Hard Dog Fabrication

Bosch Plugs

Bosch Platinum +4 & Platinum IR Fusion +4

[3/3/2010] Reviewed by: James Le

Applicable to: '90 - '97 '99-'05 1.8 liter

Performance minded spark plugs with 4 electrodes to gaurantee a spark. The 4 electrodes makes gapping obsolete.

Bosch Platinum +4 May 25 2006 to February 27 2010. For the past 10 years I have used the Platinum +4 plugs on 3 different vehicles, 1999 Honda Civic EX, 1994 Mazda Miata STO #957 (rip Zippy), and a 2000 Mazda Miata. Before installation of the +4 plugs, I've always used Magnecor 8.5MM wires. There is a definate increase in responsiveness with these plugs as compared to OEM plugs. Fuel economy stays about the same throughout the life of the plugs. Overall worth the 5-6 dollars per plug. These plugs are readily available at most places such as Autozone, O'Reilly, Pep Boys, etc... so special orders aren't necessary. Bosch Platinum IR Fusion +4 February 27 2010 to Now. An upgrade from the Platinum +4 with some Iridium in the plugs. So far I have not noticed a major difference between these and the Platinum +4, but it's only been a few days. I am expecting the engine temperature to be overall higher, but I have not noticed that either(this winter has been relatively colder than normal). Responsiveness with these might be just a tad bit more than the +4, otherwise it's unnoticeable. At 8 dollars a plug, I am not sure if there's a major difference between the two different models.

Prior to installation of the Platinum +4 plugs, Magnecor 8.5MM wires were installed with OEM plugs in place. Comments from other shops concerning the spark plugs include minor misfires and minor ignition problems that can be remedied with using a larger spark plug wire.

Under 5 minutes to remove

Bosch Platinum +4 Spark Plugs

[10/9/2005] Reviewed by: Kenneth Phillips - F14kap@gmail.com

Applicable to: '90 - '97

Bosch Platinum +4 Spark Plugs

I recently acquired a lovely 89 dodge raider from a dealer. I change virtually all fluids and other quick fix-itís. Last but not least on my list, I installed brand new BP +4 spark plugs in. Before the installation the truck would take a good minute to start; however, after the Bosch Platinum +4 Spark Plugs were installed it fired right up. The idle was great and throttle response was better. I kept and eye on the heat build throughout the idle engine, because more spark = more heat. It seemed identical to the autolight - basics that were taking out. Iím mostly new to the Bosch product line and from what I physically saw; I would recommend this product to anyone. I would also recommend that (he/she) do their homework first just to be safe.

Keep an eye on you cylinders temp. Never hurts to have a Pro check.(save now or pay later)

Under 30 minutes to remove completely

Bosch Plat 4

[10/14/2003] Reviewed by: gary - garyscheerer007@hotmail.com

Applicable to: '90 - '97 1.6 liter

Bosch Plat 4 spark plugs

The plugs showed a little improvement, but only for about 2 weeks then started the rough idling. Thought it was the sparkplug wires, changed to NGK 8mm blue and still didn't work then one day plug 3 blew out. Replaced with NGK-R plugs and the car runs fine. Don't buy plugs unless you want to replace them in 3 weeks.

Under 5 minutes to remove

[5/11/2002] Reviewed by: Tom Parker - mparker2@hotmail.com

Applicable to: '99 + 1.8 liter

4 electrode platinum spark plug

I installed these plugs based on reviews I'd read. When I first installed them, I immediately noticed that the car started faster and idled more smoothly. Unfortunately, long term use has not been so kind. After about four months of using them, I started to notice that my car would try to stall at red lights and when the A/C was turned on. Also, acceleration was slow. I took the car to my local dealer. The tech found evidence of high temperatures in the cylinders and said the #2 plug wasn't sparking correctly. He recommended I replace them with plain old NGK plugs ASAP. I did and the car has been good as new since then.

This product is not worth the money. Initial benefits are not worth possible early failure aren't much different from brand new OEM plugs anyway. I'd rather use the cheaper NGK's even though they supposedly do not last as long.

Under 5 minutes to remove

[1/26/2002] Reviewed by: Terry Coss - terryecoss@mediaone.net

Applicable to: '99 + 1.8 liter

Four-electrode Platinum tipped spark plug upgrade by Bosch.

Installed in 2001 LS based on reviews I'd read. My experience was much the same as another reviewer in that my car was rather cold-blooded and required several miles of driving to smooth out in cool weather. I did this install in Minnesota in January and noticed significant improvement in idle smoothness and driveability during the warm-up period. Throttle response is much more linear during warm-up, making for smoother gear changes. Can't say for sure there is much difference over stock plugs after warm-up, but subjectively the engine "feels" better with less shake at idle and more low-end grunt for smoother clutch engagement. I'm pleased with results and would do it again.

Be careful with black plastic spark plug wire brackets when cold. On 2001 model, this bracket has a knob that pokes into a hole in the camshaft cover to secure it. You need to remove these to get access to change the spark plugs and I broke a knob off one trying to pry it out. I think it was because it was cold (35 degrees F) and the plastic was brittle. If I had warmed the engine first it might have been OK.

Under 30 minutes to remove completely

[8/30/2001] Reviewed by: Mark Jensen - mjdk2@yahoo.com

Applicable to: '90 - '97 1.8 liter

Bosch Platinum +4 sparkplugs (replacing stock NGK's)

Removal and installation took less than 10 minutes, using a 5/8 deepwall sparkplug socket. Car is a 1996 M

After installing the plugs I immediately noticed a tremendous improvement in acceleration and the engine sounds much better. At $5.99 per plug they may be somewhat expensive but definitely worth the money. As far as getting better gas mileage I haven't had them in long enough to be able to assess whether or not there is an improvement.

Under 5 minutes to remove

[9/23/2000] Reviewed by Ted Williams - edwarddw@bellsouth.net

Applicable to '99 + 1.8 liter

Spark plug upgrade over stock.

Installation was straight forward. As always working in the Miata engine compartment was a pleasure.

If you're looking for horsepower don't buy these plugs. However, if you're looking for smoother acceleration and idling then these are the plugs for you. My Miata was cold hearted out of the crate. It would require about a 2-3 minute warm up before it smoothed out. After the installation of the Bosch plugs the car ran perfectly from cold start to full operating temp. Acceleration is smooth and predictable and the engine seems to respond quicker. (could just be subconsious rationalization over 5 dollar spark plugs.) All in all a great product. If your concern is strickly horsepower then stick with the stock champion or ND plugs.

Under 30 minutes to remove completely

[5/26/2000] Reviewed by Paul Hutcheon - abby@flarenet.com

Applicable to '99 + 1.8 liter

New design with 4 electodes (no need to gap) just install right out of the box in my '99 silver.

Have found since replacing the original DENSO? plugs (not NGK) that my car has started better and run smoother. Time will tell, but for now I feel this has been an upgrade.

Would recommend since i have always had great luck with Bosch plugs.

Price a bit high at $8 each. Will see how long they perform.

Under 30 minutes to remove completely

Reviewed by: Nathan Keysor - SirNuadha@aol.com

Replacement spark plugs utilizing a four pronged head and platinum coating.

These plugs installed easily and do not require gapping as they arrive preset from the factory. They are designed with a special four pronged head for more even combustion. I have noticed a small increase in gas mileage since installing them. Also, the engine seems to rev slightly smoother than with the factory plugs.

For $5.00 a piece I think they are a worthwhile upgrade.

Reviewed by: Bill Meyer - meyerwg@tcg.com

A platinum spark plug with four electrodes and a platinum center electrode.

I recently had my car dyno'd at a shop in Mt. View CA, and during the dyno runs I tried a change in plugs. My car is a '95 M Edition with 44k miles. I made 2 runs with the platinum SplitFires and then installed the Bosch Platinum+4 plugs. There was no increase in horsepower or torque over the SplitFires, and driveability seems to be unchanged. Now I am not quite sure where the advantage is to a $5.99 sparkplug as far as performance goes, but after long discussions about my net horsepower gains, I would recommend a standard NGK copper core plug and save yourself considerable money. I'll be returning the Bosch plugs to Pep Boys for a refund, as advertised.

This is a follow up to my review following removal of the plugs.

Since my initial review, I returned the Bosch+4 plugs and replaced them with standard copper core NGK's. Several of us got together about 4 weeks later for a Dyno Day in Mt. View. The dyno did not lie. A 3 horsepower improvement over the Bosch and Splitfire plugs. The Consumer Reports June '99 magazine did a field test on the Bosch Platinum+4 plugs and their results showed no appreciable improvement over standard plugs for their test Honda. Beware of claimed improvements.

Reviewed by: John Yang - Eunos818@aol.com

Platinum spark plugs with four tips on the end

I just recently installed them in my 95' that has 44,000 miles. They came pre-gapped and I installed them with 20lbs of torque. I paid 5.99 a plug.

These plugs did work to some extent. I felt an increase in mileage and power on the high end. Another plus I felt was the engine's rpms fell slower when i let the gas pedal go, this made downshifting much easier. I recommend these plugs!

Back to Product Reviews 29 September, 2010

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