Engine Misses, Lacks Power, and/or Emits a Popping Noise Through Exhaust Manifold on a Deceleration and/or at idle. Saturn Saturn 1992

For 1990-2009 cars

# Engine Misses, Lacks Power, and/or Emits a Popping Noise Through Exhaust Manifold on a Deceleration and/or at idle

Subject: | Engine Misses, Lacks Power, and/or Emits a Popping Noise through Exhaust Manifold on a Deceleration and/or at Idle - SOHC (LKO/L24) Engines (Cut Exhaust Valve Guides)

Models: | 1991 - 1995 Saturn S-Series vehicles equipped with SOHC (LKO or L24) engines

### Condition

Vehicles may miss or lack power under normal engine operating conditions. Also a popping noise may be emitted through the exhaust manifold on deceleration and/or at idle.

### Cause

These conditions may be caused by:

• | Electrical ignition secondary, mechanical or fuel system component(s) malfunctioning.

• | Deposit built-up on exhaust valve guides and exhaust valve stems, causing the exhaust valves to close too slowly during engine warm-up and hot driving conditions.

### Correction

Refer to the following diagnostic charts and service procedures. Begin with Diagnostic Chart on the facing page. The steps in the Diagnostic Chart that contain a circled number (e.g. 1) refer to the notes below. These notes provide additional detail on those specific steps in the Diagnostic Chart.

Notes on the Diagnostic Chart 1:

1. Validation of the ignition secondary is the first, and most critical step in the diagnosis of the misfire condition. Diagnosis steps in this block will validate the ignition secondary on a component level.
2. Carbon tracking on the spark plug porcelain insulator could easily be confused with darkened dielectric grease. To distinguish grease from carbon tracking, clean the spark plug insulator with a rag and solvent such as Saturn Brake and Choke Cleaner (P/N 21007432). Carbon tracking produces gray-black lines that cannot be removed from the insulator.
3. When the ignition secondary shorts (path other than through spark plug) a misfire results. This step checks for the type of ignition secondary system break-down that would result in such a short. To effectively do this procedure, use a 10 percent saltwater solution. Start misting the El module and spark plug terminals a the EL module first, then mist each spark plug wire from the EL module to the plug. Look and listen for spark to jump from any of the ignition secondary components.

Important: After saltwater spray test is completed, engine compartment must be rinsed thoroughly with clean water.

• | If a break-down is identified between either of the coils and ground, replace the affected coil(s).

• | If a break-down is identified at a coil to spark plug wire interface, assure that the wire was assembled with sufficient dielectric grease. If break down continues, replace the suspect wire and affected coils(s).

• | If the break-down is identified along the length of the spark plug wire, replace the suspect wire.

• | If a break-down is identified at the spark plug end, replace the spark plug and/or wire as necessary.

### PROCEDURE

### Cut Exhaust Valve Guides

Important: For the following procedures, refer to "SOHC (LK0) Cylinder Head" section of the 1991-1994 Engine Mechanical Service Manual or "SOHC (L24) Cylinder Head" section of the Engine/Fuel/Air Intake/Exhaust Service Manual, depending on your vehicle.

1. Remove cylinder head assembly.
2. Remove complete rocker arm assembly and all hydraulic lifters.
3. Remove and discard exhaust valves, and seals. (Reuse exhaust valve springs, caps, keys and hydraulic lifters. Do not remove intake valves, springs or seals.)
4. Clean carbon and varnish from the inside diameter of all the valve guides using a metal or nylon valve guide brush driven by an electric drill and solvent.
5. Using Saturn Valve Guide Go/No-Go Gauge (J43120), measure exhaust valve guides.

Notice: The (Go) green and of gauge should go through entire length of valve guide with light and uniform pressure. Use of excessive force will result in tool and/or guide damage.

- Insert Go (green) end of gauge into valve guide from either the combustion chamber side or the camshaft side.

• | If gauge passes through guide with light and uniform pressure, proceed to step b.

• | If gauge passes through guide with light and uniform pressure, clean guide again as in step 4 and report guide measurement. If gauge still will not pass through guide, refer to the appropriate model year Saturn Engine/Fuel/Air Intake/Exhaust Service Manual for valve guide repair and/or replacement procedures.

| Notice: The No- Go (red) end of gauge should NOT enter either end of valve guides. Use of excessive force will result in tool and/or guide damage.

- Attempt to insert No-Go (red) end of gauge into both ends of valve guides.

• | If gauge does not enter either end of guide, then guide is within correct specification for diameter, straightness, and roundness.

• | If gauge enters either end of guide, the guide is oversized beyond specifications. Refer to the appropriate model year Saturn Engine/Fuel/Air Intake/Exhaust Service Manual for valve guide repair and/or replacement procedures.

1. Please cylinder head, with combustion chamber side facing up, on 2 x 4 wood blocks on the shop floor or suitable workbench.

Important: Review the following information before using the SA9704E, Valve Guide End Mill Cutter W/Stop Collar:

• | Use a 1/2 horsepower variable or low speed electric drill motor,

• | Use SOHC (blue) plastic stop collar,

• | Stop collar must be located so that the set screw aligns with end mill groove,

• | DO NOT cutting fluid,

• | Use drill speed of approximately 500 rpm.

• | Apply pressure straight onto valve guide,

• | DO NOT side load tool during operation,

• | Some smoke may occur during the cutting process, (this is normal and tool life is not affected).

1. Using service tool SA9740E (Valve Guide End Mill Cutter) with SOHC (blue) plastic stop collar, cut the exhaust valve guides from the combustion chamber side. The plastic stop will make contact with the valve seat when the end mill has completed the specified amount of guide removal (approximately 10 mm [3/8 in.]). (Refer to illustration.)
2. Clean the valve guide debris, created from the cutting operation, from the cylinder head with solvent.

Important: Do not use a reamer as a cleaning tool. Machine/drill driven reamers typically need a minimum of .0762 mm (0.003 in) material cut to operate correctly and to create the desired surface finish. Attempting to use a machine/drill operated reamer without removing material may cause the reamer to bind, will burnish/smear instead of cutting the guide material and will result in decreased tool life.

3. Clean carbon deposits from the valve seat surface with solvent and a 3M Scotch-Brite Fiber pad (or equivalent).

Important: Some carbon deposits and minor pitting on the valve seat is normal. If deposits pitting is excessive, valve seat refacing or replacement should be performed by a qualified machine shop.

4. Install new:

• | Exhaust Valve Oil Seals (P/N 21006516 - 1991-1994 LKO engines or P/N 21006515 -- 1995 L24 engines)

• | Exhaust Valve (P/N 21007040)

1. Install cylinder head assembly.
2. Verify the condition has been repaired by:

• | Start engine and increase engine speed to 3500 rpm.

• | Hold engine rpm at 3500 rpm for approximately 30 seconds.

• | Release accelerate, allowing engine to return to idle rpm and observe for engine miss or propping noise. It may be necessary to repeat this step throughout the entire engine warm-up cycle until normal operating temperature of 88° C (190° F) is achieved.

### Parts Requirement

P/N | Description | Quality
--- | --- | ---
21008324 | Gasket Kit - Cylinder Head (91-94 LKO) | 1
21007332 | Gasket Kit - Cylinder Head (95 L24) | 1
21007040 | Valve - Exhaust | 4
21006516 | Seal - Valve Stem (91 -- 94 LKO) | 4
21006515 | Seal - Valve Stem (95 L24) | 4
21024468 | Wire Asm - Splg # 1 Cylinder | 1
21024469 | Wire Asm - Splg # 2 Cylinder | 1
21024470 | Wire Asm - Splg # 3 Cylinder | 1
21024471 | Wire Asm - Splg # 4 Cylinder | 1
16167763 | Coil Asm -- IGN | All Required

### Claim Information

To receive credit for this repair during the warranty coverage period, submit a claim through the Saturn Dealer System as follows:

Case Type | Description | Labor Operation Code | Time
VW | Cut Exhaust Valve Guides | T9730 | 7.1 hrs
Add: | A: With A/C | 0.5 hrs
| B: With P/S | 0.3 hrs
| C: To install rocker cover gasket, if necessary | 0.3 hrs
| D: Misfire Diagnosis | 0.5 hrs