ECU swap causes idle problems?

Discussion in '2.3L (N/A & Turbo) Tech' started by 93redfox, Jan 4, 2012.


  1. 93redfox

    93redfox New Member

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    Currently chasing a gremlin that causes intermittent tachometer operation. In this interest, I grabbed a spare ECU out of a junkyard car. It was the same as mine, 2.3 dual plug. After the swap, the idle was very strange. surged between 450-950. almost had the 'cam' effect. very heavy fueling during the surges, little puffs of rich exhaust. drove fine after 2k rpm, but part throttle operation below that was also odd and had sputtering.

    The original ECU seems to be a C1A1. The new one is an 8CC. This is the 'catch code' as it seems it called. My question is, what is the difference in these ecu's? They came out of the same cars, at least the same year range and engine, yet seem to function differently. The casings even look different. EEC-IV geniuses, are you out there?
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  2. bonestock87

    bonestock87 Founding Member

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    I don't know those ECU codes, the stock ECU on my 93 was a D1L1, it was an automatic trans car. What trans do you have and what trans was in the junkyard car? If you have a 5 speed, it doesnt matter what the donor car had. Also make sure you haven't accidentallly caused a vacuum leak.
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  3. 93redfox

    93redfox New Member

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    I don't remember what the junker car was. I have a manual trans, and after swapping the other ecu back in, the car operates just fine. For some reason the ecu pulled from the yard just doesn't want to operate the idle/low rpm circuit properly. I'm not sure if it's getting out of startup mode entirely, bc it seems that if it runs in closed loop it should correct itself fairly quickly.
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  4. tca7291

    tca7291 I can see your wieners.

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    Does it run ok in open loop? And remember the ecu that you pulled out of the junker might be faulty also, coming from a junk car, ~20 year old electronics are not the most reliable.
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  5. TripleBlk

    TripleBlk Member

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    If you can look at my "loonngg" thread "Part ID" in this forum you'll see that our basic problem was the ignition module.

    After a lot of research, I found that a bad ignition module can cause tachometer problems, as well.

    I would recommend getting a test ignition module from a salvage yard (plenty of Rangers had 2.3L).

    Good luck, and I hope this helps !
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