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General Forums => The Mess Hall => Topic started by: Matt vs YJ on June 05, 2008, 09:00:59 PM

Title: Ignition upgrades for TBI 2.5L?
Post by: Matt vs YJ on June 05, 2008, 09:00:59 PM
Hey folks,

I'm new to this forum, so forgive me if this has been discussed before, but I haven't found much info through searching or the FAQ.

I'm in the process of rebuilding the engine in my '89 YJ and I'd like to do a few upgrades as well. I plan on using the Hesco RVB04 Cam, but other than that I'm not doing anything too extreme. I already have a CAI, and exhaust upgrades are in the near future.

I'd like to do something with the ignition system, if possible. Those of you that have the TBI system know that the ignition coil is kind of integrated with the ignition control module, making it a chore to find a direct replacement.

It looks like it may be possible to modify the ICM and run jumper wires to new coil, such as the MSD Blaster type coils. Has anyone had an luck with that?

I've heard that the ignition system is very similar to Ford system, so maybe there's an upgrade possibility with Ford parts.

I "accidentally" sold an MSD box that I had (left it in the trunk of my old car), and was hoping to use on the Jeep.

Any help or ideas would be great. Again, this is referring to the TBI system, which is quite different from the MPFI systems that have the ignition control in the PCM.

Thanks, Matt
Title: Re: Ignition upgrades for TBI 2.5L?
Post by: Mr_Random on June 06, 2008, 02:14:22 AM
It IS different???

OH crap... gotta plan some more (and spend more money) now... I'm starting (late planning, early gathering) my MPI swap.

Well, thanks for warning me about that (without actually meaning to!).

Can you specify what is different between the two?

Sorry I hijacked and didn't help...
Title: Re: Ignition upgrades for TBI 2.5L?
Post by: Matt vs YJ on June 06, 2008, 07:50:23 AM
Can you specify what is different between the two?


Seems like just about everything is different:

The engine harness, dash harness, gauges, alternator, PS pump, Intake manifold, fuel pump (in-tank), water pump, valve cover, vibration damper...

You can see why I decided to keep the TBI. Besides, I just finished spending a bunch of money getting it running right before a piston blew, so I'd be wasting the money I spent on sensors if I switched to MPFI. I'd rather just buy a newer Jeep, instead of doing a swap...

Prior to the upgrades (rebuild), I was fairly satisfied with the power. So, while I'm in there I'm just gonna do a few simple upgrades to make it run better and smoother.
Title: Re: Ignition upgrades for TBI 2.5L?
Post by: Mr_Random on June 06, 2008, 12:52:07 PM
Seems like just about everything is different:

The engine harness, dash harness, gauges, alternator, PS pump, Intake manifold, fuel pump (in-tank), water pump, valve cover, vibration damper...

You can see why I decided to keep the TBI. Besides, I just finished spending a bunch of money getting it running right before a piston blew, so I'd be wasting the money I spent on sensors if I switched to MPFI. I'd rather just buy a newer Jeep, instead of doing a swap...

Prior to the upgrades (rebuild), I was fairly satisfied with the power. So, while I'm in there I'm just gonna do a few simple upgrades to make it run better and smoother.

Woo, makes this project more fun! My 86 XJ has too many one-off parts in the engine bay, replacing everything is NOT cost effective for me. I could get strictly junkyard or used parts, but even then, I could do better by getting used newer parts!

I'm glad most of these things are cheap... I'll continue researching... after work, gotta make the money to make everything work!
Title: Re: Ignition upgrades for TBI 2.5L?
Post by: Matt vs YJ on June 07, 2008, 09:21:09 PM
Any other ideas for TBI ignition upgrades? I'm sure there's gotta be someone else that decided to stick with this system.
Title: Re: Ignition upgrades for TBI 2.5L?
Post by: Mr_Random on June 08, 2008, 09:37:15 AM
Any other ideas for TBI ignition upgrades? I'm sure there's gotta be someone else that decided to stick with this system.

There are quite a few (people) out there, but I haven't heard of any TBI ignition upgrades. Do you know how it is specifically different from the MPI systems?

There ARE all those MSD/other brand ignition upgrades and stuff, but I thought they also applied to the TBI ignition...

I don't know, good luck though! I'll try to help in any way...
Title: Re: Ignition upgrades for TBI 2.5L?
Post by: chardrc on June 08, 2008, 06:32:33 PM
i have the tbi 2.5l but i haven't done any ignition upgrades yet... unless you count putting new cap, rotor, wires, and plugs in (all of the "middle grade" aka like stock at the parts store)which helped alot since i found that the previous owner had the wrong spark plugs in it :brick:
Title: Re: Ignition upgrades for TBI 2.5L?
Post by: Matt vs YJ on June 08, 2008, 09:16:11 PM
Yeah, I've done all the standard replacement stuff last fall. It made a little difference, and Champion Truck plugs seemed to work a little better too. What I'd really like to do is get a high energy coil so I can gap the plugs a little wider.
Title: Re: Ignition upgrades for TBI 2.5L?
Post by: chardrc on June 09, 2008, 05:11:30 PM
yjmechanic used to have a tbi 2.5l and was the guy to ask about the tbi system. he was even making his own throttle body spacer. but then he sold his jeep for a mpi 2.5l jeep... and he hasn't been as active since.. that i notice at least. maybe if you / we could contact him e may have done something with the ignition coil and what not.
Title: Re: Ignition upgrades for TBI 2.5L?
Post by: chardrc on June 10, 2008, 05:31:28 PM
yjmechanic used to have a tbi 2.5l and was the guy to ask about the tbi system. he was even making his own throttle body spacer. but then he sold his jeep for a mpi 2.5l jeep... and he hasn't been as active since.. that i notice at least. maybe if you / we could contact him e may have done something with the ignition coil and what not.

my bad it was Guardian7 not yjmechanic....
Title: Re: Ignition upgrades for TBI 2.5L?
Post by: Castr8r on July 12, 2008, 10:39:43 PM
FWIW...   I'm running a Blaster coil and really can't tell much difference from the stock coil.  My experience has been that Champion plugs are consistently better to use in AMC/Chtysler products.  With the stock coil, I could open up the gap to .040" with no problem; with the Blaster coil, I could probably go more but I don't think there would be much gain.  I mounted my Blaster on a home made bracket on the fender where the distributer wire would reach with plenty of slack.  The stock coil is energized thru spring clips that contact the  stock coil when it is put in place.  I used some standard push on connectors I had from a previous project to slide over the spring clips, and ran a pair of wires to the coil.  To keep it neat, I wire tied them to the radiator brace, leaving a little bit of slack "just in case."   Hope this helps.
Title: Re: Ignition upgrades for TBI 2.5L?
Post by: Matt vs YJ on July 13, 2008, 05:10:46 PM
FWIW...   I'm running a Blaster coil and really can't tell much difference from the stock coil.  My experience has been that Champion plugs are consistently better to use in AMC/Chtysler products.  With the stock coil, I could open up the gap to .040" with no problem; with the Blaster coil, I could probably go more but I don't think there would be much gain.  I mounted my Blaster on a home made bracket on the fender where the distributer wire would reach with plenty of slack.  The stock coil is energized thru spring clips that contact the  stock coil when it is put in place.  I used some standard push on connectors I had from a previous project to slide over the spring clips, and ran a pair of wires to the coil.  To keep it neat, I wire tied them to the radiator brace, leaving a little bit of slack "just in case."   Hope this helps.

Great info! That's just about exactly what I had in mind. I have a Blaster coil laying around somewhere, but it sounds like it may not be worth the trouble.

However, I'm gonna be getting that MSD box (6AL) back from the guy I "gave" it to. It turns out that they make a wiring harness to plug into the stock TBI module/coil. Maybe the box combined with the coil will make a difference. I know it helped an old Ford 302 I had a few years ago.
Title: Re: Ignition upgrades for TBI 2.5L?
Post by: Castr8r on July 15, 2008, 03:39:12 PM
Matt - let us know how it works out.  I have an old Jacobs Ign. set up for an AMC V-8 that I've thought about piddling around with.  I like the idea of multiple sparks at low rpms; it worked on a Javelin I had.  Just a hotter coil by itself doesn't seem to help much, in my opinion, but adding the multi-spark ability should make a noticable difference.

Brakes woek best when the wheels are in contact with the ground...
Title: Re: Ignition upgrades for TBI 2.5L?
Post by: Matt vs YJ on July 19, 2008, 10:52:26 PM
Just a quick update before I head to the beach for a week of relaxing and cruising in the Jeep  :biggrin:

I haven't got the box yet, but I did go ahead and wire up a brand new Blaster 3 coil and gapped the plugs to .045. As Castr8r said, it didn't make much of a difference, but it may have a little more power in the lower RPM range. I hope the box will help a little more. I'm actually hoping to improve my gas mileage, but more power is ok too.

I was testing out the 4wd (stupid vaccum disconnect :fitz:) on a gravel road last night and in 4Lo my brakes actually couldn't hold it still while idling in 1st gear. I think that's partly due to the inertia ring allowing it to run down under 300 rpm without stalling, but I feel that the ignition had something to do with it too.
Title: Re: Ignition upgrades for TBI 2.5L?
Post by: pioneer4x4 on November 13, 2008, 03:41:54 PM
any updates on the ignition set up for the TBI set up, I also have the tbi and want to upgrade ignition. who makes the wiring harness for the coil? MSD? is the harness for the coil or the box? never been exposed to multiple spark boxes before.
Title: Re: Ignition upgrades for TBI 2.5L?
Post by: Matt vs YJ on November 14, 2008, 07:10:45 PM
Wow, it's been a while, but I was just thinking of updating this the other day.

A while back I did install the MSD 6-AL ignition box, and it ran great. No pinging of any kind and it ran smoother on the highway and idled a little quieter. I didn't notice any improvement in mileage, but...

...the box died on me after about a week. I'll probably replace it with the MSD 5 box, since I don't really need the rev limiter and everything that's included with the 6 series.

Hookup is fairly simple, you don't need to buy any harness (though MSD does make one, PN 8813). Just remove the stock coil from the ignition module and use spade terminals to connect to the MSD box to the ignition module. You WILL need the tach adapter (PN 8910) if you want your stock tach to work. I used the Blaster 3 coil and made a bracket to mount it to the side of the battery tray.

Link to harness---> http://www.jegs.com/i/MSD/121/8813/10002/-1
Link to tach adapter---> http://www.jegs.com/i/MSD/121/8910/10002/-1
Link to Blaster coil---> http://www.jegs.com/i/MSD/121/8223/10002/-1
Title: Re: Ignition upgrades for TBI 2.5L?
Post by: pioneer4x4 on November 18, 2008, 06:54:49 AM
thanks for the reply, i have one more question, as for the blaster coil, does that replace the original coil or is it used in conjunction, read post that said you tap into original from the spring type contacts on bottom of original coil, but i dont see how both can be used since the distributer wire can only go to one coil, the blaster or the stock? sounds like you just remove the stock coil and leave it off, but could you leave in on just incase you get stranded and need to go back to stock set up, or just put it in glove box,and do some swaping when/if time comes? do you have a pick so i can visualize it?
Title: Re: Ignition upgrades for TBI 2.5L?
Post by: Matt vs YJ on November 24, 2008, 06:19:44 AM
Yes, you do have to remove the stock coil. I just threw it into my toolbox as a spare. Like you said, it only takes 2 minutes to change it back to stock if you ever have any problems.

Sorry, I don't think I have any pics.