[QUOTE=cruiser54;2526162]They all had coils. The early ones had distributors until they went to coil packs. Timing is adjusted by the ECT/PCM using the CPS signal as a reference.

And as far as going mega-squirt or the like, I doubt you would see much gain. A little bit with some tweaking, but not much. That's what the OP asked. Is it worth it? Nope. Not worth the effort.

 

Yes, 2000 and 2001 had coil packs and no distributor. They also had known issues for head cracking in those years.

And your talking like no one has ever tried tuning an XJ. There are folks out there running after market op systems.


I gotta say, tho, its slick the ecu can adjust timing. I always figured you rotated the distributor.

 

That's what I love about my renix. No adjustments needed.

 

coil packs. pardon my slang. every ignition system has to utilize a coil of some sort. don't be grammar policing my slang lol

fact remains the engines would gain power and mileage. the results would surprise you with wideband input and tunable timing tables. along with an adequate intake and exhaust setup.

 

yet

 

We've gone through all this on the Miatas when I had one. Similar ECU to the Renix. Little to no gain unless forced induction needed extra fuel.

 

Downgrade ftw

 

youre also comparing a 1.? liter motor to a 4L motor. not a great comparison. even if you gained the same percentage it wouldn't look like much bc they make what 95 hp?

 

yeah, and it sounds like you are comparing a "modern v8" to a decades old 4.0. great comparison there too, right? displacement is irrelevant. what motors are you familiar with? i would like to understand your background a little better. it sounds like most of your experience is with pony cars.

 

??? all I'm saying bout the jeep is the factory engine management system is not optimal and would easily be surpassed by an aftermarket setup offering more adjustment.

I've dealt with everything from na 2.3 ford to turbo 2.3 ford to sbc bbc BBQ you name it. I'm only arguing that the factory jeep eng man setup is junk and could be light years better. simmer down son

 

an engine is an engine and very few in 2001 had management systems worth mentioning.

 

Perhaps - everybody else's point is that, unlike other engines that are deliberately de-rated for fuel economy, it is very difficult to get much more out of a 4.0L. Consider the engine's history: MPFI was a huge upgrade from the carbed 4.2L. You look ANYWHERE, there are zero tangible power upgrades for a stock 4.0. Of course you could do a better job with a custom computer, wideband O2, and not having to meet emissions criteria for new model year vehicles, but it's not worth the money. If you want more power you have to get mechanical.

 

If you can do better, do it and prove you know what you're talking about. Right now you're sounding a bit pompous, like you're smarter than the engineers that designed a system that works very well for all types of situations. Put up or shut up.

 

I think that with a performance-tuned intake and exhaust and a better airbox (ram air or other forced induction), a Cherokee could see decent gains from some computer tuning, on the terms of 30-50 horsepower. Whether or not the stock ECUs can handle that much more airflow would be interesting to see. If you're going for a lot of mechanical upgrade, though, then a change in ECU might be necessary. If you're leaving everything stock, you will not see much gain by tuning an ECU. It will require upgrades on intake and exhaust.

 

You are still stuck with the poor flowing head, minimal cam and poor flowing intake manifold. It falls on its face at about 4800rpm.
Stock it has perfect AFRs and you can advance the timing 6* with a CPS mod. All said maybe 5hp with timing.
Bolt-ons CAI, TB, exhaust, and maybe 15hp.