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  1. #61

    Re: TFI ignition upgrade

    The NAPA connector (as well as many other parts that come from China now) was probably mis-wired at the factory.
    '87 Comanche 4x4 lifted 5 1/2" on 33" tires 4.0L/AW4/NP242 $3500
    Perfect combination but too small to haul my Grand Kids and wife in.

  2. Re: TFI ignition upgrade

    Quote Originally Posted by CJ-7 RX-7 View Post
    This is why I don't normally respond to posts on forums, but no one else seemed to have done so for this person, so I gave it a shot. FIRST of all, I said in MY case all of this is correct.

    I checked the polarity on the new coil BEFORE I attached the new NAPA wire harness, and that is how I came to the conclusions set forth in my post.

    I have no idea as to why the wires are backwards color coded on the pigtail that NAPA sold me to go with the coil, and it still makes no sense to me!
    Probably cheap import products from discount stores.
    Used to be, you could rely on NAPA for top quality parts,
    Now they are just another 'Discount' store selling 'China' made parts...

    I also have no idea as to the use of a negative tach signal as used by GM or Howell for a triggering signal, and do not have any idea why they would use both, (I will guess that's application specific, sine the Howell kit is derived from the GM 4.3).

    I leave that up to engineers, and please take that as a bit of a joke on engineers, as if they are left to themselves, they will come up with a myriad of ways to do one thing!
    Anyway, as you stated that they since they use both, I am correct, as I stated in my post, for my application, and not incorrect, as you stated, in your reply.

    Now, I will freely admit ignorance in a lot of the how's and why's, especially with fuel injection, as I have only done two of these swaps, and am willing to take in as much information as possible, as to avoid making mistakes in the future, therefore, I have two questions:

    One: is the reason for the voltage drain if you connect a coil's wiring backwards, and cause a reverse fire in the plug, due to it grounding itself on the head, at the spark plug threads, and wasting energy? It would seem to me that it would not fire at all.
    Coils discharge in both the positive and negative plane.

    It's not hard for a 45,000 volt discharge to overpower the 12 volt ground plane for a millisecond when the polarity is backwards.

    When hooked up backwards, you get firing from center electrode to the ground electrode,

    Where 'Normal' operation is for the actual spark to start at ground electrode and discharge to the center electrode.
    (Ionization of the gap is Positive to Negative, actual spark in the gap will be Negative to Positive)

    And just like reversing polarity when welding,
    You will dig into the softer ground electrode and erode it away MUCH faster.

    When WELDERS REVERSE Polarity, they are talking about POSITIVE electrode, and NEGATIVE ground.
    They do this to keep the HEAT of the discharge out of the material being welded, and to add a lot of filler rod into the weld since the 'HEAT' is concentrated in the ELECTRODE, not the work.

    That's why we have the POSITIVE in the center of the spark plug, and the 'Ground' on the bottom, just like the 'Work' piece with welding reverse polarity.

    It's MUCH easier to produce electrically stable center electrodes (basically a round rod cut to length) than to machine a hardened 'Ground' electrode bonded to the spark plug body.

    You are also 'Shocking' the 'Ground' plane of the vehicle with high voltage POSITIVE energy,
    And those Positive spikes are hard on sensitive electronics, like ignition modules, stereos, computers, voltage regulators, ect.
    AC pulses will kill batteries, and if there isn't sufficient circuit protection in things like voltage regulators, stereos, ignition modules you will cook them too.

    Two: How in the world does it fire, if the positive energy goes to the grounding electrode on the spark plug?
    See above for polarity issues and 'Positive Voltage Spikes' in the ground system.

    Normally the voltage ionizes the gap from center electrode to ground electrode,
    Then the spark forms from ground electrode (negative) to center electrode (positive).
    (Welding 'Reverse' polarity, keeping the 'HEAT' of the discharge contained to the center electrode which is built for the abuse)

    Since you are using a DC transformer (Ignition Coil) to produce the spark voltage sufficient to ionized the gap,
    It's much like welding.

    Welding 'Straight' polarity is NEGATIVE stick,
    POSITIVE work piece so the work piece heats up before melting the electrode down.
    (NEGATIVE is 'Cooler' than the positive electrode, the work piece)

    When you reverse that polarity (By reversing input to the magnetic winding in the coil, and that produces a reversed magnetic field around the secondary windings)
    The output of the coil is REVERSED...

    You spike the 'Ground' system with a huge amount of voltage, and you conduct the plug 'Ground' through the center electrode.
    That's bad for everything on the vehicle.
    It WILL run, but it won't run for long and it won't run well...

    The 'Spark' is much 'Cooler' when reversed since the vehicle chassis and electrical system is having to soak up so much of the output of the coil (at great potential risk to those components)

    And the electrodes at the plugs were never designed to work with a 'Negative' core electrode.
    The ground electrode is MUCH HARDER, more stable material at high voltages and designed to take the voltage discharge where the ground electrode is supposed to be very cool since most of the spark energy was expended in the discharge.

    When you reverse the discharge process, it screws with the plugs something fierce, along with every other electrical component in the vehicle.

    I see that there is a lot of respect here on this forum for you, and your answers as far as I can tell are well received,

    but I think that maybe we have gotten off on the wrong foot here, and I really don't want that.

    I want none of this reply to be taken in mean spirit, as I am sure you didn't in your reply to me, but honestly your reply come off as quite condescending in my eyes, epecially with the capitalized "incorrect" as the start of the reply.

    Well wishes,

    Didn't intend to do that.

    I just wanted people to KNOW that the 'Correct' way to connect the coils is virtually ALWAYS 'Red to Red & Green to Green'...

    If I found that the 'Red' wires in my plug were connecting to the 'Ground' terminal in the coil,

    I would have simply pushed in the little retaining tabs on the terminals with a small screwdriver and reversed them instead of connecting 'Green' to 'Red' and creating confusion for the readers, anyone you show the conversion to and myself later on when the system needs maintinance, or the next owner...
    (You will be their PO! They get to complain about YOU changing things around!)

    'IMPORT' products need to be watched CLOSELY, and about everything is made in China or India in the discount stores these days.

    That is one reason I recommend getting a FORD coil, coil connector, bracket from the salvage yard.
    The salvage yard out of a Ford vehicle you KNOW it's American made and the connectors are correct.
    You also know that Ford had an issue with the TFI modules/distributors most of the E-core coils were used with,
    And they switched to a very high quality coil early on,
    So it's VERY HARD to beat the quality of the parts in the junk yard...
    And you get the entire thing, coil, connector, bracket for about $5 so it's a GREAT DEAL.

    Some guys have an aversion to 'Junk Yard' parts, but truth be told, the manufactures use very high quality parts in the vehicles so they don't have warranty comebacks... Which eat into profitability...
    You won't see manufactures using cheap bearings, U joints, seals, RTV when they should be using a proper gasket/seal, ect.

    Nothing beats stuff like TIMKEN bearings & Seals,
    Spicer U Joints,
    Moog suspension & steering products,
    Fel-Pro gaskets,
    SPS, ARP & Milodon (in that order) engine fasteners for longevity, and they fit the FIRST TIME, EVERY TIME,

    And I'd rather shell out a few more bucks to get stuff that is going to have along service life than have to do it over and over again!

    If in doubt, use FACTORY components, at least you will get a reasonable expectancy of service life and 'Correctness' for the application...

    I hate to hear stories about things like yours.
    Just shows most of the aftermarket parts are there for PROFIT rather than to help the consumer/end user get a quality piece.
    Last edited by TeamRush; 02-17-2010 at 12:12 AM.

  3. Re: TFI ignition upgrade

    Just wanted to say that I've wanted a jeep forever and finally found me an 88 wrangler 258 with automatic. I was not happy at first with the stumbling and choking under the hood but after upgrading to a weber 32/36 and doing this tfi upgrade which by the way was explained and illustrated very well. My jeep is awesome, I love the way she jumps now. I also did the nutter bypass. You guys are great, when I hit it now she squats the rear and jumps up out the hole.....thanks guys!!!!!! Chris

  4. Hi my name is Anthony and I'm new to this so forgive me. I have a 1990 jeep Cherokee that has the 4.0L I6 in it and was curious if this upgrade will work with the multi-port fuel injection?

  5. #65

    Re: TFI ignition upgrade

    I believe it will only work with the 258 carb motor. I have a 96 XJ Cherokee with a 4.0 that had a slight skip sometimes at idle. I checked into upgrades and decided to go with the "cheaper and easier apporach" first. I bought an Accell cap rotor, wires and plugs kit from 4WD Hardware. Everything I took out looked fine, even the crapy Champion plugs. Which I think may have been the problem (Allso found a cracked heater valve. Thank God in the driveway not going down the road). The skip went away and even felt a little peppier.

  6. Re: TFI ignition upgrade

    Quote Originally Posted by TeamRush View Post
    Not really true, but some people have had ignition module problems...

    There IS ALREADY an ignition resistor (resistor wire) in the power feed line to the ignition module from the factory.
    That's not the issue.

    When you open up the plug gap, that demands more voltage from the coil, and your 23+ year old modules or 'China' import modules might not be up to the job.

    Most people complain when it goes out, but they REALLY didn't think a module older than them a lot of the time was going to last forever, DID THEY?

    There are THREE easy sloutions.
    1. Is a premium module replacment from NAPA or some place reputable. (as in NOT an Import from China, Korea, South Africa, South America, ect.)

    2. For $25 you can gut the old module housing, and use the connectors to wire up a 'John Strenk Stealth HEI'.
    Since the HEI module is used to switching 12 volts without a resistor, the factory Jeep wiring w/resistor is a snap for even the discount cheap versions!
    Junk Yard 'Stealth HEI Page

    3. Replace with a 50 state legal CDI module.
    (CDI, Capacitive Discharge Ignition)
    CDI will give you 500% to 1,000% more USEABLE Spark Energy right off the bat because of how it works...

    This diagram says, 'Small Red to Painless 'Ign' wire'....
    Ignore that.
    Small red wire to Factory module 'Two Wire Connector' 'Red' wire connection,
    Or use this, (the 'Red & White' wire connector on the right is the only one you will use.)
    Summit SUM-850520 - Summit® Ford Duraspark Ignition Adapter Wiring Harnesses -
    HELP! I've got an 80 CJ7 with 258. I've seen info on the TR upgrade on several forums, and I've made the change to the distributor base/rotor/cap and wires that are the most recent recommendation. I've seen some people say I don't have to change the coil, but others say I should since it's so old and a new coil will give much better voltage. I've decided to change out the coil. I've seen recommendations to use a Blaster 2 coil (which will fit in existing coil bracket and require no wire changes, etc.) but others say something like the NAPA IC24 coil that has to be mounted on fenderwell or firewall and needs the new ignition coil connector. Is there a great advantage over the NAPA type coil over the Blaster 2 type coil?

    Also, I read in this and other forums that I may have ignition module problems with the new coil (since my module is probably 32 years old) so I'm probably doing well to go ahead and replace it. Is this highly recommended right now?

    I bought the CJ7 a week ago and have already spent nearly $500 on upgrades (MC 2100 carb/adapters/etc. as well as the elec upgrades) and my wife keeps looking at the checkbook wondering when this is going to end!

    Any insights/directions are greatly appreciated!

  7. Cool Re: TFI ignition upgrade

    Hello, I'm not sure if anyone still checks this discussion however, I read through all 4 pages of this discussion and didn't read anything regarding spark plugs, gaps yes, types no. Can I use the new stock plugs or do i need to replace with higher temp plugs? I fell in love with this thread, I can't wait to do this upgrade. Another Question. This doesn't effect Smog checks does it? i live in California and was wondering if this would bite me in the butt when it's time to pass smog....

    Thank you for your time..


    Quote Originally Posted by TerryMason View Post
    Jeep 258 TFI ignition upgrade - Using stock Ford parts, you can upgrade the ignition in your Jeep, allowing much better performance, gas milage, and reliability

    Which engines can use this upgrade
    The Jeep 258 CID I-6 from 1978 to 1990

    Why would you want to do this?
    Before I did this upgrade my jeep would not idle, it would hesitate and die all the time. This upgrade gave my Jeep the feeling of a new engine! It idles fine (even with the carter carburetor) and has more pickup and no hesitation. I would imagine that my Jeep now gets better gas mileage and has less emissions (although I have no real proof of this). Plus this upgrade only costs about $100. The upgrade is said to be better than the HEI.

    What you need:Distributor cap, rotor, base (this distributor is a two piece type, with a base that mounts to the motor and a cap that clips to the base), spark plug wires, and ignition coil. All these parts are from a 1982 Ford F-150 Pick Up Truck With A 300 CID I-6 Engine
    OPTIONAL : Distributor centrifugal advance springs, these get installed in the distributor and give you more midrange pickup.

  8. #68
    Join Date
    Dec 1999
    Virginia Beach VA

    Re: TFI ignition upgrade

    Welcome to
    It's been a while since I did this (and since I've owned a CJ), but if memory serves, I didn't buy any better / different plugs.
    As to the smog check, I don't really have an answer for you. My guess would be that the engine would be more efficient, and would have less emissions, but you'll likely have a visual check as well, and if they mechanic knows what to look for he may fail you. Luckily, this is a pretty easy thing to reverse if you do fail - just keep all the parts you swap out.
    My 2005 Wrangler Build Thread

    “He who is without oil shall throw the first rod.” -Compressions 8.7:1

  9. Re: TFI ignition upgrade

    TerryMason thank you so much for your quick response. I'm grateful... I just acquired an 88 YJ from my in-laws and I instantly fell in love with this thing.... So now I want to make sure it runs in tip top shape...

  10. Re: TFI ignition upgrade

    So I was planning on doing this and had a question about the coil. When I search for an ignition coil for an 82 ford f-150 350 I-6, this is one of the coil that comes up, ACCEL Super Stock 8140 - Ignition Coil | O'Reilly Auto Parts. I'm not sure why it looks different then your pictures.

  11. #71

    Re: TFI ignition upgrade

    Maybe this will help. I went to the junk yard and pulled all the parts off a 1989 f-250, 300 I-6. Only paid 25.00 Good luck

  12. #72

    Re: TFI ignition upgrade

    Exactly how are you adjusting timing ? I assume advancing it maybe like 8*btdc?? Somewhere around there? Also what did you have installed on the fender next to the new coil?

  13. #73

    Re: TFI ignition upgrade

    What are your recommendationsite on brand of needed parts including spark plugs,wires,coil ,cap and rotor also does it matter if I mix brands could I use a Borg Warner coil with NAPA cap and rotor and motorcraft wires?

  14. #74

    Re: TFI ignition upgrade

    What igintion module did you get ?

  15. #75
    Join Date
    Dec 1999
    Virginia Beach VA

    Re: TFI ignition upgrade

    Quote Originally Posted by Vega View Post
    Exactly how are you adjusting timing ? I assume advancing it maybe like 8*btdc?? Somewhere around there? Also what did you have installed on the fender next to the new coil?
    It's been more than 10 years since I did this writeup, so my memory is alittle foggy. I can't remember what timing I used, but somewhere around 8* should be fine.

    Quote Originally Posted by Vega View Post
    What are your recommendationsite on brand of needed parts including spark plugs,wires,coil ,cap and rotor also does it matter if I mix brands could I use a Borg Warner coil with NAPA cap and rotor and motorcraft wires?
    I don't have any recommendations. I just used whatever the local parts shop had and it worked great.

    Quote Originally Posted by Vega View Post
    What igintion module did you get ?
    KEM 342FX
    The very first post should have all the part numbers you need. Keep in mind these part numbers are 10+ years old. If in doubt just tell them you have a 1982 Ford F-150 Pick Up Truck With A 300 CID I-6 Engine and buy parts for that.
    My 2005 Wrangler Build Thread

    “He who is without oil shall throw the first rod.” -Compressions 8.7:1

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