engine idling rough

start with a compression test to verify motor is ok.

Roy

Engine is equipped with chains so no timing belts to replace. Is the MIL indicating?

You could have a misfiring and I would suggest starting with the spark plugs and related components.

As to the noise while turning, it could be the drive axles or brakes. You need to locate the source.

I just bought this vehicle and the lot I bought it from said the only thing wrong with it was the rough idling, he said it's probably because it needs a tune up, which boy it did.
So I changed the oil, plugs and air filter and the rough idle is only slightly better. The weird thing is after you drive it for a while the rough idle goes away instantly, sometimes it comes back. I had the codes pulled and all it says is misfire bank #1, which I guess it means cylinder 1, it also brings up faulty 02 sensor, I did not change the plug wires but oh my gosh were the old plugs bad! It is amazing it ran at all with those in it. But anyway the wires did not look bad. I just hope to god this is not a fuel injector problem. Any ideas would be great, thanks.

You cannot look a spark plug wires and tell if there bad. Also do the wires have a date on them? What are the exact code numbers not code descriptions? I have never seen a bank 1 code mean cylinder 1 Miss fire. That would be a code p0301 and would say cylinder 1 miss fire. I think bank 1 lean so what are the exact code numbers not code descriptions? It will be a letter followed by a four digit number. That lean code code be your idling rough when it is cold.

There were three codes that came up before I changed the plugs.
P0301 P0171 P0201
I cannot see a date on the wires, but I was so sure the plugs were the problem. But there are the codes, hope this narrows it way down. Thanks.

So when you cleared the codes which codes come back? I would be looking into the p0171 lean bank 1 most likely you have a vacuum leak.

So am I looking at a vacuum hose or could it be something much more major? Earlier when I drove it it smoothed out all of a sudden and I swear I could not feel it running, I hope whatever it is its quick and easy. I thought about getting some crc maf sensor cleaner and trying it but it's a long shot and it's $10.00 a can. What do you think I should try doing? Thanks for your reply.

On our 2003 Ford Explorer XLT we have been having a recent problem with a rough idle. But I also noticed that when we let off that accelerator that the RPM's drop down to an idle speed no matter what speed we are going. When we go at a slower speed and are coming to a stop I see the RPM's going down to about 400-500 and then back up. It start idling really rough and starts to stall out unless I give it some gas. When it does die, I turn it back on and sometimes it will die out again and sometimes it will start back up but start idling rough again.

I have been checking for vacuum leaks, but at this time have not found any.

For starters have the PCM (computer) scanned for codes, Autozone will do it for free. If the PCM sees a problem it will store a code that will help in diagnosing the problem, get back with the exact codes. Soundsliek th emisfire may be causing the low idle.Need to fix one problem the other may be consequential

Number one fix for that code is bad pcv hose I would start looking there.

Also pcv itself and the rubber grommet the pcv valve goes in.

Got ya, I might go ahead and replace both the hose and pcv valve since they are easy and inexpensive. But what about the p0201 cylinder 1 injector circuit malfunction? Is it something to worry about? Thanks.

Also replace the rubber grommet the pcv goes into. So does the p0201 keep coming back after clearing it?

Yes after clearing the codes it still has all three. It worries me because when I first start it of a morning the engine will shake violently once it is around 1000 rpm's, it also does it in over drive, I am scared it will damage the mounts if they are not already.

Let's see where the pcv hose valve etc takes us and go from there .One code at a time.

I have a ford explorer 2001 it started idling rough out of the blue it comes and goes only. I changed the plugs , plug wires . EGR, oil oil filter when put on the comp. it gave error codes for random misfires and each time on different cylinders, mech said there was nothing else he could think of that could be wrong Help what the heck could it be ? the car runs good other than that and it only happens say 70 % of the time when you stop and its idle for more than a miute or two but sometimes runs so rough it almost dies you can touch the gas peddle and it lifts the idle and it stops for a minute or two then sometimes returns but sometimes it doesnt do it at all . I am at my wits end Help please? Dave..

I have two possibilities
1. check intake manifold and gasket for vacuum leaks
2. have the valve springs checked possible hang exhaust spring open and if so have all the valve springs replaced (we had done few on the 4.0L with SOHC )

Okay, so I did some more work on it, I replaced the PCV valve, grommet and the hose looked fine so I left it on, I cleaned the MAF sensor, somehow it had a tiny feather on the wire and got it off. I cleared the codes again, this time I took out the pcm fuse under the hood for a few minutes, I drove it again for about an hour, no change in performance, check engine light comes back on so I pull the codes again and only one came up, P0201 - cylinder 1 injector circuit malfunction. At least I got rid of two codes thought. So from here does it sound like a injector or injector harness? I also checked for vacuum leaks, the plug wires were checked and they are good. If this turns out to be an injector how hard would it be to replace? Thanks.

Do you have a multi meter to ohms check the injector?

No I do not have anything like that, I actually would not know how to check it.

https://www.2carpros.com/articles/how-to-use-a-voltmeter


I just post a how to us one for you you would ohms check it to start with.

Engine Performance problem
2003 Ford Explorer 6 cyl Two Wheel Drive Automatic 144k miles

I received a PO128 code so I replaced the thermostat. While doing this I decided to change plugs and wires. Once completed, car ran like a dream. The next day I started the car and it had rough idle and was worse when placed in drive. I have checked all vaccum lines with no leaks. Any suggestions....Thanks

Update:::: I found the problem.....I crimped wire #3 between the bracket that holds heater hoses and the motor. Careless error.

Right on, this will definitely help, I was hoping it did not come to this, but I prepared myself for it anyway. Thanks for your help, the new PCV valve helped a little, when it runs smooth it kills me because I keep thinking it died on me, but at least I know how it should run once its fixed and it saved me from having to do it later on.

Unplug the injector measure the ohms resistance across the two terminals of it compare it to the other injectors.

Well I just found out what the problem was with the injectors, the problem was that it wasn't them, or the harness, or anything near that. The intake has a coolant leak that is leaking into cylinder 1, the reason for the rough driving when it's cool is because coolant seeped into the cylinder and after driving it it runs the coolant out of it and it smooths out. The spark plug in it still looks like I had just put it in there because the coolant is washing it off. So my next question would be, is there a sealant I can buy that could fix this at least temporarily? I'm going to just replace the motor but that won't be till February. Thanks

There are pour in sealants that you put in while it's running.It shows in the video coolant stops coming out the tail pipe within a couple of mins.I don't remember the name let me ask someone.

Ok, I noticed it was slowly losing coolant but didn't see any leaks, I checked the oil fill cap and oil dip stick periodically and never seen any coolant in the oil, it never comes close to over heating, how long do you think it will last like this?

My truck started stalled one day after I came to a stop at a light and it took longer than normal for it to start back up. It did this for 2 days and then the check engine light came on. I scanned the code and it came up with P0118 coolant temp sensor high input. So I replaced both coolant temp sensors on the truck. Also since i had the upper intake off I also did the gaskets. After the repair the vehicle still idles very rough and sounds like its detonating when put in gear. Initial acceleration is rough and the revs seem to go higher than normal. Now I'm not sure why the light came on for the sensor because it is still running poorly. Is this just a coincidence or is there still another problem like ignition or a stuck erg valve?

Is the light on again? It sounds like it may be a fuel delivery problem. When you described it as detonating, are you talking about spark knock or something else?

That stuff I was thinking of was for the head gasket not a intake gasket.Your best bet would be to change the intake manifold I gasket if that's what is leaking.It will get worse no telling how long before it will get worse.

Ok, I'll look around and see what all they have for these, the guy that did the diagnosis said I could try half a thing of pepper and it might slow it down, I hope it just lasts till February, I may replace the gasket if it doesn't kill my bank account, it's got well over 200,000 miles on it and that makes me leary about putting alot of money into the motor. Thanks for all your help, if you think of that sealant let me know, someone said blue devil was good stuff but could clog a lot of stuff if not used right.

There are GM coolant tablets if the leak is really small they may help I would use a couple of them.

Cool, yeah I think I'll try that, the leak doesn't seem that bad, I only have to put some in about once a month, its running a little better, not sure why but not complaining. Hopefully I can get those tablets at any auto store. Thanks!

Probably have to look on eBay it's a general Motors product.

Ok, will do, thanks for your help.

Your welcome that's what we're here for

Ok heres an update on the situation, I tried the coolant tablets with no luck (worth a try) I took it to another mechanic and he did a compression test and it held pressure and he didn't see any leaks. I told him about one morning when I squeezed the top coolant hose and saw coolant build up on top of the motor and it dripped on to the ground but he seems to think it's a head gasket problem. Later I called a friend of a friend whos a mechanic and he strongly thinks it too is a head gasket. It just throws me off because the last time I had a blown head gasket in a vehicle it was doing everything this one doesn't. It does lose coolant slowly but I have only went through a half gallon of it since I've had this thing. Do you think some k-seal or bars leak would help this any since its not a huge leak yet or would it cause more problems than it'll solve? Thanks!

Refresh my memory have you down a chemical block check for a bad head gasket yet?The tube with the chemical that changes color if there is exhaust gas in your cooling system?You have done multiple coolant pressure test to look for external leaks?Also you have replaced the radiator cap as well?Iam not a big fan of the sealers because the can clogg up other things.

Wow I didn't realize you replied because I usually get an email when I get an answer, sorry about the long response. But I did a pressure test at about 11 - 12lbs and it held stedy the whole time, also I found the thermostat housing is leaking, don't if it's the primary leak but it seems likely that it is, it also has gotten worse, but nothing else has changed, theres still no water in the oil and no smoke from the tail pipe. Im going to replace the plug wires this weekend and see if that helps the rough running, i noticed light dots on the wires which means arching but I been hesitant because Im unsure if it would fix the problem, so if that does work then its a combination of two things which I'm hoping for, I will let you know what the outcome is with the new wires, and again thanks for your help.