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Experience:  30 yrs,experience shop owner,
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1994 Ford Ranger: Truck snatches and the check engine light goes out

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1994 Ford Ranger 4.0 with the check engine light on. Truck snatches and the check engine light goes out. Also, battery light is on, but charging system is checking out fine. Just replaced the lower intake manifold gasket due to leak.
WHAT IS THE CODE IN THE COMPUTER WHEN THE CK ENGINE LIGHT IS ON
Customer: replied 7 years ago.
512 and 998

OK HERE IS A TEST TO DO FOR THE CODE57

 

Codes:57, 341
Problem:Octane adjust shorting bar has been removed.
Test & Fix:Code 57 or 341 (on vehicles with 3 digit codes) is an informational code indicating that the octane adjust shorting bar has been removed. This shorting bar looks like the SPOUT (timing) connector and is located in the harness, usually near the EEC-IV self-test connector. It was placed in the system by the manufacturer in order to provide capability for a slight adjustment of the ignition timing. If it is removed, the PCM provides about 3 degrees less timing advance under conditions where spark knock is likely to occur.

 

HERE IS ANOTHER COMMON TROUBLE THAT MAY CAUSE THE PROBLEMS YOU HAVE

Tests/Procedures:1. Check for battery voltage on the Red wire at the MAF sensor.

2. If OK, with the MAF sensor plugged in, check for good grounds on the Black (BK) wire and the Tan/Light Blue (T/LB) wires.

3. If OK, check the Light Blue/Red (LB/R) wire that goes to pin 14 of the Powertrain Control Module (PCM) for shorts or open circuit.

4. If OK, replace the MAF sensor.
Potential Causes:Harness
Defective Mass Air Flow (MAF) Sensor
Pigtail - Defective MAF sensor pigtail connector.
Tech Tips:Ford has had problems with the MAF sensor connector

 

 

 

Customer: replied 7 years ago.

Had trouble with MAP Sensor before and replaced both sensor and pigtail. Engine runs fine but has idle that goes up and down. Check engine light will go out while driving. Truck snatches at that time like going into another gear.

IS THAT OCTANE SHORTING BAR IN PLACE?
Customer: replied 7 years ago.
Yes it's in place.

well i hate to say it but with all the different codes you have and all the syptoms , it seems you have a bad pcm

the idle fluctuating up and down is very likley a bad pcm

Ford expert and 7 other Ford Specialists are ready to help you
Customer: replied 7 years ago.
Ok will continue to check it out. Thanks so much for answering me.
your welcome
Customer: replied 6 years ago.
Sean just letting you know my issue with my 1994 Ford Ranger ended up being the computer. We had to replace the computer and the Mass air sensor.
Very good if there's anything else that I can do for you just let me know thank you