EEC messin' up?
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New User
Joined: Nov 2004
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EEC messin' up?
I have an 1988 F-150 4x4 with manual transmission. The voltmeter doesn't work or even show any voltage, the truck when under a load, will buck like a mule. It looses power and the does dead but the engine won't shut off. Then it will spit spudder and buck. I ran a code test and found that the MAP senser, TPS, EGR sernser, all have codes. I tend to think that the EEC is messing up. Does any have any other ideas. I still have to test the individual parts to be sure.
Elder User
Joined: Sep 2004
Posts: 941
Likes: 4
Sounds like you have issues with power and ground distribution. Check your battery cables, the chassis grounds, the main engine and frame ground, etc.
Check your actual battery voltage with a hand-held voltmeter with the engine off. Check across the posts, and between the starter solenoid and the engine block. Turn on the headlights and see if the voltage drops. A little bit is OK, but not below about 11 volts. Do it again with the engine at idle. Voltage should stay above 12 volts, and above 14 volts at 1500 rpm or greater.
The sensors probably aren't all bad. It is more likely that VREF is too low, perhaps due to low voltage (or ground shifts) to the ECM, which would throw off the values of all of the sensors at once.
These engines need good quality electricity just as much as they need gasoline. You wouldn't expect the engine to run well on Wizard charcoal starter, nor should you expect it to run with low or unreliable voltage from the battery/charging system.
Check your actual battery voltage with a hand-held voltmeter with the engine off. Check across the posts, and between the starter solenoid and the engine block. Turn on the headlights and see if the voltage drops. A little bit is OK, but not below about 11 volts. Do it again with the engine at idle. Voltage should stay above 12 volts, and above 14 volts at 1500 rpm or greater.
The sensors probably aren't all bad. It is more likely that VREF is too low, perhaps due to low voltage (or ground shifts) to the ECM, which would throw off the values of all of the sensors at once.
These engines need good quality electricity just as much as they need gasoline. You wouldn't expect the engine to run well on Wizard charcoal starter, nor should you expect it to run with low or unreliable voltage from the battery/charging system.
New User
Joined: Dec 2003
Posts: 4
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From: Spokane
Try this...
find where the wiring harnes goes into the ECM (driver firewall i do believe).
Let it idle then grab the bunch of wires leading into the ECM and firmly (BE CAREFUL) wiggle them. If the truck goes into a fit then there's a bad connection in the plug. I haven't corrected the problem yet but i'm currently chasing the same problem.
Tim
find where the wiring harnes goes into the ECM (driver firewall i do believe).
Let it idle then grab the bunch of wires leading into the ECM and firmly (BE CAREFUL) wiggle them. If the truck goes into a fit then there's a bad connection in the plug. I haven't corrected the problem yet but i'm currently chasing the same problem.
Tim
