8

When I put my truck in drive and step on the gas the RPM's go up to 3,000 but my MPH will stay at 10-15

When I let go of the gas a little bit I can feel the truck kind of pull and the RPM's will go back to 1000 -2000 and my MPH will start going up.

Can someone help me?

  • Have you checked your transmission fluid to ensure it has enough? – Pᴀᴜʟsᴛᴇʀ2 Jan 28 '16 at 19:42
  • Yes I did and I put in more – Erik Jan 28 '16 at 19:45
  • When you put transmission fluid in and it's low, after you run the engine with it in gear it can pump a bunch of air out of the system and then you are low again. Try filling it, running it and putting it in various gears to drive air out, then filling it again. Wash rinse repeat that until the level is correct and see if you still have the issue. Hope this helpful and good luck. – DucatiKiller Jan 28 '16 at 20:15
  • Hopefully this is the case and you resolve it! come back either way and let us know what happens. We can discuss next steps if it's still doing it. Good luck! – DucatiKiller Jan 28 '16 at 20:28
  • While I agree with @DucatiKiller's method of filling the transmission, it is of note you do not want to overfill the transmission. If it is over filled, greater pressures are exhibited and this will blow your seals out (front/rear). Your vehicle and transmission must be fully warmed up when topping off the transmission. If you do it cold and fill it up, it will be over full when completely warmed up. Pay attention when filling it up as this is very important. – Pᴀᴜʟsᴛᴇʀ2 Jan 28 '16 at 23:20
2

Given the description of the problem, I think the comments are exactly right, this is an issue with your transmission. Now you need to determine if it's just fluid level, or if there is something more serious going on.

Couple of things you can do, first, follow the instructions in the comment by @DucatiKiller. That will get you into the proper fill level. If the problem does not go away, pull out the transmission dip stick (please tell me you have one) and see if the fluid is a nice bright red. If it's getting dark or if it smells burnt, then you have a bigger problem internal to the transmission.

One other thing you can do, is look at the data from the OBD II port. If you have a scanner, many modern cars include the temperature of the transmission fluid as a data field from the OBD II port. You didn't mention what year your SUV is so I don't know if it will have it.

Another test is to move the gear shift level yourself. Does it shift right away? If it does, then maybe you have bad vacuum lines to your transmission. Basically there's two pieces to this, the transmission needs to know when to shift, and it needs to be able to shift. The vacuum lines are part of how it knows when to shift. If they are cracked, you can get what you are seeing. Sadly the pull might be saying that it's not vacuum lines, but the transmission internals. But, that's not 100%.

Things to look at:

  • What year is your SUV?
  • What are the results of getting the fluid level to be correct?
  • What is the operating temperature of your transmission fluid as seen on your OBD II scanner?

(Btw, if you don't have a scanner, and do have a smart phone, you can buy a $15 or $20 Bluetooth dongle that plugs into your OBD II port and talks to a free app on your cell phone. No need to spend almost $100 on a scanner.)

I hope that helps!

  • The transmission will be a 4L60E unless they've done some aftermarket work on it ... true for both 4x2 and 4x4 Yukons. I don't believe they made any 2500 Yukons, unless this is actually a Yukon XL. A Yukon XL 2500 might have come with a 4L65 or 4L80 transmission. Yes, the year of the vehicle would definitely help here. – Pᴀᴜʟsᴛᴇʀ2 Jan 28 '16 at 23:23

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