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Help with cpu codes 89-91

Old Jan 6, 2012 | 02:04 PM
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From: Kansas City
MO Help with cpu codes 89-91

89 na , cutting out,its kind of random. Runs perfect when cold ,after warm up it runs good with good power and accelration but will stumble randomly. I have pulled the cpu code but i am not sure how to read it. One long pause then seven shorts. if that is 17 then the oxygen sensor is the culprit.Am i reading the code correctly???
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Old Jan 6, 2012 | 02:49 PM
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From: palmyra Indiana
without looking up the info in the FSm... i'm going to say you're on the right track. if the cutting out isn't as random as you think, and it is more like part throttle cruise after about 3-4 seconds it the power falls off and you have to give it more throttle and it goes back to normal, then it's a common symptom of the O2 sensors failing. good thing they're cheap
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Old Jan 11, 2012 | 06:47 AM
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15 is the O2, 17 is the feedback system which can be a faulty O2 but can be multiple other failures as well.

http://www.banzai-racing.com/FD_S5_error_codes.htm
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Old Jan 11, 2012 | 11:44 AM
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From: Kansas City
Originally Posted by Banzai-Racing
15 is the O2, 17 is the feedback system which can be a faulty O2 but can be multiple other failures as well.

http://www.banzai-racing.com/FD_S5_error_codes.htm
Thanks, Banzai! I am still trying to get the 02 sensor out....soaking with pb blaster and then warming it up to heat it. O2 plug socket i bought at Oriellys is open on one side and will not hold when i put the breaker bar to it. Finally cut the wire off and need to get regular looong socket to get it out.
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Old Jan 11, 2012 | 01:23 PM
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From: https://www2.mazda.com/en/100th/
Originally Posted by tinmann55
Thanks, Banzai! I am still trying to get the 02 sensor out....soaking with pb blaster and then warming it up to heat it. O2 plug socket i bought at Oriellys is open on one side and will not hold when i put the breaker bar to it. Finally cut the wire off and need to get regular looong socket to get it out.
i bought the same POS socket, its almost worthless... i put a hose clamp on it, near the base, which helped
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Old Jan 11, 2012 | 03:00 PM
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Originally Posted by j9fd3s
i bought the same POS socket, its almost worthless... i put a hose clamp on it, near the base, which helped
I tried it,but no luck it would still jump a flat. I have a long 7/8 socket but i will have to dremel out the top inside ring to get it to fit.I hope that will do it.
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Old Feb 1, 2012 | 11:10 AM
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From: Kansas City State of Misery
Originally Posted by Banzai-Racing
15 is the O2, 17 is the feedback system which can be a faulty O2 but can be multiple other failures as well.

http://www.banzai-racing.com/FD_S5_error_codes.htm
Update, it was the O2 sensor. Finally just nocked of the top cermaic part of sensor with a small hammer and then i could get a regular socket on it. No more codes displaying,but still having issues of missing and stumbliing after warmup. Runs great cold,perfect but after warmup gremlins appear.Runs good alot of power and the stumblin and cut out is at beginning of accleration but is very random and does not happen alot. I am thinking it might be a vacum leak. I do have another ecu that i know is good except for ac link is broken,the only reason i replaced it. I am thinking of swaping them out and see if that does anything. Thanks for all the help.
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Old Feb 1, 2012 | 11:28 AM
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From: tulsa,ok.
Also read voltage on the Water Thermosensor from the ECU pin 2E w/key to on. Should read close to 3 volts w/engine cold but closer to .5 volts or so when engine fully warmed. Sensor helps regulate how much fuel is used dependent on the engine temp.
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Old Feb 22, 2012 | 04:16 PM
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From: Kansas City
Originally Posted by satch
Also read voltage on the Water Thermosensor from the ECU pin 2E w/key to on. Should read close to 3 volts w/engine cold but closer to .5 volts or so when engine fully warmed. Sensor helps regulate how much fuel is used dependent on the engine temp.
Ok did a search but can't id 2e pin. I did change out the ecu twice, yes i have two spares. also changed out the thermosensor. Same ****, runs perfect cold but as soon as it reaches normal temp throttle gets iratic and cuts out and dies.I never said it but i have rebuilt injectors installed also.
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