Missing while idling & bad emissions sounds

[adionne 93 XLT 4.0]

I have recently noticed my truck sounds aweful while idling and while driving. It sounds as if there there would be a large hole or such in the exhaust although there are no holes. It is a constant sound that does not get louder nor lower at different speeds? Could my cats be going bad? I changed the oil and put in new plugs this past weekend. It still has the sound. The idling sounds and feels to be missing. The idle missing and the aweful exhaust type sounds started at the same time when I noticed. FYI, I recently installed the KKM since impressed by it from installing in my other explorer a year ago. The missing and sounds started a few days after and are coming from underneath the truck from the sides not from the engine Any ideas? Thanks,

 

[adionne 93 XLT 4.0]

One more thing, my check engine light was coming on after running for about 10-15 min. That was 2-3 weeks ago and it stopped, never came on again. I think I will check the IAT sensor since I have been meaning too, however I do not know where it is located, I beleive I may have cleaned it before not know what it was =}

 

[TPLYNCH]

You may have a vacuum leak. Make sure all your vacuum lines are in good shape and that none of them have come off the "octopus" where they all congregate. There are also caps that cover the unused vacuum lines. These have a tendency to pop off too. Good Luck!

 

[gpaps]

I have the same problem. I thought it was the cat as well so I changed it about a month ago but it still sounds as if i have a huge hole somewhere underneath the engine. I do not know what that sound is. Everything underneath is in great shape.

I also have BAD PINGING problems that do not want to go away. I tried everything including cleaning the MAF, Throttle, adding CD-2,all kinds of chemicals etc... You name it, I did it. It goes away for a few days and sure enough, it returns. it seems to happen between 45 and 55 mph (rpm drops to about 1400 to 1500). Anyone have any ideas????

 

[adionne 93 XLT 4.0]

What is wrong?

TPLYNCH, Thanks, I have checked all vacume lines and all is good. I almost beleive the symptoms/sounds are coming from the muffler? Also, while I have my hood up and watching the engine I notice it runs calm for 1 sec. then shakes side to side for 2 sec roughly while idling and repeats. It shakes pretty bad, enough to worry the hell out of me. I may go buy one of those $20.-$30 code scanners and see if I get any problem codes? Do these symptoms give you any ideas to what may be the problem =( Thanks,

 

[TPLYNCH]

Three thoughts.....
1) Plugged cat/exhaust - Do you get good flow out of the exhaust pipe?
2) Spark plug wires connected to incorrect plugs
3) Fuel pressure regulator

Sorry I can't be more help.

 

[Lobo]

I am having similar issues and symptoms. I have a strange airy sound coming through the exhaust(which sounded great 2 months ago) with performance and mileage dwindling. I have replaced the fuel pressure regulator, throttle position sensor, spark plugs and spark plug wires. I have also cleaned the idle air control unit, mass airflow sensor, throttle body and everything else I could think of. My Flowmaster cat-back is a year old so I don't think that's causing the noise. I have also noticed other early Explorers making the same noise. I am starting to wonder if the intake manifold gasket has recently become a larger issue. The only other thing I can think to replace is the oxygen sensor(s). Does the '92 have 1 or 2 oxygen sensors? What do you guys think, should I replace the oxygen sensors or finally fix the intake manifold gasket problem? I am getting tired of cleaning the #5 plug. What exactly do I need to change the gasket(s)? Thanks once again!

 

[Lobo]

I also forgot to mention that my engine seems to be running extremely rough at about 1600 RMP and 50 - 60 MPH. It does it consistantly at that RPM and speed. Any suggestions?

 

[niceguy]

checked your intake manifold?

Lobo and gpaps: FWIW, when I tore the top end off my motor recently, I was surprised at how VERY loose the LOWER intake manifold bolts were. Some were barely finger tight! It's a '94 with 102K miles.

A big enough leak in this area MIGHT cause the rough running that you're talking about, because the MAS is metering fuel for one volume (mass) of air, but the engine is actually sucking more air into the cylinder through a leaky manifold gasket, thereby running very lean at that cylinder. I think there are a couple of the lower intake bolts that you get to without removing the upper intake. Check those and see if they're loose. If so, then remove the upper intake and re-torque all of the lower intake bolts. None of you have indicated mileage on your vehicles...

Lobo: If you know that you've got an intake gasket problem, then I'd fix it. If you're good with the wrenches, it should only take a long Saturday afternoon. It is not difficult, but tedious (lots of cables and hoses...). Take your time and do it right, remove fuel rail, injectors, etc., and clean them all up good, and replace all the gaskets.

adionne, Lobo, and gpaps: An old mechanic's trick is to take about a four foot section of old garden hose and use it as a stethoscope to listen to specific areas under the hood and vehicle. (For the high-tech version, stick a funnel in the end of the hose that you put up to your ear...) Try to keep your head out from under the hood away from the engine noise while listening. You can also test up and down the exhaust system with this lo-buck tool. This may help you locate the area of the problem a little better.

Other standard tests would be pull the plugs and check for inconsistent "readings" (color, fuel/oil traces, burned electrodes, etc.), and do a compression test while you've got the plugs out.

Strangely enough, I don't even know if you can adjust the timing on these engines. I'd assume so, but never done it (never needed to...). Might put a timing light on it and see if your timing is off...

gpaps: How many miles on your truck? What kind of gas do you use? What kind of driving (stop'n'go, highway, off-road) do you generally do? The lower intake gets pretty gunked up over time, and so might your combustion area. If you've got high mileage and you have a build up of carbon, etc. in your combustion chamber or on your piston tops, then the chemical fixes might work for a short period as you're experiencing, then the ping will be back. If these engines have anti-knock sensors built into them (does anyone know?), then when detonation occurs, they will retard the timing to stop the knock which would result in dramatic power reduction. This, of course, is better than blowing a hole in the top of your piston, or breaking the compression rings..... Need to find and resolve the real culprit here and get rid of that knock.

 

[adionne 93 XLT 4.0]

If you've got high mileage and you have a build up of carbon, etc. in your combustion chamber or on your piston tops, then the chemical fixes might work for a short period as you're experiencing, then the ping will be back. If these engines have anti-knock sensors built into them (does anyone know?), then when detonation occurs, they will retard the timing to stop the knock which would result in dramatic power reduction. This, of course, is better than blowing a hole in the top of your piston, or breaking the compression rings..... Need to find and resolve the real culprit here and get rid of that knock.

niceguy, you're absolutely right on your above statement. I will get to the bottom of this tomorrow hopefully and let you all what I find.

AL

 

[gpaps]

I have 130,000 miles on my truck. I do mostly stop and go on the expressway going to work during the week. I have been using 87 octane gas for a while now because of gas prices and the pigging continued. This past weekend I put in 93 octane and the pinging was resolved. Could it be a gas issue or is there a problem with my car?

 

[CougarX]

I had the same problems as you (especially the pinging) the only thing I did to fix it was retorque the intake manifold bolts. However, if you've already tried this and it didn't work its possible that the gasket is ruined. I would replace the gasket since the worst thing it will do is take a day of your time

 

[adionne 93 XLT 4.0]

CougarX, Thanks and I agree. Let me ask you this. I tightened up the intake manifold bolts a while back and one of them keeps turning-apparently it is stripped. All the bolts were fairly loose. Thus I wouldnt doubt the gasket need to be replaced. My question is/are.
1.)Will any intake manifold gasket do such as from regular auto shop and is it rubber?
2.)What do I need to replace if one of the bolt holes is stripped? And avg. cost of those parts?

 

[niceguy]

gpaps - Since the 97 gas seems to eliminate or reduce the problem, sounds like you're vehicle is running on the edge of detonation all the time. Given the experience of CougarX, it is possible that a loose intake manifold might lean out your fuel condition enough to cause the pinging. Your high miles make your truck a prime candidate for this problem. I've read several threads with comments re: loose bolts on the lower intake. Won't cost you nothin' but time to check it out...

AL - the lower manifold is not rubber. The FelPro gasket (got my kit from AutoZone) is a composite of some kind, laid over steel I think. (It's very stiff...) Upper intake gasket and fuel-rail gasket are of similar material. The gaskets have siliconized (looks like) beads around the ports. I can't recall if you need some black RTV silicone for this job or not. Check the manual, or check the instructions in the gasket set before you leave the store if you don't have some black RTV laying around the shop.

As for repairing the stripped bolt (or hole), that could be messy. Pull the bolt to see if it's the bolt or the hole. If it's the bolt, then that's obvious (and cheap and easy) enough. If it's the hole, you've got two possible options: 1) (lazy mechanic's method) tap the hole out to the next larger bolt; 2) (good mechanic's method) purchase and install a heli-coil kit. This is difficult to do under GOOD circumstances (plenty of room, good lighting, big drill press), and almost impossible to do in other circumstances. Either way, you're going to have metal chips flying around in an area that is NOT metal-chip-tolerant. Use lots of rags/paper-towels/aluminum foil - SOMETHING - to keep that stuff from winding up down in your lifter valley and oil drainback holes. Some of the other guys may have some additional experience and ideas in this area. It wouldn't hurt you to get a couple of opinions...

Michael

 

[adionne 93 XLT 4.0]

Michael, Thanks for the feedback. It looks as though I know what my Saturday looks like-Dirty ;] I plan to replace my fuel filter (140K). I noticed that going from my traditional 89 octane to 93 has eliminated the ping, although I have not been hard on her. I then will move forward with the exhaust manifold gasket. Is there anything else I can do/need to do, or check out while I am in there changing the intake gasket. Anotherwords from a troubleshooting perspective should I look for any certain signs etc while I am in that area replacing the gasket?

 

[niceguy]

while you're in there...

AL - Well, when I had mine apart (104K miles), I noted that the lower intake was VERY cruddy, especially the area around the injectors. Of course I discovered this late at night when I was trying to get it back together, so didn't spend as much time cleaning it as I'd have liked to. You might inspect this area closely (toothpick CAREFULLY around the injectors, etc.) and see if it's worth taking off the fuel rail, removing the injectors, and cleaning everything real good. I scrubbed mine good, but didn't remove the injectors. Now I'm wishing I'd taken an extra hour to do that while I was there. I'd go ahead and get two or three cans of engine degreaser while you're at the parts store. I used two cans, and didn't get it as clean as I could have.

There's not a lot else you can see, internal-wise, from the lifter valley, except of course the lifters. However, you won't be able to remove and inspect any of the lifters unless you remove valve covers, loosen rocker arms, etc. This would be a LOT of extra work. I'd inspect those that you can see in the "UP" position, but what you really need to see are the rollers down below, which you can't see without removing 'em.

Might replace the thermostat while you're there, unless you've done that recently. Mine just stuck (closed, of course) and led to all kinds of trouble (cracked head, warped head, etc., $650, etc.), so a $5 investment is cheap insurance.

Just my nickel's worth.

Have fun!

 

[adionne 93 XLT 4.0]

Michael
Great, Is there difficulty once at that point to just take out the injectors. Keep in mind that I am popping the cherry on this one. I am gathering-take off fuel rail, then take out injectors. I hate the Haynes, I need to pick up a more intricate manual.

 

[niceguy]

not sure...

AL - Mind you, I didn't actually remove my injectors, but left them in the lower intake manifold as I removed it, so take my opinion for what it's worth (it's just an opinion)...

But you are correct. Once you've got the upper intake off, and the lower intake out, the only thing holding the injectors in place is the fuel rail. I think that if you just remove the few bolts (nuts?) that hold the fuel rail to the lower intake, the injectors should come out easily - just gently rock them a little to work them out. There are probably O-rings or seals around the base of each injector, so be gentle. The injectors are electro-mechanical devices, so I don't know if it would be smart to immerse them, but I'm sure the bottom end of them will tolerate a scrubbing with an old toothbrush.

I don't know if the injectors are "keyed" to only go one way, or if you can rotate them to any angle you like. If they're not keyed, then I'd make a note of the orientation of the injectors before you pull them so you can put 'em back in more-or-less how they came out, so hooking up the cables will be a little less "adventuresome".

Of course, getting the injectors back into that lower-intake-and-fuel-rail sandwich may be about like trying to herd a bunch of cats; you'll get two in, then another will pop out. Shouldn't be hard, but you'll probably wish you had a couple of extra hands...

The Haynes manual is all I've got, also, and like you, I wish I had a "real" shop manual to go by. Oh, well...

Keep us posted.