misfire/skip help

[89frankenford]

ok so my truck has had a random misfire for about 2 months now...now that i have the money and time i want to fix it....within the past 2 months(after it started) i replaced the plugs, wires, cap and rotor. it is still misfiring. i can DEFINITELY feel it in the truck while driving and idling. seems like it is lacking in power a bit because of it. now heres the thing i do have an engine code 84 which is the EGR vacuum solenoid code. ive replaced the solenoid with 4 different solenoids from random trucks and nothing has changed. wether the solenoid is creating the misfire i have no idea...and the chances of having 4 bad solenoids is well not very likely but still possible. oh and the code still hasnt cleared...and yes i have disconnected my battery and reset it. ok with that said...for the misfire problem is it possible i could have a slightly bad TPI sensor??? i HAVE had it die on the highway before many times from that sensor being bad but it doesnt do that anymore for some strange reason. could that be my problem for the misfire?? im thinking of picking up a new one but dont want to spend the $110 for a new one unless i know it is the problem. as for the code 84 im going to check the wiring and see what i find with that. any help with getting the misfire will be HUGE for me...its eating my gas really bad and the power isnt there like ive had before thanks a lot!

 

[blacksnapon]

Could be a misfiring injector.

 

[Raptor22]

How are your spark plugs?

 

[89frankenford]

ugh that would suck...but hey they are original..i cleaned them when i rebuilt the motor back 2 years ago..is there anything i can do to help it besides pulling the injectors out? also is there a goo way to test the injectors with out taking them out? i do have noid lights but im not sure if they would work to see if the injector is misfiring

 

[89frankenford]

How are your spark plugs?

i replaced them like i said in the original post along with everything else

 

[Fordzilla80]

I wouldn't be surprised if your problems went away once you clean the dang windshield.It's a sign from your truck saying clean my windshield.


lol.j/k Travis.Hope you get it fixed.

 

[89frankenford]

I wouldn't be surprised if your problems went away once you clean the dang windshield.It's a sign from your truck saying clean my windshield.


lol.j/k Travis.Hope you get it fixed.

bwahaha possibly lol.. i guess ill find out tomorrow!

 

[blacksnapon]

ugh that would suck...but hey they are original..i cleaned them when i rebuilt the motor back 2 years ago..is there anything i can do to help it besides pulling the injectors out? also is there a goo way to test the injectors with out taking them out? i do have noid lights but im not sure if they would work to see if the injector is misfiring

Do you have a way to disable one injector at a time? If so, monitor fuel pressure, then disable one injector. If you find a bad one, the fuel pressure reading wont change. Good ones will make the fuel pressure rise (because you've stopped a "leak")

 

[89frankenford]

ok i will go borrow my friend fuel pressure gauge and see what i can . thanks!

 

[NeXtras]

pull off the EGR and clean it, make sure it moves, that can be a cause even though its not throwing a code for it

 

[1985 Ford F-150]

Hows your fuel and filter Travis? Ive picked up some bad gas in my 72 and it has a miss and is lackin power. Id check the filter and see if its clogged up. Also drain some gas into a smaller container and have a white cotton rag from an undershirt or somethin with really close fibers and see if it leaves a spot on the rag where the fuel hits.

 

[95F350XL]

I have every emission part removed from all of my trucks, and not 1 missfire. Does it miss idiling? If so pull a plug wire till you see what 1 doesnt change, then you will know what cyl to ck.

 

[NeXtras]

I have every emission part removed from all of my trucks, and not 1 missfire. Does it miss idiling? If so pull a plug wire till you see what 1 doesnt change, then you will know what cyl to ck.

It will ping or knock if anything, not nesesarily misfire

 

[flareside_thunder]

Mine had a missfire before I put a blockoff plate on my EGR...no more misfire....

 

[89frankenford]

ok so im going to see what i can do this weekend to hunt down the problem before i get a fuel pressure gauge. the other thing i have noticed alongside this issue...is when im on the accelerator fully its really really slow to gain speed...and when i completely let off the gas its slows down REALLY fast...lets just say this......the truck decelerates a HELL of a lot faster then it accelerates....isnt it supposed to be the other way around??.....

 

[mrfixit]

The vac tube going to the EGR in these is notorious for melting closed. Ford even issued a recall on it, where techs were simply to inspect the hose and "install a heat shield to protect the hose. I bought a longer piece of tubing and re-routed it away from the header, and it never got warm. pull that tube and see if it gets vacuum.
second thing; there is a multi-port vacuum port on top of the motor, with several vac lines coming out of it. make sure they are all seated firmly in place.
THIRD- Locate your MAP gas unit. It's a little black box with a vac hose attached. on my van, it was on the cowl, but in your truck it's sure to be elsewhere. With it running, pull that hose and see if it has vacuum. There should be a noticeable change in the idle. if there is vacuum and no change, you need to replace that sensor.
FINALLY- The coil in these are crap. They fail, but only after getting VERY hot. I had one get so hot that it had melted the molex plug on the front of it, and the solder joint was disconnected. Couldn't tell by looking- I had to pull it off and see. It was just SO CLOSE that most of the time it stayed connected/touching, until torque was applied, and the motor moved.
One last thought. locate all the wiring harness connectors behind your alternator area, and make sure they are pushed together tightly. another "Ghost" I found once.

 

[Fordzilla80]

the other thing i have noticed alongside this issue...is when im on the accelerator fully its really really slow to gain speed...and when i completely let off the gas its slows down REALLY fast...lets just say this......the truck decelerates a HELL of a lot faster then it accelerates....isnt it supposed to be the other way around??.....

Did you gain any weight over the last few weeks?


lol.j/k Travis.Hope ya can figure it out.

 

[89frankenford]

The vac tube going to the EGR in these is notorious for melting closed. Ford even issued a recall on it, where techs were simply to inspect the hose and "install a heat shield to protect the hose. I bought a longer piece of tubing and re-routed it away from the header, and it never got warm. pull that tube and see if it gets vacuum.
second thing; there is a multi-port vacuum port on top of the motor, with several vac lines coming out of it. make sure they are all seated firmly in place.
THIRD- Locate your MAP gas unit. It's a little black box with a vac hose attached. on my van, it was on the cowl, but in your truck it's sure to be elsewhere. With it running, pull that hose and see if it has vacuum. There should be a noticeable change in the idle. if there is vacuum and no change, you need to replace that sensor.
FINALLY- The coil in these are crap. They fail, but only after getting VERY hot. I had one get so hot that it had melted the molex plug on the front of it, and the solder joint was disconnected. Couldn't tell by looking- I had to pull it off and see. It was just SO CLOSE that most of the time it stayed connected/touching, until torque was applied, and the motor moved.
One last thought. locate all the wiring harness connectors behind your alternator area, and make sure they are pushed together tightly. another "Ghost" I found once.

ok thanks a lot!!!! im definitely going to check all those this weekend and get back to you

Did you gain any weight over the last few weeks?


lol.j/k Travis.Hope ya can figure it out.

hahah..:flipoff: yeah me too...its REALLY sad when a box truck can beat you going up a hill............

 

[mrfixit]

Absolutely positively check that vacuum port and the map gas sensor.

as I think back, my symptoms were exactly the same, and all because the vacuum hose going to the map sensor had come disconnected at the engine. When you said a box truck could beat you going uphill is what really made my head itch... but those others can do it too. Good luck.

 

[89frankenford]

ok so i checked a few things today real quick. my good friend was with me(one of my gear head friends like me) he saw me step on the gas and saw a whole bunch of smoke pour out from the exhaust and he was like whoa!. so i had him step on the gas and i saw what he saw..my exhaust is smoking like crazy...from FUEL! there is fuel getting dumped into the engine...so much of it that it is going through the engine and not being burned then getting into my exhaust and creating a lot of smoke when i press the gas. SO im going to definitely check my fuel injectors when i get the fuel pressure gauge this week. tomorrow im going to be checking my vacuum lines. wish me luck..