Rough idle and "Check Engine Soon" light - FIXED

[Pontisteve]

First off this has been a great thread and has saved me a heap of cash but here is what I'm experiencing. rough idle, bought cleaner for mass air flow and cleaned it twice, after cleaning the old IAC twice as well I decided to replace it. Replaced the 90 degree rubber elbow as described so it's new. Took the ERG off inspected and it ok but I cleaned it as well. Put new plugs and boots in. Changed air filter. I've run the UNLIT propane around every hose I could find with no motor idle increase at all. I just feel like ice tried everything and all that's left is the MAF to try and replace.
Codes I was getting we're the MAF and IAC. The CEL has come back on and unfortunately it's going to be a week before I can get back and get the MAF installed. Has anyone had any luck with aftermarket MAF units? The original equipment MAF is running $188 and I know that's cheap compared to taking the car to the dealership. Just looking for opinions and experience.

The Motor is in my 02 Eddie Bauer explorer with the 4.6L V8.

Motor ran fine for about 60 miles and now has started to revert back to the issue of a rough idle and while driving it has a tendency to shutter or stall while at speed.

What it also seems to be doing is running very rich at idle and at speed. At idle you can smell the extra fuel coming out the exhaust.

My last ditch effort will be to replace the mass air flow unit and see if that corrects the problem. What my question is does the mass air flow unit really have that large of an affection on the motor at idle? it just baffles me how the motor can go from running so smooth to so rough at both idle and at speed. At highway speeds i would also describe the acceleration as mushy and at other times fine. Very weird.

Any other things I should be looking at besides the Mas air flow unit. How about O2 sensors?

Thanks again

Harry

Again thanks for the insight this thread has provided.

Harry, don't throw parts at this thing. You will be sorely disappointed, and kicking yourself for spending hundreds and not fixing it. If you must throw money at the problem, throw it at paying someone to diagnose your car properly (and that means a GOOD technician, not just any mechanic). Or, spend your money on a good scantool. That's never a waste.

The Ford mass air meters don't fail often, and it's very unlikely to be your problem. If you must guess, try buying a used MAF off Ebay. But I can almost guarantee you it's probably a waste of money. They just don't have a high failure rate. They DO have a high rate of getting dirty. Remove the 2 security torx bits, pull the MAF sensor out of its housing, and spray the crap out of it with MAF cleaner, right on those 2 resistors. If they look dark brown or black and clumpy, they're dirty. Clean, they will look a light color and smooth and visible.

The O2 sensors would be my guess. Does the car run well when cold, and just fine at WOT, but like crap when warm and at idle or part throttle (closed loop)?

What exact codes did you get? Does your scan tool have Freeze Frame data? If so, what RPM and load and throttle position does the freeze frame data show?

 

[Pontisteve]

Oh, and what are the STFT and LTFT?

 

[Hwebster69]

Harry, don't throw parts at this thing. You will be sorely disappointed, and kicking yourself for spending hundreds and not fixing it. If you must throw money at the problem, throw it at paying someone to diagnose your car properly (and that means a GOOD technician, not just any mechanic). Or, spend your money on a good scantool. That's never a waste.

The Ford mass air meters don't fail often, and it's very unlikely to be your problem. If you must guess, try buying a used MAF off Ebay. But I can almost guarantee you it's probably a waste of money. They just don't have a high failure rate. They DO have a high rate of getting dirty. Remove the 2 security torx bits, pull the MAF sensor out of its housing, and spray the crap out of it with MAF cleaner, right on those 2 resistors. If they look dark brown or black and clumpy, they're dirty. Clean, they will look a light color and smooth and visible.

The O2 sensors would be my guess. Does the car run well when cold, and just fine at WOT, but like crap when warm and at idle or part throttle (closed loop)?

What exact codes did you get? Does your scan tool have Freeze Frame data? If so, what RPM and load and throttle position does the freeze frame data show?

Starts fine but smells rich then when it warms up it runs like crap at idle. When warm at speed runs like crap. When at temp and at a stop light it acts like it wants to stall and has. I've used a can of MAF cleaner and looking inside without removing the MAF from the box it looks clean and not dirty. I've cleaned it twice now so maybe removing it will tell a diff story.

At speed the car surges slightly as you depress the gas pedal. Let off the gas and it coasts fine then back in the gas and it continues the surging and or studdering. Sorry I can't describe that better. Plus power seems down unless you mash it to the floor then it will get up and go.

I took it to autozone to read the codes and they were p0113 and p1504

 

[apenland01]

hweb, I haven't read through all the posts, but did you pull the TB and clean it up good too? I see you did the maf and egr, but you need to pull the TB and clean it as well. All of those are free to clean and if you clean one, you clean them all (I found that out personally). You'll need a new gasket for the TB which is about $2 at oreilly or autozone. After you pull and clean all of them, reset the PCM and give it a few days to see how the idle responds.

 

[Pontisteve]

P0113 is the Intake Air Temp circuit high. This usually means you turned the key on while the IAT sensor was unplugged. If not, it could mean a break in the wire or a bad IAT. My guess is that you unplugged it while doing diagnostics and it set that code.

P1504 is a code for the IAC circuit. This too was likely set by unplugging the IAC while the key is on. Even if the engine is off. Or it could mean a bad IAC, if you are certain you didn't unplug it while the key was on.

In that case, I would do a resistance test on the 2 pins of the IAC, with the connector unplugged, to make the sure the IAC isn't open or shorted (no resistance at all).

If your scan tool supports Mode 6, you can look at Test ID 53, cylinders 1 thru 8, to see if there are any misfires on any one cylinder, after driving it around a bit.

If your scan tool supports live data, you need to look at LTFT and STFT 1 and 2, and also graph the STFT to see if the O2 sensors are sweeping from rich to lean (.1 to .9v) steadily.

If you don't have a scan tool, now would be a good time to buy one. You will want one that supports code pulling and clearing, live datastream, generic OBD2, and preferably Ford manufacturer specific data. One option here is to buy a PC-based scan tool for your laptop. You can get a lot more for your money that way, since they are not supplying much hardware.

Another option is to buy a bluetooth OBD2 scan device that plugs into the OBD2 port, then buy a scan tool app for your smart phone. The combination of these 2 can be had for anywhere from $15 to $60, turning your phone into a generic scan tool.

Better scan tools will support all 9 modes of OBD2, and manufacturer-specific codes, and will have datastream. Really good scan tools will have bi-directional controls.

 

[Hwebster69]

P0113 is the Intake Air Temp circuit high. This usually means you turned the key on while the IAT sensor was unplugged. If not, it could mean a break in the wire or a bad IAT. My guess is that you unplugged it while doing diagnostics and it set that code.

P1504 is a code for the IAC circuit. This too was likely set by unplugging the IAC while the key is on. Even if the engine is off. Or it could mean a bad IAC, if you are certain you didn't unplug it while the key was on.

In that case, I would do a resistance test on the 2 pins of the IAC, with the connector unplugged, to make the sure the IAC isn't open or shorted (no resistance at all).

If your scan tool supports Mode 6, you can look at Test ID 53, cylinders 1 thru 8, to see if there are any misfires on any one cylinder, after driving it around a bit.

If your scan tool supports live data, you need to look at LTFT and STFT 1 and 2, and also graph the STFT to see if the O2 sensors are sweeping from rich to lean (.1 to .9v) steadily.

If you don't have a scan tool, now would be a good time to buy one. You will want one that supports code pulling and clearing, live datastream, generic OBD2, and preferably Ford manufacturer specific data. One option here is to buy a PC-based scan tool for your laptop. You can get a lot more for your money that way, since they are not supplying much hardware.

Another option is to buy a bluetooth OBD2 scan device that plugs into the OBD2 port, then buy a scan tool app for your smart phone. The combination of these 2 can be had for anywhere from $15 to $60, turning your phone into a generic scan tool.

Better scan tools will support all 9 modes of OBD2, and manufacturer-specific codes, and will have datastream. Really good scan tools will have bi-directional controls.

You are correct I did pull the plugs while key was on. Prob not a good idea but was running out of ideas. I don't have a scan tool but may invest this weekend in. One.

When I did take it to ford they did show some miss fires due to there being a lot of oil around the oil fill side boots around the plugs. After these were replaced and the plugs replaced it ran really well BUT again it went down hill again fast. At that point I replaced the other 4 plug boots with really no,real change in performance. Once I did clean the IAC and MAF before replacing the IAC it ran smooth as silk. Again shortly after it went down hill. I replaced the 90 degree rubber elbow, replaced the IAC, cleaned the MAF twice maybe even three times, removed the ERG and cleaned, sprayed throttle body with carb cleaner as best I could without removal. I seem to have tackled everything everyone said helped their issue but mine still exists. Again only thing left to,replace would be the MAF, O2 sensors and ERG. I have never removed the throttle body so not sure what's involved there but will give it a shot.

I do,have a buddy who is a mechanic by trade and was planning on seeing what he could tell me this weekend.

Please keep,asking me questions and I will keep,reporting back on what I've done and if there has been any improvements.

Again thanks

 

[Pontisteve]

You are correct I did pull the plugs while key was on. Prob not a good idea but was running out of ideas. I don't have a scan tool but may invest this weekend in. One.

When I did take it to ford they did show some miss fires due to there being a lot of oil around the oil fill side boots around the plugs. After these were replaced and the plugs replaced it ran really well BUT again it went down hill again fast. At that point I replaced the other 4 plug boots with really no,real change in performance. Once I did clean the IAC and MAF before replacing the IAC it ran smooth as silk. Again shortly after it went down hill. I replaced the 90 degree rubber elbow, replaced the IAC, cleaned the MAF twice maybe even three times, removed the ERG and cleaned, sprayed throttle body with carb cleaner as best I could without removal. I seem to have tackled everything everyone said helped their issue but mine still exists. Again only thing left to,replace would be the MAF, O2 sensors and ERG. I have never removed the throttle body so not sure what's involved there but will give it a shot.

I do,have a buddy who is a mechanic by trade and was planning on seeing what he could tell me this weekend.

Please keep,asking me questions and I will keep,reporting back on what I've done and if there has been any improvements.

Again thanks

If it's running bad, it's probably going to boil down to one of 4 things.

1) An electronic issue, such as an O2 sensor problem. Have your buddy log LTFT and STFT at idle, and again at 2500 RPM for both banks.

2) A secondary ignition issue. In this truck, that means coil boots and springs, or spark plugs. If you have oil on your coil boots, that oil breaks down the rubber boots and then spark jumps thru the boot to ground, causing a misfire. While a new boot is necessary then, the real problem is the valve cover gasket or whatever it is that keeps oil out of the spark plug wells.

3) A mechanical issue. Vacuum leaks, intake gaskets, engine issues such as valvetrain, etc. While the vacuum leaks are surely a potential problem, it's kind of unlikely that you're into actual motor problems.

You can hear a motor problem pretty easy. In most vehicles, you can hold the throttle to the floor and crank the engine over. This shuts off the injectors (clear flood mode), and the car wont start. While it's cranking over (for about 6 to 8 seconds), you listen to the engine. You'll hear a rhythmic sound of each piston coming up on the compression stroke. The increase in compression on each stroke causes a decrease in starter RPM momentarily. So if you have a compression problem, you'll probably hear it with this test. If so, that guides you towards looking at engine mechanical issues, such as valve sealing, compression tests, etc.

4) Primary ignition. This means the crank sensor, cam sensor, computer, and coil packs. This is a bit tougher to catch. The most likely is the coil packs fail. They often fail because a misfire was allowed to go on for too long, overstressing the coil pack. One of the best ways to catch this is with a scan tool that can monitor misfires. Drop trans in gear, power brake it a bit to load the engine, and watch the misfire monitor. That will show you which cylinder is acting up. You then determine if it's primary or secondary ignition (coil or plugs/boots).

COP coils on these Fords are known to go bad easily. Especially if a misfire has gone untreated for some time.

 

[apenland01]

The throttle body is very easy to remove. You generally don't want to spray anything into the throttle body without removing because you are just washing the sticky gummy crap into the intake manifold.

You just pull the PCV hose from the big black air intake tube, remove the intake tube, disconnect the few things that plug into it and remove the 4 bolts holding on the intake manifold. Once you get it off, you'll be shocked at how awful it looks on the backside. The most important part is cleaning the edge of the moving valve and the wall around it so that it can operate freely.

Once you've got it cleaned up nice, reinstall it with the new gasket and reset the PCM.

I had never removed my throttle body, but did it about 6-8 months ago and it took me about an hour and a half to remove it, clean it good and it put it back in. That included a trip to oreillys to get a new gasket. A very easy job really.

 

[Pontisteve]

I'm not against removing the throttle body. But I'm also lazy to want to go to the store and buy a new gasket. So what I do is take a string of about 6 paper towels, wad them up in the shape of a wringed out towel about a 8" long, and insert it into the intake behind the throttle plate. Then I "brush it's teeth" with literally a good stiff toothbrush, clean it good with carb cleaner, and then use a long duckbill pliers to slowly pull the wet nasty paper towel out.

With this method, the paper towel catches the bulk of the carb cleaner and gunk. You could even go back in with some more paper towel to mop up any additional liquid, but I find the paper towel pretty much absorbs all of it unless you overclean the heck out of it. In which case, you could always replace the paper towel half way thru the process. No doubt, removing the throttle body eliminates 100% of the fluid from ever seeing the intake, and probably does a better job cleaning. But my method is faster. About 10 minutes total, and never seen any side affects. I wouldn't do it that way without paper towel though.

 

[Hwebster69]

Ok so here is where I am at today with the random idle problem. Took it to a mechanic buddy of mine and it was now throwing the p1309 code but wasn't giving any specifics as to where the misfire could be. I have replaced the IAC, changed plugs, boots, new air filter, cleaned everything I could checked for any vaccum line leaks and cleaned the MAF sensor.

So I took it to the dealer and he was showing a misfire on cyclinder #7 . They replaced the capacitor and it is running excellent.

A couple things I learned was I need to be checking the engine more often. Don't throw parts at it, although replacing what I did seems like it could only help with the mileage it has at 153k on it.

I want to thank the persons who are on this forum for your help advise and honesty.

One quick note it was $134.00 for them to repair as they gave me credit on the computer time from my first visit.

Thanks again

Harry

 

[Pontisteve]

The RF noise capacitor?? Interesting. I don't think I've ever had to replace one. I would love to get my scope on that ignition circuit with the bad capacitor and see what it's doing.

 

[Hwebster69]

They replaced the coil that fires the plug. Sorry called it a capacitor. My bad. Anyway they said it looked a like a couple had been relaxed in the past but not by me so might just replace all the other 7 so I know there new.

 

[Pontisteve]

Don't waste your money. Only replace them if they go bad, and always use genuine Motorcraft. What makes them go bad is bad spark plugs or plug boots, causing the coils to work harder and they overheat themselves. The problem isn't really the coil.

 

[Hwebster69]

Well plugs are new, boots and springs are new and after cleaning virtually everything and finally the #7 coil being replaced its been running flawless. What a load off my mind for now and I again appreciate the help,this thread and the people involved have given.

Thanks again

Harry

 

[dannyisaacs]

2007 Same Issues?

Would a 2007 4.6L 3v V8 have this elbow problem somewhere?
I cant find the elbow you guys are talking about?
Thanks in advance!

 

[Pontisteve]

Would a 2007 4.6L 3v V8 have this elbow problem somewhere?
I cant find the elbow you guys are talking about?
Thanks in advance!

Not this same one. The 4.6 2V generally all had about the same upper intake manifold, and this elbow was pretty common to all the 2V engines.

The 3V may have it's own issues. Just inspect every part that's rubber, between the air filter box and the intake manifold, including any hoses that branch off. Also make sure each component seals to the next one correctly, and that none of the rubber (including the large inlet hose itself) is cracked or broken.

 

[dannyisaacs]

Thanks for the quick reply! This thing is running like a dog! I replaced (after snapping 3) the plugs. No help... Replacing coil packs tomorrow or Sunday!
Next step I think would be to replace the fuel rail sensor? I unplugged it and nothing at all changed with the idle?

 

[Pontisteve]

Thanks for the quick reply! This thing is running like a dog! I replaced (after snapping 3) the plugs. No help... Replacing coil packs tomorrow or Sunday!
Next step I think would be to replace the fuel rail sensor? I unplugged it and nothing at all changed with the idle?

Quit while you're ahead. Seriously. If you don't have good diagnostic skills and the right tools, you'll guess yourself into poverty.

If you must move forward, start with the basics. Pull codes. Check fuel pressure. Make sure it's running on all 8 cylinders. Check the air filter. Clean the MAF.

 

[dannyisaacs]

Thanks Pontisteve!
I have had the codes pulled. I don't have them in front of me but they were... 300 304 307 and another that I don't remember right now.
All pointed to misfires.
This was after changing the plugs at 93000 for the first time.

I just put coils on 3 and 7.. running a little better but still running a little rough.
Ill clean the MAF in a bit!

 

[Pontisteve]

Thanks Pontisteve!
I have had the codes pulled. I don't have them in front of me but they were... 300 304 307 and another that I don't remember right now.
All pointed to misfires.
This was after changing the plugs at 93000 for the first time.

I just put coils on 3 and 7.. running a little better but still running a little rough.
Ill clean the MAF in a bit!

The thing about coils is they generally don't go bad, on their own. Especially coil on plug, since there's 8 of them. That gives them 8x more rest time than a traditional single coil. What kills a coil is high resistance... bad plug wire, spark plug, big plug gap from worn plugs, etc.

The coil stores up a bunch of energy. If it can't release it into the spark plug, it is really hard on the coil. A prime example of a bad idea is to take a coil on plug coil out of the engine, leave it plugged in, and run the car. Or to have bad plugs and wires, and just keep driving the car. It kills the coils. Equally bad is to have water down in the spark plug wells, and keep driving the car.

Having a single cylinder misfire can be bad luck. A bad plug, the first plug wire breaking (yeah, I know your car doesn't have plug wires), or even the random bad coil. But having multiple cylinder misfire codes is odd. Also, a misfire code does not necessarily mean an ignition misfire. It could be a bad injector or fuel system issue causing a fuel-related misfire. Coils aren't cheap to replace, and OEM Ford coils are recommended. So we don't want to call bad coils until we've exhausted other possibilities.

The way Ford techs often diagnose a bad coil is to hook up a scan tool, look at the power balance test, then put the automatic car in drive and power brake it slightly. This puts the engine under a light load. Then watch the power balance test, to see which cylinders quit contributing to power (misfire) under load.

The Ford system doesn't have wires, but it does have plug boots and spark plugs. The boots and coil springs come in a kit for about $5 per coil, and would be the modern version of a spark plug wire. The way I like to test them is with a test light, while the coils are removed, plugged in, engine running, and hooked up to an HEI spark tester. I use the test light hooked to ground, to see if the coil boot leaks voltage thru to my test light probe, as I wave it up and down the plug boot.

Another test is to bend the boot. If you bend it and it looks like it's kind of cracking in the bend, the boot is bad and should be replaced. Typically, if a car comes in and has a bad COP coil, it's getting that coil, and 8 plugs and boot kits.