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

rough idle and miss fire


ben10

Active Member
Solid Axle Swap
TRS Banner 2010-2011
Joined
Apr 26, 2010
Messages
1,274
Reaction score
5
Points
38
Location
Northern California, ca
Vehicle Year
92
Make / Model
ford
Engine Size
4.0
Transmission
Manual
My credo
ah SHIT!
so my truck if it sits for a day will run really rough for 10-20 seconds before smoothing out, it has gotten progressively worse... If I go to the grocery store or something where its been sitting for less than 5 or 6 hours before restarting it starts fine, but if it sits all day or overnight it starts rough again.

also occasionally driving down the road it will start to miss for a few seconds then smooth out, its an auto and I shifted gears and it continued to do it, I also tried flooring it and it continued to miss for the few seconds. I am not getting any CEL codes. I have cleaned the IAC and MAF the coil pack only has about 10k on it, same with the plugs and about 20k on motorcraft plug wires, where do I go from here? its a 99 4.0 ohv with 130k on it.
 


ben10

Active Member
Solid Axle Swap
TRS Banner 2010-2011
Joined
Apr 26, 2010
Messages
1,274
Reaction score
5
Points
38
Location
Northern California, ca
Vehicle Year
92
Make / Model
ford
Engine Size
4.0
Transmission
Manual
My credo
ah SHIT!

Stimpson.06

New Member
Joined
Oct 30, 2011
Messages
20
Reaction score
0
Points
0
Vehicle Year
1994
Make / Model
Ford
Engine Size
4.0 V-6
Transmission
Manual
my buddy had the same problem thought it was a maf sensor got that fixed it ran alittle better and then we found a vacum leak and it runs fine now
 

ben10

Active Member
Solid Axle Swap
TRS Banner 2010-2011
Joined
Apr 26, 2010
Messages
1,274
Reaction score
5
Points
38
Location
Northern California, ca
Vehicle Year
92
Make / Model
ford
Engine Size
4.0
Transmission
Manual
My credo
ah SHIT!
hmmm could be a vacuum leak I guess, I think its time for a check up on the hoses and such.
 

Earl43P

Well-Known Member
U.S. Military - Veteran
Joined
Aug 7, 2007
Messages
3,159
Reaction score
38
Points
48
Location
Farmington, Pa
Vehicle Year
2019
Make / Model
Ford F250 4WD
Engine Size
3.0
Transmission
Manual
I have two pieces of advice for you Ben.

First, Prime your fuel system before you start it.

Do that by turning the key to Run (warning lights come on in dash and fuel pump runs for 2 seconds). Then turn the key back to Off, back to Run, wait the 2 seconds for the fuel pump to prime again and crank over the starter. If that works, continue to do that before every cold start.

Loss of fuel pressure after shutoff can be a number of things, which leads me to my second suggestion....

Replace the fuel filter.

Fuel pressure bleed down is pretty common in Fords, many times it is the fuel pump itself, since it has a checkvalve in it. A stuck open injector will also cause bleed down as will a bad fuel pressure regulator. Unfortunately, your FPR is inside the fuel tank, a part of the fuel pump and sender unit. Replacing yours will be expensive, so rule out the fuel filter first.

You can drive that truck for a long time with a bad fuel pump checkvalve (most common cause of bleed down), simply prime the fuel system, as earlier described.
 

ben10

Active Member
Solid Axle Swap
TRS Banner 2010-2011
Joined
Apr 26, 2010
Messages
1,274
Reaction score
5
Points
38
Location
Northern California, ca
Vehicle Year
92
Make / Model
ford
Engine Size
4.0
Transmission
Manual
My credo
ah SHIT!
good call, I will start doing that and see if it helps, fuel filter has been replaced, no change, I am starting to lean more towards a tranny problem for the miss, the rough idle could still be a pressure regulator tho... damn my luck.
 

cr_the_machinist

New Member
Supporting Member
Joined
Nov 23, 2007
Messages
486
Reaction score
2
Points
0
Age
36
Location
Dexter, Michigan
Vehicle Year
1999
Make / Model
Ford
Engine Size
4.0L OHV
Transmission
Automatic
Have you hooked up a scan tool to see if there are any pending trouble codes stored in the pcm?
 

stiluv

01/2014 OTOTM Winner
Supporting Member
Ford Technician
V8 Engine Swap
OTOTM Winner
Solid Axle Swap
ASE Certified Tech
TRS Banner 2010-2011
Joined
Nov 6, 2007
Messages
1,181
Reaction score
3
Points
38
Age
36
Location
nevada city, california
Vehicle Year
1999
Make / Model
ford
Engine Type
V8
Engine Size
5.oh face oh oh oh
Transmission
Automatic
2WD / 4WD
Solid Axle Swap 4x4
Tire Size
40
i have a good scan tool ben if we go wheelin sunday i will bring it
 

ben10

Active Member
Solid Axle Swap
TRS Banner 2010-2011
Joined
Apr 26, 2010
Messages
1,274
Reaction score
5
Points
38
Location
Northern California, ca
Vehicle Year
92
Make / Model
ford
Engine Size
4.0
Transmission
Manual
My credo
ah SHIT!
yeah its been scanned no codes or pending codes...
 

ben10

Active Member
Solid Axle Swap
TRS Banner 2010-2011
Joined
Apr 26, 2010
Messages
1,274
Reaction score
5
Points
38
Location
Northern California, ca
Vehicle Year
92
Make / Model
ford
Engine Size
4.0
Transmission
Manual
My credo
ah SHIT!
Ok so update on the issues, I took the exhaust off to build up a new one, just the cat back. With the louder exhaust I can tell its missing under acceleration, it only does it when its cold once it warms up it starts running fine, what would cause it to miss only when the engine isn't warmed up? And its still not throwing a code.
 

92dangerrangerCO

New Member
U.S. Military - Active
U.S. Military - Veteran
Joined
Jan 15, 2011
Messages
10
Reaction score
0
Points
0
Location
Camp Lejeune, NC
Vehicle Year
1992
Make / Model
Ford
Engine Size
4.0L
Transmission
Manual
my truck used to have the same issue and used the MAF sensor cleaner from Napa which helped but also repalced the fuel filter and that helped for awhile but the item that set it straight was the PCV fliter. its a $2 part at autozone and its a simple unplg and plug back it but honestly replacing that filter has my 4.0L running dang near perfect and lost all rough idle at start up.

hope this helps you out.
 

ben10

Active Member
Solid Axle Swap
TRS Banner 2010-2011
Joined
Apr 26, 2010
Messages
1,274
Reaction score
5
Points
38
Location
Northern California, ca
Vehicle Year
92
Make / Model
ford
Engine Size
4.0
Transmission
Manual
My credo
ah SHIT!
hmmm havent changed the pcv Ill do that next.

doubt that will change the miss under acceleration tho...
 

92dangerrangerCO

New Member
U.S. Military - Active
U.S. Military - Veteran
Joined
Jan 15, 2011
Messages
10
Reaction score
0
Points
0
Location
Camp Lejeune, NC
Vehicle Year
1992
Make / Model
Ford
Engine Size
4.0L
Transmission
Manual
it might like i said my ranger was having the same issues as you mentioned before and that happened to do the trick, best of luck
 

ben10

Active Member
Solid Axle Swap
TRS Banner 2010-2011
Joined
Apr 26, 2010
Messages
1,274
Reaction score
5
Points
38
Location
Northern California, ca
Vehicle Year
92
Make / Model
ford
Engine Size
4.0
Transmission
Manual
My credo
ah SHIT!
for sure thanks for the input. ill try to get to the parts shop tomorrow and pick one up. damn that would be a nice fix hahaha
 

staker

New Member
Joined
Aug 19, 2011
Messages
3
Reaction score
0
Points
0
Vehicle Year
2000
Make / Model
ford
Transmission
Automatic
I have a 2000 ranger doing about the same thing. I was wondering if you tried to pcv valve and if it helped. i changed my tranny fluid and that seemed to help with the bucking going down the road but it still happens. My abs light is on so i'm wonding if i have a vacuum leak on the brake booster or something that might also cause it.
 

Sponsored Ad


Sponsored Ad

Members online

Member & Vendor Upgrades

For a small yearly donation, you can support this forum and receive a 'Supporting Member' banner, or become a 'Supporting Vendor' and promote your products here. Click the banner to find out how.

Truck of The Month


Kirby N.
March Truck of The Month

Recently Featured

Want to see your truck here? Share your photos and details in the forum.

Follow TRS On Instagram

TRS Events

25th Anniversary Sponsors

Check Out The TRS Store


Sponsored Ad


Sponsored Ad

Sponsored Ad


Amazon Deals

Top