Rough idle, low idle

Hi,

Based on your description, it sounds like it may do with the idle air control valve. This item is used to maintain a predetermined idle speed. On most cars it is replaceable. It's different on this vehicle. A separate IAC motor is not used with the 5.7L V-8 engine. The IAC stepper motor, which maintains idle speed, is mounted to the throttle body, and regulates the amount of air bypassing the control of the throttle plate. As engine loads and ambient temperatures change, engine rpm changes.

Now, if you are at idle and turn on the AC or turn the steering wheel, do the RPM's drop lower? Let me know.

Next, have you checked for engine vacuum leaks? A vacuum leak will cause idle issues. It can also cause looping issues at lower rpm's to fluctuate. Here is a link that explains how to locate one:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Let me know.

Joe

Wow, that will cause a rough idle if nothing else. Here are directions for replacement without removing the head. You will need to charge the cylinder with compressed air.

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2003 Dodge or Ram Truck RAM 1500 Truck 2WD V8-5.7L VIN D
Procedures
Vehicle Engine, Cooling and Exhaust Engine Cylinder Head Assembly Valve Spring Service and Repair Procedures
PROCEDURES
VALVE SPRINGS

REMOVAL
1. Disconnect negative battery cable.
2. Remove air cleaner assembly.
3. Remove air intake resonator.
4. Remove spark plug cables.

Pic 1

5. Remove ignition coil connectors (Fig. 6).
6. Remove ignition coils.
7. Remove one spark plug.
8. Remove valve cover.

CAUTION: The piston must be at TDC, and both valves closed on the cylinder to be serviced.

9. Remove exhaust/intake rocker arm shafts.
10. Install spring compressor, special tool # 9065.

NOTE: All valve springs and seals are removed in the same manner.

11. Charge cylinder with air.

NOTE: Tap the top of the valve spring retainer to loosen the spring retainers locks.

12. Compress valve spring and remove valve retainer locks.
13. Release spring compressor and remove valve spring.

NOTE: The valve springs are interchangeable between intake and exhaust.

14. Remove valve seal.

INSTALLATION
1. Install valve seal.
2. Install valve spring.
3. Using special tool # 9065, compress valve spring and install valve spring retainer and locks.
4. Release air charge in cylinder.
5. Remove spring compressor tool # 9065.

CAUTION: Verify that the pushrods are fully seated into lifter and rocker arm. Recheck after rocker arm shaft has been torqued to specification.

6. Install rocker arm shaft and pushrods.
7. Tighten the rocker shaft bolts to 22 Nm (195 in. Lbs.) Torque, using the following sequence: Center, center-right, center-left, right, left.
8. Install cylinder head cover.
9. Tighten cylinder head cover bolts and double ended studs.
10. Install spark plugs.
11. Install ignition coil on plug, and torque fasteners to 12 Nm (105 in. Lbs.)
12. Install ignition coil connectors.
13. Install spark plug cables.
14. Install air intake resonator.
15. Install air cleaner assembly.
16. Connect negative battery cable.

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Let me know if you need anything.

Take care,
Joe