Engine missing under electrical load
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Engine missing under electrical load
I have an 87 E150 302 FI with AOD transmission. It started hesitating or just barely missing one or two beats upon shifting into drive and starting out nearly a year ago. Now it sputters and misses at least half of the time. At first it was just at low rpm, but now it is at any rpm. I have replaced some sensors and spent over 800.00 at a gold shield station , including a new cat to get it to pass smog. This seems to be a good shop, they said it was difficult to isolate a single problem because the sensors were not getting consistent electrical inputs. I got a new battery and the readings are good, 12.78 v engine off, 11.8 v engine off but all lights, blower motor,, radio on, 14.3 v with engine running. I put on a new ground cable from battery to block, new starter and starter relay, and last year new coil, plugs, distributor rotor and cap, new plug wires.
Could a bad voltage regulator cause the missing, or a bad ground somewhere? If the motor is idling ok, (which is rare, it usually is up and down,) and I turn on the lights, or the heater blower,. or worst of all use the electrically operated door locks, the motor dies. I'm not much of a mechanic, but I will try any advice you guys can give me.
Thanks,
Mike
Could a bad voltage regulator cause the missing, or a bad ground somewhere? If the motor is idling ok, (which is rare, it usually is up and down,) and I turn on the lights, or the heater blower,. or worst of all use the electrically operated door locks, the motor dies. I'm not much of a mechanic, but I will try any advice you guys can give me.
Thanks,
Mike
Cargo Master
Joined: Sep 2012
Posts: 2,112
Likes: 286
From: Eastern TN
The unstable idle with no significant electrical load could be a bad idle air valve or a vacuum leak. The progression of the miss from more load to less load sounds like a tired ignition system (cap, rotor, wires and even coil). Did the shop acquit these guesses? For kicks, hook up a vacuum gauge to the intake manifold and report back what you see when the idle fluctuates. Or check a guide such as in this website - Technical Articles: Engine testing with a Vacuum Gauge - at Greg's Engine & Machine
One thing to try is running the engine from a cold start without the alternator belt. I say cold start because the same belt might drive the water pump. If you have the same fluctuating idle, it's not caused by alternator load. Don't run the engine for very long without the water pump! A minute or so without the alternator shouldn't harm a healthy battery.
Sixto
93 E150 Chateau 5.8 185K miles
One thing to try is running the engine from a cold start without the alternator belt. I say cold start because the same belt might drive the water pump. If you have the same fluctuating idle, it's not caused by alternator load. Don't run the engine for very long without the water pump! A minute or so without the alternator shouldn't harm a healthy battery.
Sixto
93 E150 Chateau 5.8 185K miles
Fleet Owner
Joined: Aug 2005
Posts: 23,668
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From: Easton,Ks
It does not sound like the shop knows how to work on your van year.
You can check out the sensors your self.
Do not through parts at it or you can make the problem worse.
First you need to do the KOEO (Key On Engine Off) electrical self-test to see if all the wiring is good and the all the sensors have normal voltages. This needs to be done on a warm engine.
Then after the KOEO self-test the computer will out-put any codes that it has in storage. These are the CM (Computer Memory) codes.
If you get a 11 code for both the KOEO and the code from CM then you need to do the KOER (Key On Engine Running) Actuators self-test. The KOER Actuators self-test will test all the solenoids and the operation of some of the sensors. Do not run this test until you get a 11 on the KOEO self-test.
If you need information on running these test you can go here:
Fuel Injection Technical Library » How To Run a Self-Test
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You can check out the sensors your self.
Do not through parts at it or you can make the problem worse.
First you need to do the KOEO (Key On Engine Off) electrical self-test to see if all the wiring is good and the all the sensors have normal voltages. This needs to be done on a warm engine.
Then after the KOEO self-test the computer will out-put any codes that it has in storage. These are the CM (Computer Memory) codes.
If you get a 11 code for both the KOEO and the code from CM then you need to do the KOER (Key On Engine Running) Actuators self-test. The KOER Actuators self-test will test all the solenoids and the operation of some of the sensors. Do not run this test until you get a 11 on the KOEO self-test.
If you need information on running these test you can go here:
Fuel Injection Technical Library » How To Run a Self-Test
/
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ChargerOnDavins
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