Engine Misfire and OMG Bosch plugs as OE in a GM!

[GMBoy]

UPDATE:
It was the plug.

I drove down and bought a cheap copper Autolite and stuck it in at the Autozone parking lot. Drove it and problem solved - not a single misfire on the graph. So, I drove back to Autozone and bought 6 double platinum Autolites. Took only 45 mins to do the whole job...thank goodness they changed the intake manifold shape. I did not have to remove anything to change the plugs. Easy as pie. I once did a tune up on a 2005 CTS and I had to loosen and move the intake - not so on the new 3.6DI.

 

[GMBoy]

Originally Posted By: Nick R
Originally Posted By: Colt45ws
Waitwaitwait.
You have a Tech 2?
How much did that run you?


Well he does work for GM, so I imagine he probably got a good deal on it, or is borrowing it.



I own my Tech 2 outright. I bought it online back around 1998 for less than I could even buy it thru our GM rep. It has paid for itself several times over.

 

[GMBoy]

Originally Posted By: 4x4chevydude
I agree if it was only a plug why waste your time for 3.50 that you can do yourself...its not worth the gas to drive to a dealer



Thank You - glad you agree. I bought the 6 plugs and I had $11 on my Autozone rewards card plus the Autolite rebate and the plugs only cost me about $11. If I went to the dealer you know it would be an all day affair and then they would only replace the ONE bad plug under warranty so I would be doing the rest anyway.

Again - another example of 100k plugs not making the distance.

 

[GMBoy]

Originally Posted By: SteveSRT8
Ouch. Extremely unusual to hear of misfires in a newer car like that with low miles.

Sounds to me like B was likely low bidder. The bean counters will ruin things fast for GM if they force the use of only the cheapest parts.

FWIW I just bought AC-Delco plugs for one of my Savanas and they are NGK iridium. Very pricey, and super long lasting!

Hint, Hint.



I hear you there. I was dissapointed. Now, my father has the same car with same miles and his is fine. I have to admit, I do drive harder than most people so maybe I shaved miles off the plug life

But, since it takes less than an hour to do the plugs my Dad has asked me to do his CTS as preventative maintenance.

 

[Nick R]

Aren't those engines supposed to have the plugs changed every 50/60k anyway? I thought the newer high compression engines had shorter plug change intervals.

 

[Colt45ws]

Originally Posted By: Nick R
Aren't those engines supposed to have the plugs changed every 50/60k anyway? I thought the newer high compression engines had shorter plug change intervals.

Maybe something to that. Newer engines are running hotter; higher compression, more timing and using DI to make up for it. Totally does not surprise me plug life is getting eaten back from run of the mill yesteryear 9:1 port injected lumps.
I have a question, though. Why double platinum? Aren't these COP?

 

[GMBoy]

Originally Posted By: Nick R
Aren't those engines supposed to have the plugs changed every 50/60k anyway? I thought the newer high compression engines had shorter plug change intervals.


Nope. Owner's manual says 100k miles for spark plugs. This is a very common thing on today's cars, but I don't agree with it.

 

[GMBoy]

Originally Posted By: Colt45ws
Originally Posted By: Nick R
Aren't those engines supposed to have the plugs changed every 50/60k anyway? I thought the newer high compression engines had shorter plug change intervals.

Maybe something to that. Newer engines are running hotter; higher compression, more timing and using DI to make up for it. Totally does not surprise me plug life is getting eaten back from run of the mill yesteryear 9:1 port injected lumps.
I have a question, though. Why double platinum? Aren't these COP?



Yes, it is COP. I used double platinum because that was what was OEM. I was expecting to find the original plugs to be Iridium, but they were double platinum. I wanted to go Iridium XP's but wouldn't you know it...Autozone only had 4 in stock, LOL.

 

[4ever4d]

Originally Posted By: Nick R
Aren't those engines supposed to have the plugs changed every 50/60k anyway? I thought the newer high compression engines had shorter plug change intervals.

Some do, the 07 300C suggest 30k changes and it is also a two plug per cylinder affair, in fact it's due for one or slightly over now that i think about it.

 

[GMBoy]

Originally Posted By: 4ever4d
Originally Posted By: Nick R
Aren't those engines supposed to have the plugs changed every 50/60k anyway? I thought the newer high compression engines had shorter plug change intervals.

Some do, the 07 300C suggest 30k changes and it is also a two plug per cylinder affair, in fact it's due for one or slightly over now that i think about it.


Thats because a lot of Chrysler products still use Copper plugs. If a car has platinum or Iridium plugs the OEM will spec as high as 100k miles. Coppers are only good for 30k miles.

 

[Robenstein]

I have run Bosch plugs in several GM cars, but I use the Standard copper plugs and they were all old Big Block or Small Block engines.

 

[moklock]

Don't really know about the 3.6L plugs, but I have seen Bosch as OEM on the Opel-sourced 3.0L L81 engine used in the Saturn L300 and VUE. they didn't have the now common 41-xxx plug numbers, just an 8 digit GM part number on them.

They were also clearly a higher quality plug than the cheap junk Bosch platniums sold at an auto parts store. The OE ones dont use those super tiny center electrodes their aftermarket plugs use.

Also AC spark plug has been shut down for a couple years now, so all the plugs are somebody else's stuff. Usually Autolite for the older part no's. and NGK for Iridiums, but Bosch must make some of the newer plugs with 41-xxx plug no's. as well

 

[SteveSRT8]

Originally Posted By: 4ever4d
Originally Posted By: Nick R
Aren't those engines supposed to have the plugs changed every 50/60k anyway? I thought the newer high compression engines had shorter plug change intervals.

Some do, the 07 300C suggest 30k changes and it is also a two plug per cylinder affair, in fact it's due for one or slightly over now that i think about it.


While most 5.7 Chryslers come with copper cheapies the 6.1 ships with NGK Iridiums and has a 100k mile suggested service interval. Same with the V6 models.

They're just saving a buck AND luring you into the stealership for crazy expensive service.

 

[GMBoy]

Originally Posted By: moklock

They were also clearly a higher quality plug than the cheap junk Bosch platniums sold at an auto parts store. The OE ones dont use those super tiny center electrodes their aftermarket plugs use.


True. The OEM "Bosch AC Delcos" I took out of the car didn't look like the Bosch Platinums you get at the parts store with the flat electrode that is even with the insulator. The OEM plugs I took out had a fine wire electrode which looked like an NGK.

 

[GMBoy]

Originally Posted By: SteveSRT8
Originally Posted By: 4ever4d
Originally Posted By: Nick R
Aren't those engines supposed to have the plugs changed every 50/60k anyway? I thought the newer high compression engines had shorter plug change intervals.

Some do, the 07 300C suggest 30k changes and it is also a two plug per cylinder affair, in fact it's due for one or slightly over now that i think about it.


While most 5.7 Chryslers come with copper cheapies the 6.1 ships with NGK Iridiums and has a 100k mile suggested service interval. Same with the V6 models.

They're just saving a buck AND luring you into the stealership for crazy expensive service.



I remember you mentioning this awhile back in a post, that was interesting. I know all the Jeeps I have had all spec'd out coppers, I wonder if the Grand Cherokee SRT8 also has Iridiums like your 300 SRT?

 

[SteveSRT8]

ALL 6.1 engines ship with identical plugs. There are very few differences in major systems in any SRT8, other than the Jeep being awd and WAY heavier.

The Magnum, Charger, and 300 are virtually identical, and the Challenger is just a cut down Charger.

 

[dailydriver]

Originally Posted By: Colt45ws
Waitwaitwait.
You have a Tech 2?
How much did that run you?


I had the very same thought/reaction!!

I could only wish I had one of those exorbitantly priced pieces of electronic equipment!!!
(I could re-write my ECM from C.A.R.B. catalyst parameters/specs to 49 state specs, among other things.

)

 

[dailydriver]

Originally Posted By: SteveSRT8
FWIW I just bought AC-Delco plugs for one of my Savanas and they are NGK iridium. Very pricey, and super long lasting!


So the Delco Iridiums are the same as the NGK Laser (pad on ground electrode) Iridiums??

 

[GMBoy]

Hello guys - Just wanted to give you an update:

My Dad called me yesteday about his CTS (same as mine, 2008 3.6DI but with slightly less miles..47,000) saying it did the same thing to him as mine did. He stomped on it hard merging and felt a miss and the CEL flashed. He brought it right over my house and the Tech 2 verified random misfire and misfire cyl 4 codes. Just like mine, but different cylinder. Driving it showed instant misfires on the misfire graph. We changed the plugs (45mins) and problem solved. No more misfire.

I have to say that if both our cars experienced spark plug life of 50k miles and less than there most be a lot of other CTS's and perhaps other cars with the 3.6DI experiencing the same issue. These plugs should be lasting more than 50k miles! I'm going to do a search and see what the warranty data says.

I hate to say it, but this does not speak well for Bosch plugs - even as OEM installed. I replaced the plugs in both of these CTS's with Autolite Double Platinums and we will see how they do. Double Plat was the OEM style plug.

 

[SteveSRT8]

sounds like another case of bean counters ruining a good car by going with the low bidder!