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post #1 of 28 (permalink) Old 12-08-2005, 10:31 AM Thread Starter
 
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MPG sucks with platinum plugs

At the last tune up (In sept) I put a set of NGK platinums in ( I got a cheap deal on them), and since then my average MPG has dropped to about 17 MPG and the highway has dropped to 22-24. Used to be about 18-20 city and 26-28 highway. Im goin back to Champion coppers tomorrow. But why the hell would it get so bad so fast? I though platinums were supposed to last longer than copper plugs The exhaust is black now when I rev it. Everything else seems fine, havent seen a CEL since the TPS went bad long ago.
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post #2 of 28 (permalink) Old 12-08-2005, 10:47 AM
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Is that why I only get 14.3 in my 89 with the 3.8? Nah, it is because I have to be WOT 92% of the time to keep up with traffic. I am lying, now that it is in the 60s and 70s, and no AC, I have averaged 14.8 over the last 750 miles or so.

Platinums last longer, but I think as you found out you might lose some power and fuel economy. Coppers work better but wear out faster. I would never put anything other than Platinums in my 3.8, I still have scars from the last time I swapped them. I go about 60k miles on a set.

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post #3 of 28 (permalink) Old 12-08-2005, 11:34 AM
 
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Plugs aren't the only thing that affect milage. I would look at your fuel filter, air filter, do an oil change when needed, etc... general maintnance items. Plugs are but one piece of the fuel milage equation

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post #4 of 28 (permalink) Old 12-08-2005, 12:02 PM Thread Starter
 
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Filters are newer, oil was just changed. Everything else is good, but Ill check the wires and cap/rotor again while Im at it. I just thought it was odd that these plugs seemed to give me worse mileage than the coppers, and went bad so fast.
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post #5 of 28 (permalink) Old 12-08-2005, 02:38 PM
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BlueLS,

In the US, we have winter blend gasolines that do not produce as much mileage as the summer blends. I'm wondering if the same thing happens in Canada.

I've only used platinum plugs in the car. I am debating on whether to go to Double Plats or just stay with single plats. I hope I can finance and install my 4.2L before I have to make that decision.

The Parts Bin Special is DEAD! It is being parted out.
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post #6 of 28 (permalink) Old 12-08-2005, 02:46 PM Thread Starter
 
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Hmm, never thought about that. I dont know if we have that, but could be. Since I already bought the coppers Ill stick with them, and they are alot cheaper than the platinums ( I cant get the discounts I used to on parts)
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post #7 of 28 (permalink) Old 12-08-2005, 02:46 PM
 
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Another reason is that copper conducts eletricity better, but at the expense of longetvity
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post #8 of 28 (permalink) Old 12-08-2005, 02:55 PM
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BlueLS,

In the states, I sell Autolite platnimus for $2.48US each and the copper autolites for $1.28US each. I've had my plats in for almost 3 years, therefore my math is this.

1 set of plats: 6x$2.48 = $14.88

3 sets of coppers (one per year): 18x$1.28 = $22.50.

The Parts Bin Special is DEAD! It is being parted out.
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post #9 of 28 (permalink) Old 12-09-2005, 02:33 AM
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I would not put Champions in anything, the last set I had lasted 10kmiles and made me think the HG had gone it ran so bad. Autolite only for me.

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post #10 of 28 (permalink) Old 12-09-2005, 12:50 PM Thread Starter
 
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Pulled and changed all the plugs today, and most of the NGKs were so worn the gaps on them were around .08 and they were only in since August.
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post #11 of 28 (permalink) Old 12-10-2005, 11:44 AM
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Not sure if this is relevant, but are the NGK's the right spakplugs for your car. Make sure that the plugs are the right tempature range for your application. Also, as noted in this thread, some are hard to get to. Extra attentation needs to be paid on getting the sparkplug wires attached right. Making sure that each "clicks" on to the SP. Of course you probably are all ready aware of all this, just checking.
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post #12 of 28 (permalink) Old 12-10-2005, 04:34 PM Thread Starter
 
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The book showed those plugs for my car, but that could have been wrong. I always make sure that the plug wires "click". With the new ones in the car runs alot better, not surprised though after seeing the condition of the old ones.
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post #13 of 28 (permalink) Old 12-10-2005, 06:03 PM
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I have been having a little problem with rough idling. I went to the local part store and bought a Ford Computer Code Reader. It showed that all the sensors, solenoids were working, but I also did a cylinder test which revealed that I had a problem with cyl # 3. So I know something is a miss. I haven't had the time to pull the plug and check it, but everything else is looking OK. This is a worthwhile tool, in my opion.
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post #14 of 28 (permalink) Old 12-11-2005, 09:41 PM
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it's possible the NGK's electrode is too long for your application and the piston pushed the gap closer together. Just a thought. Sadly, I've seen it happen on a few ocassions at the auto parts store I work at. If you want platinums, get Autolite's or Motorcraft's.
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post #15 of 28 (permalink) Old 12-12-2005, 12:43 AM Thread Starter
 
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The problem was the gap was way too big at .08 when I pulled them, the setting is supposed to be between .34 and .52 (according to the emissions sticker) I set mine at .44 usually. I was just surprised to see that the plugs had worn so much in just that period of time. Im never buying NGK again, if I ever do go to platinums again itll be motorcrafts like you suggest Thomas
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post #16 of 28 (permalink) Old 12-12-2005, 11:15 PM
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Quote:
Originally Posted by Blue LS
The problem was the gap was way too big at .08
.08 is smaller than .4x, maybe you meant .8?
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post #17 of 28 (permalink) Old 12-12-2005, 11:24 PM Thread Starter
 
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Oops my bad, ya I meant .80 was the gap when I pulled them.
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post #18 of 28 (permalink) Old 12-13-2005, 09:23 PM
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Quote:
Originally Posted by Blue LS
Oops my bad, ya I meant .80 was the gap when I pulled them.
On the bright side, you must have a great coil if it kept sparking under compression at .8
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post #19 of 28 (permalink) Old 12-13-2005, 09:32 PM Thread Starter
 
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lol I guess thats one way to look at it. Reason I pulled one in the first place was the idle was gettin rough and it just didnt have the same pickup as it usually does.
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post #20 of 28 (permalink) Old 12-13-2005, 10:43 PM
 
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i wont use any platinum plugs on anything that didnt come from the factory with them, and i sure as hell dont go with the 100k tune ups they are claiming from the factory either.
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post #21 of 28 (permalink) Old 12-13-2005, 11:05 PM
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well, platinums do last longer, regardless of wether or not the car came with them. And they last quite a while. 100k miles? it's possible, but it depends on the efficiency of the timing, engine condition (runs rich/lean, burns oil, etc), and types of fuel used, and how clean they are.
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post #22 of 28 (permalink) Old 12-14-2005, 07:52 AM
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My 3.8L came with Motorcraft Platniums. I know I found one still in the cylinder under the A/C compressor. Some fool had put CHAMPIONS on the driver's side of the engine and I forget what the other 2 plugs were. It's been about 3 years since I put in the Autolite Plats. I'm debating about putting in Autolite double plats this spring, going Motorcraft, and a range colder or go with Autolite coppers for a year.

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post #23 of 28 (permalink) Old 12-14-2005, 02:26 PM
 
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I have double plats right now and its been maybe 50k since I've put them in. From the start they're a little ruff(I believe I put in motorcrafts) it seemed it idled rough and you can't regap them easily, well not from my stand point. And it turns out it isn't just the plugs thats causing the bad idle, turns out my uncle took out the check engine light and the freaking maf was ****ty. Sry for the rant. But I had single plats with no probs
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post #24 of 28 (permalink) Old 12-14-2005, 10:25 PM
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if you regap platinums, they will no longer be platinums, they will be a resistor spark plug. Gapping them rubs off the platinum.
-Thomas

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post #25 of 28 (permalink) Old 12-16-2005, 09:16 AM
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Plugs

I had the same issue with the Bosch platnum plugs. I took out the motorcraft plugs and installed these and my mileage wend down about 4 miles/gallon. I went to Ford to buy the OEM parts and installed the regular motorcraft plugs and what a difference. Ford's service tech commented that they have experienced similar problems with other brands of plugs in the 3.8 motors.
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post #26 of 28 (permalink) Old 12-16-2005, 10:11 AM
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how much where those motorcraft plugs?
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post #27 of 28 (permalink) Old 12-16-2005, 10:53 AM
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AWSF44P for platinums, 2.29 ea. AGSF44FM for finewire platinums, 2.99 ea. Or for advanced timing, the AGSF32FM's would work well for preventing detonation. But if you're going to run performance, You might as well go with the AGSF32C's. But AGSF32FM would be the finewire platinum equivalent.
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post #28 of 28 (permalink) Old 01-07-2006, 12:50 PM
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Quote:
Originally Posted by Thomas
AWSF44P for platinums, 2.29 ea. AGSF44FM for finewire platinums, 2.99 ea. Or for advanced timing, the AGSF32FM's would work well for preventing detonation. But if you're going to run performance, You might as well go with the AGSF32C's. But AGSF32FM would be the finewire platinum equivalent.
-Thomas
When I check the part number of the AGSF32FM it comes up for the Corbra. Is this OK to run in an 88 V6?
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