I have a few questions that hopefully the Honda community can help. My 1999 Honda Accord EX is suffering misfired on all cylinders. I had replaced these parts and still did not solve the problem.
1) Ignitions system: New distributor, spark plugs, spark plug coils.
2) Cleaned EGR passage.
3) Cleaned injectors. Replaced fuel pump filter.
4) New alternator. New battery.
I removed the ECU a few months ago and used an electronic cleaner to clean the connectors and it works for a while. Now the engine is running rough and sometimes would not start especially in rainy day. I suspected the ECU's connectors have the corrosive contacts, perhaps time to change the ECU.

My questions to the community:
1) Where can I get a used ECU for a 1999 Honda Accord EX (ULEV) ECU? My PCM model is 37820-PAA-L73, 1050-378584
2) How to program the replacement ECU to match my ignition switch?

Thanks

 

Check the mechanical timing. It might have jumped a tooth.

 

The cheapest way to get an ECU is from a junkyard. EricTheCarGuy has a YouTube video on "How to pull a Honda computer #salvageyardhacks" Otherwise, check the online parts like hondapartsnow but they are many hundreds of dollars

 

The new one is ridiculously expensive. Honda dealer quoted me $1023.

 

$1023 is better than several thousand for a new car.

I am having the same issues. I have replaced the throttle position sensor, the fuel pressure regulator, the EFI main relay, fuel pump, ignition switch.. And when it's above 30 out, my car will not start. If it DOES start, it starts VERY rough, and then doesn't want to idle at all. There is a strong smell of gas under the hood. Would anyone have any ideas? Or do I need to replace my ECM as well?

 

Just FYI. I am posting on this thread, because I have the same exact car, engine and all.

 

I found out my Honda's ECU was causing the problem when I plugged in an ODB2 scanner on to it, the engine runs smooth, but once I unplugged it, it ran rough. I took out the ECU, and use the QD electronics spray to clean the pinouts and wire harness, it works for a while before the problem pops up again. You can give it a try.

 

You might try checking/cleaning the main ground for the ecu. Being the fact it runs better with a code reader plugged in, when you do this you are providing "another" ground for the ecu, On the 6th gen 4 cyl (you didn't state engine size) G101 is on the drivers end of the plenum, there are actually two sets of ground wires there.