• Welcome Visitor! Please take a few seconds and Register for our forum. Even if you don't want to post, you can still 'Like' the posts that you read.

'93 4.0 Intermittent stalling/missing/dying at idle


lucasruble

Member
Joined
Jan 13, 2011
Messages
104
Reaction score
2
Points
18
Location
Olympia, WA
Vehicle Year
1993
Make / Model
Ford
Engine Size
4.0L
Transmission
Manual
First off, I have noticed that when I fire it after cool down (such as the next day
), it will run slightly rough until I supply fuel, then allow the engine to regulate idle. I'm pretty sure this roughness is tied to my stalling/dying problem. Anyway, on to the main issue..CEL will come on intermittently and stay on for awhile, then shut off for awhile, then back on..etc.. When CEL is on, truck runs fine, but will intermittently die at idle. However, when CEL is off, while driving, it will intermittently miss, or lose power, at speed. It's a real quick miss and it doesn't happen consecutively, but will happen more than once, depending on how far I'm driving. Also, with CEL off and accelerating from a stop, it will sometimes lose power for a moment. After the quick power loss, it bounces right back and I can continue accelerating. I have tried a different TPS, cleaning the IAC & MAF, pulled some KOEO codes (KOER test won't initiate, so I can't get those codes), and checked a little for obvious vacuum issues. All to no avail. Any ideas?
 


Rock Auto 5% Discount Code: 4FF3E9EEA14805 Expires: October 1st, 2020

bmerr98

New member
U.S. Military - Veteran
Joined
Jun 9, 2013
Messages
694
Reaction score
6
Points
0
Age
53
Location
TN
Vehicle Year
1998
Make / Model
Ford
Engine Size
4.0 X
Transmission
Manual
My credo
Leave it better than you found it.
Mr. Obvious here. Plugs and wires? Did it for me with similar symptoms. No CEL and idled fine, but had the miss under acceleration.
 
Last edited:

lucasruble

Member
Joined
Jan 13, 2011
Messages
104
Reaction score
2
Points
18
Location
Olympia, WA
Vehicle Year
1993
Make / Model
Ford
Engine Size
4.0L
Transmission
Manual
I can't rule plugs & wires out, but to try to be more accurate, I shouldn't say it's missing. It's a complete, momentary loss of power (when CEL is off) sorta like all the plugs cease fire for a second, then start firing again. It definitely seems to be electrical. When the CEL is on, it idles smoothly (unless it dies, of course) after idle regulates on initial cold start. This leads me to believe that it isn't plugs & wires.
 

RonD

Well-known member
Joined
Jun 2, 2012
Messages
16,820
Reaction score
2,271
Points
113
Location
canada
Vehicle Year
1994
Make / Model
Ford
Transmission
Manual

lucasruble

Member
Joined
Jan 13, 2011
Messages
104
Reaction score
2
Points
18
Location
Olympia, WA
Vehicle Year
1993
Make / Model
Ford
Engine Size
4.0L
Transmission
Manual
That was one of the first things i did. Cleaned it with MAF cleaner. No change.
 

lucasruble

Member
Joined
Jan 13, 2011
Messages
104
Reaction score
2
Points
18
Location
Olympia, WA
Vehicle Year
1993
Make / Model
Ford
Engine Size
4.0L
Transmission
Manual
Any more ideas?
 

RonD

Well-known member
Joined
Jun 2, 2012
Messages
16,820
Reaction score
2,271
Points
113
Location
canada
Vehicle Year
1994
Make / Model
Ford
Transmission
Manual
If you can't get any codes then it could be a computer issue.
CEL on could mean Open Loop which is making it run better.

I would check fuel pressure as well, could be filter, Fuel pump relay or pump itself
Should be 35psi to 42psi at the rail.
 

lucasruble

Member
Joined
Jan 13, 2011
Messages
104
Reaction score
2
Points
18
Location
Olympia, WA
Vehicle Year
1993
Make / Model
Ford
Engine Size
4.0L
Transmission
Manual
ECU had crossed my mind. I'll have a looky. I'll have to track down a fuel pressure gauge and test that as well, for good measure. Thanks for the pressure ratings RonD.
 


Top