I've noticed an issue, I believe it to be related to the tranny. When driving at speeds in the 30-45 mph area, cruising at a steady speed, every now and then the truck seems to hesitate. It's almost like the engine is trying to die, but I take my foot off the gas pedal, and it runs fine. Is this a trans issue, any ideas? It doesnt feel like it's a trans slip, the RPM's have trouble staying up, they try to fall, but only when I have my foot on the gas. I floor it, and it takes a second, then is fine.

Any help would be greatly appreciated.

Bear

 

have you thought about the cat going bad

 

would that cause an intermittent issue, like weeks/months apart? I would go for a cat replacement before a trans repair...LOL It's only happened 3 or 4 times since owning the truck...

 

well its hard to tell without actually being able to take a look at it. but on one of my 97 dakotas, the honey comb inside the cat kinda crumbled apart. the pieces were to big to come out the pipe, and some times while just driving normal they would blow up against the exit if the cat and block the flow. but when i let off the gas it was fine. and when i would put it right to the foor, they would still block some flow but ther was enough exuast pressure that you wouldn't notice it. and depending on the angle that it was pushed into the pipe it might not block that much flow and you wouldn't have the hesitation. so let me know what you find out

 

Most likely the problem is the IAC sensor on the Throttle Body.

Mostof the timeyou can just clean it and re-install or replace it.

More info on your rig is needed before we can give you correct info tho.

Year, Engine, and anything else you got on it?

 

to me, the IAC/throttle body would be an oppositte problem, as I have had to clean these once already. That caused the motor to hesitate or die when I took my foot off the gas, this is a hesitation that occurs at low speeds/low rpm's.

I have a 99 5.2 4x4, the throttle body has been cleaned, the trans fluid is full, and this even happened before any work was done by me. I have added nothing to it other than some injector cleaner, which was after the first incident. To me it seems almost like a trans issue, but I am willing to explore other options. How would I check the cat without removing it? The only reason I say trans, is the nature of the issue. It happens at 30-45 mph, with low rpms, I take my foot off the gas and things are fine. I can return to the fuel, and the hesitation is there, the rpm have trouble staying up. I can also floor it, and return to the low rpm's, and still get the same reaction. It will last for a few seconds to a few minutes, any suggestions will be greatly appreciated.

Thank you in advance,

Bear

 

bear you are right about the iac, it would rev real high if stuck open and if stuck closed it would be hard to start and keep running at idle. so anyway to check the cat without removing it, all i can think of is to get under the truck and bang on it with a hammer and see if you can hear the stuff ratteling.

 

Not the best idea to ruin a CAT.

Most muffler shops will preform a back pressure test for free. They drill a small hole in before the CAT and after to measure pressure. Do a search on back pressure under my name in here.

Could be a TPS, speed, oroutput sensoras well.

Have you done a fuel pressure test yet? [>:]

 

when i say bang on the cat, i don't mean beat it up and dent it to hell and back. i mean hit it with a soft hammer or block of wood to see if anything rattels. and a back pressure test is fine if the cat is full clogged. but in the case i described. it will not work.

 

Bear,

I don't want to give you bad advise. Do you think this is a *trans problem posibly a serious problem*or do you think it might be a smaller problem with the engine stumbling?