Symptom A
SYMPTOM A. CARBON ACCUMULATIONSYMPTOM "A" APPLICABLE MODELS
All 1992 - 95 929 & 1989 - 95 MPV models with 2.6L and V6 engines.
SYMPTOM "A" GENERAL INFORMATION
If the engine noise is heard when starting a cold engine and decreases after the engine warms-up, carbon may have accumulated in the combustion chamber and on the piston tops. Carbon accumulation reduces the clearance between the piston and the cylinder head, causing contact and noise during combustion.
SYMPTOM "A" REPAIR PROCEDURE
Carbon accumulation can be eliminated by using Top Engine Cleaner. Carefully follow the instructions provided with the cleaner. A recommended induction procedure follows:
1. Operate engine at normal operating temperature then turn the engine off.
2. Locate the canister purge control vacuum port at the intake manifold and attach one end of the feed hose. Use this port for even distribution of the cleaner.
CAUTION:
Mazda Top Engine Cleaner must be fed into the engine through the correct vacuum port and at a feed rate of not less than 1.5 minutes per 5.5 fl. oz (162.5 ML). Use orifice (p/n E5B6-13-986) in the feeding hose. A faster feed rate may result in liquid accumulating in a cylinder resulting in hydraulic look-up and engine damage.
Supply your own feed hose (do not use the engine vacuum hose). Attach a pair of locking pliers (vise grips) to the hose to prevent suction while the engine is cranking.
3. Place the other end of the hose in the can of Top Engine Cleaner and restart the engine.
WARNING:
AN EXCESSIVE AMOUNT OF EXHAUST SMOKE WILL BE PRODUCED IN THE NEXT STEP. USE EQUIPMENT AND PROCEDURES CONSISTENT WITH OSHA STANDARDS TO VENT THE SMOKE.
4. Allow idle to stabilize. Then feed the cleaner into the engine by releasing the pliers and idling up and down (between 1500 - 3000) until 5.5 fl. oz. (162.5 ML) of the can is used. Let the idle drop and the engine should stall. If not, turn the engine off.
5. Let the vehicle sit for a minimum of one hour. Ideally, the chemical's cleaning ability increases the longer it is allow to saturate the carbon.
6. Repeat steps 1 - 4 to flush the loosened carbon from the engine. This time DO NOT allow the engine to stall.
7. Remove the feed hose and connect the original line.
8. Take the vehicle on a test drive. Select a road or highway that will allow you to safely perform full throttle acceleration form a stop. This should be done in a safe manner while observing posted speed limits. Perform standing stop acceleration at least twice in a 3 - 4 mile test drive.
NOTE:
After verifying that the engine noise is eliminated, change the oil and filter, then raise the engine RPM to allow the new oil to circulate through the engine.
MPV PURGE CONTROL VACUUM PORT
929 PURGE CONTROL VACUUM PORT
SYMPTOM "A" PARTS INFORMATION
SYMPTOM "A" WARRANTY INFORMATION
(Applies To Verified Customer Complaints On Vehicles Currently Under Warranty. Refer To The SRT Microfiche For Warranty Terms).