walight01

i'm not debating wether or not they add power, i'm just saying i stated that i changed my plugs at 20k and you missed that, thats all i'm saying.

mnkyboy

I religously keep track of my MPG every tank. Here is a list since I got my P5

Notice the higest I ever got was 31.3. That was the only time I ever drove my car out of town. These figures are on 87 OCTANE.

My P5 is a stock, manual tranny, with a K&N drop in filter. I installed the K&N filter on 8-8-02.

I drive about 98% city.

Does these numbers look ok? Should I bring my car in to get something checked out?

mnkyboy

Ok, i took a screenshot of my Excel sheet, its easier to read

Please see my post above, and tell me what you think

silver_p5_owner

The way I see it the arc will choose the path of least resistence, therefore you're paying for four electrodes that won't be used any more than one properly gapped single electrode.

JJB

In addition, current densities like to increase and gather on sharp edges (and particularly sharp points), so if there is one terminal that is more rounded than the other then the likely point of discharge will be the one with the squarer corner. More corners = more likely points of discharge.

jstand6

I have tried the Bosch Platinum +4's. Put them in at 30,000 miles. Engine seemed to rev a little better at first. About 40,000 miles engine started hesitating at certain rpm's. At 50,000 miles I pulled the plugs. They had some pretty major carbon build-up! I double checked the Bosch plugs to make sure I had installed the correct ones (temperature-wise). The plugs were the correct ones. I installed regular NGK plugs and the hesitation stopped. Pulled the NGK plugs at 75,000 miles and replaced with new NGKs. The ones I pulled looked pretty new. Those Bosch +4's were a huge waste of money and caused a hesitation. I have also tried SplitFires in the past on a '91 Escort GT (Mazda BP engine). They worked fine but didn't do anything special. Regular plugs work just fine.

ewsmith1

I put in the Bosch Platinums last night and I'll let you know what type of gas milage increase/decrease I get.

The engine does seem to idle somewhat more smoothly.

Eric...

carguycw

I've heard numerous accounts about Bosch Platinums that are similar to jstand6's story. The problem with all Bosch Platinums (+2 or +4 or not) is the center electrode, which is tiny and almost completely covered by a ceramic sleeve. Although the platinum material will *theoretically* last almost forever, it's a moot point because it fouls so easily it's not even funny. The electrode is simply too small to effectively burn away carbon deposits. Also, spark detonation will destroy them in a heartbeat for the same reason.

IMHO the extra cost is not worth it. The stock Denso plugs (which will work just fine on a mildly modded engine, and don't foul) only cost me ~$1.50 a plug at AutoZone the last time I bought a set, and it only takes 5 minutes to change the plugs. This is not too hard for me.

mnkyboy

Anyone care to elaborate on my MPG figures I posted? Im curious if these seem very low to some people.

jstand6

Considering you drive city 98% of the time in New Orleans (lots of lights, lots of traffic), and probably fairly enthusiastically (K&N filter), your mileage figures seem fine. Your highway mileage of 31.3 mpg with some city mixed in is right on and actually slightly better than EPA figures. Real-world driving generally results in lower city mileage than the EPA rating, which is rather conservative.

Now, I wish our gas prices here in San Diego were as low as yours. I'm pretty happy when gas drops below $1.50 per gallon at the cheap gas stations!

ewsmith1

Silver 5,

what is the green car that you call "cooler" at the bottom of your posts?

Thanks,
Eric...

silver_p5_owner

It's the same shot of my car in the "cool" one redone in Photoshop to be a two door, lowered, chopped roof channelled bod with different wheels.