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94 3.1L pcm problem?


ForzdaManger

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Hello all!, Recently bought a 1994 mazda b2300 4 cyl 2.3L. After about 2 weeks the check engine light came on and stayed on. The truck then started to bog down and have no power sometimes. (not always) I used my scanner and got o2 sensor, maf sensor, restricted egr flow, and failure in cid circuit. I replaced the o2, Maf, egr pressure differential feedback sensor and tried to clean the egr system. Ran scanner and then only got failure in cid circuit, voltage not what expected at egr pdf sensor, and failed low rpm test. I installed Camshaft Position Sensor and the check engine light went out and she drove much better. I Then cleared codes. Now Check engine light will come on and off while i drive. I ran the scanner again and now all the same old codes o2, maf, that are already fixed. The haynes repair manual says to check voltage of the EGR PDF sensor and it should be between 5 and 6 but i was at around 12. It says if not between 5 and 6 the problem is most likely the PCM. This morning I started her up and drove to work i noticed the presets on the radio had been reset like the battery had died. So here is my questions. Do you think i have a pcm problem or wiring problem? What would cause the radio to reset?
The haynes book shows the PCM as being under hood on passenger firewall. On my truck the EGR PDF sensor is there. What is going on?
 
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Rock Auto 5% Discount Code: F9A1A579ACFAD1: October 1st, 2021

alwaysFlOoReD

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I can't help. But I've always thought that for Mazda's that the numbers correspond to engine size. So the 2300 is a 2.3 liter. Maybe that might change how you diagnose the problem.

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ForzdaManger

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im sorry. It is indeed 2.3L that was me doing too many things at once.
 

ForzdaManger

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I found what appears to be the pcm under hood on drivers side on firewall next to fender. When I was doing research on locations, I saw something that looks like a computer on the inside of passenger compartment under the ashtray. What is this?
 

alwaysFlOoReD

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Not my forte, but I think "gem module "

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enjr44

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I thought the PCM was on the pass side under the hood; but, I can't remember. They did move them around some.

The gem (google) is someplace around the radio and does a lot. But, nothing on the engine.

I think I would put this question in the general section and hope RonD takes a look at it.
 

alwaysFlOoReD

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Ron is on holidays for 3 weeks. It wouldn't hurt to put it up on general. My 93 PCM is on drivers side engine compartment firewall.

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