Hello all, I have a 98 4x4 with 145k miles and 4.0 OHV. Symptoms are as follows;

Uses ALOT of oil. 1 quart per 230 miles. Burning bad in rear cylinders, some in middle cylinders, none in front cylinders. Screams intake or PCV issues to me, not rings or valves. Never any smoke, not even on startup. No significant leaks. MPG always 18-20mpg.

Slightly rough idle.

Miss under load below 2k rpm. Not a terrible miss, but you can feel it. Has never lit the CEL. I know the CEL is good.

Never loses coolant. No coolant in oil or vice versa. Haven't done compression test, but doesn't seem like they ever tell you much anyway.

This weekend I replaced all intake gaskets, plug wires, cleaned oil residue off and regapped plugs (they are 3 months old), injector orings, and PCV valve. Flushed and burped radiator.

It's too soon to tell on the oil consumption, but I thought the intake gaskets would have cured the rough idle and misfire. The idle IS much better, but still not perfect. But the low rpm load miss is actually worse now. Still no CEL. Could it be storing codes without lighting the CEL? Also, how do you clear codes on these, can you just disconnect battery, or do you have to clear them with a scanner?

 

SHure it could have a DTC in there Some DTC have to Fail Multiple times before it will Light the CEL but it may have Pending DTC

Sounds Like its Going threw ALOT of OIL I mean so Much OIL that you don't have to worrey about Changing IT maybe throw a Filter at it Here and there LOL

If the Oil is Coming from the PCV valve then Odds are High you have BLOW BY from Rings and or Valve Guides going Bad

Burning Oil usually Never ends to well or Easy I guess I should say


Hows your Air and Fuel Filters??



AS Far as the Misfire Could be Few of things Still

EGR Valve Issue Have you ever Cleaned it??

Fuel Inject issue I usually take a Wooden DOwel and touch it to the Injector as the truck Idle and Listen to it Click ON/OFF should be Smooth and Even Click sound as the inject turns Off/On

Vac Leak


Paw Paw should be here soon he should have some other Ideas

Good luck

 

Hello, thanks for the reply! I did not clean the egr yet, what i find strange about the whole deal is that it has gotten much worse since i did the intake gaskets the other day. Some background;

I tore the intake down and found the rear half of the upper intake full of oil. The gaskets were oily, and what is strange is the front 2 cylinders didnt have any evidence of burning oil. Those plugs were white but had no buildup on them. The middle plugs had some, and the rear plugs were pretty caked up.i cleaned and regapped them all, and put them in with new wires. They are the oem autolite platinums, but the cables were duracrap. I used them cause my dad had already bought them.

While i was in there, i replaced the injector o rings, pcv valve and hose, and all the intake gaskets. It went back together fine, although it was sucking around the egr tube. I reseated the o ring and used some rtv around it. I cant tell if its burning any oil yet, as its only been a day, but the miss is much worse. It used to miss once or twice if you mashed it in too high a gear (5 speed). Now it bucks, shudders and feels weak, almost like the power goes back and forth from 50% to full. Once it gets above 2k rpm it gets better, but not perfect. If i mash it at 1200 rpm, it just falls on its face.

It isnt flashing any cel, even when its bucking like a bronco. The cel bulb is confirmed good, it lights on startup.

I am not sure on fuel filter, it was in it when i bought the truck 5k miles ago. I assumed that wasnt it because it got so much worse after i had the intake off. I did the carb cleaner trick, havent found any more leaks.

 

Good Info Bud that stuff Really helps anything yoyu can think of


Oh you haven't had it Long

Im thinking you got someone elses Headache

Whats Strange is All the Oil in the Intake wonder if cylinder pressure is Pushing it up into the intake from worn Valve Guide

Take it to a Parts store Auto zone or Orreillys they will scan for DTC

 

Oh yeah, the previous owner was a total liar, he told me straight to my face it didnt use any oil, it used half a quart per week!

I am going to have it scanned tomorrow. The oil is annoying, but what i really cant understand is the missing, and why it got so much worse since i pulled the intake. One thing i didnt think about, all the wires are mashed together where they lace through the intake, i forgot to put the spacer in. Could this cause issues?

 

Yes wire harness issues can cause misfire

But it maybe more Random/Intermittend issue Electrical Sucks

Yours sounds like you can make it Misfire by the Throttle/RPM

Might be worth Putting some New Plugs in if you can Swing it the Oil Might be Fouling them out SOunds like A lot of Oil Plus they are cheap and Takes it OUT of the Big Picture here

Could be a Couple things going On here

An Oxygen sensor can cause it to run Rough to Since its Used to Adjust Air/Fuel Mix

 

Do you have a DVM?

Digital Volt Meter

You can use it to check Sensor Values if we can find the Specs for yours

Here is A Link to the Tech Folder maybe you know about it IDK lots of good Info there

https://www.ford-trucks.com/forums/1...formation.html

 

And Welcome to FTE

This is a Great place for info

 

I appreciate the help!

One thing i noticed, the pcv and crankcase breathers are not full of oil, which is pretty common when crankcase is pressurized. Still not sure if its still using oil, too soon to tell.

I do have a voltmeter, i will try to dig up the specs. What really puzzles me though is how its suddenly started after i pulled the intake. Dont know how that would have started a sensor issue, unless one of the harnesses didnt make a good connection (but wouldnt that throw a cel?).

I had all the plugs out, the coil out, and replaced the wires. Seems like that would be most likely thing to be disturbed.

 

You either was right at the Issue and made worse or there is 2 problems now What about the EGR Pipe Leak?? is it sealed up Now????

you will get it your Close and have some good Diagnostics going


If you live by me I will come Scan it for You Im in Utah If not theres Members all over that I know that help each other its the FTE Family Great group of folks here

 

Yeah, I got the EGR sealed up good, I used some rtv to double-check it was sealed. I did have to pull the pipe aside to get the intake out of the way, hope i didn't crack it.

 

I have a 94 2x. I had a mysterious miss such as you describe, went through all the electrics like you, added new crank sensor etc. Still had miss? Tried seafoam and it barely helped. Took truck to a shop they confirmed everything ok that I had done, did a smoke test and got a little but not much. Long story short is that I had a bad injector in the bunch that was causing the issue. Seemed to be working fine but was weak I guess. R&R's all she runs strong. You can pull the injectors again have them cleaned or for about $20 replace with new.

 

Thanks Hank! was your miss worse when you would bog it in too low a gear? I definitely need to look into injectors, I had them out and replaced the orings, so it could be that i disturbed something, or the connection isn't good. Thanks for the info!

 

the miss would just show up and it would not accelerate at a decent rate and just would not run decent at all. I had had the injectors out and cleaned at about 150000 miles. They were clogged up when I finally removed them all dirty on the tips and it was one of the rears forget which was the worst. Plugs were white from lack of sufficient fuel, but again the vehicle itself checked out fine. Just missed bad in use.

Got my Injectors from autozone, they price matched orielly. as I recall came out to about $300 to replace them not counting the gaskets etc. my time.

 

Did you lube the orings before you stuffed the injevtors back in??

ReplCE THE iNTAKE gASKET??