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ECU swap? feedback to non-feedback


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6 replies to this topic

#1 ferox

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Posted 31 May 2008 - 01:09 PM

I have an '81 4WD M/T 1.8 California model hatch. I removed all the feedback/emmissions stuff from the engine compartment a long time ago. I have an '83 hitachi carb in right now with non-feedback jetting, and I am wondering if I switch out the ECU to one from a non-feedback hatch if it will help mpg's or overall driveability, or even just idle stability. Or should I just unplug the ECU since the non-Cali '81's didn't come with ECU's?

If I should swap, will an ECU from an '89 hatch work? Any thoughts on the best (most compatible) year. I have a couple '84 hitachi carbs I am going to rebuild to swap out the '83 also. The '83 works pretty good (25 city/31 hwy grandma style driving), but pretty good isn't good enough. My point here is that an ECU swap will be working with an '84 carb not the '83. Thanks

#2 GeneralDisorder

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Posted 31 May 2008 - 01:19 PM

I have an '81 4WD M/T 1.8 California model hatch. I removed all the feedback/emmissions stuff from the engine compartment a long time ago. I have an '83 hitachi carb in right now with non-feedback jetting, and I am wondering if I switch out the ECU to one from a non-feedback hatch if it will help mpg's or overall driveability, or even just idle stability. Or should I just unplug the ECU since the non-Cali '81's didn't come with ECU's?

If I should swap, will an ECU from an '89 hatch work? Any thoughts on the best (most compatible) year. I have a couple '84 hitachi carbs I am going to rebuild to swap out the '83 also. The '83 works pretty good (25 city/31 hwy grandma style driving), but pretty good isn't good enough. My point here is that an ECU swap will be working with an '84 carb not the '83. Thanks


I don't think you quite grasp the situation here - there's no such thing as a "non-feedback ECU". Carbs equipped with ECU's are feedback. Without ECU's are non.

So the answer is that you should remove the ECU.

GD

#3 ferox

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Posted 31 May 2008 - 01:31 PM

OK. I have seen a lot of dialog about feedback vs. non-feedback without a proper definition. If I understand this correctly then non-feedback systems stopped in 1981? Will there be any other effects from removing the ECU?

#4 GeneralDisorder

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Posted 31 May 2008 - 03:22 PM

No - non-feedback continued till the end of carbs in '89 (EA81 hatch).

Feedback was always a 2WD, or California model system. 49 states 4WD's never had it.

As for a definition - "Feedback" refers to the "feedback loop" programming used by most computer control systems. The 02 sensor continously updates the computer on the mixture - the computer makes adjustments, and the cycle repeats - ad infinitum.

Thus you simply remove the ECU, it's associated sensors, valves, and duty solenoids (if you wish - you could just as well leave the junk in there), and install a non-feedback carb with proper routing of the mixture port air supply lines (no duty solenoid controls). That is all that is required to convert an EA81.

GD

#5 ferox

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Posted 31 May 2008 - 03:39 PM

Alright...I understand what feedback is I just obviously did not know which systems were feedback or non. Thanks for the clarification GD.

Not to belabor the topic, but if I understand your two posts correctly, then any 4WD with an ECU is a Califonia model.


Orginally posted by General Disorder:

Carbs equipped with ECU's are feedback. Without ECU's are non.


Feedback was always a 2WD, or California model system. 49 states 4WD's never had it.



#6 GeneralDisorder

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Posted 31 May 2008 - 04:35 PM

Not to belabor the topic, but if I understand your two posts correctly, then any 4WD with an ECU is a Califonia model.


Yep - that's the size of it.

Barring some type of swappage from a previous owner.

GD

#7 ferox

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Posted 31 May 2008 - 06:26 PM

That's interesting. Based on what I have encountered in the junkyards here, a lot of Cali. models migrated north. More than I would have guessed anyway. Thanks again for the clarification GD. I have been trying to figure that one out for a while.




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