ECU Reset
Tech/How-To/Northeast Mod
Joined: Feb 2006
Posts: 2,517
From: Rochester, New York
Mazda3s don't have spark plug wires 
though you could have plugged the wrong plug into a coil over a plug, as the guy said it would be nearly impossible.. you'd have to unwrap the wiring harness, solder an extension on, etc. The wires are only as long as they need to be to prevent that from happening.
Of course you can't see any of this on the MS3 without pulling the intercooler off so I wouldn't expect any MS3 owner to know yet
though you could have plugged the wrong plug into a coil over a plug, as the guy said it would be nearly impossible.. you'd have to unwrap the wiring harness, solder an extension on, etc. The wires are only as long as they need to be to prevent that from happening.
Of course you can't see any of this on the MS3 without pulling the intercooler off so I wouldn't expect any MS3 owner to know yet
Thread Starter
Registered User
Joined: Aug 2007
Posts: 23
From: Boston, MA
no, if you've even looked at the way these engines are set up, you know there is no way to mix up these wires unless you like completely tear down the motor, that and I changed one plug at a time, refastening the boot after each plug was replaced, meaning I didn't just unplug all four wires and change the plugs, I put the wire right back on when I finished each cylinder.
but anyways, the car is running fine now, I think its just that my last two cars didn't have any ECU So I wasn't used to the car taking that long to re-adjust after the reset. I'm trying to find out where I could get some NGK plugs around here, will I have to order them and have them shipped or are there any retail stores in the Boston area that sell them?
o and when I went to the NGK website, the only plugs they had for my car were the irridiums, they didn't show any coppers like you guys were talking about. Is that just because I have the 2.0 instead of the 2.3?
Because the NGK irridiums were listed at like $12 which is no cheaper than the BOSCH, but I'm still going to switch them since everyone here recomends the NGK. and one other thing is that the stock plugs I pulled out weren't NGk, but they were FoMoCo (I'm guessing Ford Motor Company) part number ILTR5A 13G. Does the 2.3 come with these same plugs? or does the 2.3 come with NGK's?
but anyways, the car is running fine now, I think its just that my last two cars didn't have any ECU So I wasn't used to the car taking that long to re-adjust after the reset. I'm trying to find out where I could get some NGK plugs around here, will I have to order them and have them shipped or are there any retail stores in the Boston area that sell them?
o and when I went to the NGK website, the only plugs they had for my car were the irridiums, they didn't show any coppers like you guys were talking about. Is that just because I have the 2.0 instead of the 2.3?
Because the NGK irridiums were listed at like $12 which is no cheaper than the BOSCH, but I'm still going to switch them since everyone here recomends the NGK. and one other thing is that the stock plugs I pulled out weren't NGk, but they were FoMoCo (I'm guessing Ford Motor Company) part number ILTR5A 13G. Does the 2.3 come with these same plugs? or does the 2.3 come with NGK's?
these are the stock plugs I pulled out . . .
Are those NGK's with Ford badging?
Last edited by shep61487; Aug 14, 2007 at 10:10 AM. Reason: just thought of another question
Tech/How-To/Northeast Mod
Joined: Feb 2006
Posts: 2,517
From: Rochester, New York
My original plugs weren't NGK, they were Denso.
Since the MZR engine is used by Fords, I'm not shocked (though I am dismayed) that you found FoMoCo plugs in your car.
I still haven't met a Mazda that didn't enjoy NGK plugs though
Tech/How-To/Northeast Mod
Joined: Feb 2006
Posts: 2,517
From: Rochester, New York
Tech/How-To/Northeast Mod
Joined: Feb 2006
Posts: 2,517
From: Rochester, New York
Hand tight = don't use the wrench, just take the spark plug socket with extensions needed to reach the plug and just twist that by hand until it stops.
Registered User
Joined: Jul 2004
Posts: 24
From: San Jose, CA
I could be an idiot, but I want to ask why are you changing your spark plugs so soon on a base Mazda 3? How many miles do you have on the car? Was it running badly before you changed them? I'm pretty sure you don't need a tune-up until about 60K mi.
Thread Starter
Registered User
Joined: Aug 2007
Posts: 23
From: Boston, MA
didn't think 25,000 miles was that early for a tune up, I was changing the oil and filter and air filter anyways, so I figured I'd do the plugs because its simple enough, that and I wanted to try out those new bosch plugs, but in retrospec, I would've gotten some NGk because thats what everyone around here seems to recommend.
Registered User
Joined: Mar 2007
Posts: 8
From: Altamonte Springs Flori-duh
Hey guys, New Poster,
Getting to the point, Usually how long does it take for the computer to completely reprogram itself? should I keep waiting for the car to clear itself up or should I start considering that I did something wrong and have the car looked at or switch the stock plugs back in . . .
Another consideration, when I was reinstalling the battery, I dropped a nut to the left and it got stuck underneath that electronics cluster and i used a rather strong magnet to pick the nut up, is there any chance that the magnet screwed with any of the electronics in that box . . .
Getting to the point, Usually how long does it take for the computer to completely reprogram itself? should I keep waiting for the car to clear itself up or should I start considering that I did something wrong and have the car looked at or switch the stock plugs back in . . .
Another consideration, when I was reinstalling the battery, I dropped a nut to the left and it got stuck underneath that electronics cluster and i used a rather strong magnet to pick the nut up, is there any chance that the magnet screwed with any of the electronics in that box . . .
I'm not familiar with the exact type of ECU (usually I work on motorcycles) but its a closed loop system so it can 'learn' your driving style and modify fuel delivery/ignition to a certain degree.
Even manufacturers programs are based on common code/pre-programed maps (OBD/OBD2)
The important thing is to get plugs with correct resistance as ECU gets a voltage feedback from 'stick' coils. (the only way to check they are working correctly is to measure primary peak voltage) If plugs had different resistance, the PPV signal will be incorrect and can cause problems.
You really didn't need to disconnect battery to change plugs, you could either leave ignition off or if your worried about screwing something up, disconnect the plug/coil assembly one at a time.
As for damaging ECU/electronics with a strong magnet, doubtful if any real damage could be done but I guess its possible to create a default setting in flash memory so could take a few miles to re-learn settings from sensor inputs.
PJ