Recommended Spark Plugs run rough?

[Headnsouth]

I just got done chasing my tail on a problem that lasted 25k miles.

Back in 2005 I changed out the plugs on my 98 Pontiac Transport. At the time it had 140k miles and I knew it needed new plugs but if anyone has ever done plugs in one of these they are a PITA to replace at least the back 3 anyway.
I installed Bosch plats in lieu of OEM AC Plats. I figured whats the difference and always thought Bosch made good stuff. Since the installation of the bosch I'd get an itermittent rough idle and DTC for multiple cylinder misfires and specific cylinder misfires that would vary from cylinder to cylinder. The rough idle was similiar to the symptoms I had prior to the plug swap.

Yesterday I swapped out the bosch for the OEM and the van runs smooth again and the CEL cleared. I'm now getting P0420 & p0102 and I'll work on those next weekend.

My question is why do some plugs not run so well in a vehicle they are recommended for? The bosch plugs were regular plats nothting fancy.

 

[cmhj]

Ya', I hear you.

Over the years I've run into this a lot. Certain plugs just don't work well with certain systems. In many cases the plugs suggested by the manufacture seem to in most cases be the way to go.

It's a whole lot easier to just use what is suggested or what you know worked in the past.

May find that running all over town looking for that deal in the end usually drives one nuts and more money was spent in the long run anyway. However, I'll admit in my youth I played around with many things.

 

[clembrewer]

I had the same problem with regular bosch platinums in a Hyundai. On a 4-cyl engine, the number 2&4 plugs (I think) had the center electrode worn out at about 14K miles. Had to do with the way the spark traveled trough the system.

Switched to NGK V-power and never had another problem.

 

[tunabreath]

GM DIS systems don't like anything but AC Delco Platinums.

At $6-7 a plug at the parts stores, it gets pricy.

 

[Headnsouth]

Thanks for the responses but whats GM DIS?
The AC's are 100k mile plugs and @ $6 thats not to bad.

 

[Chris142]

Is this the van that your supposed to remove the dog bones to acess the plugs?

 

[Headnsouth]

I tired doing the plugs that way. I didn't find it any easier so I did them from underneath. Still a PITA.

 

[The Critic]

Originally Posted By: Headnsouth
Thanks for the responses but whats GM DIS?
The AC's are 100k mile plugs and @ $6 thats not to bad.

DIS= Distributor less ignition system. The Bosch Plugs don't seem to work very well in GM or Ford applications at all. They do fine in some imports though. Also, only use copper plugs in your Saturn.

More info about the GM DIS can be found here:

http://findarticles.com/p/articles/mi_qa3828/is_199907/ai_n8876015

 

[rriddle3]

I've always found it best to keep the same type plugs that came in the engine from the factory.

 

[MrCritical]

Never use Bosch in a GM vehicle.

 

[Headnsouth]

I still don't understand why so called compatible plugs did not work correctly in my vehicle. What makes Bosch any different than AC? These were straight up platinum plugs no forked tongue, super x fire gizmo's.
Plug are a very simple piece of equipment at least I think it is.

 

[The Critic]

Originally Posted By: Headnsouth
I still don't understand why so called compatible plugs did not work correctly in my vehicle. What makes Bosch any different than AC? These were straight up platinum plugs no forked tongue, super x fire gizmo's.
Plug are a very simple piece of equipment at least I think it is.

Possibly it's due to the multi ground electrode design?

 

[Headnsouth]

here's plugs I took out.
http://www.partsamerica.com/ProductDetail.aspx?MfrCode=BOS&MfrPartNumber=4041&PartType=960&PTSet=A

 

[The Critic]

Originally Posted By: Headnsouth
here's plugs I took out.
http://www.partsamerica.com/ProductDetail.aspx?MfrCode=BOS&MfrPartNumber=4041&PartType=960&PTSet=A

Those are the single platinums. Not sure why you'd have a problem with those.

 

[Eddie]

As said before some plugs just seem to perform better in some engines. The misfiring, varing from plug to plug sounds more like ignition wires to me. I usually just go with the OEM brand and type as I know they have been tested by the factory in the engine I bought. JMW Ed

 

[mrsilv04]

My mechanic scolded me at least 15 years ago for using Bosch plugs in a '87 Monte Carlo with a 305.

On the invoice he wrote: "Bosch Plugs... NO! NEVER!"

 

[rpn453]

I put Bosch plugs in my '87 Grand Am and it seemed to idle poorly compared to the old plugs. Since then, I've heard about a number of people having problems with Bosch plugs. I avoid them.

 

[Headnsouth]

Originally Posted By: The Critic
Originally Posted By: Headnsouth
here's plugs I took out.
http://www.partsamerica.com/ProductDetail.aspx?MfrCode=BOS&MfrPartNumber=4041&PartType=960&PTSet=A

Those are the single platinums. Not sure why you'd have a problem with those.

yep, thats why I'm scratching my head. Nothing fancy about those plugs yet it caused issues.

Wires were changed at the time of plugs swap..

 

[brianl703]

My brother put Bosch plugs into his 1996 Ford Contour V6, against my advice.

Since then he started getting lean codes and then finally started getting a cylinder 3 misfire code.

The other day he replaced the plugs and wires (using Autozone store brand wires and Motorcraft plugs), the problem went away, it idles better, and it accelerates smoother. The codes have not returned since he cleared them.

For Ford vehicles I would not use anything other than Autolite or Motorcraft.

 

[Headnsouth]

I've read many posts as to the problems ppl have had with bosch plugs but so far no explanation as to why they cause problems.