Hello All;

All the following have been replaced on the truck.

High Pressure Fuel Pump and assembly
Idle Air Control Valve
Spark Plugs
Oxygen sensor (Bank 1 sensor 1 Oxygen)
Fuel Filter

The most recent item that I replaced is:
Coil Pack
Spark Plug Wires

Now, with the Coil Pack replacement, the truck drives good, as long as I do not floor it (After it heats up, about 15 minutes).
Basically, if I try to pass someone, the truck acts as if it is chocking out, like it is not getting any fuel.

Before replacing the Coil Pack.
It would chock out at any given time, rather just barely pressing the gas peddle, or just sitting idle.

I took it to a friends muffler shop, and he stated that it is not the exhaust that is causing the issue.

I am at a loss.
Is there anything else that I can check?

Keep in mind.
The truck seems to drive fine, as long as I do not get down on it, and try to take off fast after it heats up.
When it is cold, I can take off like a bat out of hell, and it runs like no-ones business.

Thanks

 

It will be a real dog if the ignition timing isn't advancing when it's warmed up. Probably should be 30 BTDC at 2,000 RPM s

 

Could you give some information on how to test for this?
I have heard of Ignition Timing, but have never messed with it.
And where would it be at on the engine?

 

Well it looks like the 4.0 does not have a distributor & timing is not adjustable. I've never had a Ford without a distributor, so I don't know how or if you can test the timing. If you have a repair manual what does it say??

 

Sounds like a sensor acting out once the system goes in to closed loop (warmed up). I would start by unhooking the Maf sensor and see how it runs.

 

Is your "Check Engine" light on? Have you tried to pull any codes from the computer? If it runs that poorly, then it's likely that some sort of codes have been set along the way.
I was thinking along the same lines. The engine coolant (ECT) sensor is another sensor to consider.

As noted, there's no way to "manually" change the timing on a EDIS ignition. It's entirely computer-controlled based on various sensor input(s). You'd need a tuner or chip of some sort to do it.

 

Does the engine buck at all or does it just feel down on power? If the latter, check to make sure the throttle is opening all the way. Remove the air intake tube and peek inside while someone holds the pedal to the floor. Make sure the butterfly is all the way open. It's not uncommon for the throttle cable to stretch with the result that the butterfly doesn't open all the way. Search for "Ranger throttle cable mod" or similar on youtube for the fix.

I assume you've checked that the air filter is not clogged up even though it's not on the list of things you've replaced. If you haven't checked it, you should.

Does that mean he did an exhaust backpressure test to check that the muffler and/or catalytic converter were not plugged?

 

Most recent video people.
Any and all ideas all welcome.
(This is taken from the description I wrote up for the video)
This truck is going to be the death of me.
Can someone tell me what the heck is causing this blasted issue.
This only happens after it has been running for 10+ minutes.
I used WD40 to check for air leaks, and thought that I found one, and I put clamps
On the hose, as their was no cracks in the hose, just not snug enough around the line it was connected to.
If anything, after tightening up the hose around the line, it made the issue worse.

I took the truck to a local muffler shop, and they said that it is not the exhaust that is causing the issue.
All the things that are new on it.

High Pressure Fuel Pump and assembly
Idle Air Control Valve
Spark Plugs
Oxygen sensor (Bank 1 sensor 1 Oxygen)
Fuel Filter
Coil Pack
Spark Plug Wires

 

Exactly. The problems remind me of the time my MAF sensor quit working on my '94 OHV 4.0.

 

@wtroger
I unhooked the MAF and it did nothing different.

@Rockledge
For Engine Codes, there are 2 of them, however, since this is a 95 motor in an 83 ranger, the codes are referring to something that does not exist in the wiring. And has never existed. And the truck used to run perfect for nearly 10 years, so them 2 codes are not relavent in this issue.

Referring to the ECT.
What is the ECT?

@Mikeman
The engine does shake violently when it starts to act up, like it is not getting any fuel.
The Air Filter is a K&N Filter, and has been cleaned and charged.
exhaust backpressure = > To be honest, I do not think that he knows hows to test, besides listening for noises.

@phoskins
As I wrote above to wtroger, I disconnected the MAF plugin, and there was no change.


Any other idea's?
Once again, this is the latest video, of which is also posted above.

 

throttle position sensor? also, i have a 93 4.0 that was bucking and having problems. changed all plugs and wires, cleaned the MAF sensor and while it ran better it was still having problems. codes were pointing to the maf so i found out how to test it. it tested fine but i was still having problems. i decided to change the maf anyway and that was the problem.

 

thanks jswford.
I am going to do some checking on the "throttle position sensor" tomorrow.
The MAF seems to be OK, I hope.
I will check it out tomorrow as well, and clean it again to see if that will help.
The TPS, I am going to attempt to get it off, as the screws did not want to let loose the last time I tried to remove it.

 

Did you replace all of those goodies before this started happening or after? If after, how soon after? When did the problem happen relative to cleaning the air filter? Did the plugs look like the engine was lean or rich?

If you were a little too generous with filter oil, some of that may have traveled downstream and contaminated the MAF. That's one of the benefits of a K&N filter, or any filter that uses an oiled element.

If it runs fine when cold and when you give it lots of throttle, that would seem to indicate that the exhaust backpressure is where it should be and not contributing to the problem. I would agree with the muffler shop, if that's any consolation.

The fact that it runs fine when cold suggests that something related to air/fuel ratio could be contributing. When it's cold, the engine runs open loop (more or less ignores O2) and runs a little on the rich side for driveability. Once warm, then the computer starts paying attention to O2. Some sensor could be telling it to run too lean or too rich once the computer switches over to closed-loop mode. Sensors that affect air/fuel are the O2 sensor, MAF, ECT (engine coolant temp), IAT (intake air temp) and TPS (I think).

In addition to what you already said you'll be doing, I would check the ECT sensor resistance when cold, at various times during warmup and when the problem occurs. Same for the IAT. In addition, pull the IAT and see if it's crudded up. Clean if needed. There was a guy who went by the name of Fordman who listed ECT and IAT sensor resistances vs. temperature. I can't remember what year(s) they applied to, but it should give you some idea what to look for. Even if you don't know what the resistance should be, look for a drastic change. A short or open would be a bad sign. You could also try disconnecting one at a time and seeing if that has any influence.

Have you checked fuel pressure or at least pulled the vacuum line off the fuel pressure regulator?

Retrace your steps and see if there's anything you've overlooked. Not everyone is like me and gets it right the first time. That was an attempt at humor. I'll stop now.

Keep in mind that the advice given is worth everything you paid for it. Keep plugging away at it. Once you find the problem, you'll probably kick yourself for not finding it sooner. Until then, it's frustrating. That's the way it works for me a lot of times. Keep us posted.

 

This is another video I just did.
This is the unplugging of the MAF during the bad / rough idle.

Going to read what Mikeman posted now.

 

@Mikeman
I would replace parts as I did research for issues that the truck was having.
So, everything was done as needed.

When I first started working on the truck, I replaced:
Spark Plugs
Oil & Filter
Water dumped and replaced with Radiator fluid and water.
Idle Air Control Valve (this was bad)
Fuel Pump and Assembly.

All the above was done prior to cranking the truck up.

Still hunting and fishing around.
And yea, I will get as good as you one day, and get things the first go around.