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Edward
Edward, ASE Certified Technician
Category: Ford
Satisfied Customers: 2768
Experience:  ASE certified. Auto Transmission rebuilder for Ford Motor Co. from 91 to 2000
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I have a 1997 ford f150 has high miles but has always ran

Customer Question

I have a 1997 ford f150 has high miles but has always ran great but I changed the oil and hooked up the camper and left the house only to go 70 miles and the truck started missing so I pulled over and looked under hood for a bad wire or something I then proceeded to get back on the freeway only to pull over 5 miles down the road because now it is missing really bad I changed the wires plugs and the coils but still the same
Submitted: 1 month ago.
Category: Ford
Expert:  Edward replied 1 month ago.

Hello and thanks for your question. My name is ***** ***** I will do all I can to help.

Expert:  Edward replied 1 month ago.

Did the check engine light come on while you were driving by chance? If so, do you know what codes it may have stored?

Customer: replied 1 month ago.
check engine light did not come on but does work and its a 4.6
Expert:  Edward replied 1 month ago.

Alright, for this problem to occur and it not to set a code, I'm going to have to say it's likely fuel pressure related. If it was misfiring it should have set a code, and if it was any sensor or mass air flow sensor it should have set a code. Is this the original fuel pump in the tank to your knowledge? or has it been replaced ?

Customer: replied 1 month ago.
as far as I know its original. when I took the plugs out some were black but not oily others were white
Expert:  Edward replied 1 month ago.

I follow you, how does it run now? Does it crank up and run fine or still have this cutting out problem?

Expert:  Edward replied 1 month ago.

That could be consistent with lack of fuel. do you have a fuel pressure gauge by chance?

Customer: replied 1 month ago.
after plugs wire boots and coil packs it did nothing different acts like its only running on half the cylinders I will have to get a fuel gauge to test pressure it runs really rough all the time from start to putting it in gear but the truck had no signs before this no loss of oil water or anything like a light switch turned off
Expert:  Edward replied 1 month ago.

Alright I follow you, From these symptoms, Here is what you will need to do to figure it out, You'll need a noid light to check injector pulse, and a spark tester to check coil output. and a fuel pressure gauge to check fuel pressure. (spec is 30-40 psi)

Check the fuel pressure first, should be around 35 psi running, and go up slightly when you hit the gas.

If fuel pressure is OK, check each coil wire for spark, if one coil pack is completely dead of spark, you can try to swap them (coil packs from side to side), and see if you get spark on the wires you didn't have spark on previously. if you have spark now, replace the coil pack, If you still don't have spark, it could be the ECM itself, as the ECM grounds the coil packs to give you spark .

If you have spark on all cyclinders, then use a noid light to make sure all the injectors are firing.

It's going to be one or the other in my opinion.

Either the coil pack is bad, the fuel pressure is low and the fuel pump is failing, or the ECM has ceased to fire a coil pack. This is barring any really weird issue like a loss of compression or water in the fuel tank if it happened immediately after getting gas somewhere. These are gonna be the most common things that come to mind and I feel confident it's one of these problems.

Let me know if you have any further questions. Thank you.

Customer: replied 1 month ago.
I have used the noid light and all injectors are pulsing I have checked the spark all are firing the coil packs are new
Expert:  Edward replied 1 month ago.

Alright, And you are sure it hasn't gotten any codes stored correct? I would double check it even if the check engine light isn't on just to be sure. If you have spark on all cylinders, and you have all injectors pulsing, then I'm still leaning towards fuel pressure, otherwise I can't think of anything else it would be other than an internal engine issue.

Customer: replied 1 month ago.
I will let you know after I check fuel pressure
thanks
Expert:  Edward replied 1 month ago.

Alright, sounds good. Thank you.

Customer: replied 1 month ago.
I just checked the fuel pressure. gauge went up to 35psi as I gave it gas it dropped a little but I can rev it past the rough feeling and it starts to go back up seems to run better at 3000 rpms miss is not as bad sounding or feeling
Expert:  Edward replied 1 month ago.

It should actually go up when you rev it, but 35 psi is correct. How does it idle? does it miss when it's idling?

Customer: replied 1 month ago.
it has a miss sound and rough run at idle all the way up to 3000 rpm then it seems to get better
Expert:  Edward replied 1 month ago.

I would check compression next. If a cylinder is low, it will gain compression after you get the rpm's up usually. If you have spark and all the injectors are firing and fuel pressure is 35 psi. Then I would check compression next.

Customer: replied 1 month ago.
I have done passenger side first cylinder 90 first revolution 120 second next cylinder 0 next 90 -145 next 0
Expert:  Edward replied 1 month ago.

Check them all and let me know.

Customer: replied 1 month ago.
driver side first cylinder first revolution 90-125 2nd cylinder 0 3rd cylinder 90-120 4th cylinder 0
Expert:  Edward replied 1 month ago.

Wait, you don't have any compression on number 2?

Customer: replied 1 month ago.
ok #1 90-120 #2 0 #3 90-145 #4 0 #5 90-125 #6 0 #7 90-120 #8 0
Expert:  Edward replied 1 month ago.

your counting cyl. 1 as the cylinder closest to the radiator on the passenger side and going back to the firewall on that side is 1234,

Then starting on the drivers side is 5 6 7 8 right?

Customer: replied 1 month ago.
Customer: replied 1 month ago.
I cant under stand how 2-4-6-8 have no compression at all will not even move the needle they are on different sides and every other one
Customer: replied 1 month ago.
my brother used rotella for the oil change I don't know if that would be a factor or not
Expert:  Edward replied 1 month ago.

Can you hold the throttle wide open and check it again? Something in the intake maybe???? restricting airflow.

Expert:  Edward replied 1 month ago.

I don't know, either those cylinders aren't getting air for some unknown reason, (I'm reaching there) or something is broken.

Expert:  Edward replied 1 month ago.

If it was on one side I would say it was a timing chain, but not both.

Customer: replied 1 month ago.
when I rev it up to 3000 rpm it sounds almost normal it don't make any weird noises or knocks when running except the fact it is missing
Expert:  Edward replied 1 month ago.

Something is broken, or something is jammed up in the intake, that is the only reason I can think of that you would have dropped 4 cylinders.

Expert:  Edward replied 1 month ago.

Check it at wide open throttle though. just to be sure it's zero compression for sure.

Expert:  Edward replied 1 month ago.

Anything new with it? did compression come up any holding the throttle wide open?

Expert:  Edward replied 1 month ago.

What is the 8th digit in the VIN, is it a W?

Expert:  Edward replied 1 month ago.

I want to check some references.

Customer: replied 1 month ago.
It's at work I won't be able to do more till tomorrow I'll let you know vin am
Expert:  Edward replied 1 month ago.

Alright, thanks.

Expert:  Edward replied 1 month ago.

I believe it's possible the timing chains may have slipped, be it valves, timing, or broken camshafts, or something along those lines. I would pull the valve covers and take a look.

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