engine miss, # 4 misfiring & running rich.....................
Senior Member
Joined: Mar 2004
Posts: 243
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From: Virginia Beach VA
you could have gotten a bad coil pack for #4 even thought you said it was changed to a new one. switch the wires to another cylinder and see if it still does it. if the problem moves to the new cylinder thats the problem.
Senior Member
Joined: Feb 2004
Posts: 146
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From: Bailey, CO
Sorry I couldn't get back to you this morning.
Based on what happened to me when I changed my injectors it sounds like you have an electrical problem with the signal to the injector.
Check to see that the connectors are all tight, especially the connector on cylinder #4, which should be the front cylinder on the passenger side.
With with your ear placed on a long screwdriver on the injector listen to see if you hear a clicking sound indicating that the injector is operating.
The speed of the clicking should increase with the speed of the engine.
If the injector is not operating purchase a noid light and install it into the injector connector. Start the engine and check to see if the noid light flashes. If it does the inector receiving proper voltage.
If it doesn't further diagnoses may be necessary. The insulation on the wire may be cracked or melted and the wire is shorting out.
When the connectors are not tight, even on one injector, the engine will run rough and rich.
When you solve this problem please post the results so other people don't have to suffer through 8 months and $2000 of misery.
Thanks
Bob
Based on what happened to me when I changed my injectors it sounds like you have an electrical problem with the signal to the injector.
Check to see that the connectors are all tight, especially the connector on cylinder #4, which should be the front cylinder on the passenger side.
With with your ear placed on a long screwdriver on the injector listen to see if you hear a clicking sound indicating that the injector is operating.
The speed of the clicking should increase with the speed of the engine.
If the injector is not operating purchase a noid light and install it into the injector connector. Start the engine and check to see if the noid light flashes. If it does the inector receiving proper voltage.
If it doesn't further diagnoses may be necessary. The insulation on the wire may be cracked or melted and the wire is shorting out.
When the connectors are not tight, even on one injector, the engine will run rough and rich.
When you solve this problem please post the results so other people don't have to suffer through 8 months and $2000 of misery.
Thanks
Bob
Technical Article Contributor
Joined: Oct 2003
Posts: 1,490
Likes: 0
From: Topeka Kansas
Originally posted by rustysgirl
excuse me? not it's not a put on. I am not a mechanic. we have been messing with this truck for 7 months. $2000 parts & labor later, still the miss. My mistake it runs RICH! the #4 plug is soaked, when they took it out & changed the plugs & wires for the second time. the # 4 plug is always soaked with gasoline, which means it's running rich. Now if you can tell me why it is running this way, maybe I should ask you (to the person that ask me if this a put on)......................if you tell me what the problem is, I should ask you is this a put on? I'm asking for advice not a smart remark.
excuse me? not it's not a put on. I am not a mechanic. we have been messing with this truck for 7 months. $2000 parts & labor later, still the miss. My mistake it runs RICH! the #4 plug is soaked, when they took it out & changed the plugs & wires for the second time. the # 4 plug is always soaked with gasoline, which means it's running rich. Now if you can tell me why it is running this way, maybe I should ask you (to the person that ask me if this a put on)......................if you tell me what the problem is, I should ask you is this a put on? I'm asking for advice not a smart remark.
Last edited by temp1; Aug 3, 2004 at 09:15 PM.
Technical Article Contributor
Joined: May 2004
Posts: 6,509
Likes: 6
From: Georgia on my mind...
What plugs are you running in it? Pull all the plugs and recheck them. 4.2s use two different types of spark plugs, one side of the ignition fires from the positive side, the other fires from the negative side. It's common for do it yerselfers or other's less than informed to run out to PepAutoBoysAdvanceZone, buy a set of Bosch Platinums that have the incorrect grounding electrodes, slam 'em in there and call it done. Then everyone wonders why they start running weird. I think the latest Motorcraft number for the correct plug is AGSF-34-EE. The 34-EEs can be run from either side of the engine.
Edited to add:
Also, just because you're seeing a #4 misfire doesn't mean that #4 is the problem. DIS ignitions fire two cylinders at once. A fault in the companion cylinder, that is, the cylinder that's fired on the exhaust stroke opposite to the one fired on the power stroke, can manifest itself elsewhere. Companion cylinder to #4 is #3; verify that there aren't any obvious problems there as well.
We need to start looking at things like injector pulse width, O2 voltages and fuel trims next.
Edited to add:
Also, just because you're seeing a #4 misfire doesn't mean that #4 is the problem. DIS ignitions fire two cylinders at once. A fault in the companion cylinder, that is, the cylinder that's fired on the exhaust stroke opposite to the one fired on the power stroke, can manifest itself elsewhere. Companion cylinder to #4 is #3; verify that there aren't any obvious problems there as well.
We need to start looking at things like injector pulse width, O2 voltages and fuel trims next.
Last edited by Quintin; Aug 4, 2004 at 10:30 PM.
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Member
Joined: Jul 2004
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I would like to thank everyone here for your help. Sorry about the post earlier. But this truck is driving everyone involved nuts. Ok. I'll , if you take the wires off the coil pack & hold them up one @ a time, they all have a nice long spark that pops & crackles & is blue, except the #4, which is about 3" & yellow. Second set of plugs & wires (Motorcraft). Didn't do a thing for it. Bad coil pack? This is a new coil pack I might mention. My husband is going use a ohmmeter & test the damn thing. We've had this thing to FORD 3 times & they hook it up to a dyo machine & swore it was plugs & wires. 
I don't smoke, but I just might start or just light the end on the stick of dynomite & drop it in the gas tank of this thing. Thanks again guys.
I don't smoke, but I just might start or just light the end on the stick of dynomite & drop it in the gas tank of this thing. Thanks again guys.
Junior Member
Joined: Aug 2004
Posts: 1
Likes: 0
Gearhead99 may be right.
What my 1998 4.2 did was slam the rods after 56,000 miles.
The dealership was aware of the fixes and instead recommended a "NEW" power plant ($4,000+). The dealership mechanic said it was from the Taurus/sable/continental/windstar family of 3.8L.
There is a TSB notice on it.
Apparently the #4 cylinder is a common weak link on gasket.
Maybe the fuel to H2O mix is to high for plug flash point making it look like it is running rich?.
Autosafety.org has some information on this.
I bought mine new with camping gear as its heaviest load, with 3000mi/6mos oil changes.
Look for steam in the morning when you start your car as well as coolant loss.
Mine was running fine until I had it ferried for a couple of weeks up to Washington. When I started it my wife said she saw a bunch of steam come out the tail pipe and I had "The Knock".
The rub is the dealership won't tell you about the 4.2Liter family, unless you sleuth...
No telling about the future of F-150 "Built Tough".
All the best
What my 1998 4.2 did was slam the rods after 56,000 miles.
The dealership was aware of the fixes and instead recommended a "NEW" power plant ($4,000+). The dealership mechanic said it was from the Taurus/sable/continental/windstar family of 3.8L.
There is a TSB notice on it.
Apparently the #4 cylinder is a common weak link on gasket.
Maybe the fuel to H2O mix is to high for plug flash point making it look like it is running rich?.
Autosafety.org has some information on this.
I bought mine new with camping gear as its heaviest load, with 3000mi/6mos oil changes.
Look for steam in the morning when you start your car as well as coolant loss.
Mine was running fine until I had it ferried for a couple of weeks up to Washington. When I started it my wife said she saw a bunch of steam come out the tail pipe and I had "The Knock".
The rub is the dealership won't tell you about the 4.2Liter family, unless you sleuth...
No telling about the future of F-150 "Built Tough".
All the best
Technical Article Contributor
Joined: Dec 1997
Posts: 9,417
Likes: 11
From: Windsor,Ontario,Canada
The first thing to do is to check for a spark with a tester and it should be a bluish white. As your posts mentions that it is not then measure the resistance of the #4 wire. It should not be greater than 7,000 ohms per 30.5 cm (1 foot). If this checks out then the coil has to be checked.
JMC
JMC