1st Post. Bosch Spark Plug Problem.

[85Dave]

Hi y'all. I have a 1992 Explorer XLT that I bought new in 1991. About 2 years ago (118,000 miles) I installed Bosch Platinum spark plugs because they are supposed to last a long time. As we all know, plug changes on Explorers are not the easiest thing to do. Anyway, about 6 months after the plug change the truck started bucking when going up small hills in overdrive. The condition continued to get worse and worse. I thought it may have been the lock up converter, or something in with the injectors. Couldn't tell exactly if it was engine or transmission related. I am getting ready to go trout fishing on the White River in Arkansas, and will be towing my boat. I dreaded the thought of putting up with the bucking in the mountains. I found this website 2 days ago, and started searching threads. I found 1 thread that described my condition exactly. What he found was that the Bosch platinum plugs were bad. I put in some Autolite copper core plugs a few hours ago, and WOW...what a difference. More power, better throttle response, no more flat spots, and most importantly, the bucking is gone.

This website rocks!!!

-David

 

[aldive]

Were the plugs the +4 ,odel?

 

[espnfreak]

welcome to the board!

 

[85Dave]

They were the standard Bosch Platinum plugs, not the +4s. Thinking back to when I first installed the plugs, I noticed that the engine did not idle as smooth as with the old Autolites. Apparently they have not been performing up to par ever since they were new.

And thanks for the Welcome!

-David

 

[Jason94sport]

Are you sure they were the correct ones for you explorer? Also clean out your MAS sensor. This is know to be a cause of rough idle, & bucking.

 

[85Dave]

I've been trying to chase this problem down for a year and a half. The engine started backfiring through the intake a few months ago. I replaced the TPS, used injector cleaner, replaced the O2 sensor, the air filter, and cleaned the MAS (I learned how from this website). All these changes seemed to help, but it didn't solve the bucking/jerking problem.

I don't know if I have the right Bosch part number for my vehicle. Its what Autozone gave me when I bought them, so I assume its the right number.

One other thought. Platinum does not conduct electricity as well as copper, especially when the platinum wire is many times smaller than the copper electrode. But copper does not last as long in this type of service. Therefore, a _new_ copper plug will perform better than a new platinum. Manufacturers are using platinums now because EPA requires the emission control systems to be maintenance free for 50,000 miles (spark plugs are considered to be part of the emission control system).

Thanks for the advice!

 

[jsdean]

That's really odd, b/c you will notice (at least on the OHV) that the manual says to only use platinum plugs. I just replaced my factory ones with Bosche platinums, and it's smoother (course the truch has 92k miles on the first set of plugs)

 

[85Dave]

I don't have the owner's manual in front of me, but the sticker under the hood specified Motorcraft(Autolite) AWSF42C, which is a copper core plug. My Explorer was manufactured in 1991. This must have been before they started using platinums. I remember the original set of plugs were copper core plugs, not platinums.

 

[Jim F]

What year did Ford start using DIS (distributerless Ignition System) on the Explorer. With a DIS system it is determental to have dual platnum since three of the six plug are firing in reverse.

Check my explaination in the following thread:
http://208.38.138.31/forums/showthread.php?threadid=30083&highlight=DIS

 

[85Dave]

My 92 does not have a distributor. It has a crank sensor, computer brain, and twin coil pack. So I guess its a DIS?