Truck sputters at higher speeds

[surewhynot]

I stumbled on something weird. I knew that the coolant temp sensor was bad, since it was really just laying in pieces, so I went to autozone to get a new one. On the way there, the truck was running bad. I went to buy the sensor and they said there were two styles, so I went out and unplugged mine to see which it was. I plugged it back in after I knew which one to buy and wiggled it around a little. The truck started running fine.

I replaced the sensor and haven't been able to get it to sputter since. Could that have been the problem? I hate not knowing if it's fixed or not. I guess I'll hafta drive the piss out of it and see.

 

[lil_dq]

good luck with that.

 

[Truckin4life]

could be, maybe the bad sending unit was putting the truck in and out of limp mode?

Just an idea.

 

[6L PWR]

the bad sending unit was putting the truck in and out of limp mode

Sheesh, you just described him AND his truck at the sametime!!

 

[A_G]

well tony, i got the exact problem as you.

past a quarter it bucks and runs like crap. if you feather the throttle it sounds like a back fire. i have an open exhaust, on top of feeling the power loss, i also hear it.

I noticed mine having a rough idle.

I had codes pulled it came abck 02 sensor and MAF. 02 sensor is bad because exhaust (it doesnt exist).

So i saved up and dropped in My MAF sensor (120 ) but it didnt fix it, only gave it some power id been missing. Im about to do the filter change and see what happens.

I personally think its the coil crapping on us. Like a wind or something going bad.

Something ive noticed, if you keep it above 2k on my truck it doesnt have the constant issue. but between 1800-2100 rpms it runs like dirt (hwy cruising speed) and it eats my gas. i usually kick the OD off and just go.

SOmething i did notice, it started happening (it seemed) on the front tank if i switched to the back itd work better. Well i started just running round on the back tank and its doing it to. did it from 3/4 tank yesterday. so ****ing annoying.

I think im going to pick up a coil for it this weekend, im gonna try and get my fuel filter done to day and see waht happens.

If that dont work.

Theres a shop here thats got a rolling road and a (spectograph, the before there was a computer, diagnostic heartbeat looking thing VINCE??) you know what i mean.


VINCE, check the damn lift pump, check the filter housing for a squished gasket. or by god a hole in the bladder in the tank...

 

[blacksnapon]

well tony, i got the exact problem as you.

past a quarter it bucks and runs like crap. if you feather the throttle it sounds like a back fire. i have an open exhaust, on top of feeling the power loss, i also hear it.

I noticed mine having a rough idle.

I had codes pulled it came abck 02 sensor and MAF. 02 sensor is bad because exhaust (it doesnt exist).

So i saved up and dropped in My MAF sensor (120 ) but it didnt fix it, only gave it some power id been missing. Im about to do the filter change and see what happens.

I personally think its the coil crapping on us. Like a wind or something going bad.

Something ive noticed, if you keep it above 2k on my truck it doesnt have the constant issue. but between 1800-2100 rpms it runs like dirt (hwy cruising speed) and it eats my gas. i usually kick the OD off and just go.

SOmething i did notice, it started happening (it seemed) on the front tank if i switched to the back itd work better. Well i started just running round on the back tank and its doing it to. did it from 3/4 tank yesterday. so ****ing annoying.

I think im going to pick up a coil for it this weekend, im gonna try and get my fuel filter done to day and see waht happens.

If that dont work.

Theres a shop here thats got a rolling road and a (spectograph, the before there was a computer, diagnostic heartbeat looking thing VINCE??) you know what i mean.


VINCE, check the damn lift pump, check the filter housing for a squished gasket. or by god a hole in the bladder in the tank...

Just off the top of my head, without looking at specs, look at your tp sensor data with a scanner to see if its dropping out at that rpm range. I cant remember if yours has a distributor or not, but the 5.0 had at one time an issue with the mounting plate inside the distributor wearing out.

 

[surewhynot]

It started acting up again, so I'm down to checking sensors at random. I don't know what else to do. I tried checking the map sensor and at 0in vacuum it read 159hz, which is where it should be. As the vacuum drops, so should the numbers. I pumped it up to (or down, lol) to 25 in of vacuum and there was no frequency change at first. I thought I'd double check, so I tried it again and it went to 85hz, about where it should be. I haven't gotten the truck to run bad since. I wonder if that could be my intermittent problem. I'm stumped.

 

[surewhynot]

It did it again, and while it was running like ****, I probed the map sensor wires and it reads like it should. I'm at my wits end.

 

[john112deere]

I'm at my wits end.

Short trip...

The only thing I can think of is if you find another Ford 351 (if that's what it is) of the same vintage that runs good, and swap sensors, dizzy components, etc. back and forth between the two of them...

 

[Blue Goose]

.....and make sure it's OK with whoever owns it...

 

[A_G]

im seriously considering the a injector.

Its getting progressively worse on mine to where if, i slow down whil that issue is happening, it will have no power...taking off full throttle 30 mph...maybe...

I think when it warms up/vibration from driving. that one of the wires going to one of the injector is shorting and causing the injector to be an open spicet just draining fuel intot he gine, flooding it. But im not sure how to test this.

 

[john112deere]

There is a new development. The truck is having this problem most of the time now. But, I can shut it off, re start it immediately and it will run fine for a few miles. This is why I believe it's electrical.

I'm back to wondering about fuel pumps...

I know electric fuel pumps can behave like this... (Lost one in Denver- car shut off in the middle of I-70, but after I let it sit a minute it fired up and ran well enough to drive to a motel, and then to a Ford dealership the next morning. No codes, either. That was in a 2000 Focus.)


Have you tried (if you can) monitoring the fuel pressure while it's acting up?

*Anthony- if you had an injector shorting and dumping fuel into one cylinder, I'd think you'd be able to find which cylinder it was by looking at the plugs...

 

[surewhynot]

I have checked it while its acting up and got normal readings. But, with everything giving good readings, I'm not ruling anything out yet.

 

[flareside_thunder]

My next guess would be either the screen in the pressure regulator has some crap in it or it sounds like wnat my Buick was doin.......next guess is in tank fuel sock...replaced or not when you replaced the pump it could be sucking up some scale......you shut it off...loses suction, scale falls to bottom......etc etc. Tried to beep ya but your phone is off or something.

 

[surewhynot]

The only thing is Junior, fuel pressure is reading fine.

Vince, you mentioned EGR. Mine is clean and functioning, but I checked the evp and it is reading out of spec. With 0 vacuum it's supposed to read 5k ohms. Mine reads about 3.4k. At 10" vacuum it should read 100 ohms. Mine reads around 1140 ohms. Could this cause the symptoms?

 

[F 150Cobra]

try to block off the egr and see if it does any difference?? i did that to mine.. i just put an gasket where the egr goes in the intake

 

[flareside_thunder]

possibility of a bad coil?

 

[surewhynot]

I put a new coil on it.

 

[blacksnapon]

The only thing is Junior, fuel pressure is reading fine.

Vince, you mentioned EGR. Mine is clean and functioning, but I checked the evp and it is reading out of spec. With 0 vacuum it's supposed to read 5k ohms. Mine reads about 3.4k. At 10" vacuum it should read 100 ohms. Mine reads around 1140 ohms. Could this cause the symptoms?

Just for a hoot, I had a Cougar doing the same thing. It ended up a reddish sandy debris in the tank would plug the pickup and stop the engine. Immediately it would restart. When it shut off, the debris would fall back into the tank, letting it run.

 

[surewhynot]

Looks like I'll be dropping the tank.