#3 plug responsible for engine surge/shudder???

[pacman]

Hi all,

I just dropped off my '97 EB for a broked seat track and asked them to check on my RPM surge/engine shudder problem. It was only noticible when at idle and would occasionally drop the RPM's about 100 (causing the shudder) then come back up. This would happen every 15-30 seconds, hot or cold, A/C on or off, sitting in drive at stoplights.

Well, they just called me back and said they are going to perform the tensioner TSB repair (while it is there) and the problem I am experiencing is because of a bad #3 spark plug (and by the way, it isn't covered under your Premium warranty 6Y/60K (I only have 36K), nor is it covered by the "100K between tuneups" clause, it is only covered by the "check the fine print" 3Y/50K engine warranty...). So they can change it for only about $100. I told them not to and that I would do it myself, but after reading some of the horror stories about changing the plugs on the SOHC engines, I am wondering if I should call him back...

So, what do you think? Is it possible the idle RPM surge is being caused by a bad plug at only 36K miles? Could this be a result of the tensioner problem? Should I attempt to replace the plug on my own (actually I would go ahead and replace all 6 while I am at it (I have changed MANY plugs and have the tools to do it - I have also rebuilt a couple of engines and cars, so I am mechanically able)) or should I let the pros replace just the one bad one?

Thanks,

 

[BajaXplorer]

why not let them change the cam tensioner RECALL and then if things dont change, just change the plug yourself. yeah its a pain but at least you know it was done right.

my .02

 

[pacman]

That's exactly what I am going to do. I figure for the $100 they want to change one plug, I could replace all 6, add new wires, and have enough left over for a nice dinner!

 

[410Fortune]

If a plug is "bad" there is usually a reason, especially on the SOHC, it is common for them to have loose or bad lower intake gaskets, there is also a TSB on this. Dont let them get away with this, if it's a dealer they know that the TSB exists and should be telling you about it that it needs to be fixed. A burnt plug is a sign that this may be happening with your SOHC....

 

[pacman]

Hmmm...interesting. I will have to ask them why they think the plug failed - and see what they say (if they say anything other than, "well, we need to pull the plug to determine what happened, and that will cost you ..."). I didn't realize that a bad lower intake gasket would cause a burned plug. Wonder what other symptoms would occur? Guess it's time to do some searching of the ol' forum!

 

[410Fortune]

Othey symptoms, loss of vaccum, excessive fuel consumption, rought idle, rough performance, loss of power, coolant in oil, etc..........some of this sound familiar?

Youcan do a search for this topic here and find everything you need to know to inform yourself before you call them back..

 

[pacman]

Well, after a search of the forum, the only symptom I can say that I have noticed is the rough idle. I don't have any other symptoms, so my guess is that the gasket is ok right now. I am hoping the tensioner repair will fix my problem, but if not I will check the condition of all the plugs. I am not too worried since I still have 10 months on my extended warranty, but I don't want to wait either.

 

[pacman]

Well, I got my Explorer back last night and lo and behold, they did both the tensioner and intake gasket TSB's! I asked about what they think happened to the #3 plug and they said they couldn't tell without pulling it, and that would cost me. So, I will be replacing all 6 plugs (hopefully tomorrow) and I will let you know what I find on #3. It seems to be driving better now, but I still notice the RPM surge at idle, so I will trust the mechanics and replace that plug (and the rest while I am at it!).

Thanks for all the help!!

 

[410Fortune]

Well the intake gaskets were leaking and thats most likely what killed the #3 plug.

 

[pacman]

Well, I replaced the plugs last night and found that most of them were very pitted and the gap was way too big. Specifically, #3 was "burned" (very brown). After replacing the plugs, the engine starts easier and my surge/shudder is gone. We'll see how it does over the next week while I am doing my normal driving around.

Thanks for all the help and suggestions, especially about how to change the plugs - it only took me about 2 hours to replace all of them.