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Discussion Starter #1
Dodge dakota 5.2l 5 speed manual

Hi I am having problems with a bucking feeling when I expecially am using cruise or keeping the throttle steady like on the highway. Very hard to exprience around the city but mostly always once and a while on the highway. It feels exactly like the feeling of driving in 2nd gear letting off the gas and quickly jabbing the gas makes the truck jerk and buck. I replaced the plugs, wires, cap and rotor and coil. Also checked for codes and nothing. Looked at the tps and it shows .67v blades closed and 3.7 fully open.

Thanks for any help to where to start looking
 

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Check EGR. It is still possible the TPS is acting up. It is possible to not have a CEL with either EGR or TPS not working properly. Good luck.
 

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Discussion Starter #3
sry forgot to put the year

98 dodge dakota 5.2l. Yah i dont have a egr valve. So that makes it easy I dont have to worry about that..
 

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Discussion Starter #4
yah still no luck. I even bought some gasline antifreeze since its cold here an it did not seem to help it.
 

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check your plugs, wires, rotor and cap, one of them might be the problem.
 

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Platinum 2K R/T
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Replacing the TPS should solve the problem and is rather a cheap part to replace if you do it yourself.

My original TPS acted up on a 3hr drive back from Oxford MI a few years ago. It was worse with cruise control engaged, even more so on level roads, the rpms would jump around making me think it downshifted to third - very annoying and commonly misdiagnosed as a transmission problem.
 

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work in progress
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another thing it could be is your od unit on the tranny if the planetary gears are bad they tend to bind up under load and cause bucking and will go away when you downshift or turn off the od mine was doing this just before it started slipping and i changed it out
 

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You could also have moisture inside the distributor, wires, even the plugs. Did you degrease the engine recently? Just making other observations to rule out.
 

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Discussion Starter #9
i just replaced the coil wires plugs cap and rotor. But I will try the tps. Because it mostly does it when u are barly pushing on the gas and at a steady pace, expecially cruise control. I measured the tps and it is at .76 volts idle and will only reach 3.8v max wot.
 

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Keep us updated with what this problem is. These magnums as you know are really picky with many things.
 

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AirFuelEddie
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Too bad you dont have access to a scope. The TPS would be easy to detect showing a 'flat' spot on the potentiometer. Have you tested the injectors for Pulse width? A DVOM set on Ms,(milliseconds), and hooking the red lead to the injector's power wire and the black ,(COM), lead to a suitable ground. Turn the warmed up engine on in neutral, and observe the idle RPM's Milliseconds reading. It should be around 3.0Ms or so. Now rev the engine to 2000 RPM's,(NO LOAD) it should read approx. THE SAME(Test each injector at the connector, dont break the insulation on the wire, backprobe with a thin pin), if not, an engine sensor is at fault. The TPS can also be checked for proper resistance it should sweep gradually with no spikes. If there is a spike detected then the resistance will be much higher at that point. If all these things 'check out' I would look at the VSS next.(vehicle Speed sensor).
 

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Discussion Starter #12
okay the tps didnt solve it but it did make the truck seem to rev smoother and it does seem the drive better. But never helped the problem on the highway bucking and shaking. But I did notice the idle even before the new tps the idle goes to 600 and wait a few seconds and the throttle will blip about 50, 100 rpm and it shakes the engine pretty good. Even heard the tranny jump around ( gears, clutch felt it in the shift knob) from the quick rpm jump. It just does this 2-3 times idling, then it runs smooth with the odd surge but ever so slight. I would say that idle jump if the truck was in gear on the highway would be the exact symptoms. So i wonder if the miss or abrupt idle jump is related to the highway mess I have??

Thanks for the help so far guys !!!
 

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Discussion Starter #13
okay just found out and used my obd tester and it is a missfire. But not a hard code to start the engine light. P0300 multiple missfire and separate missfire codes for cylinder 1, 5, 6.
 

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AirFuelEddie
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How many miles are on the engine? If there are over 75k an injector cleaning might be in order. If you have access to a scope the waveform for each injector opening event, then freeze frame that event will tell you if the injectors need cleaning,(the waveform will be erratic at the opening, then follow a normal pattern, until seated). If you dont have access to a scope,(Chrysler DRB, Snap-On AVR, ect), then the cleaning might help.
 

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Discussion Starter #15
okay ill try the cleaning too. But I also tried the trick with pulling off the plug boots while the engine is running. And 1 5 6 cylinders dont change when i pull the boot off. Even tried other cylinders but they change to way the motor runs. So i guess maybe the ngk fr5-1 plugs went south on me? I just change the plugs not too long ago too. And nope dont have the scope. Anyway to test with a fuel pressure tester?

Truck has 126000km

thanks for all the help
 

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AirFuelEddie
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More importantly, is fuel volume. Many tests show the pressure fine but the volume is faulty and keep up with the fueling demands of the engine under load. I like the OTC or Snap-On fuel system tester which measures fuel volume and of course pressure. Keep us posted
 

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Discussion Starter #17
okay so far i tried all u have said to try and i just did the IAC valve. So i still have these symptoms:

Only when warm:

1. idling give it gas revs up but tries to stall when it reaches idle surges a couple times and stays relatively steady at idle.

2. Occasionally there is a quick 100 rpm idle jump outta know where like a burp or hiccup in the engine.

3. Cruising around stopping at a red light engine surges 2-3 times and quits and runs smooth again.

Now im pretty sure that quick idle hiccup is what is causing the problem on the highway. Sure seems the same feeling just not as bad cause it is only at idle. One website I found was

http://dodgeram.org/tech/gas/Trouble/Problems.htm

There is has a bulletin on checking your battery and the ASD relay. I looked at the relay and all i can see is at the relay terminals it is 11.8v and the battery is 12.8??? But otherwise the relay tests out and i even changed relays when the engine was acting up and still the same. But the battery i dunno it does have 14.2 volts. But one thing I tried is #1 rev it up and tries to stall symptom, but i disconnected the battery negative and instead of it trying to stall and surge a couple times it stalled completely. So maybe a problem with the battery?? Maybe i will change the negative post connection.

Thanks for reading this long book
 

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Just a quick thought have you looked over all the ground wires? A bad connection could be causing some of it. Also a bad spark plug is not unheard of. The plug wire routing could also be a cause or a vacuum leak somewhere.
 

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Discussion Starter #20 (Edited)
fuel filter i dunno when it was last changed, but like i hope its the problem because i hate to drop the tank for that. alos i checked the fuel pressure and its right where it should be at 46 And plugs no i just changed them all and rerouted the wires too. So that should be good. Vacuum leaks i kinda looked around didnt see anything around the motor. Checked vacuum and it is at 16hg. Ill look at the grounds today and rule that out.

But thanks for replying
 
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