Idle Sputtering 1996 Expl EB with 5.0L Engine

[myexpl]

I am new in this forum. I have 1996 Eddie Bauer 5.0L 8Cyl engine AWD Explorer. It is excellent condition and is about 100K miles. Two weeks ago, engine suddenly coughed up and check engine light started flashing. I knew that it was misfiring. According to manual, SUV had spurk plugs that need no replacement until 100K mile. I took the car to a freindly shop (I use them often) and they told me that scanner showed that cyl. 7 and 4 misfired and it was time for the tuneup. I asked again high performance spark plugs replacement. They installed that iridium spark plugs costing each almost $14. I got the car back and started noticing next day that in idle speed there is an annoying sputter and slight jerk . I asked the guy. He said he did not change the fuel filter. I got an original mopar fuel fileter and he installed last Monday. It did not make any difference. He tells me that the engine is getting aged. He also claims that it could be dirty fuel injectors. He said, he can clean them up with a special machine that uses a special detergent to get rid off the carbon residues in combustion chambers. He is asking $130 for that.

I looked through the internet, some claims that this could be the Idle Air Control valve issue. They would get dirty as well. Some suggests that it could be wrong spark plug replacement too. If it is a wrong spark plug installlation (I am not so sure the mechanic could be that stupid doing such a thing. BTW, he also changed the spark plug wires when he did the tune up), then I should have a problem when I am speeding as well, Right? I am confused. I saw some articles about bad air hoses with cracks causing such thing. Can anyone help me by giving a hint rather than shooting in the dark with this mechanic? They were good and a reasonable place. That is why i choose to let my car handled by them.

Thanks!

 

[jhowell]

If the check engine light was on and it was indicating a misfire on two cylinders, then the coil should have been replaced. The coil is the only place where the computer can detect a misfire. There is nothing to monitor the actual operation of the spark plug that would specifically indicate a misfire.

According to Chilton, 4 and 7 are controlled by coil 3 of the left hand coil pack. Based on the fact that 4 and 7 are misfiring and they are the only two plugs/cylinders that run from that coil in the left hand coil pack, then you can assume the problem is in the coil, specifically the left hand coil pack. Replace it.

When mechanics say things like "the engine is aged" they're trying to get you prepared to spend a lot of money that you don't need to spend.

Your mechanic is incompetent and/or dishonest. When I read your post, I immediately thought it was the coil. If your mechanic was competent, he should have known this as well.

Don't let him clean your injectors. That will not solve this problem. Do not start chasing after possible leaks in hoses. These things will only result in you spending money but not solving any problems.

You can replace the coil yourself. It isn't hard. BTW, the left hand coil in this case is the one on the passenger side.

 

[myexpl]

If the check engine light was on and it was indicating a misfire on two cylinders, then the coil should have been replaced. The coil is the only place where the computer can detect a misfire. There is nothing to monitor the actual operation of the spark plug that would specifically indicate a misfire.
.

Check engine light came on before we did the tuneup. That is why he told me about the 4 and 7 misfired (he used the handheld scanner to pull the code). He did change the plugs and wire-set. I was surprised that he did not change the air and the fuel filter when he did the tuneup. Although there was no more check engine light issue, I insisted to change the fuel and air filter with original motorcraft parts since i detected the idle sputtering next day or so. He did changed them as well because i brought those parts from the dealer. So, there is no engine light indication now whatsoever when it sputters during the idle speed for the cold start (even I feel it when the engine warmed up during the idle speed but no sputtering when I drive the car no matter what the speed is). When it suputters, the car have a subtle rocking as if someone leaned on the car. There is no smoke or noise comes from the muffler. Just shakes as if someone kick the tire. It is not like being choked that it would stall on me but it scares me that it would misfire and the check engine light would come on again.

That is the problem diagnosing the cause of the sputter. No help from the engine light codes. I poured a commercial "fuel injector" cleaning solution (from Pep Boys) into the tank yesterday. Seemed that it helped a little bit but I hardly used the full tank of gas. So, I do not know this would be a clogged injector problem (or the gum around the ring) that I am facing.

I spoke to the mechanic today (same guy) on the phone, he told me that this would not be IAC valve when I mentioned that to him. He tells me that the check engine light would pick up the code if IAC malfunctions. He also claims that the sputtering is not related a misfire. According to him, if it was, the engine would sputter while I am driving and check engine light would come on. Since check engine light is quite (I can see the light is working because it comes on when I turn the ignition key and goes way with a normal delay after the engine starts). He tells me that "drop the car and I can run in idle for awhile and go through the diagnostics." He still tells me cleaning inside the cylinders (combustion chambers, o-rings, and the injectors) with that special machine of his shop would not hurt at 100K if I never done this before. He says he is going to check the vacum leak as well.

I wish I can be handy like you guys to pull the parts out and change them. First, i do not have any tools. Second, I am so bad even at home i would not try to repair or change a leaky faucet. I tried to do those things when i was young. But, i usually broke the things and cost me more to get them repaired. My brother is just the opposite of me but he is 5000 miles away.

I had a friend that he attempted to change a water pump on his Honda about 30 years ago. He went and bought the parts with a photocopy of the pages of Chilton book from the library to do the job. He somehow did not see the astrisk on the schematic that warning him not to pull that pin out completly when he was taking the water pump out. I think he said asteriks indicated "just loosen up the nut to slide the pump but do not pull the pin out. That pin unfortunately was related to the timing chain. When he thought that he completed the job and saved a good chunk of money, he started the engine proudly. Every cylinder were overshot, bent, and seized in the engine. He ended up junking otherwise perfectly good car for a few bucks.

 

[jhowell]

OK, for starters, those engine flush services don't harm the engine. They might give you a very slight improvement in performance, mileage, etc, but they're not going to eliminate the symptoms of the problem that you've described.

If the vehicle is shaking as you have described, then I would still suspect the ignition coil that I previously mentioned. Like I said before, the ignition coils are the last point where the computer is capable of detecting a misfire fault. If your plugs are old, dirty, and not firing, it won't generate a misfire error code. The same thing goes for the plug wires. It's probably not bad that you replaced them, but they weren't the cause of the shaking you have or the error codes.

To be honest, I have no idea why your vehicle isn't showing an error code now. But the fact is, it had an error code previously. The code was erased but the defective part that caused the code was not replaced, and you are still exhibiting symptoms of a bad coil.

The engine in your explorer is a 90 degree V8. This configuration is inherently smooth and balanced. That's one reason why they've been so popular over the years. I'm not surprised that you don't feel a problem when driving down the road. I'm not surprised that it only seems to appear when idling. In addition I've seen defective coils function fine when cold, but malfunction when hot. I suppose the opposite condition is possible as well.

Have your mechanic attach a timing light to the plug wires for the 4 and/or 7 cylinders. The timing light can detect when a spark passes through the plug wire. When it detects the spark, it causes the light to flash once. So if you plug in and start the engine, you should see rapid flashing in a smooth and consistent pattern. If the pattern is erratic or not flashing at all, in your case, the coil is bad because you've already replaced the plug wires.

Everything you've said still suggests a defective coil.

Out of curiosity, where do you live?

 

[Turdle]

Try autolite platinum plugs. Your spark plugs are mis firing. I am almost certain.

 

[myexpl]

OK. He installed iridium plugs ($13.95 a piece) 3 weeks ago. They suppose to last 100K mile. I will tell him to pull them out and examine them. He should also use the timing light to observe firing. And change the coil as well.

I am from New Jersey. BTW, what my SUV, the 1996 5.0L 8 cyl. AWD Eddie Bauer, has a timing control? Chain or Belt? Manual dosen't say.

 

[myexpl]

Friends! I just saw this thread, Engine shakes at Idle. Looks like the poster stan1986gt described very similar problem of mine.

He said:

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I have an 05 Explorer, 90,000 miles, 4.0 engine. The engine shakes at idle and I can't figure it out. Not missing when you listen at the rear of the truck, but the engine is shaking noticeably. Smooths out when you accelerate. I have changed the plugs and wires (initially had a code of #6 misfire, but I now have no codes after clearing the computer).

______________________________________________________________________________________________

Doesn't look that he resolved it He got responses regarding IAC and he changed plugs, wires, even injectors with no avail. He did not say anything about the coil though! I hope it is a coil. Otherwise, this affair of mine will turn out to be a money pitt.

 

[jhowell]

OK. He installed iridium plugs ($13.95 a piece) 3 weeks ago. They suppose to last 100K mile. I will tell him to pull them out and examine them. He should also use the timing light to observe firing. And change the coil as well.

I am from New Jersey. BTW, what my SUV, the 1996 5.0L 8 cyl. AWD Eddie Bauer, has a timing control? Chain or Belt? Manual dosen't say.

I assume these plugs are made by NGK? They should be fine. If they're the plugs I'm thinking of, they should last a long time. He can use a timing light, or whatever is his preferred method to determine is cylinders 4 and 7 are firing. If you're going to have him change the coil, there is probably no need to check for firing on those cylinders.

Yours is the same year, model, engine and drive train that I have. Virtually all American made vehicles use timing chains. As long as you do regular oil changes, they require no maintenance. My '96 has 275,000 miles and it's on its original timing chain.

 

[myexpl]

I assume these plugs are made by NGK? They should be fine. If they're the plugs I'm thinking of, they should last a long time. He can use a timing light, or whatever is his preferred method to determine is cylinders 4 and 7 are firing. If you're going to have him change the coil, there is probably no need to check for firing on those cylinders.

Yours is the same year, model, engine and drive train that I have. Virtually all American made vehicles use timing chains. As long as you do regular oil changes, they require no maintenance. My '96 has 275,000 miles and it's on its original timing chain.

That is what I wanted hear that. Because the mechanic and the dealer on the phone told me that my SUV has timing chain. Since manual does not mentioned the type and I keep seeing timing belt discussion on the explorers, I wanted to make sure.

I am glad to hear that you had that many miles on yours. I do not abuse my cars at all. Oil changing and regular maintenance always being done like a clock work. I had a Chrysler 1988 new Yorker with Mitsubishi engine (that was the deal that Chrysler bailed out first time with a goverment loan and try to learn how to make reliable cars from Japanese with the push of Lee Iacoca.) Although the car had a beautiful interiror, the body with a lot of amenities came as the standard, the 3.0L V6 engine was small for that car. (later on they kick up the notch to 3.6L). They used the same engine on their famous money making vans earlier as well. Almost all of the owners of thoese new Yorkers and vans started blew the gasket and having terrible oil leaks around 75K-80 miles, I drove mine up until 180K without a hitch. The car was almost getting to be an antique at 20 years of age but it needed A/C conversion which would be costing me about $750. The shops started to refuse with dealing with freon. I decided to donate it and got an Acura as a replacement. So, I am not taking "your SUV is getting aged" crap lightly. The mechanic's intention was to tell me "Do not be that nitpicky after 100K out of these engines" rather than "lets get you a new engine" when he told me "the engine is getting aged" BS.

I'll keep everyone posted when he finds what the problem is.

 

[Turdle]

As goofy as this sounds,as mentioned earlier, a misfire may be detected if a timing light is connected to each spark plug wire, one at a time, with engine running. If the plug circuit is firing, the timing light will get a trigger pulse and flash. This will identify a bad plug-and wire, unless the spark is still making it's path to ground ( fouled plug arcing to head-cracked wire arcing to block etc)

I've seen new plugs fail, right out of the box, and found them using this method. It will also eliminate or point to the coils if they are the issue. At least it is a start.

Timing chain jump issues rarely occur in the v8 ohv engine. Most of what you are reading concerns the SOHC v6 explorer.

 

[myexpl]

UPDATE: The mechanic found a vacuum leak one of the hose that ends up with a T. He says it is over the brake booster. One side of the Tee has a rubber cap. He says it is size 3/8.

He wanted to get the damaged cap from dealer but they told him that those were discontinued. He ordered from somebody else. I will stop by tomorrow for him to install the cap. He did a make-shift repair by closing the area with a clampfor m to drive. My SUV immediately started running smoothly durig the idle. I can only detect very very subtle stumbling when I start the engine cold with the clamp. When it warms up, there is no problem. I am sure when we get the proper cap, it will be the end of my problem. .

 

[jhowell]

That sounds like good news and a cheap fix. Thanks for updating us with the outcome.

 

[myexpl]

That sounds like good news and a cheap fix. Thanks for updating us with the outcome.

He put the cap in today. However, it still needed a plastic clamp (he used the one like police uses to handcuff for mass arrests) for to be tight. It is not doing it while it is cold now or when I stop for a stop sign or red light These are short waits (this is an improvement from what was before). However, if I wait longer in idle (because of traffic crawls) in drive position (it is automatic transmission), say 4-5 minutes, I feel very subtle hickups. For instance, I was waiting on the Costco's gas line to save a nickel per gallon, it did it a few times. In longer idle waits while the auto-transmission engaged, the idle speed is going up and down (it is normal I presume, because the speed is getting adjusted by the thermostad). The tachometer needle doesn't move but I hear the speed changes. Seems like the idle speed is around 900 rpm (the needle rests just under 1000 mark). I am disappointed to say the least. There may be more vacuum leaks.

I do not know whether it is time to knock my dealer's door.

 

[myexpl]

Is there any chance that this mechanic (who I am dealing with for a number of years) made a stupid mistake and swtched a set of wires from the coil to the spark plugs. I saw a discussion and one guy was advising the other one to replace the spark plug and the wire one at a time in order to avoid such a mistake.

 

[jhowell]

You would assume that he got it correct. But you can always pick up a Haynes repair manual and check it for yourself.