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Completed Project My 98 super charged EX

Use this prefix for completed projects that are not "How to" articles or threads asking for help.
1998 Explorer 4.0 SOHC
Bought it with a melted alternator/wiring harness from a junkyard for $1,000
Fixed it, drove it for two weeks, then I boosted it.
Started with an M90 supercharger kit from
Upgraded to an M112 Lightning supercharger that was a prototype kit.
Next was the M122 off a 2012 GT500
I have reached 20 lbs of boost (with ARP head studs) and a 12.83 in a quarter mile.

1. How it looked when I brought it home.
2.The M90 supercharger installed
3.The GT500 supercharger installed
4.How it looks now
green ex.jpg
Lowered Rear.jpg
Exploder wheelie.jpg

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No spacers!

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i can tell you this, trying to shove a 10 inch rim in the back is going to be real tight. that and you may have to do what i did when i bought my rims and tell them they are for something else and run spacers.

What size are your rims again?
And your tires?


I found some cool looking rims made by a company called XXR.
Then I mentioned them to my students and one of them said they used them and they cracked.
Then I looked on the internet and there are many posts with cracked XXR rims.


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tires are
245/50 r20

the rims are
20x8.5 with at 42 offset, and a center bore of 72.6......and yes, i have spacers. but i dont think i will run them when i go to the track


I was thinking of maybe having the rear wheel wells rolled, and cut the plastic a little for more clearance.

The 29" tire I was suggesting is 275/55/17. The 60 series is 30" high, each series change is 5%, a 1" change in diameter. The section widths change at 10mm each, and those make a 1/2" diameter change. Those are a very close rule of thumb, within tenths of an inch.

Here's the first wheels I changed to on my Mountaineer in early 2004, stock Cobra wheels with 255/60/17's. That's a 29" tire, 30mm offset like all OEM 17x8's of the 94-04 Mustangs, and no spacers. It's a very good fit(for a 255mm tire), just a little tight inboard.

The 275mm tire would surely be too tight(10mm closer) at the ball joints, requiring a spacer. The offset for the wider tire has to get less, to move the wheel/tire outboard to match the fatter tire(section width). I'd bet you will need close to a 20mm offset wheel if it's in the 8-9" width, for a 275mm tire. So look for wheels near that, and try to find forged wheels if possible(lighter and stronger).


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my second choice of wheels would have been a touren tr70. they say they will bolt up and fit. they come in either black or silver finish and are a 18x8 and where a 35 offset, but i cant remember the hub bore



if you do a google search on them, i did find a site where they had a pic of what ever truck you had and they put the rim in the picture, but do you think i can find it now? NO!

The aftermarket 18's I've been using are 35mm offsets, they required spacers for the 265mm tires I began with on them.

Be careful with even the thinnest spacers, my 1/4" spacers would not work with the aftermarket wheels. The hubs were too thick, the studs didn't come through far enough to use the spacers. I had to have new ARP studs fitted, and that was something I wouldn't do again. So check for thread(lugnut) engagement for any wheels you try, you have to have at least 1/2" of threads.

I think the factory hub bore size is 70.3 millimeters.


I am thinking maybe spark plugs, wires, PCM, Vampire, or injectors. I don't know if it is spark or fuel injectors cutting out. The misfire only happens under heavy load so I am ruling out compression but who knows. As soon as I let off the pedal the misfire goes away. I am actually kind of happy to have something to diagnose. lol.

So today I had off, time to check out that intermittent misfire on number 6 cylinder. It only happened under load with about 15lbs of boost and around 4,000 rpms. Not so easy to verify the concern/repair.

I had replaced 2 spark plugs in my previous post and did get the other 4 in this week. Took it out for test drive and the misfire was still there. I unplugged the J&S Vampire unit and the misfire was still there. Replaced the PCM with one of two spares I got from the junkyard(I also reprogrammed them to my truck) and still had the misfire under load.

Next I unplugged the PCM and checked the resistance of the injectors and primary coil windings, at the PCM connector. All the injectors were 13.9 ohms. The 3 coil primary windings were .9 to 1 ohm. I did this at the PCM to check the harness and the components together. All that looked good.

I did a relative compression test with the WDS scan tool. Compression was good in all cylinders. Then I monitored some "pids" in datalogger like injector fault pids and some other stuff. All looked good. I then did a fuel injector flow test with the WDS, all injectors flowed around the same. The last test I did with the WDS was a spark KV test. Number six had a narrow range of fluctuation unlike the other cylinders. That usually means the spark is happening outside the cylinder. Funny it showed to be slightly unusual at Idle, there was no misfire at idle.

So I dug out my old stock ignition wires(PepBoys) and put number 6 on. Misfire under load is gone! Now I can go racing again next Friday!


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Please tell me you don't have that WDS in your garage just laying around for occasional use. I can't imagine what the cost would be .


Please tell me you don't have that WDS in your garage just laying around for occasional use. I can't imagine what the cost would be .

I have two of them, one in my garage and one in my house.
I paid about 1,000 for the first one with all the cables and docking station.

I have also took them apart and installed more ram, and instead of a hard drive they run off a memory card now. One of the docking stations had a bad power supply which are not available anymore, so I got a power supply for an older home computer and it worked except for the charging of the WDS. To get that to work I installed a laptop charger in line between the power supply and the correct terminal on the docking station motherboard. That provided the 16-18 volts needed to charge the WDS unit. I did not come up with this on my own, I searched and searched and found some info in the internet, it may have been from Europe or Australia.

I used to teach engine performance diagnostics with the WDS until the IDS came out. The WDS only works up to 2005. Now we use the IDS for everything at work. I am convinced that there is not a single Factory Scan Tool in the world that is better than the IDS, it is very user friendly. The WDS is very similar, just slow. Probably because it runs off Windows 98.

Wow! Love the process of elimination and logical progression.


Engine performance diagnostics is my favorite area of the automotive field. It took me years to learn all the systems and start to apply what I learned. Then when you think you got it mastered, they come out with new components or change the ones that were already around. lol.

I ordered new wires, I use Davis Unified Ignition(DUI) "Live Wires".
The company has a second name: Performance Distributors
I don't understand the two names thing but what ever.

I ordered the wires through Summit since they have free shipping. The price was 99.00. There is a considerable wait time according to Summit, said they would ship out in December. We will see, maybe they will ship sooner. No big deal, truck runs fine with one old carbon impregnated design wire on it.
The Live Wires are solid core spiral wound design which are supposed to provide more current to the plugs.

ASP has my box of pulleys I sent them, I will await there call to find out what they can do for my 8 Rib change over.

You'd make a great teacher I'll bet. :salute:

I look forward to what ASP responds with. Do tell them that others are very interested in the PS pulley they come up with, and a custom crank pulley. I can use the same PS one you end up with, but a crank pulley with a different center(94/95 Mustang 302).

If your plug wires are very close to any big heat sources, you might think about getting the wires from Magnecor, theirs have the best insulation, and supposedly a life time guarantee. The last I checked, they cost around $100 for the SOHC, $130+ for the 302's.

Some companies have failed to honor their guarantee, Taylor and Aurora that I've read of.

Aurora definitely doesn't stand behind their warranty. Those wires do not hold up to heat well at all.


The Magnecor's look like a good alternative to the Live Wires.
They have kits for my Explorer, in the 8.5mm size which is supposed to be good up to 1,000°F

They also have a true 10mm wire that can handle up to 1,200°F but would have to have them custom made.

I checked the website for the DUI Live Wires and they claim 1,400°F temps.
Probably just a pissing contest between the wire manufacturers.
The Live Wires have a fiber looking mesh wrap on them that has seemed to hold up pretty well, I guess it could help prevent some damage that might occur from rubbing other components in the engine compartment.

I also looked up the date of when I got these first set of wires and they are almost 2 years old. I have pulled them off many times to look at or replace the spark plugs, and other things like the ARP heads studs etc. I noticed the last time that I replaced the plugs that the number 6 wire didn't seem to click on right. Other than that I can not see any damage or reason why it would be causing my misfire. I even did a resistance test while wiggling the wire to see if it was intermittently open. No change in resistance at all. I have also used dielectric grease from the start with these wires, I have a huge tube of that stuff and use it every time.

I've had the Magnecor wires on my 98 302 since about 2005. They have maybe 50k miles on them, and I hope they will fit my 99 Explorer when I put a 302 in that with non-P heads. They look and feel well made. I only worry about the ends sticking onto plugs, or the twisting to get them to let go.

BTW, the charge going through the wires don't travel along the center core, so much as in the outer windings around that. So resistance tests rarely will show a bad wire with a minor miss. The outer part of the wires are the most critical, protection and function. I only learned that from reading the Magnecore site, and rare instances of people saying the same thing, before and since.

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