Help with issues
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Cargo Master
Joined: May 2001
Posts: 3,208
Likes: 13
I want to update this old thread. It wasn't the PCM. It was after a session with a very good tech and multiple diagnostic tools was intermittent loss of 5 volt reference voltage. Tightened those pins there are two and it has been symptom free now for over 1000 miles.
Tuned
Joined: Sep 2005
Posts: 331
Likes: 1
From: Charlton, NY
What pins are you referring to? On a sensor? Or on the PCM plug?
Logistics Pro
Joined: Jan 2001
Posts: 3,740
Likes: 37
From: Central NYS
Being brought up on carburetors, I understand your thinking on this, but here's what happens:
Upon misfire, the O2 sensors don't sense unburned fuel. They sense the excess oxygen due to the misfire. (They are, in fact, "oxygen" sensors.
)If a slight misfire, the excess oxygen causes the PCM to add fuel to compensate for the perceived lean condition.
If the misfire becomes more severe, the PCM cuts back the fuel supply to the misfiring cylinder to protect the catalytic converter
Logistics Pro
Joined: Jan 2001
Posts: 3,740
Likes: 37
From: Central NYS
Actually, at start up, the PCM uses the CKP to figure out which cylinder to fire. Lets say, as the starter cranks the engine over, the CKP signals cylinder #1 is approaching TDC. That's not enough information for the PCM to fire the #1 spark plug, because it doesn't know if cylinder #1 is on compression or exhaust. That's why it needs the CMP at start up (to determine which stroke #1 is on, and which injector to fire).
Once the engine gets started, the PCM can keep track of just where the crank is in its rotation and doesn't really need the CMP to keep running. Once the engine is running, if the CMP signal disappears the PCM can set the P0340, and the engine will keep running.
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Cargo Master
Joined: May 2001
Posts: 3,208
Likes: 13
The loose pin(s) was in the connector attaching the the PCM. One can lose the 5 volt reference voltage by either a shorted sensor, loose pin, or bad wire. The loss of reference voltage cause the PCM to turn on codes for sensors that use it. That was the reason for a ton codes plus it causes the system to go dead rich. P2196 p2198
Tuned
Joined: Sep 2005
Posts: 331
Likes: 1
From: Charlton, NY
The loose pin(s) was in the connector attaching the the PCM. One can lose the 5 volt reference voltage by either a shorted sensor, loose pin, or bad wire. The loss of reference voltage cause the PCM to turn on codes for sensors that use it. That was the reason for a ton codes plus it causes the system to go dead rich. P2196 p2198
You don't happen to know the pin numbers which were problematic?
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