ecu not storing codes

[theSOB]

i'm throwing a code for the egr cuz i disconnected it. understandable. but every time i start up the car, no code appears. it doesnt show up until the car warms up. i'm assuming its just not storing codes for some reason, and every time i start it, it acts like a new ecu learning howto drive the car most efficiently. my other ecu does the same. any ideas why?

[HondaFan81]

If your observations and/or assumptions are true, then something is up with your electrical system causing a low/no power issue.

Does your clock also reset and you have to adjust it as well? If so, that confirms the above.

[theSOB]

If your observations and/or assumptions are true, then something is up with your electrical system causing a low/no power issue.

Does your clock also reset and you have to adjust it as well? If so, that confirms the above.

thats the weird thing, everything else stays as it was set; clock, radio, etc.

i was hoping there was a certain fuse or wire that i could check. i'll double check the ecu this weekend

[theSOB]

ok, so took a while but i tried throwing my other ecu in and the same thing happens. not storing codes. all other electrical items are working fine. i don't think its plausible that i have two bad ecus. is there a certain wire to the ecu i can double check?

[evil_demon_01]

i'm throwing a code for the egr cuz i disconnected it. understandable. but every time i start up the car, no code appears. it doesnt show up until the car warms up. i'm assuming its just not storing codes for some reason, and every time i start it, it acts like a new ecu learning howto drive the car most efficiently. my other ecu does the same. any ideas why?

When you say its not "storing codes" Do you mean that when you jump the short connector no codes flash?

Also I thought the Egr doesn't require a signal until the engine is up to operating temp

[theSOB]

When you say its not "storing codes" Do you mean that when you jump the short connector no codes flash?

Also I thought the Egr doesn't require a signal until the engine is up to operating temp

that is true, it does not read faulty until it gets to running temp. I can read the code, but only at running temp. after the ecu gets a code, it should store it and remember it so every time i start the car, i should get a cel for my egr, regardless of temp.

what happens is every time i start my car, no codes show. i have to wait for it to reach running temp til the cel comes on. thats not normal

[James Matteu]

I agree if you are using OBD-I ECUs that the code should be stored from one trip to the next.

I am curious, did you disconnect the EGR Lift Sensor (on top of the EGR Valve) or EGR Solenoid (inside the black box that has all the vac lines going to it)? If you disconnect the EGR Lift Sensor, I would think the ECU would see the input missing from start-up. If you disconnected the EGR Solenoid, then I imagine the ECU would not realize something is wrong until it is unable to control the EGR after the engine warms up.

As far as the engine running like it has to re-learn everything, try running the car with the blue connector jumped. I thought this keeps the ECU in Open Loop; no trip data collection, no HO2S input.

If you suspect a power loss at the ECU, unplug it and probe the memory wire. You should see voltage with the car off, and there should be zero ohms resistance between it and the memory fuse (a good way of making sure you've got the right wire).

[theSOB]

I agree if you are using OBD-I ECUs that the code should be stored from one trip to the next.

I am curious, did you disconnect the EGR Lift Sensor (on top of the EGR Valve) or EGR Solenoid (inside the black box that has all the vac lines going to it)? If you disconnect the EGR Lift Sensor, I would think the ECU would see the input missing from start-up. If you disconnected the EGR Solenoid, then I imagine the ECU would not realize something is wrong until it is unable to control the EGR after the engine warms up.

As far as the engine running like it has to re-learn everything, try running the car with the blue connector jumped. I thought this keeps the ECU in Open Loop; no trip data collection, no HO2S input.

If you suspect a power loss at the ECU, unplug it and probe the memory wire. You should see voltage with the car off, and there should be zero ohms resistance between it and the memory fuse (a good way of making sure you've got the right wire).

i've disconnected everything. only thing i have from the black box is the map sensor.

so there is a memory wire? and fuse? where are those located, do you know? i suspect its something like that as i've tried two different ecus with same results

[James Matteu]

Memory fuse is a 7.5A fuse in the Under-Hood Fuse/Relay box, the memory wire is a small gauge Red/White wire; you will need to consul a pin-out for your ECU to determine its exact location.

[YK86]

That is normal. The CEL will NOT come on right away for something like the EGR after you shut the car off and turn it back on. But it is still stored and will appear if you jump the service connector.