Ok I've been plagued with this very random misfire/powerloss/hesitation problem going on a couple of months. You could drive the truck anywhere from 50-300 miles without having an encounter of this problem. It seems to do it now mostly on continous long trips over like 30 miles. It one time threw up a P1131 code which quickly went away on it's own. This is a list of stuff that has been recently changed: plugs, wires, coil packs, air filter, pcv valve, fuel injectors, tps, idle air valve, MAF cleaned, fuel filter, and egr valve. I sprayed with brake cleaner for vacuum leaks around the intake tonight after driving a continous 50 mile round trip it messed a few times on the way back. When I sprayed the EGR valve mounting area it idled rough when it was hit with brake clean and idled up. So there's a leak there. Or is it stuck? It will be driving normal and usually when you come to a stop the engine will start missing really bad and then when you take off there's no power at all. You keep your foot on the gas and eventually it will feel like all the power is just turned on. If it does it while you're driving highway speeds it will feel like you've lost a cylinder but it's not as dramatic as when you come to a stop and it starts missing. I can't be 100% but I don't think the EGR wasn't leaking before I replaced it and it was still doing the same thing. I'm wondering why the Check Engine Light won't pick up an obvious misfire when you can you actually feel it. And why if it was the vacuum leak would it only start doing it after many miles of driving? I'm almost to the point of taking it to Ford just for a diagnosis but it's $120. I haven't paid much for all the parts I replaced because most all of them were warranty.

 

You've been busy on this one.

Were all of the above items replaced at the same time, just for this trouble shoot??? Were all of the above items really bad????
Were all of the replacement parts OEM????

Be careful spraying brake cleaner around the engine compartment looking for a vacuum leak, as brake cleaners, especially chlorinated recipies, aren't rubber, composit, or plastic friendly, as they're stress crack promoters, so can cause plastic parts to stress crack & if ingested by the engine, aren't O2 sensor friendly either.

The only thing that comes to mind about why it could miss so badly & the CEL not light up, is that the miss is being caused by something that the engine controller/computer isn't monitoring. All that said & with the P1131 lean code that went away on its own, right now, without more clues, makes me want to suspect an acting out fuel injector.

SO, how did each cyl spark plugs read, as you removed them. Did any cyl plugs show signs like they've been running lean, if so, go to that cyl & have a listen to its fuel injector to determine if it sounds different than the others????

As Murpheys Law may be messing with you & you may have more than one problem & as you say the problem mostly comes about after a long drive, if you have CCDF going on too, it could cause an intermittent miss as the combustion chamber deposits flake off & cause a valve to not seat well, or a spark plug to misfire. This type of misfire can cause the O2 sensor to give the computer some wild reports about O2 in the exhaust & have the computer get confused about what to do about fuel trim & seeing as how this is a 4banger, fuel trim is adjusted for All cyls, all a vicious circle!!!

SO, if your scantool will read fuel trim, monitor both long & short fuel trim & O2 sensor output on a drive & see how its doing. If your scantool will also monitor the fuel injector timing/switching profile & spark plug triggering, also monitor those along with the others & let us know if anything shows up.

If your scantool won't do all that, maybe consider opting for an inexpensive ELM scantool, running freeware FORScan or the like software discussed here https://www.ford-trucks.com/forums/1...-scantool.html, to use with your viewing device, laptop, smart phone, ect via a corded, or wireless WiFi or Bluetooth connection & have the ELM monitor the engine controller parameters mentioned above, while you drive & it acts out & see if it can spot whats going on.

The ELM can be had shipped for about $25 now.

A bunch more thoughts for consideration, let us know how your trouble shoot goes.

 

I first started with the spark plugs and wires at 300,000 miles just as maintenance. Remember the engine is a used one that had 50,000 miles on it when I got it so now it probably has 150,000 on it. After that the TPS actually messed up and threw a code so I replaced it and it fixed it. All the rest of the stuff has been replaced within the last two months ending with the fuel injectors. I put new Standard Ignition fuel injectors in. It helped with power eventhough it still does the random misfire and loss of power. I do have a scanner that reads fuel trim but I have no idea how to read it so it makes no sense to me. I can hook it up while I drive. The EGR, PCV, and fuel injectors were all possible causes of the P1131 under the Ford service guide so as most were under warranty I tried them out with new ones. I'm using non-chlorinated brake cleaner I sprayed for vacuum leaks. After it had the random misfire when I drove a few days ago for about 50 miles straight and I sprayed the EGR mounting area it idled rough. The next morning first thing I started it up and sprayed it again but there was no change in the idle or roughness. It was just running normal. I do notice that sometimes I hear the spark knock like it's got some deposits. But when I took out the spark plugs last week to swap out the ignition wires again the plugs looked normal for 15,000 miles of service and none was any different than the other and the gap was within .044-.046. It's hard when it's random and no Check Engine Light code is coming up to help you narrow it down.

 

The P1131 code came on again and briefly stayed on for a few miles like 30-40 miles and went away again on it's own. I had my scan tool hooked up while driving this time so it caught freeze frame data. Although I didn't get the 02 sensor info. I did get the fuel trim. I was reading about fuel trim online as to what it means and I remember it saying that - means it's not getting fuel and + means it's getting that much fuel. It also stated that a normal reading depending on driving terrain should never be in the - or + double digits. I did fix the EGR valve gasket leak. But the freeze frame data was caught before I replaced the gasket but it's still acting up anyway. The short term fuel trim when the P1131 came on was 42.2 and the long term fuel trim was 0.8 and I was at 54mph. When I was driving tonight I was watching it and it made 50 miles without acting up with great smooth power and by the time I almos got to Summit it started to act up a little and then leaving there 30 mins later for another 50 mile trip it acted up several times when it was messing up I noticed the fuel trim was at -11.24 and about the same short and long trim. It went up to 42.2 on the short term fuel trim when I mashed the gas in while it was messing up. I'm trying to avoid having to drop the tank and change the fuel pump until I know for sure it is a problem. It won't act up right when I start it up and let it idle so the fuel pressure is always spot on 65-72psi. I read the vapor recovery system could cause P1131 but I don't know what to check. Everything else has been covered under P1131 diagnosis except that I don't know for sure if the fuel pump pressure regulator is failing.

 

Ok, good idea to replace the EGR gasket & monitor PID things with your scantool while driving. Was the 42.2 reading a + or -????

If no vacuum leaks, no acting out/sticking fuel injectors or misbehaving MAF & O2 sensors, the fuel trim should be within +/- 5%. If the 42.2 was a +, then the computer thought it had to add that much fuel to correct for too much air in the mixture.
So until we have more clues, an acting out fuel injector & or maybe a randomly sticking open or otherwise acting out PCV valve, or dryrotted/leaking rubber hose to it, all of which are down stream of & not monitored by the MAF sensor, could randomly corrupt fuel trim & still belong on the suspect list for now. The 4banger PCV vlave rubber elbow likes to dryrot & crack in the outside bend of the rubber hose, so check the hose closely & replace the PCV valve if its past time.

So, it would be helpful for you to also include monitoring the O2 & MAF sensors, along with fuel pressure while driving & its acting out. Folks over on the Taurus forum have gone so far as to hook up their fuel pressure gauge & drive with it duct taped to the base of the windshield, so they could monitor fuel pressure while driving.
More thoughts for consideration, keep us posted on how the trouble shoot goes.

 

When the code was read while driving it was a positive 42.2 and when it was acting up last night I floored it and it didn't hardly move when I did that and it again was a positive 42.2. When this situation happens it's basically like it drops a cylinder and when you mash the gas all the way down to get it going it doesn't move hardly and then all of a sudden it kicks like a turbo as the cylinder comes back alive. I don't know if it's actually dropping a cylinder or not but you can actually feel when it's going to start acting up because you can feel a sudden power drop. I can't say it's certain 100% but I tried to see what the conditions were when it happens the most and it seems to be only after a long period of highway speeds of 50-70 and then you slow down and speed up again then it's more likely to happen when you again start accelerating faster. I also did replace the pcv valve and noticed no cracks or even deterioration in the hose. I used a motorcraft pcv valve. I do think my scan tool scans pids for maf, and 02. I've thought about taping my fuel pressure gauge to the windshield too but it still wouldn't even reach. Is there any kind of tool or gauge I can screw onto the testing port and drive with safely besides trying to rig up a fuel pressure tester?

 

Ok, more good feedback. With no other trouble codes & the fuel trim being +42.2 when it lays down, then suddenly waking up, it still sounds to me like a fuel injector intermittently acts up. Again, if your scantool can look at the fuel injector squirt times, also have it display those & when it acts out, take note of any cyl injector squirt time that looks different.
Too bad we don't have an O2 sensor for each cyl, so we could quickly see whats going on with each one. We just have an O2 sensor for each bank of cyls, so when one acts out, we have to test other things in each cyl, like cyl balance, compression, fuel injector squirt tests, remove spark plugs for a read, ect, to try & get a grip on which cyl to move high up on our suspect list. Thats why I preiously ask for a "spark plug read", as how the parts that fit into the combustion chamber look, as they can offer up clues to whats going on in there.

Another thought just entered my feeble mind. If your scantool will perform a cyl balance test, next time its acting out, before it clears up, pull over & quickly have the scantool perform a cyl balance test & see if it'll flag a particular cyl.

On the cyl balance test the scantool cuts individual fuel injectors off, then measures rpm loss & if there is no further rpm drop on the cyl under test, it means that cyl fuel injector isn't working right & that could speed up your trouble shoot.

Another thought that would fit the drive cycle scenario is CCDF. CCDF = Combustion Chamber Deposit Flaking. This is when combustion chamber deposits flake off & prevent valves from sealing, or short out spark plugs & cause a cyl power drop, this can happen more at hot, high rpm, like highway driving!!!! Another reason for a spark plug deposit/condition read, as it can offerf up clues about whats going on in that particular cyl.

More thoughts for consideration, keep us posted on your trouble shoot, hang in there & you'll likely find the problem soon.

 

Well my scan tool isn't that fancy. I know it doesn't do a cyl balance test and I'm not even sure it actually reads 02 read out eventhough it's listed on the PID values under view live data while driving. They're always steady at 0.00 never change. The MAF lbs/in was within .01-.06 it may have gone a little higher but when I was looking at it the whole day while driving and it was driving normal with no acting up it was always in the low ranges of .01-.06. It does read spark advance. But I wasn't paying attention to it. I drove intermittenly today with a few miles so it never acted up. When I replaced the fuel injectors the old ones I took out weren't full of corrosion or carbon. They didn't even look that bad. It was acting up before I changed the fuel injectors and after I changed all 4 of them with new Standard Ignition fuel injectors. So I'm going to be confident in the fuel injectors and say they're good. When I changed the wires thinking it was a bad wire I pulled all 8 plugs and checked the gap on them and they were all within .044-.046 and they all had the same gray ash deposits normal amount throughout all 8 plugs. I didn't see anything that was abnormal or obvious. I know that sometimes when it started acting up I could hear a spark knock but I don't even hear that anymore. How common is the carbon flaking? I always run a seafoam treatment through the vacuum line once a year exactly 1/4 pint as it specfies. I was going to try a top end cleaner kit this time instead of just the Seafoam treatment. I always add a fuel injector cleaner every 3,000 miles along with my oil change.

 

Ok, thats good input, so it was acting out this way Before the fuel injectors were replaced. Sounds like you'e been proactive about combustion chamber deposits too, so since the injectors have been replaced & you've been proactive about combustion chamber cleaner uppers lets put deposits & the injectors lower down on the suspect list & think about this some more.

I know you said you've heard spark knock & that would go along with & verify the lean code & a fuel starvation condition, so seeing as how you have an intermittent power loss & lean code, next time it acts out, pull over & while its running rough, without delay hop out & loosen the gas cap & see if it quickly stops acting out. If so, replace the gas cap. The fuel pressure gauge might show a pressure drop & the fuel pump flow rate will be wimpy while thats happening, as the cap is supposed to vent the tank as fuel is used, so if it doesn't do that, it'll take a while for the engine to use enough fuel for a negative fuel tank pressure to come about that the fuel pump can't over come, then the engine will starve for fuel, it'll loose power & it'll throw a lean code & the engine will run rough or stall, or if the fuel cap suddenly vents, power will suddenly return, kinda like your experiencing. Most time it happens after driving about 20 miles, but seeing as how yours is a 4banger & gets better mpg/doesn't use as much fuel as the V6, it would require a longer drive for it to use enough fuel to act out. Doesn't happen often but i've run across it 3-4 times in the past 5-7 years.

When it acts out, can you hear any engine noise, like a valve tic, that might suggest a mechanical problem, like a valve sticking????

The O2 sensors reading 0.0 isn't right, they should be rapidly switching between .9 & .1 volts, with the average being around .45 volts. since you don't have trouble codes for them not working & its running ok unless it acts out, sounds like its a scantool, program, or maybe a vehicle scantool setup problem.

More thoughts for your suspect list.

 

No when it happens I'm not hearing anything other than the spark knock. No mechanical condition. It sounds like all the 2.3 and 2.5's sound like a sewing machine. My scan tool must not test my O2 sensor output watching live data because I have a separate function a O2 monitor test and it says my vehicle isn't supported by that function. So in the manual it refers me to do a on-board monitor test instead. Which while looking at the on-board monitor tests I have no clue what all the codes mean. I looked through all the monitor tests that came up and 3 failed that I wrote the results down to. I have no clude what the ID refers to or the mod $10. It even had a misfire monitor test but it listed like 10 different cylinder misfires so I didn't know if it was applicable to mine since I've got a 4 Cylinder. I don't even have a bank 2 so I don't know why it pops up. But here they are.
Not10 front switch ratio bank 2
ID 21
MOD $10
Test(:1) 1024.0
Min(:1) ----
Ma:1)1.0
STS Fail

Vapor Generation Max Pressure Rise
ID 00
MOD $10
Test(in H2O) -63
Min(in H2O) 1
Main H2O) ---
STS Fail

Delta Pressure for Downstream Hose Test
ID 12
MOD $10
Test(in H2O) 21
Min(in H2O) ---
Main H2O) 6
STS Fail

 

It was a bad mass air flow sensor. I tried cleaning it and it didn't help. First I changed the upstream O2 sensor and it seemed to help and then I went ahead and changed the MAF and it's been doing fine ever since over weeks now. Been thousand miles or so without incident whereas before it was starting to foul up every drive. Also just to let you know some more tech questions might be coming. I got a 1992 Supercab Ranger 4.0 automatic with 99,000 miles I just bought for $1000. That also puts my abused 1993 2.3 manual Ranger back in the driveway for some much needed repairs.

 

OK, good find,fix, feedback & to hear all seems well after replacing the MAF sensor. Strange that it never tripped a misbehaving trouble code.