P5 1.8 coil swap project

[danielschweer]

I happen to see this post as I logged onto the forum. I have a 626 valve cover if anyone is interested.

Just e-mail me and I can send you a pic, I tried to sell it here a few months back with no luck. I don't post much but as you can see I have been here a while.

interested, how much are you looking for?

 

[Kansei]

Too bad us turbo guys can't run them... Unless you mount the coils over the intake mani.

I think my turbo is down far enough that I could (msp manifold/turbo).. maybe. hmm maybe the wires are long enough that I could mount somewhere else. Mounting over the intake manifold would be nice as I wouldn't even have to trim the MSP engine cover to do it.

 

[Maxx Mazda]

I think my turbo is down far enough that I could (msp manifold/turbo).. maybe. hmm maybe the wires are long enough that I could mount somewhere else. Mounting over the intake manifold would be nice as I wouldn't even have to trim the MSP engine cover to do it.

It's not that you physically can't, cause it will fit physically, but the coils overheat and you get bad misfires. Trust me, I had it happen.

 

[i12drivemyMP5]

I think there was a pic back awhile where someone who had turbo had them mounted back near the throttle body somehow. I just trimmed the 2 boots on plug wires since they are covered up until I can score a 626 valve cover & do the wrinkle black with polished letters. Already have 2nd set of plug wires waiting. Here's how the trimmed MSP engine cover looks........http://www.msprotege.com/members/i12drivemyMP5/coils_1.jpg
http://www.msprotege.com/members/i12drivemyMP5/coils_2.jpg
http://www.msprotege.com/members/i12drivemyMP5/coils_3.jpg
http://www.msprotege.com/members/i12drivemyMP5/coils_4.jpg
http://www.msprotege.com/members/i12drivemyMP5/coils_5.jpg
http://www.msprotege.com/members/i12drivemyMP5/coils_6.jpg
..........SRI back in place now too. Here's a before pic with SRI.......http://www.msprotege.com/members/i12drivemyMP5/MOTOR.JPG

 

[Kansei]

It's not that you physically can't, cause it will fit physically, but the coils overheat and you get bad misfires. Trust me, I had it happen.

I doubt doubt it with the heat, but there's a difference between having a log manifold with the turbo right next to the coil pack and the msp where it's hidden way down. ah whatever I'll still buy the stuff and find a way. I hate the wasted spark system, and although this doesn't change that at all, at least all four spark plugs are attached with the same wiring. Of course I have no scientific evidence to back this up, but I just figure the plug directly attached to the coil gets a better spark than the other..

 

[njaremka]

I doubt doubt it with the heat, but there's a difference between having a log manifold with the turbo right next to the coil pack and the msp where it's hidden way down. ah whatever I'll still buy the stuff and find a way. I hate the wasted spark system, and although this doesn't change that at all, at least all four spark plugs are attached with the same wiring. Of course I have no scientific evidence to back this up, but I just figure the plug directly attached to the coil gets a better spark than the other..

it does. the check in the shop manual has different resistance values for the "coil" plug and each of the plug wires. you are at basically zero resistance to the plug directly under the coil, 6-12 ohms on the #1 lead, and 1-4 ohms on the #3 lead. i would bet with this set-up, each of the leads has close to the same resistance, for a more even fire across the cylinders.

 

[Maxx Mazda]

it does. the check in the shop manual has different resistance values for the "coil" plug and each of the plug wires. you are at basically zero resistance to the plug directly under the coil, 6-12 ohms on the #1 lead, and 1-4 ohms on the #3 lead. i would bet with this set-up, each of the leads has close to the same resistance, for a more even fire across the cylinders.

Although you're correct, you thinking is flawed. Even though 2 of the cylinders may get less spark energy, it does not effect the actual burning of what's in the cylinder. Once it's ignited, the fuel / air mix will burn the same as in all other cylinders, regardless of how strong the initial spark was.

 

[njaremka]

it just seems to me that the firing would be a little more consistant, is all. whether or not there is any benefit, i did the conversion after my stock coil took a crap, and i need repalcements any way.

 

[SilverProtege5]

Although no noticable gains from the butt dyno, the engine does run smoother and look nicer I might add.

 

[Kansei]

Yeah I don't really care if there's a noticeable different or not, I'll need new coils soon so I might as well go this route.

 

[pasadena_commut]

you are at basically zero resistance to the plug directly under the coil, 6-12 ohms on the #1 lead, and 1-4 ohms on the #3 lead. .

So? The spark plug is open = infinite resistance, until it arcs. At that point it's probably close to a dead short, but I don't know that for sure. A couple of ohms on the wires won't change the voltage at which the plug arcs. I don't know what the output voltage is on a P5 coilpack, surely it's in the thousands of volts if not tens of thousands of volts. 12 ohms of resistance in line is still going to leave plenty of current to heat up the ionized path across the plug and fire off the fuel mixture in the cylinder.

Here's a reference from model planes - the guy put huge resistors in line with the test plug and it still fired:

http://www.ultralightnews.com/enginetroublshooting/resistorcapsandplugs.htm

 

[OmegaSport20]

subbbbbin.....

 

[TreFlip999]

where can i get the colored wires i see everyone has?.

 

[njaremka]

whether or not the plug will fire isn't the key. the key is in this statement, taken from that link -

"Once the plug fires the resistance comes into being. The coil cannot get rid of its energy in the shortest possible time due to the resistance.


"This reduces current flow in the spark and it takes quite a bit longer until the energy in the coil has expelled itself via resistor and spark gap. This results in a longer spark. However the spark is weaker due to energy loss in the resistor."



based on the above statement, different resistance will cause a different spark duration, which CAN cause bad firing. the different resistances in the stock system, would cause me to believe, again based ont he above statement, that there is cause to believe the stock 2.0 liter ignition system is not an optimum set-up.

So? The spark plug is open = infinite resistance, until it arcs. At that point it's probably close to a dead short, but I don't know that for sure. A couple of ohms on the wires won't change the voltage at which the plug arcs. I don't know what the output voltage is on a P5 coilpack, surely it's in the thousands of volts if not tens of thousands of volts. 12 ohms of resistance in line is still going to leave plenty of current to heat up the ionized path across the plug and fire off the fuel mixture in the cylinder.

Here's a reference from model planes - the guy put huge resistors in line with the test plug and it still fired:

http://www.ultralightnews.com/enginetroublshooting/resistorcapsandplugs.htm

 

[njaremka]

that link did have some good reading. and after reading only that link, i am convinced that the 1.8 liter set-up is better with the stock ecu.

 

[danielschweer]

kind of on topic--- are there any year restrictions for compatibility on the 626 valve covers, i'm looking at one from a 1994, should i grab it?

 

[khaosman]

kind of on topic--- are there any year restrictions for compatibility on the 626 valve covers, i'm looking at one from a 1994, should i grab it?

You need a 99+ or something... it needs that cam position sensor bung. Pic here: http://www.mazdas247.com/forum/showpost.php?p=3015632&postcount=9

 

[Moonman8]

kind of on topic--- are there any year restrictions for compatibility on the 626 valve covers, i'm looking at one from a 1994, should i grab it?

the 94 626 valve cover will not work with 2.0L in the Pro5's. The valve cover I am using is from a 2001 626 to give you a reference. I don't think the FS-DE 2.0L goes back to 1994 but someone please correct me if I'm wrong because I know the FS-DE was used in several different cars.

 

[njaremka]

i think from my research it was somewhere around 97-98-ish on the 626 valve cover, and 99+ on the protege 1.8 cover.

 

[Kansei]

kind of on topic--- are there any year restrictions for compatibility on the 626 valve covers, i'm looking at one from a 1994, should i grab it?

Probably won't work. It has to have a hole on the left side for the cam position sensor, which the earlier ones didn't have.