DTC help

[JoshT]

Hey folks I know I don't post much but I really need you help on this one.

Background:

I bought my 99 Ranger about 5 years ago. First thing I did when I got it home was the standard tune-up stuff and it ran fine. A few months later the O2 sensors started throwing codes, but I can't recall what they were now. On suggestion of forum members I replaced the O2 sensors and cleaned the MAF and TB. At this point the truck probably had close to 100K and I knew from reading that it was probably about due for the sensors to go out anyway so it wasn't a problem. The codes were cleared and didn't come back. less than 6 months later I bought an X-Cal2 from Doug at BamaChips. Shortly after putting it in the truck started throwing codes once again for something to do with O2 sensors. I contacted Doug to get his imput, he said it was bad O2 sensors. Since I had just replaced the sensors and they had worked fine for months before installing the Tuner I knew they weren't the problem. I told him what I had done about the sensors and cleaning, and he said that the engine must be getting more air than is standard so he "adjusted" the tunes and re-sent them. The codes never came back.

FF to 2 years ago. The truck started to run rough, at first it would only do it occasionally so I didn't worry to much about it. It continued this for a few months before getting worse, when it got worse I started diagnosing. At first I though it was the truck so I did the standard tune up, and it cleared up for a while. Only for a while though because it came back, this time I put it in the shop. The told me that it was a bad plug and or wire (can't remember which), so I changed them. Once again it cleared up for a while but came back. This happened 3 more times within a year. Ok it's not the plugs and wires causing the problem, and I'm not going to take it back to a shop just to be told the same thing. Then I got the bright Idea that maybe it's the tuner causing the problem, for the last 6 months or so I have been swapping it between different tunes and stock and every time it would go away for a few weeks and come back. I would leave it set on a tune for no less than a month, but it would never throw a code. About 3 months ago it got really bad to the point that it wouldn't hardly crank in the morning so I broke down and put it in the shop again. Guess what they found, bad spark plug and plug wire. Is it just me or is there a pattern here. My fuel filter was also rough, apparently the place I had been filling up had a sub-par holding tank or something, replacing that helped. Within 2 weeks of replacing this spark plug it was starting to do the same thing again, but it would never throw a CEL or a code. At the beginning of August I put it back to stock again and now it has finally thrown for codes within the past week.

IIRC the plugs that were giving me problems were on the driver side of the block, first two but I can't recall how these cylinders are numbered I think it would be 4 and 5.



The Codes:

P0133 - This one actually appeared on the 16 or 17th of August.

Drove my new to me car (bought it on the 13th) from the 17 through the 22nd when the clutch gave out. (It was a 500 dollar car I can't complain.) Picked up the truck from my parents on the 22nd. Checked codes again today and got these:

P0171
P0303
P1131


I'm guessing that the O2 sensor probably isn't the source of my problem though I will replace it anyway to be on the safe side. Any ideas what could cause all of these?

Please help me out here I really want to get this problem sorted out once and for all. I would start throwing sensors at it, but that costs big $$$ which I also have to use to fix the car. With past experience there is no need me for me to get it scanned because they will just find a bad plug or wire. So I'm relying on your collective wisdom and experience for this one.

EDIT: FWIW the past symptoms at their worst. They included hard starting, and severe missing/skipping when first started in the morning. So bad it sounded like it was only running on a couple of cylinders, but by the time I got out of my drive way that would be cleared up (usually). Rough Idle all the time, would literally shake the truck while sitting at a traffic light. Missing while going down the road, guessing that is the right word, best description I can give is bucking.

Currently it has started with it's first start of the day routine not very bad right now, but getting worse. I noticed bad hesitation and throttle response while driving it today.

 

[fireguy12117]

P0303 - cylinder misfire
P0133 - fuel control system fault
P0171 - air fuel ratio too lean/reach for PCM to correct
P1131 - Oxygen sensor fault

oxygen sensors are throwing codes because of a condition they are detecting thats out of range, not necessarily because they are bad. fuel systems fault is probably just a generic fault (i got one because of my EVAP system not purging) tied in with the root cause of the problem. air fuel not able to be corrected by PCM is a big clue, as is the cylinder miss fire.

your generation truck has the nice feature of being able to tell what problems potentially exist in what cylinder. on a quick search 0303 should be cylinder 3. check out the tech library to get a better idea what the 4.0 is in terms of firing order. id then double check your plug and plug wire on #3, make sure the boot is sitting tight on the plug, and on the coil pack.

don't count out bad wiring. I've had a nearly completely bad wiring harness. on older trucks it can be bad grounds or bad harnesses, not bad sensors causing codes. the PCM cant tell if its a bad wire or sensors, it just knows what it is supposed to see from sensor X. check to make sure there are no loose connectors anywhere, either because it popped loose, was never hooked up correctly, or the shop did something accidentally while they were under the hood.

i'll assume your clearing the codes as you scan them. when you do that it puts the PCM back into learn mode, so things drive well for a bit while the PCM 'learns' the engine and tries to run the motor on bad data from somewhere.

Definitely take the bama chip out of there until you find the issue with the drivabilility. i would not buy any more sensors until you find the bad one- if it is even a bad sensors- they may all be perfectly good, but there is some condition (dead cylinder) causing the readings to be out of range.

the last part of the post sounds like you are describing the exact result of a dead cylinder (P0303), however a vacuum leak could also cause similar symptoms, but all 4 codes point to a fuel issue.

 

[JoshT]

To be more precise:

P0133: 02 Sensor Circuit Slow Response (Bank 1 Sensor 1)
P0171: System too Lean (Bank 1)
P0303: Cylinder 3 Misfire Detected
P1131: Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 1

As I said the first time it has thrown codes since Doug "fixed" the programmer was 2 weeks ago. Yes, every time I changed the tunes in the computer it would have to re-learn, but it never threw codes. Actually I am not clearing codes as I read them, because I want it to throw as many as it can. I figure that the more codes it throws the better I'll be able to track down the source.

I got that the O2 sensor codes are just generic, but that doesn't change the fact that something is causing them. P1131 is telling me that there is something wrong with the O2 sensor, because as P0133 is telling something is causing it to respond slowly. I figure that these were probably preemptive warnings to the other two codes.

I can tell you now that the problem does not originate from plugs or plug wires. Yes there may be a bad plug but it was something else that caused it to go bad. If it had cleared up after the second set of plugs and wires then yes it could have been a coincidence. Instead it has had happened 4 or 5 times now. I replaced them the first time to "fix it" when I did the tune up, the next 3 were from it being run through diagnostics and being told by professional mechanics that the results said it was bad plug or wire. The last time I had it put on a machine (different shop, much more knowledgeable mechanic, with a lot more experience) he found a bad plug and it was either cylinder 3 or 4 so he replaced it. Now it's doing it again. That's to many bad plugs/wires in too short of a time to be coincidence, something else has to be happening.

"The Shop" doesn't do anything on my truck other than run diagnostics. I replaced the O2 sensors on it the first time around and know I connected them properly, that said next time I have the chance I will check to make sure that they are still connected properly.

The idea of a dead cylinder has crossed my mind but it doesn't make any sense. If there were a dead cylinder why would it be able to run perfectly after re-programming the computer? That would be caused by a problem outside of the computer's capability to control right? As such clearing the computer's memory and causing it to re-learn shouldn't make the problem disappear for a little while. This goes the same for a bad ground, re-programing the computer wouldn't make the bad ground turn good for a while then come back.

I don't disagree wit the fact that it could be an electrical problem, but with the way in which the problem comes an goes I don't see how it could be a problem with the wiring harness. If it did not disappear with re-programming of the computer then yes I could understand it, but re-programming should not affect wiring. Now I do think it could be an electrical problem in one of the sensors or possibly even in the computer itself. I know that they keep telling me that a plug is bad but they never tell me why they think it is bad. Could the problem be that the coil pack is not firing properly and as such the plug is not firing properly. I think a bad engine ground could be ruled out because the rest of the cylinders seem to be firing properly.

If the issue is fuel related problem, there is so much stuff that could cause fuel problems and it is not giving me anything more specific than to lean, misfire in cyl 3 and it's all on bank one. What could cause these. Is it a bad sensor causing the fuel trims to go to low? Is it a vacuum leak, and if so why isn't it affecting both banks? Is it a bad injector(s) causing bank 1 to run to lean, or bad wiring causing it not to work? The last mechanic I took it to decided to test and clean the injectors, but he didn't find any bad ones. Maybe a bad head gasket, or manifold gasket it allowing extra air in. Hell could it be a bad MAF that is not properly reading the amount of air coming into the engine?

I guess that the easiest thing for me to diagnose would be a vacuum leak. Isn't there some aerosol fluid that can be sprayed around to detect a vacuum leak. I've heard that you can spray some chemical and if there is a vacuum leak in the area it will cause the engine idle speed to increase. Anybody know what I'm taking about?

 

[fireguy12117]

when you say reprogramming the computer are you talking about the bama chip? i cant shed any light on what you describe since i have no idea really how those chips interact with the engines PCM.

when i meant bad wiring, i meant an actual broken wire inside of the harness. my IAC controller had one bad wire inside of the harness that a shop couldn't figure out but a $5 ohm meter and 20 minutes in a parking lot could.

yes, there is a distinct pattern with that plug; have you compared how the plugs have failed each time?

those codes point to a lean bank, and a dead cylinder. id be looking real close for a burned up spark plug and a bad wire on injector 3- either the power, or the signal from the pcm.

 

[JoshT]

The X-cal2 isn't actually a chip, it's a tuner. It plugs into the OBD-II port and downloads then replaces the stock programming with aftermarket, some folks call it re-flashing.

I knew what it was that you meant by a bad/broken wire, I just don't understand how a broken wire could disappear for a while when the computer is re-flashed and then come back.

Like I said they didn't tell me what was wrong with the plugs just that they or the wires were bad. I replaced them each time, I know I looked at the plugs but can't recall now how they looked.

The spark plug is probably burned up now, but that's not the cause of the problem it's the effect. I just don't want to keep throwing spark plugs at it I want to fix the root cause of the problem otherwise it'll keep happening. I'll try to test the injector wires once I get the clutch in my car replaced. Can't afford to have the truck parked right now. It'll probably be after Labor Day weekend, so when I get the chance how would I test the signal from the PCM? Also is there any way to test the injector outside of the truck?

 

[JoshT]

Aside from reading codes, the tuner will not be used again until this problem gets sorted.

 

[fireguy12117]

can you retrieve the original program with that device, or once you flash it, its gone?

i was trying to find some correlation between the relearning period emulating what you're saying about problems coming and going, because yes a flat out broken connection wouldnt act like that, an intermitten is just that, it wouldnt correspond to a regular period of you redoing the programs, so i was wondering if somehow there was a connection to your noticing symptoms and there being a 'relearning' period.

a simple ohm meter could perform continuity tests. you can probe the harness at the PCM, out to the injector connector to verify that there is a good path. do you have a wiring diagram to help with that?

my 93 during the rebuild somehow fried the PCM but not a single check engine light for all sorts of drivability issues. i forget what series of steps i took, but it involved swapped 4 different MAF's to determin i had a bad PCM that would not read that signal right.

my point i think is that its not impossible that the injector output signal of the pcm is bad.

 

[JoshT]

My understanding of how the tuner works is that it downloads the stock programming into a memory on the device and then uploads the aftermarket to the computer. When you get ready to go back to stock it wipes the computer and re-uploads the stock programming. I do not believe that any of the adjustments that are made while it is learning are saved to the device, I believe that it is just the basic programming that is saved.

I've got the Haynes or Chilton manual and dad has a multimeter so once I get the chance I'll give it a go.

Bad MAF was one of the problems I had considered but put that out of mind when it was only affecting one side.

 

[fireguy12117]

Yeah, all the codes are pointing a different direction.

i just wanted to mention that i didn't have any indication of a bad sensor, wiring checked out good and i had no way of eliminating anything in the circuit until i got my hands on some junk yard PCMs to determin it was in fact the PCM itself not reading the MAF.

if the wiring between the PCM and injector ohms out good, you test the other wire on the injector (i think it goes to a common power supplied from a PCM relay or something) and that tests good, and your able to look at an old plug and its burned up, id suspect maybe a bad pcm output on that injector. thats about the only reasonable explanation towards how you fried 5 plugs on the same clyinder.

oh yeah, if you search around you should be able to find some info about testing the injector itself. i did a half ass test with measuring the resistance of three at a time and comparing bank 1 and bank 2 ohm readings because i was lazy and didnt want to fight with pulling the plugs to isolate each inejctor. my set up is batch fire so 3 are connected together. the ohm readings matched so i played the odds that there wasnt a bad injector however it could have been that i had 2 bad ones, one on each bank...anyhow...total shot in the dark but something like 6 ohms resistance on the inejctor. if you have an open, or much higher resistance, it's suspect.

 

[naford]

Dude cylinder 3 misfire and bank 1 lean. Do you think it could have to do with cylinder 3 having a problem? Pull cylinder 3 plug tell us what it looks like. Do a compression test and verify that all cylinders are close. I have had good luck with taking a long screwdriver and listening to the click of injector at idle. Compare it with other cylinders.

Sit down and let me tell a tale. Had a Grand Margue 4.6L V8. Cylinder 1 missing and bank 1 lean. Plug looked OK compression was a little off. Tried plug, plug wire, pulled plug wire with motor running. Nothing seemed to help. Called a Ford mechanic. told us to pull the valve cover and to check the lifters. Pulled the valve cover and found the lifter resting in the top of the head. Put the lifter back in car runs great. I'm not saying this is your problem but I think some testing is in order.

 

[JoshT]

Well nothing is going to be happening with this for at least a few weeks. I totaled the 84 this morning so the 99 is the only ride I got until I can get the clutch replaced in the Probe.

 

[JoshT]

Ok back on this again, for a short time anyway.

So the week before last I had to replace the alternator and as a result the computer got re-set. I now have misfire codes on CYLs 3 and 4. Got it into a stealer ship this morning and found out that I have bad compression on CYL 3. I have seen no signs telling me that compression is not leaking onto the crank case, and it's not burning oil. I also have seen no signs that combustion gasses are escaping into the cooling system, or the other way around. One of the things the dealer suggested is that it could be a stuck valve and/or carbon build up. Does this make sense? Should I maybe run Seafoam through the engine to clean out carbon deposits and see if it makes a difference? I've always looked at the stuff as being a snake oil but a lot of people here and else where swear by it.

I know that ultimately I will probably have to pull the head, but I want to try everything that I can before going to that extreme.

 

[Nhaz]

Seafoam is cheap, try it first. I think yer pulling a head anyways in the long run.

 

[naford]

If you could pull the valve cover over number 3 and see if either the lifter is bad missing or if the valve spring is broken you could save alot of time.

 

[JoshT]

Ok, this is an OHV engine the lifter can't be seen with the valve cover off. On top of that I currently have no place to do the work. I don't want to do anything on this engine until I at least have a concrete pad to do the work on that way if I drop something I can find it easily. I would prefer to wait on opening it up until I have a shop built, which hopefully won't be long.

On other note I will be trying the seafoam treatment this afternoon, hopefully I won't have to take it any further than that.