Replacing spark plugs

. How many junk Bosch plugs have you replaced? Were they installed with a torque wrench? Were they the correct plugs for the applications? I began my career as a German auto tech in 1976 and I prefer Bosch. What kind of experience is your opinion based upon?

My experience is based on both American engines and European and Japanese....

Jeep straight six ones in particular...

I have seen a whole pile of older Jeep engines come to me for help because no one can make them run.

When I look, see Bosch and say 'bad plugs', they 'all' say, but but but, they are the expensive plugs and they are new!

As soon as I toss them out and drop Champion plugs in, the bad running and missing at idle issues are gone.

Bosch 'used' to be good good plugs and they worked well in my past experience for some of the higher compression engines, like VW and Volvo but the Jeep 'thumper' engines just don't like them from what I have seen.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 (More Off Road album links at bottom of the view page)

That missing letter probably indicated no internal resistor.

"R" innit?

Delco, for one, offers a chart to decode spark plug ID numbers:

-- "We began to realize, as we plowed on with the destruction of New Jersey, that the extent of our American lunatic fringe had been underestimated." Orson Wells on the reaction to the _War Of The Worlds_ broadcast.

I never tried to keep count. If I had to guess I'd say I have had around

50-60 vehicles that didn't run right with Bosh plugs.

Were they installed with a

Don't know as I wasn't the one that installed them. That said, why do you think a torque wrench would make a difference ? I personally never use a torque wrench on spark plugs and have never had a problem in over 30 years.

Were they the correct plugs for the applications?

I had no way of checking that.

You are the ONLY tech I have run into that actually likes Bosh plugs. Everyone else has had problems with Bosh plugs at one time or another.

What

I have been working on cars for over 30 years, most of that professionally. I have worked in dealerships and independent shops. My experience with Bosh is that the customer comes in complaining about the way their car runs, check engine light may or may not be on and they just had a tune up done 1 week to 1 month ago. I bring the car in to look it over and all the tune up parts are new. Remove Bosh plugs and replace with any other brand and car runs great. This gets to be a common problem so anytime I get a vehicle with a driveability problem that has Bosh plugs installed I replace the Bosh plugs first. Everytime the Bosh plugs are replaced with another brand driveablity problems are gone as well. I also can say from experience that some cars appear to run OK with Bosh plugs. I have run across a few vehicles that had Bosh plugs installed that ran fine. However, every tech I have talked to has had a similiar ( read bad ) experience with Bosh plugs. Oh, I looked at all the Bosh plugs that I replaced because of problems and you could see nothing wrong with the plugs, they all looked like new. Yet a new set of plugs, anything but Bosh, cured the problems. That's my experience and that's why I won't use anything Bosh makes.

Yep

There is no such thing as " high output plugs".

I'll say it again, there's no such thing as "high output plugs". My bet is that the parts guy gave you a shorter reach spark plug instead of a long reach plug. I have run across that before on the older GM's and they will run like crap with the shorter plugs installed. If the missing digit had been at the end it would have been an "R" designating a reistor plug. That wouln'd make the car run poorly. A missing digit in the middle would either be plug reach or heat range.

I'll bet what the parts guy was trying to tell you is that the sprk plugs were listed for the "high output" engine option, not that it was a "high output" spark plug

Platinum plugs will last longer, that's all. They will not make the engine run an different.

The following excerpt is from the 2003 Mopar Spark Plug Catalogue (page 9)

"The spark plugs below are specifically designed by Bosch for the optimum performance of your Mopar engine. Each package contains four spark plugs." and then lists the engines are recommended sparks.

I'll forward a copy to Bill for his records.

Depends on where you live. If your engine is spec'd with platinum plugs for emissions [should be in your owners manual] then a mechanic might get in trouble replacing them with anything else, depending on the local smog laws.

You could always call a dealer parts place and ask them if that engine spec's platinum plugs as oem. Apparently some of the 99 engines do. A dealer parts department would also be able to tell you if you must replace them with platinum for smog reasons or not.

tinman proclaimed:

Looks like it, the Mopar part number is Mopar SP000ZFR5N Resistor Copper Plug

The only mention I can find of platinums is for the HO 4.7

Ask your mechanic if he has a smog license and wants to keep it. Some states are more hostile than others regarding smog scams.

billy ray proclaimed: