Hey guys got a question about my '95 5.2. So recently my truck started acting weird when driving. When I start it up, it will feel like it is pulsing or shaking at idle and when I start moving it just feels like an earthquake is shaking my truck. When I accelerate to WOT it goes away and accelerates smoothly but as I let off and decelerate the shaking and pulsing returns. Other than WOT this vibration is consistent and it definitely feels like I'm running on 7 cylinders. Spark plugs, wires, cap, rotor, basically everything is new. I just swapped this rebuilt 5.2 in and had no trouble for about 2 weeks. Any advice on where to look? Spark plugs look good and I'm getting good spark to all cylinders. Fuel psi is 44 and compression is also good on all cylinders. Thanks

 

How old are the O2 sensors? I would also have a look at the crank sensor, and make sure it didn't have a bad experience during the engine swap. They are commonly victims of that.....

Could try unplugging the O2 sensor, see if it runs any different.

 

The upstream O2 sensor and the crank sensor is brand new. Went OEM on those parts. What will unplugging the O2 sensor do? Inject more fuel into the engine?

 

Unplugging the O2 sensor just disables it from having any affect on fueling.

Maybe plug wire routing? There is a TSB for that in the 2nd gen ram faq/diy forum.....

What plugs did you install?

 

Okay I'll try that. And I'm using Autolite 3923 gapped at .040"

 

Ok, good choice on plugs.

 

I've been experiencing some misfiring issues myself. Granted, your issue sounds a bit different from my own.

Given that it occurs while idling, you may want to look into cleaning or replacing the IAC valve. Some throttle body cleaner and a paper towel should do the job.

 

Yeah that came to mind too but my IAC is new and my TB is cleaned up pretty well. Anyways it's not much of an idle issue. The rpms don't fluctuate at all it's just I can feel a slight miss when it's idling. When I start driving the misfire is way more prevalent. Could a clogged fuel filter/bad fuel pump cause something like this?

 

Fair enough.

That could definitely be the case. You can see if the injectors are firing by placing a long screwdriver alongside of the injector. The screwdriver acts as a stethoscope. If you don't hear clicking, there's probably something wrong.

Someone on here suggested that I try diagnosing the truck manually. If you turn the key on-off, on-off, and then on again, your check engine light will appear. The light will flash in a series of codes. I ran mine last night and came up with a code 14. I'm going to replace my MAP sensor and see if that does the trick. My truck really only hesitates on acceleration.