motor missing under load only
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Freshman User
Joined: Dec 2001
Posts: 39
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From: South of Austin, TX
motor missing under load only
After doing front end work an old problem came back.
The motor on an 95 AWD 4.0 Aerostar misses once every few minutes when placed under even a small load, ie 55 MPH.
It misses very badly (wont even keep it's speed) when placed under a heavy load of acceleration.
This was fixed last time by changing the mass air flow sensor.
I'm not sure that this is the problem this time. I hope not becuase the part is out of warranty.
How about he throttle position sensor or the oxygen sensor. Could this be a cracked spark plug? There has been no check engine light on at anytime during this present occurance
Thanks in advance
The motor on an 95 AWD 4.0 Aerostar misses once every few minutes when placed under even a small load, ie 55 MPH.
It misses very badly (wont even keep it's speed) when placed under a heavy load of acceleration.
This was fixed last time by changing the mass air flow sensor.
I'm not sure that this is the problem this time. I hope not becuase the part is out of warranty.
How about he throttle position sensor or the oxygen sensor. Could this be a cracked spark plug? There has been no check engine light on at anytime during this present occurance
Thanks in advance
Postmaster
Joined: Apr 2001
Posts: 3,818
Likes: 3
motor missing under load only
Your symptoms sound very much like bad spark plug wires, especially if you hear rattling, pinging sounds associated with the engine miss. This is a very common problem on these engines beginning around 60,000 miles. Replacement is reasonably simple, just remember to replace one at a time and to spend a little more for a good replacement set. (Motorcraft or Bosch). As others will attest, the cheaper sets often lack the correct coil pack connectors and generally do not last much past 30,000 miles.
Thread Starter
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Freshman User
Joined: Dec 2001
Posts: 39
Likes: 0
From: South of Austin, TX
motor missing under load only
It turns out that the connector to the crankshaft position was loose. I was going sensor to sensor spending my way.
First I changed the gasoline filter.
Then, It cost me $200 to find out. $65 for a mechanic to tell me the throttle position sensor was bad, and the oxygen sensor too.
Well I changed them with NAPA parts and SAME problem.
Then I bought a set of plugs - same problem.
Then I bought a fuel pressure sensor - no problem.
Then I checked the Air Temp Sensor - no problem.
Then came the position sensors and a loose connection!
Apparently - hesitation/missing on acceleration is possibly a crankshaft position sensor! But there was NO ERROR code!
