Decemberist

CRLAMBERTJR

I'm getting ready to replace my OEMs. Just bought a set of 4-holes. I'd take $50 for my old ones and pay the shipping. They work fine, just upgrading.But have to wait for mine to get here. LMK, pm me if you're interested. CURT

Cummins93

Did you reset the fuel trims?

jessenator

^^^^^^ This.

If you don't do the Jeep ECM reset key and light dance, the trims are going to cause some rough running, because its' essentially pumping more fuel, richening up the mixture. Jeep ECMs do not adjust trims on the fly like more modern vehicles do.

How's your MPG? That's another indication that your trims need to be reset.

4WD4EVER

X3

Near the end of the article is the "Resetting the PCM" section:

https://www.google.com/amp/s/thexjgu...ctor-swap/amp/

There may be nothing faulty with the injectors you purchased. As a matter of fact, they may turn out to be one of the most practical upgrades you'll make.

Let us know how it goes.

Ralph77

Jeep ECM reset key and light dance. That is a funny way to put it. I do it anytime I make a major change. But could somebody explain why I am turning my headlights on and off? That is one thing that I could never understand.

SteveMongr

Turning on headlights with battery disconnected will drain any remaining charge left in systems,components, capacitors.
Resetting the computer places fuel trims back to the factory base-line. From there the computer 'learns' what adjustments to make. A lot of what it learns comes from how it is driven during this process.

Tbone289

The headlight on-and-off thing is actually a good idea for resetting other makes too. It reduces waiting time for charges to drain.

EDIT: But, that's on-and-off with the battery disconnected.

Ralph77

Now that I get.

Tbone289

Right, actually that's what I meant as well. I have no idea what turning them on/off after reconnecting the battery does, unless the PCM recognizes this as some sort of reset signal.

jessenator

I too thought it was a signal to initiate a reset on the computer.

So if it's just voltage dropping out to reset the volatile memory on the ecu, I wonder: if my xj had sat for almost 4 years, the last of which with no battery charge left according to the PO, could I just fire it up and be good to go?

Cummins93

Possibly, my 99 with 4 hole injectors ran terribly after a dead battery for about 2 minutes. 3 attempts to start.

Greenz

Just upgraded to 4 hole a couple of weeks ago. Reset ECM and it ran rough for a few minutes. It even set a code. Thought I made a mistake too. Then it slowly smoothed out. Now it runs great. Better than when I bought it with 40k miles on the clock.

Tbone289

Is there an easy way to confirm that the reset has occurred with an OBD-II reader?

The reason I ask is that I've reset mine a couple of times in the past year--once when I cleaned up throttle body/IAC, etc and once when I upgraded from OEM to 784 injectors. Neither time could I really tell any difference at initial startup or idle. Granted, it ran fine before each event, but it would just be nice to know if the reset was successful.