to normal. Any ideas? Thanks.
It can’t “race” under load unless the transmission or clutch is slipping. Are you sure it’s not the cooling fan cycling on and off? Even engine driven fans have a clutch and when engaged, make a lot of noise…
Change the dirty fuel filter and check the fuel pressure under load conditions. The fuel pressure may be “boosting” every once in a while. You’ll need to observe the fuel pressure for several minuets (hours) to determine if it’s SOMETIMES erratic.
Caddyman is correct. If the engine races while you are in gear, but the vehicle does not increase its speed, that would tell us that your transmission is slipping. Since Chrysler’s record with automatic transmissions is not good as their vehicles age, you might want to consider having the transmission checked by a reputable independent transmission shop.
On the other hand, as Caddyman also suggested, it is possible that you are just hearing the radiator cooling fans cycling on for a brief time.
You MAY have a faulty TPS (throttle position sensor).
A broken or loose TPS can cause intermittent bursts of fuel from the injectors and an unstable idle because the PCM thinks the throttle is moving.
Thanks for all replies. The engine rpm are certainly increasing. A slipping tranny would seem to be the answer if it didn’t happen once in a while in neutral, don’t you think?