Timing advance/retard, crank sensor, fuel injector pulse

[dbrant]

Hello everyone i just have a quick question for people who have knowledge on this subject. I am trying to change the timing in my 1996 jeep cherokee 4.0 ive read online that moving the distributor does not effect the timing, but slotting the crankshaft sensor can advance it or retard it by about 6 degrees. is this true? and if i adjust the crankshaft sensor would that change when the fuel injectors pulsed as well as the ignition timing? or does it only effect the ignition timing?
Thank for any help and knowledge

 

[SlowXj]

I believe hptuners now has xj tuning avaliable. I would look there

Sent from my SM-A426U using Tapatalk

 

[RCP Phx]

The "Ignition firing timing" is done by the ECU in the programmed "mapping". The CkPS and the CmPS only reports the "physical" timing of the motor and they have a small percentage of tolerance that has little impact on the over-all function. I don't believe you can do much tuning on the '96 ECU, I had my 2000 computer re-mapped but it a JTEC II +.

 

[RCP Phx]

Btw, what are you wanting to accomplish? "Tuner Chris" is located in Cali and would be your best contact for info on what can be done on your year. He goes by "hexdmy" on this board.

 

[Cummins90]

Advancing the CPS does add some power but you will need to run at least midgrade possibly premium if you experience any knock.

The 96 and up ecu can be re mapped to achieve a timing bump as well. It can even be tuned for forced induction.

 

[dbrant]

Thanks for the replys everyone.
So i have a sidemounted supercharger on it running about 10-11 psi, 36lb injectors with a fuel timing calibrator but that only does timing retard under the certain condition that you tune it too. i also have a MSD 6al-2 but that doesnt seem to have a timing advance on it unless some of you know how to do it on there, maybe im missing something on it. just trying to figure out a way to advance it with what i have because i dont want to have to buy another thing like hptuners in order to do it, unless i absolutely have to.
Im already running 91 octane with the lucas octane booster dumped in it.

the problem that im having is when i floor it it seems to be backfiring, seems do be popping out the exhaust and not into the intake. Ive been told by a couple people and read online that most likely i need to change the timing on it. But it only does it when i floor it. when i let the engine slowly rise to 4.5k rpm everything seems fine and it doesnt backfire. do you guys think when i floor it and putting more pressure/heat into the cylinders it could be pinging thats causing the backfiring that im having, since if i slowly letting the rpm rise it runs amazing.

 

[Cummins90]

Install a wideband sensor. Boost and timing advance are not something you want to do. You can advance the timing in the 1bar section of the map just shy of the transition zone. I wouldnt do anything with the timing or run the engine above 1 bar until you check your AFR on the WB.

 

[dbrant]

i do have a wideband afr sensor installed, first start up its around 11.5-12.5 at idle, then when it gets warmer it runs at 14.7 at idle, and when i get it running and press the gas itll drop to about 10-11. havent payed attention to it when i floor it and get the backfire sound. ill test it out today and let yall know my results.

 

[RCP Phx]

I'm surprised your 6-AL doesn't have any timing control, my Dis-4 has all kind of controls built-in!

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[dbrant]

so today i was flooring it and the afr was around 10.5-11. and also i decided to take off my msd from my ignition and turns out that was my problem. sending back the msd for a new one since its not working as its supposed too. thanks everyone for the replys, i will definitely keep everyones comments in my thoughts for future upgrades on the jeep