Intermittent check engine light
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Intermittent check engine light
my check engine light has been going on and off for the past 3 weeks or so. the light comes on when i start up and causes the engine to run very rough when i push the accelerator and when the light shuts off it runs fine. the light will not stay on long enough for me to make it to autozone to get them to plug their reader in. the light usually stays on for about 5 or 10 minutes then goes off once the truck gets warm. any suggestions?
Post Fiend
Joined: Mar 2007
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From: Texas
That's important info. The free scans at the auto parts stores, and the low priced scanners you can buy will not work on the 7.3. Odds are you still have the code stored in the engine, they just can't see it with their equipment.
Can you describe the rough running a little better? How long does it act this way? Does it run for several minutes like it's not firing on all cylinders? Truck shake a whole bunch? Only act like it's got a slight miss? Just acts like a quick hiccup then everything is fine again?
Do you have any mods, chip or tuner in the truck?
Can you describe the rough running a little better? How long does it act this way? Does it run for several minutes like it's not firing on all cylinders? Truck shake a whole bunch? Only act like it's got a slight miss? Just acts like a quick hiccup then everything is fine again?
Do you have any mods, chip or tuner in the truck?
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i have an edge juice with attitude. the truck acts like it is not running on all cylinders and shakes pretty bad when i give it gas, then if im going down a hill or slowing down and let off the gas it is smooth. the truck only does this when the check engine light is on. i could be accelerating with the truck running bad and shaking then when the check engine light goes off the truck runs perfectly normal. i guess ill have to take it to ford and get them to read it. on a side note can you guys recommend a reader to buy for my truck that can read transmission codes and all others
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Post Fiend
Joined: Mar 2007
Posts: 26,966
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From: Texas
Sounds very similar to another recent problem we saw here. https://www.ford-trucks.com/forums/8...ck-shakes.html
Read through the 2nd post there and do the ohm test that is outlined. Then come back here and let us know what you find.
Read through the 2nd post there and do the ohm test that is outlined. Then come back here and let us know what you find.
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so here is the results of the ohm test. the driver side seems off but is it enough to warrant pulling the cover?
Driver side starting at the firewall side.
G 2.5
G 2.1
I 4.6
I 4.5
C
I 4.6
I 7.1
G 2.1
G 2.6
Passenger side starting at firewall
G 1.0
G 1.0
I 5.1
I 5.1
C
I 5.1
I 5.1
G .9
G. 9
I posted something about the overdrive light flashing too in another thread because it didnt come on till about 2 weeks after the SES light started flashing. I didnt think it was related but i guess it could be. any info on that would be helpful too. Thanks for the help
Driver side starting at the firewall side.
G 2.5
G 2.1
I 4.6
I 4.5
C
I 4.6
I 7.1
G 2.1
G 2.6
Passenger side starting at firewall
G 1.0
G 1.0
I 5.1
I 5.1
C
I 5.1
I 5.1
G .9
G. 9
I posted something about the overdrive light flashing too in another thread because it didnt come on till about 2 weeks after the SES light started flashing. I didnt think it was related but i guess it could be. any info on that would be helpful too. Thanks for the help
Post Fiend
Joined: Mar 2007
Posts: 26,966
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From: Texas
7.1 on the #2 cylinder (farthest forward on drivers side) is definitely a good reason to pull the valve cover. The passenger side is consistent, but on the high side as well. The injectors I've tested usually ohm out around 3.2 ohms. Did you read far enough into the other thread about re-torquing the rockers and injector bolts? With the valve cover removed, it would be a good time to do this.
With all the numbers on the drivers side reading high, it sounds like you've got a loose connector under there. Pull the IC tube (big aluminum tube), intake hose off the turbo, remove the looooooong bolt that holds the 42 pin connector over the valve cover (square box with a bolt in the middle), remove the little hose off the doghouse (raised thing on the back of the valve cover, use a hose clamp to re-install) and remove the valve cover bolts. The VC gasket is re-usable. The hardest part is getting that bolt off the back of the valve cover (drivers side). You can't see it, but a 3" extension and shallow socket will get it out. There should be enough pictures and a video in the other thread to give you an idea of what to look for.
Don't get discouraged. You're in good hands here at FTE, and think of all the money you're saving doing this yourself.
With all the numbers on the drivers side reading high, it sounds like you've got a loose connector under there. Pull the IC tube (big aluminum tube), intake hose off the turbo, remove the looooooong bolt that holds the 42 pin connector over the valve cover (square box with a bolt in the middle), remove the little hose off the doghouse (raised thing on the back of the valve cover, use a hose clamp to re-install) and remove the valve cover bolts. The VC gasket is re-usable. The hardest part is getting that bolt off the back of the valve cover (drivers side). You can't see it, but a 3" extension and shallow socket will get it out. There should be enough pictures and a video in the other thread to give you an idea of what to look for.
Don't get discouraged. You're in good hands here at FTE, and think of all the money you're saving doing this yourself.
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i did read in the other thread about re-torquing the bolts. i will do that when i have the cover off. thank you for all of your help. could that also be causing the overdrive light to be flashing or do you think that is a separate issue?
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oh yeah, and one more question, i am supposed to be driving to atlanta tomorrow. if i dont think i will be able to get it done tonight does it hurt the truck to drive it like this or should i just go ahead and rent a car?
Post Fiend
Joined: Mar 2007
Posts: 26,966
Likes: 50
From: Texas
Depends on how far Atlanta is from you. If it's a loose UVCH (under valve cover harness) plug or an injector issue, you run the risk of losing the entire bank. That means trying to drive the truck on only 4 cylinders, with a possible top speed of around 40 mph. I'd either stay up late tonight or rent a car for the drive tomorrow unless you're less than 20 min. from Atlanta.
A loose connector should not cause the O/D light to flash. I drive a stick shift, so I'll have to look into the flashing O/D light.
Good luck, and enjoy your trip.
A loose connector should not cause the O/D light to flash. I drive a stick shift, so I'll have to look into the flashing O/D light.
Good luck, and enjoy your trip.