Stutter or jerk at low throttle?

[bigcanoe]

Today I had a series of shudders or stumbles when driving the car. I was going about 45, up a hill, and I gave it slight gas. I am not sure of gear as it’s an automatic. It has 95k miles and is a 2008 GT convertible. No CEL was thrown and I just ordered a reader to check codes and do some real time monitoring. It did it again, similar, but less pronounced, again under low throttle later. The car had been driven about 15 minutes. I had come to a stop sign. Stopped, turn right onto a 45, going down a hill probably coasting, get to up hill, give very slight throttle to accelerate up hill and it happened. So I think I was coasting beforehand. Otherwise it’s driving fine.

Any ideas what to check or scan for?

 

[Bullitt95]

You could start by cleaning the inside of the throttle body and cleaning the MAF sensor element. This might just solve your problem.

 

[bigcanoe]

Thank you! So far, a few ideas: plugs, coils, fuel filter, MAF/TB, torque converter, transmission, etc.

 

[cbxer55]

Mine does it as well. And every time it does, I just click off the OD and it goes away. It's like the car can't decide if it wants to drop out of OD, or stay in it. I don't really think it's an engine thing, because turning off the overdrive fixes it up quick. I mean, I use the shifter as a hand rest anyways, and my pinkie is usually on the button on the passenger side. So when it does the stutter, I just click it off. Shudder gone. Try it sometime.

Mine is usually in the 40-45 mph range as well, only when going uphill. Flat ground or going downhill, never happens.

I have three Fords with automatics, Lightning, Mustang and Ranger. Myself, as soon as the engine is running, I turn the OD off. And leave it off until speed necessitates it's use. 40-45, my Mustang is much more enjoyable to drive with OD off. More responsive to throttle. Same with my Lightning and V-6 Ranger.

 

[bigcanoe]

Wow thats interesting, I will try that in the same place and see

 

[cbxer55]

BTW, if you were doing 45, it was in OD. Fifth gear in other words. And it was what I call "hunting". Trying to decide if it wants to be in 5th gear, or downshift to fourth. Sometimes, just giving it more throttle cures it. But every time, turning the OD off cures it.

Just because it's an automatic, doesn't mean you can't shift it manually. I do a lot of the time. To me, it shifts too early left to it's own devices. And to me, it shifts into OD too early for my liking. It's all done in the name of CAFE, Corporate Average Fuel Economy. The company as a whole, has to meet a certain MG for their entire line of vehicles. And anything they can do to eek out an extra tenth of a MPG, they'll do.

 

[bigcanoe]

interesting, how do I manually shift it?

 

[cbxer55]

Use the floor shifter on the console to shift it. You have to push the button on the left to move it back from the normal position. Once pushed, pull the shifter back to 1. Watch the tach and shift it to 2 when you feel. Then 3. Then drive. Then OD if you want. Like I said, I usually have OD off unless speed is north of 50 mph.

You're likely better off not doing it if you have to ask. LOL!!

 

[bigcanoe]

Oh, I thought it was something fancy like VW has...I got it

 

[cbxer55]

Anyway, next time you're chugging up a hill at 45 or less, kick the OD off. You'll be glad you did. It's like the car got a swift kick in the azz! As Brad Pitt said in Once Upon A Time In Hollywood, after taking a hit off an acid-dipped cigarette, "And away we go!"

 

[bigcanoe]

Drove again today, nothing major. If I’m cruising along, speed doesn’t seem to matter and I give it medium throttle I feel a brief rumble behind me like the exhaust or trunk area. Then the power kicks in. Still no codes or pending codes on the OBD reader. I will attack the easy stuff then plugs and coils.

 

[John Ainsley]

Mine does it as well. And every time it does, I just click off the OD and it goes away. It's like the car can't decide if it wants to drop out of OD, or stay in it. I don't really think it's an engine thing, because turning off the overdrive fixes it up quick. I mean, I use the shifter as a hand rest anyways, and my pinkie is usually on the button on the passenger side. So when it does the stutter, I just click it off. Shudder gone. Try it sometime.

Mine is usually in the 40-45 mph range as well, only when going uphill. Flat ground or going downhill, never happens.

I have three Fords with automatics, Lightning, Mustang and Ranger. Myself, as soon as the engine is running, I turn the OD off. And leave it off until speed necessitates it's use. 40-45, my Mustang is much more enjoyable to drive with OD off. More responsive to throttle. Same with my Lightning and V-6 Ranger.

I agree with cbxer55. I keep the OD off until I need it. No shudder on mine, just a bit of a drone sound going uphill in New Hampshire mountains with the Flowmaster exhaust system. Maybe the car is asking to put the top down. lol

 

[bigcanoe]

Changed the fuel filter, cleaned MAF and TB today. It ran much better than before afterward. I have plugs but may put them off since the cleaning seems to have fixed the majority of the issue.

 

[Bullitt95]

 

[cbxer55]

Mine drones a bit as well. I looked under it and definitely not the stock exhaust. It's a V-6 and it has three inch exhaust from the cats back, and only two cats. The aft cat is gone along with the o2 sensor. Two 2.5 foot sections of three inch running straight back from the cats. Run into a three inch Y under the passenger seats. Then a three inch pipe curling over the axle to a three inch T. Then two three inch pipes running out to the mufflers. It's not real loud, but sounds good. Only thing I intend to do is four inch tips in place of the three inch tips. Maybe I'll get that done this week.

 

[cbxer55]

I got the fluid and filter changed in the transmission today. The old fluid was definitely not good. It was a yucky brownish color. Won't have time to drive it for a distance til the weekend. But on the drive there and home, the blinking OD OFF symbol didn't return. But, I also didn't hit the OD OFF button either. It usually comes on after using that. So we'll see this weekend.

 

[Bullitt95]

The old fluid was definitely not good. It was a yucky brownish color.

That color suggests burnt clutches and overheated fluid. If you're lucky, there'll still be enough friction material left on the clutches to prevent slippage. You certainly did the right thing changing the fluid and you might have just dodged a bullet.

 

[cbxer55]

That color suggests burnt clutches and overheated fluid. If you're lucky, there'll still be enough friction material left on the clutches to prevent slippage. You certainly did the right thing changing the fluid and you might have just dodged a bullet.

Yah, I am going to hunt for a good transmission cooler kit, so that there is something other than just the radiator cooling the fluid. Both my Ranger and Lightning have coolers hanging in front of the radiator and ac condenser. Part of the "tow" package. I bought the car in November 19, and frankly had no idea if it had ever been done before. Evidently not.

The car drove and shifted fine before the change. I'll take it out for a drive here one day this weekend and see what happens.

I've had my 98 Ranger 20 years and changed the fluid and filter twice, at around 10 years each time. Had my Lightning 10 years and will be doing that here soon. Have a deep pan for it with a 4 X 4 filter and 16 quarts of fluid. Mag-Hytec pan. The pan matches the differential cover. Bought as a matched set.

 

[cbxer55]

Hey OP, you need to change the fluid and filter in your transmission. After doing so yesterday, mine no longer stutters at all. I can drive it around in D with OD on, and it no longer has any indecision about which gear to be in. Also the start from a standstill is much better. Suspect it was slipping.

My fluid was yucky looking and smelling when drained. Kind of a burnt smell.

But anyway, the stupid OD OFF light continues. Comes on after about 10 minutes regardless whether I hit the OD button or not. Shut it off, restart it, comes on after about 10 minutes. But, it drives and shifts without problem. I wonder, changing the fluid in the pan doesn't change or affect the fluid in the converter. Pan is around 50% of the total fluid. SO there could be another 50% still not good. May have to take it to a Valvoline place and have them do one of those things where they remove the lines of the radiator and do a full fluid change, including the stuff in the converter.

 

[Potomus Pete]

Dont be too happy with you new transmission feel. Sometimes a flush can be a flush of death. I have had three auto. trans die after the change. The grit is what helps the bands grab.