I have an '03 ram 1500 4x4 with a 5.7 and a 545rfe transmission. When it hits 5th and at about 1500 to 1800 RPM the trans "hiccups". It's like it's trying to fall on its face. When I take it out of o/d it does fine because it's above 2k RPM. But even if o/d is off and the RPM hits the 1500 - 1800 mark it still hiccups. Any ideas? I'm stumped here. I don't even know where to start. Oh, there are no codes. None. Im not very well versed in automatic transmissions. So, even a starting point would be helpful.

 

What do you mean by "hiccups"?? Is it gear hunting??

 

No, it isn't gear hunting. It will be in gear, but when the RPMs reach about 1500-1800 it stutters. Like, maybe the engine momentarily lost power. Now, it may be that the problem is the engine as the RPMs do not go up when it does it. If you've ever experienced when a ring and pinion begin to go out, it is very similar to that feel. That feeling when the teeth start to skip. However, unlike losing a rear end, this only does it at the 1500 to 1800 RPM area. It won't do it when I put it in 2nd or 1st. It's almost like the more load you put on it the worse it happens.

 

Sure its not an engine misfire at low RPM????

 

after reviewing the matter, you have a very good point. I may have a coil or two going bad. But wouldn't the misfire set off a code?

 

Is the check engine light on? And if it was were you able to pull any codes. How is the transmission shifting?

 

No, no codes. The transmission is shifting fine otherwise. I think HeyYou may be on to something. The greater the load (higher gear) the more pronounced the stutter. It isn't a violent stutter or hiccups, but just enough to let you know it's there. Additionally, it's worst if I'm pulling a hill. The RPMs don't race as it stutters, and that is why I think HeyYou may be on to something. What I thought was the transmission may actually be the engine misfiring. The only mystery is why it wouldn't trigger a code. Fuel mileage is in the gutter. Somewhere around 9 mpg. I gapped the plugs at 45 and the coils all seem to be firing okay. Just at a loss.

 

Oh, I forgot to add, every 10 to 15 start ups it has an extremely hard time starting. It will turn over and catch but not start. I have to use throttle to get it to start. And, even then, there are times it just doesn't want to start. I ordered new injectors that should be here in a day or two. I'm hoping things will improve with them.

 

Have you check fuel pressure too? Should be 58 + - 4 PSI. Replace the spark plugs too with Factory champion plugs.

 

My wifes Durango lead me on a wild goose chase for better part of 3 months. Shed come home tell me car was bucking when driving. I'd go drive it, nothing abnormal. Finally it started RPM hunting every so often but nothing definite. I had a used Tcase put in a couple years ago so I started to look at that but nothing weird there. Started to think trans stutter, I had a friend of mine drive with me he suggested misfire, but it had never triggered a check engine light. Long story short over a few weeks of changing coil packs (plugs only had 40k on em) I decided to pull a plug and to my surprise these 40k plugs were out to over .085" gap. 6 new plugs and its been smooth as glass since.