Just installed Bosch Platinum-4 plugs in my 2005 V6 with CAI, GT Muffler, and SCT X2 tune from VMP. Performance seems noticibly changed for the worse...no longer has the SNAP @ about 3300 RPM and instead of building power steadily from there, it's just "winding out" like the powerband is FLAT..?

Any ideas guys?

 

What about your COP's? Are those installed properly?

 

COP's ??? Sorry, but even after searching, I can't figure out what COP's means..

 

coil over plug

 

So you're asking if the electrodes encased in rubber which slip over the plug are all on their respective plugs?

If that's what you mean, then I'm pretty sure they are - I believe the engine would run really ROUGH if even ONE of them were not connected to the plug... AND wouldn't the car give me a warning message if that were the case?

 

Here is the best advice you can get. Take those crappy Bosch plugs out now and either put the stocker back in or go buy another new set of Motorcraft plugs.

Those Bosch plugs are junk and Bosch plugs do not work well in ford's

Also I do not believ the V-6's have the COP setup. I thought they still ahd plug wires.

 

bah so what if you lost a few HP, you're about 100hp under powered anyway

 

My winter beater was coughing a bit on long hills so I tried those plugs to see if they would improve performance. It barely ran at all with them. And I mean barely! Got some new conventional plugs and the problem was cured.

 

 

It's always been my experience selling plugs that for many cars you need to go with the original equipment brand and type. Some cars will just not run on different brands and types. The most common situation is Asian vehicles that only run properly with NGK or Nippondenso plugs.

Another common mistake people make is assuming plugs are gapped to spec for the car right out of the box. Of course this does not apply to non-gappable plugs.

 

That's a GOOD one LEO!.. I'm LMAO & AGREE! The 4.0 NEEDS a supercharger! Not to mention POSI so you can get it to the ground...

I'm going to grab a set of Autolite 5143 plugs and see what happens...I'll let you guys know.

Doesn't make much sense to me; how can JUST a different plug alter the powerband so much? Unless it's like altering the timing..? That may explain it.. the design of the Bosch is 4-prong vs. the standard plugs being single-prong.. the spark may be occuring "early", thus burning a portion of the fuel prematurely??

 

Take out Bosch plugs.............They don't work and yes you did loose power. It happened to me as well on another mustang. Nippondenso Irridium or motorcraft.

 

YUP!... I pulled the Bosch plugs & slapped in a set of Motorcraft SP-498 OEM plugs & IMMEDIATELY got the SNAP back in my engine! Frikin AMAZING that just spark plugs can make such a difference!

Thanks to all for your help!