Mechanics

2600I PICKUP DOES NOT RESPOND TO ACCELERATO

1991 Mazda b2600 • 4 cylinder 4WD Manual • 77,000 miles

My pickup has been running perfectly for a week after installation of a new heater core and heater control. When started today (cold, 20F morning) it started immediately, ran the fast idle warmup then cut back to normal idle speed. When I attempted to drive it the engine accelerated to about 2000 rpm but did not have sufficient power to drive the vehicle. More accelerator pressure caused it to barely run, very rough and rich and missing, then stop. Re-starting while warm, it would run smoothly at the 2000 rpm speed but any more accelerator would cause it to choke down and stop as described above. Plugs, wires, distributor parts, air filter and gas filter are new. Gas pressure measured at 35 psi. This is a low mileage (77,000) ranch vehicle but has recently had a few trips on the highway at legal speed. Have disconnected and replugged everything within reach. Suggestions?

PS Since this is a timing chain vehicle the engine warning light has been on since 60,000 miles. Haven't wanted to pay the $150 that the local Mazda dealer charges to turn it off.
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Farrel Lytle
January 26, 2011.



The CEL can indicate various problems and new ones could have occurred so it is best to retrieve the trouble codes and find out the cause.

Here are the procedures for retrieving and clearing trouble codes.

RETRIEVING CODES
TROUBLE CODE ACCESS

1. Engine must be at normal operating temperature. Using jumper wire, ground Green 1-pin check connector. The check connector is on the right side fenderwell, near the fuel filter and the Green, 6-pin self-diagnostic connector.

NOTE: ECU constantly checks for malfunction of input devices. However, ECU only checks output devices for 3-second period after ignition is turned on and Green check connector is grounded.

2. Turn the ignition to ON position. The codes may be read by counting the number of pulses of the Malfunction Indicator Light (MIL). MIL is under the engine symbol marked CHECK in the center of the instrument cluster.

3. The code will repeat or other codes will flash, if more than one is stored. See Fig. 3.

4. If there is more than one code stored, the LOWEST numbered code will be displayed first. Remaining codes are displayed in order from lowest to highest. Refer to appropriate TROUBLE CODE IDENTIFICATION chart for diagnostic procedure.

CLEARING CODES
1. Disconnect negative battery cable. Depress brake pedal for at least 5 seconds. Reconnect battery cable.

2. Ground test connector with jumper wire. Turn ignition on, but do not start engine for 6 seconds.

3. Start engine and run at 2000 RPM for 2 minutes. Verify no codes are displayed.


KHLow2008
Jan 28, 2011.