At my wits end with this issue

[Threeelectric]

Patch the holes in the air intake with duct tape temporarily to see if that helps. A leak in the air intake will also cause rough idle and shaking.

 

[TwistedFish]

Patch the holes in the air intake with duct tape temporarily to see if that helps. A leak in the air intake will also cause rough idle and shaking.

Well actually, i was pointing out the hose shown in the picture... its just completely broken and doesn't connect to anything.

 

[TwistedFish]

Got it!
The advice for keeping it above 1/2 during the winter surely doesn't apply to your area.
We are usually in Hawaii a couple times a year, but covid. Damn shame, it'd be nice to meet up and pick @ you rig from a couple angles

Yeah man, anytime you are, pm me for sure!

 

[Motsbro]

Couple thoughts. Had an 2000 mountaineer for about 17 years. Fixed about everything. Stalling/rough idle issues tended to be two things. Primarily the EGR value. It get carbon build up and sticks open. Removable and cleanable (carb cleaner) and a Q-tip on my truck. Cleaning it eliminated stalling almost immediately.

Near the end of its life it really ran rough at idle. I turned out to be a dry rotted vacuum line that had slipped off. Put it back on while it was running and the engine settled right down. Was quite surprised b/c I'd been through the whole sparkplug, MAS Cleaner, intake cleaner, new sparkplug wires, etc etc. with no luck. Put a clamp on it on the old hose and all good until the rear end blew up. BTW, on the rear end, check the rear differential fluid, particularly if you see on the center of the wetness on the rear axle.

I had the thud a few times as well. Turned out to be the sway bar link. If you noise is coming form the outside or feels like its under the floor, that's likely it. There is one on either front suspension. $15 for a pair. Old ones I cut off, bc rust. News ones install easily. If its broke, you can see it. Replaced mine a couple times of the years. 15 minute job. If the thumping in interior, its likely a blend door actuator related to switching form hot to cold or from vents to defrost to floor. Its likely vacuum driving on your car so a vacuum leak could be causing the issue.

On over heating, if you have old hoses, replace them. The old ones can collapse causing overheating issue. Its worth replacing the radiator if you see any signs of leak (steam coming from the radiator itself or coolant stains down the sides) or if its original (Can accumulate a lot of rust blocking the . Certainly DIY for the mechanically inclined but lots to remove (serpentine belt, fan and clutch).

 

[Threeelectric]

Well actually, i was pointing out the hose shown in the picture... its just completely broken and doesn't connect to anything.

So looking back at the pictures I see the one end disconnected and just laying there. Is the other end connected to anything?

 

[1sicbronconut]

4.0's are prone for head cracks, does it seem to miss worse when you first start it and then smooth out some? Get it good and hot and see if it runs worse when first started, when it's hot and sits overnight or any longer period the coolant will leak down into the cylinder and cause a miss. If you have access to a radiator pressure tester and a bore scope you can get the engine hot, pull the spark plugs, and look in the cylinders with the bore scope for coolant I've actually seen it running down the cylinder walls on some new Eco Boosts!!

 

[TwistedFish]

So looking back at the pictures I see the one end disconnected and just laying there. Is the other end connected to anything?

It seems to be connected to some sort of air intake near the grill

 

[TwistedFish]

4.0's are prone for head cracks, does it seem to miss worse when you first start it and then smooth out some? Get it good and hot and see if it runs worse when first started, when it's hot and sits overnight or any longer period the coolant will leak down into the cylinder and cause a miss. If you have access to a radiator pressure tester and a bore scope you can get the engine hot, pull the spark plugs, and look in the cylinders with the bore scope for coolant I've actually seen it running down the cylinder walls on some new Eco Boosts!!

It seems to usually start up fine cold, warm up a bit and start to have a rough idle. Then, if I shut it off, and start it up again, it cranks a lot longer and has a hard startup

 

[Kesp4.0]

The dangling hose that you posted draws hot air from the manifold and heats up air entering the intake until the vehicle gets to operating temp

 

[TwistedFish]

The dangling hose that you posted draws hot air from the manifold and heats up air entering the intake until the vehicle gets to operating temp

Oh nice, so since I’m having issues with it running hot anyways, this isn’t really an issue?

 

[TwistedFish]

Couple thoughts. Had an 2000 mountaineer for about 17 years. Fixed about everything. Stalling/rough idle issues tended to be two things. Primarily the EGR value. It get carbon build up and sticks open. Removable and cleanable (carb cleaner) and a Q-tip on my truck. Cleaning it eliminated stalling almost immediately.

Near the end of its life it really ran rough at idle. I turned out to be a dry rotted vacuum line that had slipped off. Put it back on while it was running and the engine settled right down. Was quite surprised b/c I'd been through the whole sparkplug, MAS Cleaner, intake cleaner, new sparkplug wires, etc etc. with no luck. Put a clamp on it on the old hose and all good until the rear end blew up. BTW, on the rear end, check the rear differential fluid, particularly if you see on the center of the wetness on the rear axle.

I had the thud a few times as well. Turned out to be the sway bar link. If you noise is coming form the outside or feels like its under the floor, that's likely it. There is one on either front suspension. $15 for a pair. Old ones I cut off, bc rust. News ones install easily. If its broke, you can see it. Replaced mine a couple times of the years. 15 minute job. If the thumping in interior, its likely a blend door actuator related to switching form hot to cold or from vents to defrost to floor. Its likely vacuum driving on your car so a vacuum leak could be causing the issue.

On over heating, if you have old hoses, replace them. The old ones can collapse causing overheating issue. Its worth replacing the radiator if you see any signs of leak (steam coming from the radiator itself or coolant stains down the sides) or if its original (Can accumulate a lot of rust blocking the . Certainly DIY for the mechanically inclined but lots to remove (serpentine belt, fan and clutch).

Hey, so as far as that clank goes, i think i may have found the culprit. When the engine starts chugging, it looks like my catalytic converter kinda bounces around. The guy who had this before me must have sawed it off (or taken out) everything past the cat converter, so thats pretty much where my "exhaust pipe" ends. It looks like this:

 

[njtinman2001]

i would say take a compression check first. any cylinder under 75 lbs would be a dead miss. then start looking for electronic issues. i don't remember does it have an egr valve?the other thing is to pull wires at the plugs with it running and listen for a difference, i know you said that you changed the wires but i have had 1 bad wire and was chasing a problem with parts that i already changed.

 

[410Fortune]

cooling system pressure test
Engine compression test

with the exhaust hacked off like that you are losing some low end torque, but it still should run properly
Cheap spark plug wires do not like being put on and taken off the spark plugs...many times new wires get fubar from testing....something to look at.......they like to break inside and leave the metal bit on the spark plug
I run wires made by packard wire with a 400 ft lb pull strength on the boots.....auto parts store wires like Omnispark and others (under $60-80 at the local stores) are GARBAGE and are the reason why many of these engines have a "miss"

 

[Motsbro]

Hey, so as far as that clank goes, i think i may have found the culprit. When the engine starts chugging, it looks like my catalytic converter kinda bounces around. The guy who had this before me must have sawed it off (or taken out) everything past the cat converter, so thats pretty much where my "exhaust pipe" ends. It looks like this:

I think you got it. I have an 01 pathfinder that had a clank and it turned out to be something similar. Fortunately its exhaust had a angled metal post welded to it that anchors the exhaust in a rubber bushing. The post was not in the bushing (cause the excess vibration and noise) but forced it in with a bit of muscle. In your circumstance I would get on of those exhaust hangers with the rubber strap and find a good place on the frame to mount it.

 

[TwistedFish]

Have you read the codes yet? while the first gen's ECU is primitive reading the codes will provide clues we can use to help you. You can try Chanting under moonlight while naked and smeared with chicken blood, casting chicken bones on the ground and reading the patterns for clues. But, others have found this method less reliable and your neighbors and local law enforcement frown on it.

I was bothered by an occasional stumble that I could not figure out. After several years it finally got bad enough to cause a code in the ECU. It was the MAF very slowly going bad and a new one cured the problem.

I hate seeing people buying lots of expensive parts and throwing them at the truck, hoping that it will solve the problem.

Read the codes, run the fuel pressure test, run the compression test remembering to pull all the plugs and hold the throttle open. Check the condition of the plugs, if they all look the same, great. If one or more look different let us know.

Hi, not sure if you're read my update, but I checked the codes and everything... I pasted the update in my original post as well. If you could check it out, that would be awesome!

 

[TwistedFish]

I bet you it’s a bad coil pack
Grab a meter and ohm it out.
it will cause all your symptoms and overheating. If you have changed plugs and wires.Coil packs are the next thing to check. Like another member said. You only need 3 things for an engine to run. 1. Oxygen, you have Oxygen because your engine is running.
2. Fuel. You have fuel because your engine is running. Keep in mind a fuel injector could be bad or clogged on one of the cylinders. Injectors should be checked after coil packs.
3. Spark. You have spark for sure at some of your cylinders because your engine is running.
so you need to make sure you have spark at all cylinders. A visual inspection is not enough. A coil is a coil of wire that’s coated so it won’t short out. basically it’s a step up transformer for voltage to create enough to make a spark. When a working but faulty coil Gets warm, the Wires will expand and contract inside the coil itself sometimes causing a short which causes a loss of spark or weak spark. A completely bad coil will produce no spark at all. A faulty or bad coil will cause a misfire. And give you all the symptoms you describe. Check your coils resistance While cold and again while warm after running it a few minutes and compare with what the manufacturer says is within normal operating range. If they aren’t the problem next you move to checking each fuel injector. Let me know if this helped. Good luck

Interesting, is there a write up somewhere on checking voltage? I need to buy a new meter, but even if i had one im not sure id know how to check, and don't really want to accidentally electrocute myself lol. Thanks for your reply!

 

[TwistedFish]

Couple thoughts. Had an 2000 mountaineer for about 17 years. Fixed about everything. Stalling/rough idle issues tended to be two things. Primarily the EGR value. It get carbon build up and sticks open. Removable and cleanable (carb cleaner) and a Q-tip on my truck. Cleaning it eliminated stalling almost immediately.

Near the end of its life it really ran rough at idle. I turned out to be a dry rotted vacuum line that had slipped off. Put it back on while it was running and the engine settled right down. Was quite surprised b/c I'd been through the whole sparkplug, MAS Cleaner, intake cleaner, new sparkplug wires, etc etc. with no luck. Put a clamp on it on the old hose and all good until the rear end blew up. BTW, on the rear end, check the rear differential fluid, particularly if you see on the center of the wetness on the rear axle.

I had the thud a few times as well. Turned out to be the sway bar link. If you noise is coming form the outside or feels like its under the floor, that's likely it. There is one on either front suspension. $15 for a pair. Old ones I cut off, bc rust. News ones install easily. If its broke, you can see it. Replaced mine a couple times of the years. 15 minute job. If the thumping in interior, its likely a blend door actuator related to switching form hot to cold or from vents to defrost to floor. Its likely vacuum driving on your car so a vacuum leak could be causing the issue.

On over heating, if you have old hoses, replace them. The old ones can collapse causing overheating issue. Its worth replacing the radiator if you see any signs of leak (steam coming from the radiator itself or coolant stains down the sides) or if its original (Can accumulate a lot of rust blocking the . Certainly DIY for the mechanically inclined but lots to remove (serpentine belt, fan and clutch).

I checked, my truck actually doesn't have an egr valve, apparently its not a ca emissions tested vehicle lol

 

[TwistedFish]

i would say take a compression check first. any cylinder under 75 lbs would be a dead miss. then start looking for electronic issues. i don't remember does it have an egr valve?the other thing is to pull wires at the plugs with it running and listen for a difference, i know you said that you changed the wires but i have had 1 bad wire and was chasing a problem with parts that i already changed.

Ohhhh am i supposed to pull the wires at the plugs? When i tested this previously I had the engine shut off, pulled one from the distributor, started it, shut it off, put it back, pulled another one, started it, shut it off, put it back, etc etc. And couldn't find any real difference...

 

[TwistedFish]

cooling system pressure test
Engine compression test

with the exhaust hacked off like that you are losing some low end torque, but it still should run properly
Cheap spark plug wires do not like being put on and taken off the spark plugs...many times new wires get fubar from testing....something to look at.......they like to break inside and leave the metal bit on the spark plug
I run wires made by packard wire with a 400 ft lb pull strength on the boots.....auto parts store wires like Omnispark and others (under $60-80 at the local stores) are GARBAGE and are the reason why many of these engines have a "miss"

I'll look into doing an engine compression test tomorrow, its raining wayyyy too much today. I did buy the compression tester though, so thats a good start haha. As for the cooling system pressure test, what exactly would that do?

 

[army1959]

Hi all, I've been trying to use this ex as a learning experience for myself, as well as to eventually use as my daily driver. Obviously, for that to be the case, it needs to be running perfectly, and i shouldn't have to worry about it being a danger to myself or others. However, with this particular issue, I'm stumped.

The ole' rough idle. Ah yes, the very bane of my existence. Starts up rough when warm, idles rough no matter what i do, and (sometimes) will stall at stoplights, or long periods of idle.

What have I done to fix it? Well, i've replaced the positive battery cable, checked for vacuum leaks, cleaned the maf, replaced the ects, replaced sparkplugs and wires, cleaned the throttle body, checked the large intake tube (plastic) for cracks, checked each vacuum line on the tree for leaks (done by plugging them simultaneously, this provided no change to the idle), and checked the iac (I unplugged it, and the engine slowly died).

At this point, the only things I HAVEN'T done, are replacing the MAF, replacing the pcv valve, replacing IAC (though it seems to be working fine), or anything relating to fuel.

Fortunately, it's annoyed me enough at this point to document it, so here's a video of a (warm) start.



Note, the oil guage ALWAYS reads high, and always "flickers" like that. When the idle is getting rough, the voltage meter also does this (because its about to stall).

Main points to take away here are the surging and rough idle. If anyone else notices anything that is ALSO an issue, or has any questions, please let me know.

Thanks in advance, and have a great day!



EDIT: UPDATE

Hi all, just got back inside from running some codes and checking a few other things people recommended. First off, I'd just like to say thank you for your support so far! This forum has one of the best communities by far.

Down to the nitty gritty:

1: I checked the PCM. Unplugged it, started the engine, plugged it back in, started the engine. No change

2: While looking around for the PCM (before i realized it was under the dash) I found 3 or so wiring harnesses just hanging around. This had to be something done by the previous owner, but I'm not sure what they do. Pics are posted below (or above idk)
View attachment 319130
View attachment 319131
View attachment 319132
View attachment 319133


3: I noticed that one of the main air intake hoses ( near the lower radiator hose) is just... broken. Pics posted below.

View attachment 319134
View attachment 319135

4: I used the paperclip method to run the codes, and got 3 while KOEO:

1. 79: A/C is on or pin 10 is shorted to power
2. 66: Vane Air Flow (VAF) or Mass Air Flow (MAF) signal low – VAF MAF (Also listed on the website: Transmission Oil Temperature (TOT) signal low (possibly grounded) – Transmissions)
3. 63: Throttle Position Sensor (TPS) signal too low TPS

This is pretty informative! Maybe now we're on to something? Idk.

5: I took the radiator cap off and looked inside. Pics are attached. It smells off, and upon closer inspection of what dripped off the radiator cap, it seems to have some sort of dirt or particles in it. The liquid itself does seem to still have somewhat of a green-ish sheen.
View attachment 319136
View attachment 319137


That wraps up my update! I hope you all can help me, and know that I'm putting in as much effort to fix this as you all are to help me. Again, thank you so much!

that stuff you are seeing in the radiator looks like bars stop leak , i would do a flush , and more than likely you will have to change the thermostat