: Spark Plugs



cowboy cad
12-15-04, 12:11 PM
I recently changed plugs,wires and one coil pack because of a miss. I replaced the plugs with bosch platinum as they were less than half the cost of ac delco, I noticed a drop in fuel mileage and started reading posts here some about positive and negative firing on the northstar. Could someone clear this up for me? My dealer does not know anything when I mention dual plugs he does not know what i'm talking about he gave me a number for ac delco platinum plugs the number is 41-950 is this what I need? How much should they cost me he wants almost $9.00 each for them.

Spyder
12-15-04, 02:07 PM
950's are what my N* had when I got it...9 bucks is about right, you might find them a buck or two cheaper at napa or somewhere other than the dealer...

bsandnes
12-15-04, 03:25 PM
Thats interesting that your mileage dropped. In my experience, the Bosch is probably the WORST plug that I have used...ever. I treated my shortstar to a set of Iridium NGK's. So far these have been worry free with no adverse effects.....spendy though

oki-inu
12-15-04, 04:25 PM
I just replaced my plugs and wires. I bought AC Delco 41-950 from Autozone at $5.99 each. They are also available from Advance Auto Parts for $5.98 each. The car runs noticably better now, don't know about gas mileage yet, I just put them in.

ellives
12-15-04, 09:19 PM
Thats interesting that your mileage dropped. In my experience, the Bosch is probably the WORST plug that I have used...ever. I treated my shortstar to a set of Iridium NGK's. So far these have been worry free with no adverse effects.....spendy though

Get rid of those Bosch plugs. I've heard nothing but bad about them. In fact a mechanic friend of mine has told me horror stories of customers of his who replaced their own plugs with Bosch and subsequently the vehicle wouldn't run. When he replaced with factory plugs the vehicle started and ran better than ever.

Use the AC Delco stuff. Given they last as long as they do, why cut corners?

Ells

mcowden
12-15-04, 11:01 PM
I admit I had been skeptical of claims that Bosch Platinums were junk, but now I've seen and felt it for myself and I have to agree. They suck. As soon as I changed out the BPs for the AC-Delco 41-950 double platinums, it was like magic. Starts faster, runs smoother, mileage hasn't changed at all so far, but the temperature has dropped here significantly since I did it so I'll let you know in the spring. The BPs I took out had about 40-45k miles on them. One of the platinum tips was gone (cyl. 8) and the nub was wearing badly. Other than that, they looked OK, and I wouldn't have complained about the performance, starting, or mileage, but the difference when I started it the first time with the 41-950's was astonishing. No kidding. Worth every penny. The BPs are cheap for a good reason. Stick with what everyone knows works in the car.

Good luck...

M C
:cheers:

BeelzeBob
12-15-04, 11:17 PM
The Bosch platinum plugs cost half as much because they are half as good. They only have platinum center electrodes...none on the ground electrode.

Wade thru the following old post....it has the explaination you are looking for on page two or three....

http://www.cadillacforums.com/forums/showthread.php?t=22486&page=1&pp=20&highlight=negative+polarity

cowboy cad
12-16-04, 10:16 AM
Thank you all for the info. I will be replacing the bosch plugs shortly. I am still curious about the other recent post about the northstar firing some from positive to negative and some negative to positive this is the first I have heard of this.

Ranger
12-16-04, 12:42 PM
Just put a set of A/C Delco 41-950's in my car. $6 ea. at Carquest.

BeelzeBob
12-16-04, 08:55 PM
I am still curious about the other recent post about the northstar firing some from positive to negative and some negative to positive this is the first I have heard of this.



Did you read through all the pages of the post I referenced??? It explained the pos-to-neg and neg-to-pos issues.... What other questions or curiosity?? It is the way a direct fire ignition coil with dual windings works. That is why the dual platinum OEM plugs are necessary...so as to have the platinum on the positive terminal all the time. since you don't know which one is going to be positive without probing the coils the plugs need to have platinum on both electrodes. All direct fire ignition systems that use coils with dual winding fire plugs this way.

cowboy cad
12-19-04, 12:40 PM
Thanks!