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Old 09-02-2005, 05:20 PM   #1
BrysImpreza
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Default Change your plugs!

My car has been running very sluggish lately, the filter is clean, tried using 89 octane and fuel system cleaners .. nothing.

I have 27,500 on my car, so I was thinking about checking out the plugs to see how they were looking / burning. Well, they looked OK, except for the fact they were CHAMPIONS!

For as long as I've been driving and working on Subarus (1995) everytime I'd change out the plugs, they had NGKs as OEM plugs and I'd replace them with NGKs and never had any problems. For as long as I've been working on engines, I've always found Champion sparkplugs to be some of the worst I've ever encountered.

I picked up a set of Autolite Platinums (NGKs were out of stock), installed them last night. My car idles smoothly, accelerates better and after filling up yesterday I've gone 76 miles and the gauge hasn't moved from "Full".

I don't know if anyone else has had a similar experience, but I'd highly suggest putting a better plug in if you have a later model N/A Impreza.

Bry.
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Old 09-02-2005, 06:03 PM   #2
redsube'
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i had a similair experience in my 02 wrx. car became very sluggish and gas mileage was really bad around 200-240 miles per tank. depending on how spirirted i drove it.

i switched to ngk BKR-7EVX iridium one step colder plugs and the car drives much smoother. gas mileage increased to just under 300 miles a tank!!!!!!


IBPOINTOFPOSTCHANGEYOURPLUGS
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Old 09-02-2005, 06:52 PM   #3
imprezar25
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how much better are aftermarket plug wires then stock?
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Old 09-02-2005, 06:54 PM   #4
Matt Monson
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There were number of our cars delivered with Champions, including my personal MY00 2.5RS. Yes, it is a good idea to pitch those bugger straight in the can...
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Old 09-02-2005, 06:55 PM   #5
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Quote:
Originally Posted by imprezar25
how much better are aftermarket plug wires then stock?

on non turbo cars the plugs really dont matter (unless you are using nitrous)

just get what is reccomended. you wont see any performance increases ebcause of expensive plugs that supposedly have 4 sparks (which doesnt even happen)
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Old 09-02-2005, 11:17 PM   #6
donut
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when i first bought my 98RS in 99 i drove it from boston to P-cola FL for tranning. the very first mod i did was swap out the stock ngks for a set of bosh +4 . it was like i had a differant car. it rev so much faster and just seem to run better. now with 98k and a blown hg it does't matter wut the f@#$ i use.
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Old 09-02-2005, 11:35 PM   #7
BlkTS02
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After doing some reading on plugs it seems that alot of people had issues with the bosch +4 plugs.


Last time I put in new plugs I got one step hotter NGK v-power. Didn't really notice a difference, but gas mileage did increase slightly.
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Old 09-03-2005, 10:12 AM   #8
BrysImpreza
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Quote:
Originally Posted by BlkTS02
After doing some reading on plugs it seems that alot of people had issues with the bosch +4 plugs.


Last time I put in new plugs I got one step hotter NGK v-power. Didn't really notice a difference, but gas mileage did increase slightly.
Yup, I wouldn't put them in an N/A car, they seem to do ok for Forced induction. But I even remember how quickly Champion plugs would corrode and fail in my old mini-bikes, go-carts, etc. Anytime the engine wouldn't start, I' look at the plug and see it was black. I hadn't run my old go-cart in like 12 years, the Bosch plug I left in there sparked and the engine coughed to life on the second pull.

I know cars and small engines are quite different, but it just shows something about reliability.
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Old 09-03-2005, 11:58 AM   #9
Hayes
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My 2000 Forest came with Champions and they looked great when I changed at 30,000 miles. My experience from the old days was to stay far away from Champions. I replaced with NGKs and they came out looking great at 60,000 miles. Maybe Champion has finally got it together after 30 years of selling junk, but I'll stick with NGK for now.
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Old 09-03-2005, 12:58 PM   #10
FalconRS
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Bosch +4 plugs are TERRIBLE. The idea is solid, more stuff there for more sparks, but it doesn't work, it actually reduces the spark's exposure to the air-fuel mixture. I've had nothing but idle problems and high-rpm misfires in every application I've seen them used, including one of my own which was enough to show me the light.

I love the NGK Iridium plugs. Haven't replaced the plugs in my '05 RS yet, but I've got 40,000 kms (25000 miles) on it now so I think I'll change em out soon. I've always used NGK plugs, mostly the coppers. But in my last (boosted) car the coppers would miss slightly at the top end unless I brought the gap down. Switching to exactly the same plug, but to the Iridium model, with the same gap, no misfires and I could actually INCREASE the gap, increasing spark exposure (see complaint about the Bosch +4's above) and reducing tendency for spark blow-out. Basically, Iridium has properties that allow for a stronger spark. Yes, they're expensive, $10 CDN/plug for Iridium vs. $3 CDN for Copper, but you get what you pay for.

Incidentally, I also tried the same NGK plug (same part number) but in the Platinum line, and it performed pretty much identically to the Copper...the difference being platinum will last longer than the copper cores. Iridium has durability roughly equivalent to platinum plugs, if not a little better. Seems the platinum's rang in in the $8 CDN/plug range. For me, the Iridium's are a worthwhile investment.

EDIT: Just curious, I haven't looked into it yet, but what NGK part number are you guys using for stock or mostly-stock 2.5's? Have you seen any gains or drivability improvements from going one heat range colder? All my experiences have been with boost and domestic OHV engines.
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Old 08-31-2006, 06:20 PM   #11
V8Slayer
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Will spark plugs made for a SOHC work in a DOHC? I can't seem to find the part #'s for the DOHC NGK Copper/Iridium plugs. Just wondering if they are interchangeable or if anyone has part #'s.
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Old 08-31-2006, 08:31 PM   #12
FalconRS
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These will work fine in either DOHC or SOHC n/a cars, and are stock heat range:

NGK BKR5E-11 ("V-power" standard copper, cheap, but don't last long)
NGK BKR5EGP ("G-power" platinum, more expensive, longer lasting)
NGK BKR5EIX-11 (Iridium IX, most expensive, longest lasting)

NGK FR5AP-11 are the direct stock replacement plug for 03+ SOHC motors, and these were the plugs that came in my '05, not champions as some people have found in their cars. These are also harder to find. They are NGK's "Laser Platinum" plugs, and are supposed to be a higher grade (more durable) than the standard platinum plugs. But as such, are more money and even closer in price to the Iridium's. For me it's a no-brainer. Iridium all the way.

I've been trying out some BKR6E-11 copper plugs this summer, they're one heat range colder than stock. Initially they worked very well, improved performance, etc. BUT, we had a bit of a heat wave back in June when I put them in. I've really noticed the last couple of weeks, when we've had cooler temps, my gas mileage has gone down the tubes and performance has dropped off. As such, I've got a set of BKR5EIX-11's sitting here waiting for a free evening to wrench on the car. Colder works well during the hot summer, but don't cut it as a year-round reliable option.

Last edited by FalconRS; 08-31-2006 at 08:44 PM.
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Old 08-31-2006, 08:46 PM   #13
SubaruDriver502
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you buy the car new? A previous owner could have changed them
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Old 08-31-2006, 09:01 PM   #14
FalconRS
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Had to wait 3 weeks for it as I wanted the new 05 in CGM, didn't like any of the colors of 04's they had on the lot. So yes, from the factory with NGK FR5AP-11's.
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Old 09-01-2006, 04:59 PM   #15
fastenova
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My 2 cents... NGK V-power plugs are great. They're not too bad to replace on flat 4 motors, and I would replace them between 30K and 50K. I have had nothing but problems with Bosch plugs on these motors.

Just to put things into perspective, I run Bosch Platinum +2s on my V6 4L in my truck and they rock...

Application built, I suppose.
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