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Swap Engine computer?

jimmydaux

jimmydaux

NAXJA Forum User
Location
Centerville, Utah
Would there be any benefit in replacing my 1998 212k computer with a 1998 79k computer? Mine seems to be working fine, but would a newer one be a refresher? Im not sure that they "wear out", hence the question ;)
 
Nope. No moving parts on the CPU boards.

Now I'm new to jeeps so there might be some trick I don't know about.
 
Be sure and replace the old air in your tires also. You can be sure that air is tired and needs to be refreshed.
 
Tim_MN said:
Be sure and replace the old air in your tires also. You can be sure that air is tired and needs to be refreshed.
Click to expand...

LOL! :roll:

Seriously, are you just asking for the asking or is there an underlying question, like a lack of performance?
 
I already replaced the old air. It was a bit too firm for my taste.

I have stutter that happens after maybe 10 seconds driving from a cold start. It hesitates real bad unless I floor it then it jumps back to life. It will also happen after sitting at idle for a while. I get a check engine light and it tells me o2 sensor high voltage but the sensor has been replaced several times, all with the same result. I just put in a new engine and used most of the sensors from that jeep but the problem still remains. The sensors that werent changed were the IAT coolant temp sensor and both o2 sensors. I used the newer throttle body with all attaches sensors as well as the newer fuel rail and injectors. Coil and distributor also came from the newer jeep. I cant figure out what this hesitation is, and im puzzled since it persists even with so many things replaced yesterday. I am going to try again for 02 sensor swaps and also change the IAT sensor and the Coolant sensor. I was thinking that the problem could have originated from the computer, which was why I was contemplating the swap.
 
You may have the dribbles, as in a leaky injector that lets fuel leak into the intake (presents at cold startup) and at low RPM times (presents at idle).

Same injectors as on the old engine?
 
Nice job on the swap.

What code number? GOOGLE that code number for some ideas. With an engine swap, I'd suspect wiring. The oxygen sensor isn't even in play 10 seconds after a cold start; default fuel/air mixture is used.

What is the status of tuneup hardware? Plugs, wires, cap, rotor? Basic stuff but you don't want to chase your tail because of a worn component.

Checking fuel pressure and testing your throttle position sensor would also be on the list along with injectors....
 
No this is the newer set of injectors now. I also had the problem with the old set and a set of tl1's. So 3 sets with the same problem. The tune up stuff should be primo and I had the same issues before the most recent change. Accell cap, rotor and wires are less than 6 months old, champion truck plugs at about a year or 8000k miles. I figured the o2 sensors didnt play into it that early, but thats what the checker code reader was telling me the problem was. Ill try to get the code pulled as soon as I get a chance. Anything else that could cause those problems?
 
Well, the IAC--idle air controller stepper motor handles the engine idle speed as well as taking care of what was the transition circuit in carbs--moving from idle to an open throttle.

New TB with sensors--did that include the IAC? If so, you may need to check the ohms in the harness between the IAC and the PCM, as that would be the only thing left as a carryover.

A flat spot in the TPS is also a possibility, but I think you said you changed that along with the TB, so that dumps me back to suspecting the harness.
 
jimmydaux said:
Ive had 3 different IAC's on there, 3 different map sensors, and 4 different TPS's. Guess ohm check is in order.
Click to expand...

That is the only thing I can think of that you haven't already covered/replaced.

Post up your results.
 
Fuel pressure is good. I want to somehow check the fuel pressure gauge while im driving and hit the hesitation though. that may mean removing the hood or rigging up a camera and a light under the hood to see how it reacts. I have the other computer, I guess I might as well give it a go and see if for some strange reason it fixes the issue. Ive had three different cam sensors on it, and two different CPS's, one on each motor thats been in it. I do have an engine wiring harness that I was going to sell, maybe I should put that on it to see if that resolves my problems.
 
Yeah Ive cleaned up nice and purdy. I have the FSM, ill have to start digging through it to see what I can find as far as wiring checks and ground location.
 
ehall said:
If the ECM works theres nothing to be gained from replacing it. However it's a good idea to have a spare--they ain't making anymore of them.
Click to expand...
X2. 50 bucks at the yard now will save you a bundle in the future if yours croaks.

Tim_MN said:
Be sure and replace the old air in your tires also. You can be sure that air is tired and needs to be refreshed.
Click to expand...
Yeah, the old air likes to leak out of one of my tires. Only the bottom air though, the top air is fine, I found some guy selling bottom air for Jeeps on ebay so I think I'm going to pick some up.
 
kastein said:
Only the bottom air though, the top air is fine, I found some guy selling bottom air for Jeeps on ebay so I think I'm going to pick some up.
Click to expand...

Maybe we can get a group discount on that bottom air, I'm always running out of it at the worst times.
 
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