Semi-complicated ECU question.

[Geonovast]

Do the chrystler ECUs having any sort of battery in them so they remember adustments they've had to make to their settings? This problem with my 2.5 is not making any sense. Fuel pressure would explain it if it did it all the time, or just randomly. Since that's not the case, and it's only as soon as it warms up or after starting it back up when it's warm(gas stop, etc.), and it only does it for a few minutes.

 

I have changed TPS, IAC(TB swap), cap, rotor, wires. Changing plugs and fuel filter tomorrow.

 

The biggest thing that's sticking out in my mind is that the computer simply has to relearn the motor every time it warms up.

 

I was thinking if the ECU has something like a CMOS battery in computers that I could replace and avoid finding a working ECU.

[Geonovast]

Do the chrystler ECUs having any sort of battery in them so they remember adustments they've had to make to their settings? This problem with my 2.5 is not making any sense. Fuel pressure would explain it if it did it all the time, or just randomly. Since that's not the case, and it's only as soon as it warms up or after starting it back up when it's warm(gas stop, etc.), and it only does it for a few minutes.

 

I have changed TPS, IAC(TB swap), cap, rotor, wires. Changing plugs and fuel filter tomorrow.

 

The biggest thing that's sticking out in my mind is that the computer simply has to relearn the motor every time it warms up.

 

I was thinking if the ECU has something like a CMOS battery in computers that I could replace and avoid finding a working ECU.

[BLHTAZ]

Nope...no memory or battery. It is simply an ECU that does it's pre-programmed job on every start up.

[BLHTAZ]

Nope...no memory or battery. It is simply an ECU that does it's pre-programmed job on every start up.

[Eagle]

What year is your 2.5L?

 

If it's a Chrysler ECU, it does "learn" from driving, but it uses the vehicle battery to store what it learns. Some people plug a 9-volt transistor battery into the cigar lighter to hold that data when the vehicle battery is disconnected.

 

The Renix ECU does not "learn." Every start is a cold boot from the default settings.

[Eagle]

What year is your 2.5L?

 

If it's a Chrysler ECU, it does "learn" from driving, but it uses the vehicle battery to store what it learns. Some people plug a 9-volt transistor battery into the cigar lighter to hold that data when the vehicle battery is disconnected.

 

The Renix ECU does not "learn." Every start is a cold boot from the default settings.

[Geonovast]

91, so Chrystler.

[Geonovast]

91, so Chrystler.

[BLHTAZ]

damnitman... I keep skipping over that fact that it's a 2.5L ... sorry ... :oops:

[BLHTAZ]

damnitman... I keep skipping over that fact that it's a 2.5L ... sorry ... :oops:

[Geonovast]

damnitman... I keep skipping over that fact that it's a 2.5L ... sorry ... :oops:

 

lol...well, I had an extra ECU sitting around (the extra that came with that 93 XJ that was sittin here for awhile) and I'd thrown it in, but it wouldn't run with it. Either it's dead, or for a 4.0. There's no stickers on it, and since the Chrystler 4.0 and 2.5 ECUs use the SAME DAMN CASE, the only way I would know is to throw it in the 4.0. The original ECU from that truck is on it's way, but unfortunatly I don't think that's the problem anymore.

 

If you forget again... just look down a few pixels..

 

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[Geonovast]

What year is your 2.5L?

 

If it's a Chrysler ECU, it does "learn" from driving, but it uses the vehicle battery to store what it learns. Some people plug a 9-volt transistor battery into the cigar lighter to hold that data when the vehicle battery is disconnected.

 

The Renix ECU does not "learn." Every start is a cold boot from the default settings.

 

I don't know if what it's doing is similar... but I have an aftermarket cruise system that gets its power from the main power wire under the dash.

 

Everytime the truck would be shut off, once started and warmed up it would miss, act like it was learning.(Even tried shutting it off while driving, then immediatly started again and it did it.)

 

However, if I leave the cruise power on, even if not activated, and I shut the truck off, once I get going again it doesn't miss at all. I still get horrible mileage, but it remembers what its doing. This really tells me the ECU or one of the few sensors I haven't changed yet is shot.

[Eagle]

It shouldn't miss, skip, buck, belch or backfire even when "learning." Learning only fine tunes the operation. If you disconnect the battery (say, to replace the battery) the ECU loses its stored "learned" parameters, but it reverts to the factory-coded operating parameters and the vehicle should run fine based on those settings while it adjusts to your driving style and location.