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Old 06-25-2006, 04:24 AM   #1
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Default i fried my 1990 miata with a 2001 alternator

ok heres the story...

bottom line i screwed up and overlooked the fact that when swapping a 1.8 from a 2001 into a 1990 miata using the 2001 alternator is a huge no-no.
sadly the incorrect alty overcharged my battery (later a friend told me my safcII was reading 16 volts) cooking my battery plumping it up like the incredible hulk. ever since then my car hasnt ran.

heres what ive done to try to remedy the situation...

i have bought a re-furbished autolite 1994 miata alternator.
i bought a brand new battery from batteries plus (miata specific).
i have replaced the main fuse (80 amp) that showed signs of damage from overcharging from incorrect alty
i tested the +B terminal at the diagnostics connector and i DO have +12V
i tested both the white/green and white/red wires at the main fuel inj relay both DO have +12V.
i have peered into valve cover, cams are turning.
i tried bypassing the SAFC AFM hook ups (my safcII shows 100% airflow reading even with the AFM disconnected!!!)

heres the current diagnosis...

i have no CEL with key on. (it doesnt come on like it should be when key is first turned on)
my safcII shows 100% airflow reading even with the AFM disconnected!!!
motor turns but wont fire.
when i turn the key on/start i can hear the walbro fuel pump turn on, then shut off after short time (3 seconds?)
no evidence of spark with timing light connected.
things non-engine related that works: healights, blinkers, parking lights, wipers, gauges, instrument lights
thing non-engine that dont work: my stereo (lol)
(and related to alty mishap, my "room" fuse on drivers side fuse box keeps popping even with key out of the igntion.)

im still searching/reading on this issue, i have not tested the open circuit relay yet, but i hope to do it soon. im also gonna pull my ECU and open it up and look for obvious burn marks etc. im really hoping i can remedy this problem before july 8th (battle of the imports @ pacific raceways in seattle) i want to see what my turbo set up (precision GT3076R) on the 1.8 is capable of.

Thank you very much in advance for any help you guys might be able to throw my way.
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Old 06-25-2006, 07:55 AM   #2
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just got back in from the garage, i did the unplug/plug in of the main fuel injection relay, and it does click, i pulled out my ECU and opened up both covers (top/bottom) and it looked clean but had a slight "electrical burn" smell. with the ECU out of the car i replaced the "room" fuse in the underdash fuse box, and the door buzzer came on. the fuse didnt pop. so i decided to plug in the ECU to test the fuse reliabilty, when i plugged in the CONN #1 (side with power wire for "room") the fuse immediately popped and the door buzzer quit.

this leads me to believe the ECU is the culprit. with the ECU unplugged the SAFC still read 100% (which i believe makes sense since 0 voltage = 100% AFM reading right?) and secondly the check engine light didnt even flicker throughout this whole process.

does anyone have any feedback as to whether a bad ECU is 100% probable or should i still check the circuit open relay.

many thanks
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Old 06-25-2006, 10:16 AM   #3
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i'm not good at testing or checking electrical stuff. i describe my methods as "monkeys ******* footballs" but if there is a bad circuit, and you put in another ecu, you could damage that one. that's my thinking. if it were me, i would try to find another car of the same years(s) and put your ecu in that car, see if it runs.

i hope someone else here has better advice.
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