RPM Jumps around on long drives?
 

Engine acts fine on short trips around town, but now when a trip hits the hour and a half or two hour mark the engine starts to act up. At constant speeds the RPMs will jump around--will jump and 1/8th of the way to the next level then immediatly drop again, it will cycle through this sometimes doing it over and over again--sometimes only occasionally. And will occasioanlly have trouble gaining speed after longer use (2hrs or so), almost like the gears won't shift--may jump to 5000rpms before gears shift. Then after a day or two will act fine again for short trips--any ideas?

2003 64000mi

RE: RPM Jumps around on long drives?
 

Could be alot of things but what I thought of first is an internal transmission problem. You say it happens only on long trips. That makes me think the transmission is overheating and causing your troubles. When was the transmission last serviced? Has the trans fluid even been changed?

RE: RPM Jumps around on long drives?
 

I recently had the 60,000 mile service done, the transmission should have been flushed then.

RE: RPM Jumps around on long drives?
 

Check you paperwork and make sure they did change the fluid.

Also, was that the first time the fluid was ever changed (it should have been done at 30K too)? Many times if the car is older and has never had the trans fluid changed, it's better to leave the old fluid in there. What happens is the oil fluid contains particles of the clutches as they wear and that help keep a worn trans in gear. Draining the fluid and replacing it with new fluid can cause it to start slipping.

RE: RPM Jumps around on long drives?
 

It was in the paperwork as being completed with the 60k service--I'd have to check the prior paperwork for earlier changes, although it has had all the recomended services. If the tranmission fluid change is part of an earlier service then it was probably done then too--I'll have to double check this though.

RE: RPM Jumps around on long drives?
 

The first thought that comes to mind is to make sure they used SP-III automatic transmission fluid. Using ANYTHING ELSE can damage the transmission. Ask the shop (was it a dealer or independent shop?) that did the work what fluid they used. If they used "universal fluid", they messed up and owe you a new transmission because ONLY SP-III should be used in Hyundais.