I have a 94 5.0 2wd truck with just over 150k on it and it runs very quiet and smooth still but Im having a hell of a time figuring out a few problems.

First off to cover basics in the last 4 months it has had plugs,cap,rotor,wires,seafoam,K&N,fuel filter,new tanks & pumps,vac leaks fixed,O2,March pulleys,pcv,coil and shift kit.

Well my problems are terrible MPG,very weak power and massive detonation. I drive 80miles a day to and from work all on the e-way and I rarely drive over the speed limit yet on its best tank I might get 180 miles before empty. It always feels like it takes sooo much pedal to get moving and just keep up with traffic. And from the day I bought it there has been a spark knock problem I just cant seem to cure. As soon as it goes in to OD it rattles its brains out and Im really getting worried Im goin to melt a piston or take out a rod bearing.

So far I have played with the timing and its down to 5º BTDC with no change. I blocked off the EGR at the upper intake to take that out of the equation.No CEL.No codes. I have never had to add oil or coolant either. I have found and fixed every bad vac line and spraying carb cleaner all over intakes shows no signs of other leaks.

I realize the lack of power is most likely due to such low ignition timing setting but it really feels and acts like its running way lean......but then I remember the mileage sucks also so how can that be??

Im really stumped here and Im almost ready to just yank the motor and rebuild it to see if there is massive carbon in the chambers causing hot spots which would cause the detonation.

any other ideas? This thing is killing me.

 

Check the threading on your plugs, I recently had one to get all outta whack from dirty threads/electrode, then partial cross threading due to a faulty lug thread.
With the engine running, look and see if you have a plug wire that wants to dance, if so, then it's usually a loose plug. Another simple check, plug gap. Also, check air filter as well, easily overlooked poer thief. Your cat could be stopped up as well. With the vac lines, triple check them all, I had one come loose causing it to run like crap on start up, not really sure what the heck it's even for.
You said you cleaned it with carb cleaner, does your truck have a MAF sensor? If so, I know on mine at least, it says specifically not to clean it with carb cleaner, etc. That could be your whole problem if so.
Lastly, in you ignition parts replaced I didn't see rotor button listed, has that been replaced as well?
That's all I can think of at the moment, hope you get it figured out soon

 

Ah crap, forgot to likewise mention that dreaded possibility of a stretched/worn out timing chain. Also, if the 5.0's exhaust manifolds are as short as mine on the 4.9, look where the exhaust bolts up to it, an exhaust leak there can be VERY deceptive, I've seen people talked into a valve job when all they needed was a donut gasket or to tighten up the down pipes.
Last thing that comes to mind is valve lash adjustment, which can give all the problems you listed. If you've got the haynes/chilton manual on your truck it's a fairly simple great big P.I.T.A. type process to adjust

*edit* I just re-read the initial post, doesn't sound like you got the MAF sensor with the carb cleaner, but I'd check it out to be safe, there's gotta be someway to clean em I just can't call it to mind at the moment. And timing being off is gonna screw your mileage either way, lean or rich, because if the timings off, it's gonna be dumping fuel that won't all get burnt due to timing.

 

Put your EGR back on...that's what's causing atleast some of your prob. EGR helps reduce combustion chamber temps. I had done the same on my pickup an had the same prob. Timing clear back to 6 an still would want to do it. Put it back on and try it.

 

One of the EGR's purposes is to lower peak combustion temperatures as a means towards reducing the generation of the nitrogen oxide (NOX) emissions - so I agree with the previous posters to get it back in service.

IIRC, your model year still has the SPOUT connector that must be pulled whenever setting timing - just checking....

If this is something that has just come on during the cold weather months - perhaps try a different brand of fuel, or try a tank of the next-step up in octane to see if the symptoms change. As I understand things - winter-blend fuels are formulated for higher volatility - making for easier cold-weather starts at the expense of heightened risk of pre-ignition. My rule-of-thumb is to run the lowest octane fuel that won't knock.

Does the engine seem to run hot? Again, a condition that would lead to pre-ignition.

It's been a few years ago, but I had the same situation. IIRC, a good set of ignition components solved the problem - coil, wires, plugs, cap&rotor.

 

No such thing as "no codes" You'll at least see 11 or 111=system passed. EGR removal=bad idea.

What plugs are you running? If not Stock Motorcraft Copper cores, install some immediately. Partly because they generate less heat than Plats, & transfer heat away from combustion chambers much more efficiently. They are also intentionally designed to fail before causing piston damage. Doing this may help your Ping problem but won't cure it. It's more of an insurance policy.

Your engine, if stock is engineered to run on 87 octane. I can see where you would run higher octane for your current situation, but it will eventually make pinging more prevalent, even at the highest octane available to you. I think I'd reinstall your stock air filter too for now.

Also helpful, but not a cure either, would be to add a bottle of "Water Wetter" to you coolant.

I have heard setting your timing too low also generates extra combustion chamber temps, changing the flame front impact on the piston surface.

When setting you base time, you are removing your SPOUT plug to do it, then replacing it, correct.

Also not a cure, but something to try. Remove SPOUT plug. Set base time to 10BTDC. Don't replace the SPOUT plug. Run w/ it like that. It won't hurt anything, but will give you stock base time, but not allow additional ECU timing advance normally added during the acceleration curve. Report effect.

A restricted Cat comes to mind as something to check for.

 

there are 3 things it could really be...

1) bad injectors....

if the injector(s) is bad then it wont deliver the proper amount of fuel and that cylinder will run very lean and do the death rattle even with timing pulled out. Loss of power is a good indication with a death rattle is a good indication of an injector partially flowing

these are easy to find using a test light...hook the clamp end of the test light to a ground. With the sharp end of the test light pierce the spark plug boot at the distributor cap and touch the terminal. that cylinder with be shorted of spark and there should be a definite drop in rmp thats audible to the ear. try that on all cylinders and note the ones that either dont drop at all or drop very little and then check the injectors on that cylinder. If you can make it spark rattle sitting there and also short the cylinder and stop the rattle then you have the cylinder thats doing the rattle...

2) Bad fuel pump (Low Fuel pressure)

Test fuel pressure idle and thru the RPM sweep...for the V8 it should hold a very steady 45psi and not drop any. Inline 6-cylinder should hold a very steady 58psi. if it does drop change the fuel filter and retest...after that change the fuel pump(s)

3) plugged Catalytic converter.

this is also easy to test...you will need a vacuum gauge with a pressure side as well or a 0-15psi pressure gauge. Pull out the O2 sensor and find a 14mm fitting that can be adapted down to a 1/8in brake line and stub out 6-8in of metal line. attach the pressure gauge with enough line to make it into the cab. drive the vehicle...

Pressure on the gauge should NOT exceed 5psi at any time if it does you my friend have blockage...2psi is normal 0psi is better

and thats that.....

 

Ok where to begin....
Yes I set timing with spout out.
Yes rotor {button as you say} is new.
I only recently blocked off,but not unplugged,the EGR after setting timing to 5º didnt help detonation.Problem was same with EGR functioning.
I have tried timing everywhere from 5 to 16º with no change.
I used stock replacement Autolite plugs of the non-platnum type.
I have tried a full tank of 93 octane full with no improvement.
Detonation happens from stone cold to fully warmed and I have a 5.0 HO Mustang plastic clutch fan{all brand new} and I modified my shroud for perfect blade coverage to insure truck runs normal temps.
I have used gas from a hundred different stations so I doubt its a fuel issue.
I thought about a stretch timing chain as well but when the timing light was on it the marks never changed when I added some rpm's up and down to see if there was slop in the chain. Normally if this were the case on deceleration the timing marks would move.

I guess Im leaning towards the injectors and cats next. Im going to cut off the exhaust between both converters and hollow them out and reweld it back up. I can send my injectors to CruisinPerformance near me to have them cleaned and flow balanced for $12ea.

 

Well I havent road tested it yet but I believe I may have found the problem.

I bought some rebuilt and balanced injectors that are the plastic 4 hole pintle type and a intake gasket set. I was leaning towards the injectors causing my issue but upon disessembly I found that the intakes were full of oil. When I say full of oil I mean I poured oil out of the upper! Im not talking a couple drips either.It was so much I actually started laughing because it was just a rediculous amount of oil inside.

I think the reason it was getting in the intake was a combination of two things. First the cheap PCV I put in was quite weak and I found oil in the line going to the upper. Also the aftermarket cold air kit Im using just has a 5/8" rubber hose run from the oil fill neck to a fitting just behind the MAF for a breather.Well it runs slightly down hill so to speak and it was also full of oil, as was the entire intake tubing and throttlebody.

I ended up cleaning out all the oil out of the intakes off the motor and put in a replacement Motorcraft PCV. I also made a new breather line that is a molded hose that comes off the oil fill neck and makes a 90º bend straight up and then loops back down to the inlet tubing.This should keep alot of the oil from being sucked into the intake.

So the motor is all buttoned up with new injectors,pcv,breather hose,egr hooked back up,timing set at 10º,new intake gaskets and a fresh oil change. After I finish the brake job and rotation in the morning I will test it to see if the spark knocking is gone and if my power is back.

 

Probably aught to do a "Seafoam" treatment to compression chambers & gas.