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My sig is longer than yours
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2,163 Posts
Discussion Starter #1
SO yea, chipped my buddies pm6, 90 crx si. No matter what map i burn, stock pm6, ng60 wit pm6 tables, etc, it will idle at 3k and stay there. it revs freely, no codes.. Swap in my old 88 si ecu and it runs fine. We're tinking bad ecu but figured it was worth a shot to post..
 

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I wanna be just like Jimmy!!
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3,148 Posts
did you cut the jumper to return it to stock, to see if it still did it? i wouldn't write it off, until you try that
 

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()*#$(*$
93 Legend L Coupe.
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11,404 Posts
OBD0 ECUs don't need jumpers cut. Install chip, be happy, usually.

As far as why it's reving up that high, If the ECU was not working corrrectly, you would be getting some kind of indication at the ECU that you botched it up. I would look for a vaccuum leak. The easiest way to test for a vaccuum leak is to get a large, really cheap can of carb cleaner. Let the car idle, then start spraying the carb cleaner all over the intake manifold. If the idle dips or the car stalls, that is the area of your vacuum leak. If it passes this test, then it's probably the ECU, but just to be sure, I would follow the troubleshooting flowcharts for the idle circuits as found in the Helms.

Also, can y ou get good shots of the soldering done? You may have a cold or incomplete joint somewhere. This would be a pretty easy fix, as you would just desolder then reseolder the chip or socket.
 

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My sig is longer than yours
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Discussion Starter #9
if it was a vacuum leak it would idle high like that when i put my old 88si ecu in, which it doesnt. Soldering job is fine as well, ive done more soldering in my life than i care to think about, definatly no cold joints here :p
 

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I wanna be just like Jimmy!!
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so, how do you turn an obd0 ecu back to stock? do that, and see what happens...
 

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97 GSX-R 750
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1,548 Posts
was the ecu fine before you chipped it? Sound like a bad ecu since it worked fine w/ yours but if it was fine before you chipped it and you soldered it good that doesn't make too much sense?
 

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I'd try burning the stock PM6 map on another chip and install that in the socket [pgmfi.org for stock .bins ]. If it still has the 3k idle but when a non-chipped PM6 ECU is connected it idles fine, its obvious the ECU is bad ... either the socket or the actual ECU hardware is at issue. Check the continuity of the connectors where the wiring harness plugs in. Are you using an AT29C256 chip? When the chip is installed in the socket, check the continuity from the chips' pins to the soldered connection on the underside of the board.
 

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1991 crx dx
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i was going to ask the same thing that burnoutboy did was the car running fine before you chipped the ecu. that should tell you if the ecu was bad or not. Am i right?
 
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