tfi upgrade

[jeep90]

just installed the tfi upgrade, very impressed!!! dont think my jeep has ever seen 4000 rpm. nor 90 mph. my only question is since i advanced the timing it runs much better and more power, but am i gonna hurt my engine. someone said advance it as ffar as you can without detonation. how do i know if it is detonating? other than that i love it, and i would like to advance the timing more but how far can i go? its probably at like 13 btdc now. but i didnt hook my timing light up to it yet. any help would be appreciated.

p.s. should i go with the nutter bypass now? how much difference would that make
thanks in advance

 

[84_CJ7]

MY CJ w/258 and the TFI upgrade is running at 13 BTC@1600 RPM. You'll know that you have advanced too far when it starts "pinging" on acceleration. Just keep moving it a little at a time - when it starts to ping back it off a hair. Then you can check your timing and see where you are.
I would advise doing the Nutter bypass as well. Do a "Nutter bypass" search of the postings, I submitted a post a couple weeks back explaining how I kept and used the factory plug at the ignition module.

Scott

 

[jeep90]

thanks bro, but ever since this upgrade i cant search anything. i would really like to know how to keep the factory plug though.

 

[jeep90]

the message board upgrade not the tfi

 

[84_CJ7]

Found a copy of it -

I finally did the Nutter Bypass. I had already converted to the TFI upgrade, removed emissions and installed a Weber so the ECM wasn't doing anything. For me it only involved making the disconnect of the orange and purple wires at the ECM and routing directly to the ignition module. The problem that I encountered was a plug at the module that omitted the purple wire. I did not want to cut off the connector and run 4 spade connectors to the module so I solved my problem this way.
(Note: When I say module connector I do not mean the connector at the end of the ignition module, I am referring to the connector that it plugs into - part of the wiring harness.)
I spliced my orange and purple wires near the ECM where I had cut them and ran new orange and purple wires to the connector for the module. I cut the orange wire at the module connector and spiced the new orange wire there. Now if you look at the connector it has a spot for the purple wire but nothing is there. I took a small screwdriver and worked my way through the connector to where the spade should be. I then took a larger screwdriver and worked it through from front to back. Then I used the screwdriver to keep an opening in the connector as I worked the purple wire through. Once the purple wire was through I put a spade connector on the end and forced it back down into the module connector. Put some dielectric grease on it, plugged it into the module and it's like a factory connection. So if I have to change the module out its one plug and no big deal - keeps it clean, too.
Others may have done the same thing but I have never seen it mentioned. Thought I would share tip that has worked out well for me.

 

[jay79cj7]

I just tried to search about this topic last night, but I couldn't get the search function to work... Excuse my ignorance, but why do you need to adjust the timing when you do this upgrade? I have been thinking about trying it this summer, and want to learn a little more about it.

 

[84_CJ7]

I just tried to search about this topic last night, but I couldn't get the search function to work... Excuse my ignorance, but why do you need to adjust the timing when you do this upgrade? I have been thinking about trying it this summer, and want to learn a little more about it.

It's not so much that you "need" to adjust the timing but with the gain of a hotter spark after the upgrade you are "able" to advance the timing, giving you more power and higher RPMs.

Scott

 

[jay79cj7]

So I can get better performance through advancing the timing... Does this have any negative effect, such as putting more wear on the engine? Is there any benefit to doing this mod and not changing the timing?

 

[84_CJ7]

A "hotter" spark can begin the combustion sooner by advancing the timing, and then burning throughout the piston stroke giving you more power.
Because your spark is hotter you can burn sooner and LONGER.
No additional wear on the engine - it should actually run better - cleaner.
Gas mileage should improve since you are getting more power transferred from every stroke of your engine.
You can still see gains from the upgrade without advancing the timing but by not taking advantage of the upgrade you're cutting yourself short. It's similar to having a 4WD that is always kept in 2WD. Why bother having a 4WD if you're not going to use it? The same with this upgrade; if you're not going to take advantage of it why go through the trouble?
Food for thought.

Scott

 

[jay79cj7]

Thanks, but I still don't understand the reason for advancing the timing... I think that the spark fires before TDC so that the max pressure of combustion occurs during the downstroke. So, a "hotter" spark seems like it would get the combustion going faster, so why give the spark a bigger head start? I know you are right, but it seems opposite. Want to give a newbie a lesson?

 

[84_CJ7]

Thanks, but I still don't understand the reason for advancing the timing... I think that the spark fires before TDC so that the max pressure of combustion occurs during the downstroke. So, a "hotter" spark seems like it would get the combustion going faster, so why give the spark a bigger head start? I know you are right, but it seems opposite. Want to give a newbie a lesson?

A lot of the older stock ignition systems did not deliver enough spark to use the entire stroke. With a hotter spark you can take advantage of the FULL stroke by advancing the timing. If you advance too far you lose power through predetonation (ping). When you retard the ignition you are compressing the amount of stroke you are able to use. Retarding the ignition decreases power. The trick is to advance your timing until it "almost" pings at accelleration (like the top end of third gear before you shift). This gives you the most power by utilizing the full stroke, and if correct, gives you the most vacuum. Hope this helps. Maybe someone else could jump in and help you understand more - if necessary.

Scott

 

[jay79cj7]

That makes sense now. Thanks!