94 Aero rough running
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Joined: Mar 2003
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94 Aero rough running
I have just purchased a 94 Aero with the 4.0 in it. I drove it home about 12 miles and it was pretty loud(needs exhaust). Ut is running rough however and seems to miss at idle. I bought a code reader and get no error codes from the engine.The previous owner said he pressure tested the cooling system to see if the head gasket was blown but it seemed to hold pressure thus he was convinced its not a head gasket. The engine has over 150,000 miles on it. Any suggestions as to where to start first? Or should I just pull the engine and replace it with one from the local junkyard-they have a dozen or more Aeros. I would rather replace it with a 3.0 engine-can this be done easily? I would get the engine ,tranny and computer together(they have one with 23,000 miles).Any help -suggestions would be appreciated.Need this van as baby number four is due in three more months.
Postmaster
Joined: Apr 2001
Posts: 3,818
Likes: 3
94 Aero rough running
First, welcome to FTE and congratulations on being a new Aerostar owner.
You may have stumbled onto a bargain if the price was right. I say that because the 4.0 engines are practically bulletproof internally. With luck and a few simple procedures, you may soon have a nice running van.
Since you really do not know what the vehicle's maintenance history has been and the muffler has been neglected, chances are other things have been as well. Let's start with the simplest and least expensive items.
These engines are prone to idle problems due to either the mass air flow sensor (MAF) or the Idle Air Control valve (IAC). There are many postings in this forum about removing and cleaning these items. Try just cleaning them first. Do a search under IDLE CONTROL or MASS FLOW (each search word reqires a minimum of 4 letters, so avoid using AIR in the search terms).
Spend a few dollars to change the oil & filter if not done recently as well as replacing the air filter and PVC valve. This will give you a good baseline for diagnosing any future problems.
Replacing the spark plugs and wires is always a good idea since you do not know the history. Plug wires especially are known to break down with these high voltage systems. As a new Aerostar owner, your first impression when looking under the hood is "no way". Rest assured, they can be changed with the correct tools.
The plug on the passenger side, furthest back can only be accessed from underneath. A 3/8 in. ,thin wall, 17mm, deepwell Craftsman socket from Sears will allow JUST enough room to get a small breaker bar on. Again, search under PLUG REPLACEMENT for additional information and tips. Install a decent set of platinum tipped plugs to avoid having to do this again soon. A good, single tip, plug runs around $3-4 each, good for around 60-80,000 miles.
When replacing plug wires, do ONLY one wire at a time to avoid getting them mis-routed. Buy a good set of Motorcraft or Bosch wires. There are special clips on these wires and cheaper sets either do not have them or are such poor quality, the clips break while installing them.
A new muffler can be purchased from Advance/Checker/Kragen, etc for around $19.99. Search under MUFFLER REPLACEMENT.
Hopefully these few corrective measures will have you running smooth in a hurry. Post back with your findings
You may have stumbled onto a bargain if the price was right. I say that because the 4.0 engines are practically bulletproof internally. With luck and a few simple procedures, you may soon have a nice running van.
Since you really do not know what the vehicle's maintenance history has been and the muffler has been neglected, chances are other things have been as well. Let's start with the simplest and least expensive items.
These engines are prone to idle problems due to either the mass air flow sensor (MAF) or the Idle Air Control valve (IAC). There are many postings in this forum about removing and cleaning these items. Try just cleaning them first. Do a search under IDLE CONTROL or MASS FLOW (each search word reqires a minimum of 4 letters, so avoid using AIR in the search terms).
Spend a few dollars to change the oil & filter if not done recently as well as replacing the air filter and PVC valve. This will give you a good baseline for diagnosing any future problems.
Replacing the spark plugs and wires is always a good idea since you do not know the history. Plug wires especially are known to break down with these high voltage systems. As a new Aerostar owner, your first impression when looking under the hood is "no way". Rest assured, they can be changed with the correct tools.
The plug on the passenger side, furthest back can only be accessed from underneath. A 3/8 in. ,thin wall, 17mm, deepwell Craftsman socket from Sears will allow JUST enough room to get a small breaker bar on. Again, search under PLUG REPLACEMENT for additional information and tips. Install a decent set of platinum tipped plugs to avoid having to do this again soon. A good, single tip, plug runs around $3-4 each, good for around 60-80,000 miles.
When replacing plug wires, do ONLY one wire at a time to avoid getting them mis-routed. Buy a good set of Motorcraft or Bosch wires. There are special clips on these wires and cheaper sets either do not have them or are such poor quality, the clips break while installing them.
A new muffler can be purchased from Advance/Checker/Kragen, etc for around $19.99. Search under MUFFLER REPLACEMENT.
Hopefully these few corrective measures will have you running smooth in a hurry. Post back with your findings
Last edited by aerocolorado; Apr 18, 2003 at 10:58 AM.
New User
Joined: Apr 2003
Posts: 14
Likes: 0
From: Berwick, LA USA
94 Aero rough running
Is there a place to get a daigram for the plug-wires? I changed mine, and being a newbe, I did one side at a time.. i THINK i got them right, but it got a little confusing at one point... and the van isnt running that great.. however, it was running badly befor the wire change.
Also, I could not get to my driver-side back #6 plug.. i dont have a jointed ratchet arm to get to it. So i left that one in and changed the rest of the plugs and all of the wires.
Anyway, is there a diagram or instructions on making sure the wires are placed correctly.
Also, I could not get to my driver-side back #6 plug.. i dont have a jointed ratchet arm to get to it. So i left that one in and changed the rest of the plugs and all of the wires.
Anyway, is there a diagram or instructions on making sure the wires are placed correctly.
Senior User
Joined: Feb 2003
Posts: 155
Likes: 0
From: Edmonton, Alberta
94 Aero rough running
Here is the diagram for 94 4.0 litre
3 6
2 5 Engine cylinders
1 4
front of vehicle
3 4
2 6 Ignition Coil
1 5
front of vehicle
Firing order 1-4-2-5-3-6
I got this out of Haynes Auto Repair Manual
1986 to 1996 Aerostar
When I replaced the drivers side rear plug (twice so far) I used a 3/8 in plug socket and I had to pull the rachet part way out of the socket in order to clear the other parts. It's a really tight fit. Each time I change this plug I wonder what kind of moron designed this setup.
3 6
2 5 Engine cylinders
1 4
front of vehicle
3 4
2 6 Ignition Coil
1 5
front of vehicle
Firing order 1-4-2-5-3-6
I got this out of Haynes Auto Repair Manual
1986 to 1996 Aerostar
When I replaced the drivers side rear plug (twice so far) I used a 3/8 in plug socket and I had to pull the rachet part way out of the socket in order to clear the other parts. It's a really tight fit. Each time I change this plug I wonder what kind of moron designed this setup.
