Archived Acceleration shudder

[KRStone]

Good evening TDR,

I was driving my '96 2500 CTD automatic down the roadway here outside of town; T/C locked up and in overdrive. I was going 45 or so and pressed the gas pedal to accelerate.



The boost built up quickly from nothing to 17-ish.



The truck shuddered, I let off and it went away. This was an uneasy feeling.



Transmission is serviced every year, had the bands tightened last summer.



Is this a slipping torque convertor? I've heard of it, but never experienced it. The truck has a fuel plate slide but no other power mods. I'm at 200k miles so I'm thinking of injectors- which I will want to be an upgrade.



Does this sound like a slipping convertor and can I order just a convertor and install it myself?



Thanks guys, I want to be careful about driving the truck until I figure it out.



KRS

 

[Sticks]

You said you boost built up, what did your RPMs do?

I also presume that it was just the one time? No other problems with it since then?

 

[KRStone]

No other problems, I re-created it a few times.



I didn't even think of looking at rpms! The shudder was disconcerting.



KRS

 

[Sticks]

If the RPM climb, but the speed does not, then yes, you have transmission issues. If the RPMs do not climb, then something in your driveline is not right. Transmission, 4wd, axle, brakes... Check the smoke as well. If you are getting black smoke and boost climbs, then the engine is fine, just dealing with the load. If the engine is actually shuddering, getting puffs of white smoke, then you have a fueling issue.

The fact that you can duplicate it is a plus.

Start with visually looking at every thing from the transmission back and make sure all is good.

If it is an auto transmission problem, I don't have the experience or knowledge to assist you, but someone will chime in.

 

[tp0d]

With that many miles, I`d investigate the TPS. Not too hard to clean, but expensive to replace (100-200 last i looked). Was it raining when you had the issue?

On my old truck, I had good luck taking my tps off and cleaning it with TV tuner cleaner from radio shack. I also added a mystery switch, which was veryyy handy. I`d strongly recommend it.

-j

 

[Sticks]

12 valves have a TPS?

Been a while and a great many hits to the head since I worked on one in a truck.

 

[KRStone]

Mine is an automatic, and it has the TPS on the injection pump. Never touched mine. I too have a can of contact cleaner and lubricant from Radio Shack.



It wasn't raining when it happened.



Crawled under, everything else it tight and seems right.



As for mystery switch; I have a BD Torq-Loc; and it was engaged. Should be doing the same thing as the mystery switch.

 

[tp0d]

not sure what a torq loc does, but a mystery switch, properly installed, allows the user to -tell- the transmission to stay locked, period. I did mine on a remote wire, so I could hold it in my hand while driving. Didnt mount on the dash. Worked real nice for downhill coasting with a load

Not hard to take the TPS off, and give it a good hose down thru the hole in it that connects it to the throttle linkage. Put the hole facing up, soak her down and let it sit for a bit. Others have drilled holes in theirs, i didnt have to go that far

good luck

-j

 

[KRStone]

Not hard to take the TPS off, and give it a good hose down thru the hole in it that connects it to the throttle linkage. Put the hole facing up, soak her down and let it sit for a bit. Others have drilled holes in theirs, i didnt have to go that far



good luck



-j

But it's adjustable with slotted mounting holes, right? How do you be sure it goes back on exactly right?

 

[KRStone]

Driving home tonight, I recreated the shuddering.



Had the TC locked up, 50 MPH, pushed the throttle down deep:



No white smoke, RPMs went up quickly 100 rpms or so.



KRS

 

[Sticks]

A 100 RPM increase is not all that much a full throttle application.

Sounds like something is binding up.

Does it drive normal if you do the same thing when it is not in lockup?

 

[KRStone]

It shudders much worse if not in lockup, and RPMs shoot way up.



Also, it's not full throttle; not sure I've ever pushed the pedal all the way down.

 

[Missouri Mule]

KRStone, is your transmission in overdrive when you mash the go pedal? On the 5 spd manuals fifth gear/overdrive isnt 'supposed to use for fast acceleration at relativity low speeds, 45 would be a relativity low speed for 5 psd but may be not for an auto. I'm thinking that if your in overdrive the trans mite be trying to down shift to 3rd. Could be your tq acting up.

Did you slide the stock fuel plate forward or did you slide a after market plate forward. Increased hp and quick take offs can take the tq out.

Is there black smoke coming out tail pipe? You mite not git any smoke because your boost is jumping up pretty quick.

As rpms increase is your speed increasing also?

 

[JTruelove]

After I put the the larger injectors in. When I would put my foot in it (around 20 psi boost) then let off, I get a shutter. Is that the same thing your experiencing?

 

[KRStone]

After I put the the larger injectors in. When I would put my foot in it (around 20 psi boost) then let off, I get a shutter. Is that the same thing your experiencing?

No, it's during acceleration.

 

[KRStone]

KRStone, is your transmission in overdrive when you mash the go pedal? On the 5 spd manuals fifth gear/overdrive isnt 'supposed to use for fast acceleration at relativity low speeds, 45 would be a relativity low speed for 5 psd but may be not for an auto. I'm thinking that if your in overdrive the trans mite be trying to down shift to 3rd. Could be your tq acting up.

Did you slide the stock fuel plate forward or did you slide a after market plate forward. Increased hp and quick take offs can take the tq out.

Is there black smoke coming out tail pipe? You mite not git any smoke because your boost is jumping up pretty quick.

As rpms increase is your speed increasing also?

Hey MM,

Yes, it's locked in overdrive.

Back when Dad owned the truck he did the fuel slide. I found the paperwork from a diesel shop, all it reads is "fuel slide". Knowing Dad, it would have been the stock plate.

Black smoke during initial acceleration, then goes away like it should.

RPMs are increasing, yes; they jump a little when it shudders.

KRS

 

[DieselLady]

First the 12v does not have a tps. it has a mechanical linkage to the pump.

second, yes it sure does sound like a torque converter.

With that many miles and those mods. I would put money on it.

 

[HHhuntitall]

If it's a 12v in a Dodge with an overdrive transmission wired for factory harness use, it has an electronic throttle position sensor on the injection pump throttle assembly to monitor throttle postion, so the computer knows how much throttle is being applied. Part number from Oriely's for 94-98. 5 12v: BWD EC3061 - Throttle Position Sensor | O'Reilly Auto Parts



I've seen several that, even with little mods, can cause the clutches to slip when the torque converter is locked up. I'd wager it won't do it at higher rpms, just whenever you're under 1800-2000. Your stock transmission pump can't keep enough line pressure to keep the clutches applied, and they are slipping under the torque of your engine, even with the transmission "Mystery" switch, which, when turned on, opens a solenoid in your valve body to apply line pressure to your lock up clutches. Ever notice how, when the switch is on, you can upshift, but not downshift? The line pressure keeps the clutches locked until the engine rpm falls low enough the transmission pump can't apply enough pressure to keep the clutches engaged, or you disengage it. I'd also wager your transmission is fine, but time and wear is beginning to show in it's performance.....

 

[Missouri Mule]

The 96 Ram has a 47re in it which is a electronic trans. There are several sensors that feed the PCM data including the TPS(Throttle Postions Sensor).

 

[KRStone]

Willing to clean my TPS, but worried about realignment.



KRS