bzauche

Hey all,

Quick question. I am planning on doing several upgrades in the next few weeks, in order to hopefully gain back a few MPG's (and maybe a little power too), that I will be able to take advantage of for the whole summer. I am planning:

Cowl Air Intake
Bored Throttle Body
784 Injectors
Replace all 4 o2 sensors (don't have record of them ever being changed)

Would it be best to do all of these the same day, so the computer only has to re-learn its fuel settings once?

Also, what is the best way to reset the ECU?

BeaglesXJ

You could do all of the work the same day. It wont hurt the engine. As for resetting the computer I just take the leads off the battery and leave them off for a little bit.

jeff2285

you cant reset on OBD2 computer that way you will have to bring it to the dealer.

ehracing67

Check this out; http://www.quadratec.com/jeep_knowle...article-89.htm

It works. I use it every time.

bzauche

Thanks for the responses everyone! I guess I'll try to do all the work the same day if money allows, then reset the ECU once and for all.

macgyver35

I've always been confused on this issue.

First, there seem to be about 6 different ways to reset your computer posted here and there with no clear info on what really works for which year models.

Second, I though the entire point of modern computerized engine management was that the computer would automatically adjust on-the-fly based on input from various sensors while in closed loop mode. That way, as things change (air/fuel filters get dirtier, fuel octane changes, atmospheric pressure and oxygen content change due to altitude, etc) it automatically compensates. Seems to me if it has the ability to adapt, and the sensors report back accurate info (O2 levels, etc.) there is no point in erasing everything. If I change or clean my injectors, the computer will "know" pretty quickly based on feedback from the O2 sensors and adjust the pulse width. I mean, I don't have to forget how to write just to switch from a pencil to a pen.

If anyone can enlighten me I'd appreciate it.

hankthetank

I think you're right. All obd2 ecu's have a base map/table. It always references those tables while its running. When a sensor malfunctions, you notice it because its out of the ecu's range to compensate for...then the idiot light comes on.

TheJerm

The computer does record and monitor how the vehicle is driven, like where the shift points should be and the like. So if your always full throttle everywhere it will be more prone to dump more fuel in on given throttle input and hold shifts longer. The base fuel maps are used till the o2 sensor heats up and vehicle goes to open loop, generally in 10-20 seconds or so. Resetting the computer will just erase what the computer expects how the motor runs and what you to drive like. Then it runs on closed loop till it figures out what is going on then adjusts.

Ive noticed with mine for a while after wheeling it sucks more fuel and mileage dips, but as i baby it the mileage will improve. Then again I have OBD1. Both OBD's are similar, just OBD2 in universal for all vehicles so inspection stations and auto stores can read the computer easily.