Sorry for the newb question. I've been doing some reading, but haven't seen much on the comment of actual benefits of the SCT tuner.

I have two rigs: 98 Wrangler TJ with a 96 5.9/46RE in it (running a 98 PCM) and a 98 Ram 5.2/NV3500, both stock engines.

The TJ was a fresh rebuild, .030 over, and has been getting 10mpg since I put it in. Power was underwhelming, to me at least. I'll be getting center dump block huggers for it to reroute the exhaust sometime. The trans will not shift up at WOT, unless I back off the throttle a bit.

The Ram has 160k on it, but runs strong, plenum doesn't seem to have any oil in it. I'll be DDing this and using it a couple times a year to tow the Jeep.

Question is: What sort of difference will an SCT tuner make on either of these vehicles? More power? Better MPG? Both?

Thanks!

 

As long as both have the plenum fixed, fresh tune ups, and a 180 T-Stat, you will notice quite a bit more power, the trans will shift better, your rev limiter will be extended to 5100, and you will get better mileage if you can try to keep your foot out of it with the new found power.

 

these are MY experiences, fwiw..

the SCT got rid of the death flash, while coupled with the plenum gasket repair/plate swap should have brought me back up to factory HP/TQ (245/335ish).. that is good.. I noticed this greatly...

the differences in the 'canned' tunes (87, 91, 93), that I can see are this: The 87 tune isn't worth it... I like the power available in the other two so much I don't even use the 87, though I tried it out for a couple days.. The 93 is too rich and thirsty for me.. the 91 gives me more power, and good economy in a balance between the two... I only run 93 gas btw, no matter what tune I'm using..

the power/performance increases are noticeable with the tuner, but they aren't going to set the world on fire- don't build yourself up for a letdown there.. but they are likely good enough that you will be happy with the purchase.. I'll tell you where the SCT shines though- that is the removal of the PCM torque management feature..

TM feature does all kinds of things to the relationship between your tranny and engine.. it's purpose was to increase longevity of the tranny, due to it's weaker parts and pieces.. the removal of torque management feature, to me, was as great if not better than the engine tune.. I didn't realize how bad I hated that thing until it was gone..

the SCT is rated second on my list of mods done.. I can only imagine (and drool) about a custom PCM build/program.. I was amazed at how much it helped a death flashed engine in fuel (likely upwards of 1.5mpg) and HP/TQ (maybe 5% according to my levi's dyno)..

 

its worth it, these things are detuned to begin with from the factory, sct lets the true power out

 

Good to know. I didn't want to spend the money on that first if it's barely noticeable with a stock engine.

One more: Will having the 91 or 93 (we don't have 93 here) tune affect passing DEQ (emissions testing)? Will I have to revert back to the 87 tune?

 

It will take you about a minute flat to replace any of the SCT tunes with your original tune. The device stores your factory tune. If you're passing an emissions test now, you will then too- if you don't its not because of the tune.

The tuner will be locked to one engine/truck. If you're needing a tune for both, you'll be needing two. You'll end up with two though. :-)

 

The 93 Tune added quite a bit to my truck. It made the truck a lot more responsive. I was amazed at how well it did after the 93 tune was installed. The rev limiter being at 5100 RPM will freak you out the first time it goes into the red, but don't worry about it.

 

Can't comment on the SCT, but this is normal, especially after a rebuild. My 46RE(tarted) does this too. I've gotten used to it.

I've heard this is a safety mechanism for the torque converter.

 

well my experience is that good gas helps the right power to light the fuel and tuner to get that extra jump but fresh air.but a tuner is the best to go