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ECU Differences.

90xj06

NAXJA Forum User
Location
Peabody, MA
i have a 90 that i swapped the engine into an 88. i used the injectors and tps from the 88's original motor. and it seems like it doesn't have as much umph as it did before i swapped it.

assuming that the injectors and tps are working as it should. could the ecu be the difference?

ill probably swap it over anyhow but im just curious.
 
Yeah the 89-90? Ecu Is rated higher hp , but that's the limit of what I know ( except I got a 90 ecu on the shelf for some reason)

Anyway Team Renix should be rolling up any moment now :)


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So at least with that figure there is a almost a 5hp difference. And I'm assuming that's a model year and not date of manufacture. Looks like this one was first registered in 87 with 5 miles on it.
 
Could it be that your '88--C101 connector junction on the firewall has corrosion within.., sending weird signals to it's '88 ECU? ('89 and '90 don't have that connector). Beyond cleaning/restoration of C101, swapping out the '88 ECU in favor of introducing the '90 ECU might help for your '90 engine. Not positive, just speculating.
 
After inspecting the c101 it looks to be in good shape. I will remove it at some point. But I want to make sure it looks clean. I will swap the ecu and see if it makes a difference
 
I doubt it is the ECU. What all did you swap from one to the other? Why did you make the swap? There are many sensors and minor issues that can cause a huge diference.

AFter 13 years I found the main source of the weak power on my 87 was a bent control rod from the throttle body to the side of the manifold where it connects to the gas pedal linkage was bent. Reshaping it to the 89 jeep rod doubled my low end torque. That is just an example of many little issues I found. One was a bad TPS that passed all the known TPS tests at the time. I had to invent a smarter test, the one I developed in the 10 year old RenX files thread here.
 
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The original motor threw a rod. I did not swap the intake and exhaust manifold. But did confirm the throttle is opening all the way. I just swapped fuel injectors yesterday. Going to try it now
 
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