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Problem with a rough idle 2003 dodge 4.7l 2 wheel drive.

1860 Views 59 Replies 4 Participants Last post by  immattj, 
Branden.d
I recently noticed a small movement with my drive belt tensioner. A little backstory on my recent issues: I've replaced 3 radiators in the past year. the first probably due to old age, i suspect. The second one and most likely the third one were because I didn't bleed the system correctly or because I bought cheap radar detectors off Amazon. So anyways, recently the truck started to get a little hot due to the third radiator having a leak in the fin just on the other side of the plastic side the top hose is connected to. I still drove the truck until the truck was probably close to having no water in the radiator, and on that day, i think all the radiator water did leak out because the truck then began getting much hotter, probably to the point where you could say definitively it was overheated, and I drove it for idk, 5-10 minutes with the gauge at 65-75%, then the truck started to act weird, so I pulled over and turned the car off and opened the hood. then left for another 2-3 hours with the truck just parked to cool off.



I came back and decided to drive it a bit more after putting some water in the truck. I took it just across the street and then pulled over and added more water to it to get it back to my house. I changed the radiator and thermostat and antifreeze and distilled water, and then I started it to start bleeding the system. I did it for like 2-3 cycles for like 20-25 minutes with the engine running and the heater on and the bleeder screw removed. After I felt like the thermostat was opened, I turned the car off and refilled the system, which only took a little more water.

The next time I turned the car on, it felt like it was idleing rough. I let it run for about enough time to get it running at normal operating temperature, shut it down, and check the water level. I didn't lose any coolant. Then, when I took it around the block, it was kind of rough running, and I also felt some hesitation when pressing the gas pedal. I put it back in the garage, thinking maybe it's possible that overheating the engine could cause the valve seats to get stuck open or closed because I watched YouTube and that was stated in a few videos.

So it very well could be that my motor mounts have totally failed. For awhile, I've been thinking the motor has been sinking a little and also going closer to the firewall and to the passenger side. A visual inspection of the mounts shows very noticable breaks in the rubber but no metal-to-metal contact yet.

But then I noticed as the car was running that the drive belt tension and pulley had a weird motion to them. I took the belt off, and this attached video is of this possible solution.





There is a lot to unpack here, but I would appreciate your suggestions and ideas as to why my car could be running so rough. Just a few more mentionable things:



The lights on the dashboard are pulsing or surging.

-The drive belt tensioner has a forward and backward movement when applying pressure to make the belt loose enough to install it around all the pulleys.

No water was detected within the oil.

and the oil has just been changed since the radiator has been replaced after the rough idle.

- Also took the air intake off and sprayed the throttle body orifice with the T.B. cleaner.

as well as replacing the throttle body position sensor, neither of these two helped the idle issues.

Also, I checked one plug on each side of the engine; the plugs look normal and are gapped correctly; there are no oil signs on the threads or any abnormal burning or discoloration signs. looked normal.

- plugs and coils were replaced about 7 months ago. The air filter was replaced two months ago.

car has been smelling rich for about 2 months now but i let it go for awhile because the car hasn't been showing any other issues other than overheating but that's maybe stopped and I haven't tested it out enough to find out because I think the car is still not running right so I don't want to push it to force the problem to get any worse.

-Car just passed 203k miles, which I regret even thinking about.



Any help is greatly appreciated, and hopefully someone on here can provide me with more information that may help with my truck's problem.


2003 dodge dakota tensionier pully, normal to move such as the video shows. forward and back motion video link because it wouldn't upload on this forum no matter how I tried to shorten the video or make it less resolution.
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oldmarine
I won't attempt to address all the issues you brought up. (I'll share!) Your belt tensioner definitely needs to be replaced. There's enough wobble there that the belt could come off, especially during acceleration or at higher RPMs. Second, if your cooling system continues to overheat, do a chemical check of the coolant to see if exhaust gases are present. Your head gasket could be leaking only between the cylinder and the water jacket, and you won't see evidence of oil in the water or water in the oil. Third, as you said it is smelling rich, buy or borrow a scanner that can read live data in the engine and check your fuel trims - short term and long term. If the total fuel trim for a given bank is more than 10 (i.e., if bank 1 short term is 8 and bank one long term is 9, totaling 17), you have to find what is causing the PCM to feed extra fuel into the engine. Often this is a vacuum leak.
You didn't mention a check engine light or codes. Use the scanner to check for codes and correct as necessary. If you need help on the codes, be sure and state the code exactly -- not what the description says. For example, give the code "P0442" instead of "evaporative emission system problem".
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oldmarine
There's a pretty comprehensive discussion of the evaporative emission system here. There are two possible locations for the purge solenoid, next to the battery or on the firewall. But as far as I know the only location I'm aware for for the leak detection pump is behind the battery and below the power distribution center (underhood fuse box). The OP on that thread provided a good hand-drawn diagram at entry #6, which is a very good reference for the components and tubing.
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oldmarine
I just did some more research on the leak detection pump. The 4.7L engine uses a different pump than the 3.9L and 5.9L (which are the same), and is located in a different place. The few videos I can find on YouTube show that the pump is located under the truck on the driver's side, near the charcoal canister, and is on a bracket bolted to the frame. Follow the hoses from the charcoal canister, and one of them should go to a component with two hose connectors and a three wire connector. That is the LDP.
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oldmarine
That's a vacuum reservoir, used to assist cruise control maintain a steady vacuum source. It's located under the cowl below the windshield on the passenger side. It has nothing to do with evaporative emission controls. I was looking in RockAuto under exhaust and emission to see if anything looked like this picture, and there it was, right under vacuum hose. I guess they couldn't find another category to put it in. ;)

RockAuto is out of stock on that item, so you may want to hang on to it. It may become valuable. :LOL:
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oldmarine
The numbers I was giving were just an example. (Short term 8 + long term 9 = 17). In your video, and I'm assuming this was done at idle, you have a short term about 0 (+ or -) + long term about 15 = 15. Any time the total is more than 10 (or less than -10 for rich conditions), it should be investigated and corrected. The fact that your short term is about 0 is good. That means that whatever is causing the lean condition isn't changing. One thing to check is to accelerate the engine to 2500 rpm and see what the fuel trims are. If the total is less than at idle, it generally means that a vacuum leak is causing these readings. If the total doesn't change much, you'll have to look elsewhere.
I'm glad you included the MAP value on your video, because this may be the source (or one of the sources) of your fuel trim issue. The MAP value of about 4 is VERY low, unless you're at a very high altitude. At 5000 feet, a normal idle reading would be around 8. At sea level, a normal idle reading would be around 12 - 14. A reading of 4, as in your video, could be due to a bad MAP sensor, or possibly the wiring changing the voltage (not an open or a short) going to the PCM.
A bad MAP sensor signal means that the PCM is not sending the right amount of fuel to the engine in relation to the amount of air coming in (measured in part by the MAP sensor). This can cause drivability issues that you described in your initial post. MAP sensors don't go bad very often, but it seems this may be one of those times.
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oldmarine
From the FSM for the 4.7L engine:
The MAP sensor is located on the front of the intake manifold. An o-ring seals the sensor to the intake manifold.

Also from the FSM:
The MAP sensor is used as an input to the Powertrain Control Module (PCM). . . The MAP sensor input is the number one contributor to fuel injector pulse width.
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oldmarine
A value of 4 is definitely incorrect. I included the latter information from the FSM to show that the MAP sensor signal is very important to the engine performing properly. With the wrong information from the MAP sensor, the PCM is not delivering the correct amount of fuel (injector pulse width) to the engine for the conditions, and causing drivability issues -- stumbling, hard starting, loss of power, etc.
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oldmarine
I'd be really interested what your fuel trims and MAP reading is after you changed the MAP sensor. If it was causing the problem, it may take a little while for the PCM to adjust down your fuel trims.
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oldmarine
Spark advance will vary a lot -- PCM regulates it based on RPM, throttle position, engine load, MAP sensor, and various other inputs. On (much) older cars, spark advance was based on RPM and vacuum, so you can see the similarity.

Your short term fuel trim can vary a lot also. When things are stabilized - RPM, load, etc - it will vary only a little. You didn't say what the MAP sensor value was.
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oldmarine
99DakotaNate said:
I'm glad my 99 3.9 has no cruise control, this no vac res. Wish I had an EGR valve though...
Click to expand...
I'm pretty sure you have vacuum powered actuators in your HVAC system though, so you have a vacuum reservoir.
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oldmarine
Branden.d said:
4.1
Click to expand...
Branden.d, if your MAP reading is still 4.1 (that's what it was on the video you posted), changing your MAP sensor didn't change anything. What is your MAP reading with the engine off and key on?
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oldmarine
Just the MAP numbers right now, key on/engine off, and then with the engine idling (which you stated was 4.1).
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oldmarine
Something is wrong with how your PCM is reading (and reporting to your scan tool) the signal from the MAP. With key on, engine off, it should be reading the atmospheric pressure. In Las Vegas, your altitude is about 2000 ft above sea level. So your atmospheric pressure should be in the 27 to 28 range (mine shows 30, but I'm at sea level). Yours is showing 13.6. At idle, with normal vacuum, it should be in the 10 to 12 range. Yours is in the 4 to 5 range. You should also be getting a DTC in the P0105 to P0109 range because of the very low reading. My guess is you have a problem in the wiring or connector -- corrosion, bad wire, etc. -- or your PCM has issues.
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oldmarine
The intake manifold can get a little oily inside because the PCV system pulls oil fumes into the intake manifold. It shouldn't affect the performance of the MAP sensor.

One thing I did notice on your photo of the MAP sensor connector, is that it is gray. The throttle position sensor (TPS) on the throttle body has a very similar connector, same basic shape and three wires. According to the FSM, the connector on the TPS is gray, and the connector on the MAP sensor is black. Is the connector on your TPS black? Is the wiring long enough on both connectors to reach the other sensor? I'm thinking they may be swapped, which would really confuse the PCM.
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oldmarine
A valve cover gasket leaking badly may be the source of the smoke as oil drips on to the exhaust manifold, but it will not affect the MAP readings. Oil leaking out of the valve covers means the PCV system is not even creating enough vacuum to keep the oil from leaking out, so it would not affect the intake manifold vacuum.

As you have already changed the MAP sensor and are still getting bad readings, I suggest you check your 5 volt system used for many of the sensors. If you have a DVM, check your MAP connector as follows: check pin #1 (on the left in your picture) that it has a red wire coming in to the pin, and the voltage at the pin with the key on of 5 volts. Then check pin #2 for a black wire with light blue trace coming in to the pin, and that the pin is grounded.

If you're not getting 5 volts at pin #1, or if pin #2 is not grounded, check the connector for the throttle position sensor (TPS). It's on the throttle body, and the connector is very similar to the MAP sensor connector. On the TPS connector, check that a red wire is coming to pin #1, and that you're getting 5 volts at that pin with the key on. Then check that pin #3 has a black wire with a light blue trace, and that it is grounded.

If you're getting 5 volts at the TPS but not at the MAP sensor, check wiring and connector for the MAP sensor. If you're not getting 5 volts at either connector, check the pins at the PCM. Both the MAP sensor and the TPS are powered (5 volts) from the same wire on the PCM, and both sensors are grounded from the same wire on the PCM. (5 volt power, connector 1, pin #17 on PCM, sensor ground, connector 1, pin #4)

If you don't feel comfortable doing these checks, see if you have a friend who has experience, or invest in the services of a professional mechanic. Be very careful when doing these checks with the key on. Make sure you are contacting only the pins, and only with a DVM (i.e., don't use a test light connected to the battery). Excessive voltage or shorting may damage the PCM.
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oldmarine
On RockAuto, the purge solenoid for the 4.7L is different than the one for the 3.9L. But looking at the pictures of the ones available, you can see that the port furthest from the electrical connector is labeled CAN, which should be where the hose from the canister would connect. The other port should be for the vacuum line going to the intake manifold or throttle body would connect.
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oldmarine
I don't have a 4.7L, and have never worked on one, but researching my references, have come up with a possible explanation.

Is the pooling oil puddle towards the rear of the engine? More on the right side than the left? The PCV system has a hose which runs from the oil filler fitting at the front of the engine to the rear of the intake manifold, apparently very hard to reach and impossible to see. The hose ends in a rubber elbow which fits on to a nipple on the lower rear of the intake manifold. This elbow deteriorates and allows the oil/fumes coming through the hose to spill out. It apparently can also cause a vacuum leak and results in high idle speeds. To check, reach behind the intake manifold, and in the lower center of the manifold see if there is a nipple/fitting there with the hose/elbow attached (or unattached).
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oldmarine
Branden.d said:
I just found out that it's 13.6 key in on position. And the map sensor reads at 5.4 as soon as you start the vehicle then a few seconds after levels out at 5.2.
Click to expand...
I finally figured out why your MAP readings are so much different than I expected. Your scanner is reading atmospheric pressure in pounds per square inch (psi), while mine reads in inches of mercury. The FSM references inches of mercury, and my scan tool uses those same units. 13.6 psi is the same as 27.7 inches of mercury. And that is about the standard atmospheric pressure in Las Vegas (approx 2000 feet elevation). So your MAP sensor was giving good information, just in units that didn't make sense to me. My bad!
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