2001 Dodge With Rough Idle

Try a cylinder leakdown; a poor valve seat seal can result in misfire detectable at idle and only idle.

How does it run on the road? You say shaky idle? What is causing it to be out of balance? Is it engine harmonics, or out of balance firing- cylinder to cylinder? sine this is a speed density engine, you can rule out vacuum leaks, fuel pressure oxygen sensors and a host of other things. Can you post up a scope capture of the relative compression with an ignition sync on #1 plug with a pressure…

Hello I had a Dodge truck same year same model , engine would shake at idle, like out of balance. It would run great going down the road , no misfire codes, Eventuality found bad intake valve seat on one cylinder head. Used pressure transducer to find it, Then leakdown test on cylinder, could hear air coming out of intake manifold.

It's been awhile since I worked on them, but, I would recommend removing the dist cap and check the rotational play in the rotor, should be close to zero, check it in several places throughout the rotation of the dist. If there is close to a quarter of inch movement, the oil pump drive hear bushing is worn and the bushing and oil pump drive will need replacing.

Right on, David A worn oil pump busing can cause a number of drivability problems on this engine...

I believe the computer fine-tunes the idle speed with ignition timing.

What is the actual idle speed?

Idle speed is around 600

In gear or static? Does the vibration change in gear? Did you replace the flexplate or possibly misalign the torque converter to the Transmission Pump? Minimum air idle spec is 500-900, does the vibration exist at 800 RPM?

The reason I suggest flex plates is there appears to be 2 plates available for this engine with significant counterweight differences.

Jeff- What does "shaky at idle" mean? Is it misfiring(if so, why not say that?) or is it more of a vibration issue? Any codes?

It feels rough. shows no misfires. is a new reman engine. Sitting in the drivers seat you feel that the idle is a little rougher than normal. we all know that even new engines don't idle perfectly smooth but smooth enough that the customer does not notice it. this one is definitely noticeable. and it is frustrating to the customer to the point that it either gets fixed or he is getting rid of it.

vacuum waveform...

If "shaking" means "vibrating" then maybe the guy damaged the torque converter when installing the engine. Unbolt it, and hold it back with a prybar, while an assistant starts the engine.

I have thought about that how ever the ring gear is on the torque converter. I have thought of maybe they damaged the flex plate but that would show up on the wave form of the cam and crank wave form that i did.

What's the idle swing range? How about bad mounts transmitting normal vibrations that are usually absorbed by good mounts? Why was engine replaced?

Is this reman engine from NOW, or is it from a while ago, and only the vibration started NOW. Maybe the balancer spun, if the latter. Otherwise it sounds like the engine is a bad reman.

Hello, Geoff I recall diagnosing the same type of problem on a reman 360 Ford FE many years ago. I forget how I diagnosed it, but it turned out that the rebuilder reground one of the cam lobes on #5 cylinder out of time. Changed the cam, the sun began to shine, the grass turned green, and the bees began buzzing :0)

Surprised that didn't misfire, Gary.

Actually, it just didn't run smooth. I forget whether it was the intake or exhaust that was out of time. But the shop in question had worked on it for a day or two and couldn't figure it out...

Since you stated it was "many years ago" I'm betting the manual running compression test, is how you diagnosed it.

Probably so. And then there was the split overlap test like we used on race engines. On the overlap stroke, each valve lifter should have an equal amount of lift. Of course, that didn't work so well on dual-pattern cams, but on the average it was as pretty accurate way of dialing in timing on stock cams...

The overlap stroke?

Exactly it, Geoff Conventional thinking teaches us that the exhaust and intake strokes are separate events when, in fact, they're one and the same when we're talking about developing maximum horsepower. Keep in mind that appreciable airflow through the valve seat takes place around a minimum of .050" valve lift, When the valve timing on the "overlap stroke" is correct, the intake valve opens…

Still don't understand your statement "On the overlap stroke, each valve lifter should have an equal amount of lift." A stroke is either going-up or going-down movement. Valve lift is measured with a dial indicator (or lasers or whatever) at specific moments, not during movement. I can only guess you were saying to measure the lift at TDC between Exhaust Stroke and Intake Stroke and that those…

Still don't understand your statement "On the overlap stroke, each valve lifter should have an equal amount of lift." A stroke is either going-up or going-down movement. Valve lift is measured with a dial indicator (or lasers or whatever) at specific moments, not during movement. Just my way of saying things because I tend to think of engine performance in dynamic terms. I can only guess you…

Sorry Goeff for the late response this is the second reman engine from now. the other one ran the same. I thought the same thing But was wrong.

Have you done any testing other than fuel injectors? Have you inspected the damper/pulley for cushion failure, or the flexplate for lateral runout? Have you checked crankshaft endplay?

Yes, Dampener appears ok as far as the rubber however i suspect that it may be AM do to the numbers … Being on it. i can not verify it is original. i have searched and those number give me nothing. I did take off the inspection plate and look at the flex plate while running seems to run true.

Does the shake suddenly stop at a certain speed, or does it seem to gradually diminish?

It seems to be at idle only, running it is smooth, Best i can describe is it feels like a vehicle that has dirty injectors i would call it an uneven idle. LTFT at Idle is 3.7 In drive it is 5.0

Hi Jeff: My response is based on your other replies. Look at the screens on the injectors. If you see debris, clean them out and replace the fuel rail. HTH, Guido

I have replaced injectors and check the rail for any rust and debris

HOOK UP A SCOPE AND SEE IF YOU HAVE CRANK FLUCUTUATION, DO YOU HAVE A VIBRATION ANNLIZER change

Jeff, Lots of good advice here to get you thinking. Sometimes as we run into a brick wall we get frustrated and need to step back. We have all been there numerous times in our career. Have you checked to see if the distributor is synced properly? This controls the injector syncing. Back in the day we did it with the DRB or multimeter. It should be in service information. As mentioned a worn…

Dist is sync to 0. dist wear has been checked, i also have ran into problem with AM 02 Sensors. but i dont see a problem with the 02 sensors and i did replace the front one with AM because the oem was a couple days out at the time. never changed a thing when i replaced it.

i do not have a vibration analyzer. i have hook up a scope and got a good wave form of cam and crank. I did not see any amplitude variations that would lead me think there was a problem with either.

How is the compression

Compression is good and even, I don't have a gragh but during the injector balance test with dbr all cylinder seem to drop the same. i have a pico but my son is the pico user i'm just the old school guy and he has been on other things.

I had one of these a while back. if this started after the reman engine was installed possibly the engine builder installed the wrong camshaft which was what I ran into.

Second reman engine is in it. i talked to the original shop that replaced the engine to begin with and he said it ran the same after replacement. He stated he did all he could do and that the driver is just to picky. To me if it was my truck i wouldn't like it either.

Hello, Jeff Simple test: Using a quality vacuum gauge, what does the intake manifold vacuum look like? I don't know what your operating altitude might be, but the engine should be idling at 18"Hg to 22"Hg at sea level. At my altitude of 8,000 feet, most engines idle at 12"Hg to maybe 14"Hg, so prorate those numbers to help determine a normal reading at your altitude. If the intake vacuum is…

"Does anyone else feel this site is hard to navigate i have not used it much. just wondering" - it's aimed at the smart-phone-generation. The main guy told me he thinks of it "as an app" (not like a web site). I don't even own a smart phone, so I much prefer regular web-sites too.

I've only ever used this site from my smart phone, so I'm not sure about any issues from a PC, however , I do find the search function to be a little "clunky". It took me awhile to find the search function, then it brought up a variety of posts. I did find what I was looking for in the end though. �

What about the cover on the bottom of intake. I would like to see your vacuum reading 18-20. This picture is with cover plate removed.

When those covers leak you have vacuum in the crankcase. Pull the oil cap off, disconnect pcv valve and see if you have vacuum there at the oil cap.

Carl, wasn't there a TSB about those plates? Can you remember the symptom/fault that would lead someone to look for it? I only "saw" this issue once and I wasn't doing diag yet. I cannot remember what fault brought the truck into shop.

I have already replaced the Gasket with a metal one and have checked for vacuum at the dip stick tube.

I assume these use knock sensor input to control timing? Noise at idle?

There is no knock sensor on this one.

Need to review how timing advance is controlled.