Need help with rough idle/hesitaion-with a twist

[quadrazer]

Greetings everyone. I've been looking at this forum for some time and I finally decided to register and post a problem I have with my 2002 Ram 2500 4x4 with a 5.9L gas V8 that has 134,000 miles on her. I sure hope someone can help me diagnose this problem, because I'm quite literally stuck on this one.

The short version of the problem is simple....the truck has a horrible idle while in park that rises and drops at random. This happens the instant you start the engine. I can feel the whole truck shake, and the rpm rolls from near stalling to 1500+rpms. When you put it in drive, it stumbles a bit while holding the brake. When you go to give it light throttle...it hesitates, surges and stumbles as it tries to get moving. If you give it a lot of throttle, it will push thru it and go. Driving between 40-50mph while holding a steady speed, the truck will buck hard, and at random. The problem is much worse when cold (meaning first start up/drive of the day) and is not as pronounced when the engine is completely warmed up, but it is still there.

The odd twist of this idle/hesitation problem (and probably the most important part of this issue) is that it clears up completely when I shift to neutral. If it's in park, it idles horrible and stumbles bad when I try to rev it. Then I put it in neutral and she idles smooth at 625rpm, and will rev normally, with no stumble at all! How is that possible?!?

I have done quite a bit work to the truck in the past 2 weeks, due to a blown plenum gasket which was eating oil and killing me on fuel. Here's what I have done so far:
New plenum and intake manifold gaskets
New distributor cap and rotor
New NGK double platinum spark plugs
New spark plug wires

When I removed the intake, I cleaned the inside of the intake very well, and pulled the IAC to clean it and the IAC port in the throttle body. The inside of the intake was filthy when I first took it apart (oil streaked all over the place), so after I had everything clean and put back together, I dumped 2/3 can of SeaFoam into the tank, put in 10 gallons of premium fuel in it, and did a vacuum injection of the remaining 1/3 can of SeaFoam directly into the intake manifold via the PCV vacuum port hose (per the can's instructions). After that tank of fuel was ran thru, I filled up full on premium fuel and have used all but 1/8th of that tank of fuel with NO change at all in the rough idle/hesitation problems. While I had the intake off, I had to remove the distributor due to a broken off distributor cap hold down bolt that happened when I tried to remove the cap. I marked the base and rotor locations prior to pulling it and lined it back up when I reinstalled it.

I am also getting 2 codes with the CEL (check engine light) on. The codes are: P0340 Camshaft Position sensor A Circuit (Bank 1), and P1341 Manufacturer Controlled Ignition or Misfire.

It should be noted that the truck is not using any oil now and the fuel milage has improved, but is not back where it should be. Sorry for being long winded, I just want to give as much info as possible to aid in diagnosis.

Any ideas or suggestions would be greatly appreciated!

Thanks,
Brian

 

[smiley]

I think that camshaft and crankshaft sensors cause issues. I think camshaft sensor is more idle related and crankshaft sensor will cause it to stall if bad. Replace that camshaft sensor and see if that is it. I think it would be the issue. I have seen vaccuum line crack cause similar issues too.


$miley

 

[pavester]

transmission solenoid, take it to a trans shop. it should be a ~$250 fix. i know on my old 5.2 2nd gen it would idle all fcked up and raise and drop rpm like crazy, got the solenoid replaced and didnt happen again...

did the same thing on my 3rd gen too, stalled a few times also...happened to be the egr valve..87000 miles will clog that sucker up good....$35 bucks later it ran perfect

 

[quadrazer]

I think that camshaft and crankshaft sensors cause issues. I think camshaft sensor is more idle related and crankshaft sensor will cause it to stall if bad. Replace that camshaft sensor and see if that is it. I think it would be the issue. I have seen vaccuum line crack cause similar issues too.
$miley

Sorry for the delay in getting back here. Yesterday afternoon, I took my truck to the Dodge dealer to have one of their techs plug in their scanner to see where I was at with the timing (since I had removed and reinstalled the distributor).
Since the truck won't idle steady in park, he checked it while idling in neutral and said I was 8 degrees out of range. I climbed up, loosened the dizzy hold down bolt and adjusted it while he watched his scanner. After it was in range, I tightened down the hold down bolt.....he cleared the codes, reset the PCM, shut off the truck and restarted the truck in park.
It didn't change anything...still idles all over the place in park. He suggested a cam position sensor (based on the codes he pulled from the PCM), but wasn't 100% sure it would be the issue, since it runs fine in neutral. After discussing it for a bit, I decided due to the high mileage on the engine, I would change the timing chain/gear set before I went any further. I asked him if I found the timing chain is stretched pretty bad, would putting on a new timing set throw off the timing setting that we had just established? He said it could, and I should bring it back to him on Monday after I change the timing set so he could recheck where the timing is.

Well, I changed the timing chain/gears out this morning, and man was that chain stretched! I measured almost 9/16 deflection on the slack side if the chain! In went the new set, buttoned everything up, and fired up the engine..........and the problem is STILL THERE!!!

Rough idle, hesitation, bucking, CEL on with the same codes....and now she is sucking gas like crazy! My 5.4 mile round trip to and from the gas station used almost a 1/8th tank of gas! On the plus side, the engine revs a lot faster with the new timing chain set. Since the cam position sensor (and adjusting the distributor) are what sets the fuel sync timing, I can only hope that installing the new timing set is what threw off my fuel timing, causing the poor gas mileage.

So from here, I will take the truck back to Dodge on Monday, have him check (and most likely have to readjust) my timing. If the problem persists after that, I will change out the cam position sensor. Beyond that....I don't know.

transmission solenoid, take it to a trans shop. it should be a ~$250 fix. i know on my old 5.2 2nd gen it would idle all fcked up and raise and drop rpm like crazy, got the solenoid replaced and didnt happen again...

did the same thing on my 3rd gen too, stalled a few times also...happened to be the egr valve..87000 miles will clog that sucker up good....$35 bucks later it ran perfect

A tranny solenoid is a possiblity, as the engine runs fine in neutral (no load on the engine)...but the question is which solenoid? There are 3 different ones in there (TCC, Gov, and overdrive). And since the PCM is throwing 2 codes related to the cam pos sensor, I would hope it's for something related to the sensor itself...or something directly related to it.

As far as EGR...my truck doesn't have one. I believe they quit installing them on the 2nd gen Rams from 96 to 2002. But the symptoms sure would suggest a stuck open EGR!

 

[quadrazer]

Ok guys, here's where I'm at now. I pulled the distributor cap with the #1 cylinder at TDC to verify the rotor points towards the correct mark on the cam position sensor....which it does (which was fun to see with a mirror and a drop light). While I had the cap off, I pulled the cam pos sensor out to check it out. I found that the magnet on it was covered in what looked like small rust/dirt particles. Using pipe cleaners and compressed air, I completely cleaned the magnet until it was shiney again.

I reinstalled everything, reset the PCM, then fired up the engine. Still idles like crap, but the CEL didn't come on right away like it did before. So I saddled up and took it for a 53 mile drive. During that drive, I made 3 different stops for a few minutes each where the truck was shut off each time. The rough idle and hesitation/bucking are still there during light/part throttle accelerations, but she runs good down the highway at 65 on cruise. The entire trip, the CEL never came back on. I plugged in my code reader when I got back, and it was showing a P1391 Manufacturer Controlled Ignition or Misfire as a ghost code (CEL was not on).

This suggests a few things to me. First, I was dealing with 2 problems all along, one being the CEL p0340 code due to the dirty cam pos sensor (which is now taken care of), and the other being the rough idle/hesitation/bucking problems that I still have. As far as the P1391 ghost code, I believe that is due to the distributor timing not being completely in range to set fuel sync, which will be corrected Monday when the dealer plugs in his scan tool to verify where it currently is, versus where it needs to be.

Which leaves me with the origional drivability issues I first posted about. And as pavester suggested, I can't help but think that since the truck idles fine in neutral, but not in park, and runs rough under load, this HAS to be a transmission issue. The question is...where do I begin to look.

Any ideas? And pavester....which solenoid did you have replaced in your tranny?

 

[pavester]

i wanna say the gov solenoid....it was a good two years ago so my mind is a little foggy pertaining to this....i know the name had to do with something pressure related

 

[quadrazer]

The biggest problem that I see in this is really the most confounding:

How could the truck have a rough idle in park, and miss, buck and hesitate at light/part throttle, and buck at random between 40-50MPH.....BUT RUN COMPLETELY NORMAL IN NEUTRAL??

In neutral, it idles perfectly smooth at 625RPM, and will rev just fine with no miss or hesitation.

I also verified my TPS voltage throughout the throttle range and it checked out just fine. CEL is not on. So the question is....what components have no effect on engine/PCM operation when the transmission is in neutral? This seems like a load sensitive problem....and it seems to point towards the transmission (as suggested by pavester). As much as I am ready to just throw in a gov solenoid just for the sake of trying it, I'd hate to be out $100 for a part that didn't fix the problem. So is there a way to make a diagnosis of that part?

Any information from anyone would be GREATLY appreciated! Because I'm no closer to figuring this out than I am when I started. PLEASE HELP!

 

[pavester]

Take it to a transmission shop and have them check it out. I know mine didnt show any cels...would cruise fine, but if i let off the throttle to say slow down to turn into the neighborhood it would start surging and even try to die...happened a few times and i had to throw it into neutral and rev the **** outta it to not let it die

Sent from a bauce ass phone

 

[quadrazer]

Well, I haven't drove the truck in 3 days. Went out and started it tonight, same old idle problem. Only now, the P0340 code came back with the P1391 and the CEL is on. Both of these codes together seem to point to the cam position sensor....again.

I whipped out the old voltmeter and tested the cam position sensor by back-probing the wires at the connector while it was plugged in. It passed according to the specs. The input wire voltage shows 5.1 volts going into the sensor (key on/engine off). The output signal wire shows a pulse between 0 and 5 volts with the engine cranking. Other than the possibility of the signal not getting to the PCM, the only other thing left that I can think of is the dizzy timing is off from when I installed the new timing chain. This will be verified tomorrow when I go back to Dodge and have them plug in there scanner.

I'll post the results from the scan and any other info I get from the Dodge tech tomorrow. I'll keep my fingers crossed that we can find something to aid in diagnosing this problem via the live data from the scanner.

 

[KGBIGCOUNTRY]

Keep us in the loop bud

 

[quadrazer]

Keep us in the loop bud

Sorry for the delay in getting back here. The holiday weekend proved to be more work than relaxation!

I went to Dodge on Friday and had him hook up his scanner. He checked my fuel sync timing, based on where the distributor was set and found it was in range. So much for the easy fix!

After checking what he could with the scanner, we weren't really making any progress. But he did provide me with some VERY valuable information, in the form of two different manuals, both of which were specific for my year/model truck...the Factory Dodge Service manual, and the Powertrain Diagnostics manual. Unfortunately, they are not mine to keep, just on loan to use. Both of these manuals are incredible for information alone, but the Diagnostics manual is a literal step-by-step/how-to book on how to diagnose and repair any codes your PCM throws. So that's where I plan to start today.

Ironically, when I started reading the step by step procedures for the P0340 code in that book (listed as "No Cam signal at PCM"), the very first step has me checking the crank sensor....not the cam sensor. So that is where I will begin today. Thankfully, the books list the pinout locations for every single wire in the PCM harness which simplifies testing for them...as far as checking for voltage, ohms and continuity. My hope is that the problem is either the crank sensor, or a wiring issue, and NOT a seperate problem in the transmission. And, that the P1391 code is tied to the P0340 code due to the same problem. We shall soon see.

I will keep you informed as I get new information. Hope everyone had a great holiday weekend, and Happy Fourth of July!

 

[Bigtman07]

Good deal man. That is some awesome info to have!! Hope you get it all figured out.

 

[quadrazer]

Well...after following the form flow diagnostics in the Dodge Powertrain book in regards to the P0340/P1391 codes, everything checked out fine. Crank and cam sensors tested good, and the related wiring for each sensor both to and from the PCM also tested fine for input and signal voltage, proper ground and continuity. Since the diagnostics take you thru different steps based on your findings to each test, I went back thru and retested every step in the diagrams, to ensure I checked everything possible. My first set of tests, by the book, showed this as an intermittant problem. My second set of tests, using the steps that were not required based on my findings the first time thru, suggested replacing the PCM....which I don't plan to do...except as a last resort.

After checking everything related to these codes by the books, I reset the PCM and started d the truck in 'Park'. Same old problem. She starts right up....idles up for a second or two and then immediately drops RPMs and idles rough as heck with a hunting idle, and trying light throttle gives hesitation/miss. Within 5 seconds or so, the check engine light comes on with both of those same codes.

I then tried something a bit different. I cleared the PCM again and let the truck sit overnight. Went out the next morning, put the truck in neutral and started it up. It started fine, and idled perfect. While it was in neutral, I let it idle for 5 minutes, then revved it up a bit, and let it idle for a minute.....not a single problem, no check engine light, no miss....nothing. Then, I shifted into Park and right away, rough idle and within a few seconds the CEL came on throwing the same two codes.

So....now I'm back to the thought that something in the tranny is causing this. My plan now is to unbolt the torque convertor from the flexplate (flywheel), slide the convertor back a bit into the transmission to get it away from the flexplate, then start the engine with the tranny still in park. I know this will throw some tranny codes since the tranny input shaft won't be spinning, but it should tell me one of two things. First, the PCM will read that the tranny is still in Park, so if the rough idle still is there...it tells me that the problem lies with the PCM. If the rough idle is gone, the the problem has to be in the tranny or torque convertor.

I welcome any thoughts on these tests you guys might have.

 

[quadrazer]

Well, so much for that idea. The ring gear that the starter engages is not on the flywheel, it's on the torque convertor itself. So I wouldn't be able to start the truck if I unbolt it and push the convertor back, because the ring gear goes with it.

I guess I can drop the tranny oil pan and see if I find anything there.

I'm quickly running out of ideas here.........

 

[furhotrod]

Re:, Brian

2000 Dodge ram 1500 V8 5.2 automatic. I am having a very similar problem with my truck. It started today. I was on my way to work when my truck stalled in a McDonald drive thru. It would not start back up. Just kept turning over and turning over. I pushed it out of the way and started to look for problems. I could hear the fuel pump come on, I had gas, no spark. I was thinking coil. But than I noticed the plug wire going to the coil from the distributor cap was corroded. I barley touched it and it fell apart. Anyway, I towed it home. Got all new plug wires, distributor cap, and rotary button. The distributor cap was all ate up inside, there were two points that were cut clean through and the rotary button did not look to good. What gets me is I did this about a year ago, luckily all all these parts where still under warranty, so nothing out of my pocket.

So after I installed the new wires, cap, and rotary button, I gave the truck a crank. It starts now but idles rough. Strange thing is Last year I took a trip to WV and on the way home it did the same thing. It would drive awesome on the highway but as soon as I let off the gas it wanted to idle real rough and wanted to die on me. The whole ride home. But once I got back home, the next day I started it up and was perfect. No idling problems until today and it is the same problem. When I start up my truck it does not idle right. It goes from 800 rpm down to 300 rpm and back up and down,etc. When I put it in gear and take off it spits and sputters but than its fine driving on the highway until I slow down to turn a corner or stop at a light. sometimes it dies but sometimes I hold one foot on the brake and the other foot I feather the gas to keep it running.

I just replaced the IAC (Idle Air Control Valve)
and the TPS (Throttle Position Sensor)
Still acting the same. I read on your post that your truck Idles good in neutral. Not mine. It idles rough in park, neutral, reverse, and drive.
any ideas would really help. and if I figure it out I will let everyone know.
Maybe my problem is something els. Spark plugs? coil? any ideas

 

[raelayotte]

its the TPS

 

[dgallegos23s]

Hey man I was just wondering if u ever found out what the problem was I have a 1999 dodge ram that is doing the same thing and I was reading this and the last thing you say was you were going to check the tranny out was it in the tranny and where so I can fix my thank you

 

[dgallegos23s]

p1391

Hey I have a 1999 dodge ram that I have had for a while I put a new mototr and tranny and all new part on motor I've spent abt 5000 in the truck it run but still can not get rid of a small misfire it throws p 1391 manufacturer ignition misfire and the rpm go up and down when idling and worst when you accelerate

So if anyone has any idea plz let me no I'm lost at this and it getting frustrating