Hey, I have Honda Prelude 1997 H22A, 5th gen base manual and for some time now I have had this weird starting problem: when I turn ignition on check engine light comes on and stays on around 30 - 90 min, then disappears and then car can start normally. Winter time when there is not that much air humidity car starts more normally so doesnt that mean theres some bad connection somewhere? When car starts it drives normally.

I have checkd some grounds, main relay is resoldered, ecu doesnt have bad solders.....getting spark all the time. This is kinda annoying problem and kinda have no glue where could find the fix for this.

Car is OBD1 converted with Hondata.

Anyone else have had this kind of problem? Thanks.

 

Try to find check engine code when is on, possibly is the IAC

 

Also forgot to mention that its having Skunk2 IM so Idle Air Control is bypassed

 

Bad capacitors inside the ECU. Repair or replace it.

 

One electric shop looked ECUs solderings and said soldering was ok.. capacitors are different thing?

 

Capacitors are like small batteries... just because they are soldered in and appear correct doesn't mean that they work. These ECU's are now somewhere between 28 and 31 years old and the capacitors have an operational lifespan of 8,000 - 10,000 hours. When they fail, electrolytic fluid (which is an acid) leaks out and damages the board.

 

no acid anywhere, circuit board is clean.

also tried with new/another main relay - no change

 

When the CEL is on and you cannot crank the car, what is occurring is that some circuit pathways inside the ECU are not energizing... and thus, the ECU is not fully powering up. In your case, once power has been applied to the ECU for some time (warming up the ECU board), these problem circuits are beginning to function, and then the ECU seems normal and the car runs like normal. It may not be a cap problem at all... it could be some other components that are suspect. What you need to do is try one of your friends working OBD-1 ECU's and just try to start the car. If everything cranks right up and functions without the issues that you have been experiencing... then you know the problem IS your ECU. You may not be able to fix it and might simply have to purchase another socketed ECU from a good source and install your Hondata S300 inside it and move on.

 

got capacitor kit and got em changed, cleaned some more grounds - no change

 

Changed also IC17 component (Toshiba TA8903SN)

"Does your obd1 obd2 ecu not activate your main relay?
This is one of the main part that controls your main relay from functioning."

No change.

Damn, next thing I guess is to get another/new Hondata S300 ready OBD1 ECU

 

Got new P28 ECU for S300. Now it seem to start normally again 🤞🏻