I have recently adjusted the distributor on a 1994 OBD1 H22A engine without jumpering the connector at the shock tower. Will this just adjust the timing mechanically but not at the ECU? If someone can explain the principle behind why the connector needs to be jumpered that would help me out alot.

Thanks

 

i never jumpered anything when i adjusted my timing

 

I'm prity sure if the service connector isn't jumped the ECU will not accept the changes and the timing should go back to what it was in a week or so depending on conditions (driving, driving style, fuel type etc etc).

I didn't jump the connector the first time I adjusted my timing, the car ran great initially (for a week) and then slowly I could sense the timing was being retarded. Just jump the connector and start the car, get the rpm to 700 and check the timing through the cap by the fly wheel. If's its still ok then the jumping of the connector should fix it all up/save the change but I assume it will be out again.

 

The ecu will immediately change your timing back. Its definitely not some old 350 chev.

 

Thanks for the replies

So basically having the service connector jumpered allows the ignition map to be over written in the ECU? And if it isnt jumpered it will always revert back to the previously saved settings?

 

what you are doing is eliminating any timing advance when you jump the connector, so that you are correctly setting the base timing. Otherwise, the ignition timing may be slightly advanced or retarded when you are adjusting, so it may not be where you want it to be.

 

Guys, is there any online reference regarding this?

 

Weired never heard of this before.

 

it is stated in the Helms manual.

 

I know the service manual states it but never explicitly say why need to jump the SCS connector at the first place.

Read somewhere that by jumping the SCS connector, whatever ignition timing made will not default back to stock timing after adjustment. In this case I'm advancing my d15z7 from 12 deg stock to 14 deg as RON91 (recommended minimum grade fuel) is not available anymore instead replaced with RON95 hence advancing the timing a couple.

But the thing I don't get is that there is no way the ECU will know that the physical angle of the distributor has changed unless ECU picks up something from the knock sensor and retards the timing to suit.

Whether it is true or not I've short the SCS anyway to advance timing and now running fine on RON95 @ 14 Deg advance.

If anyone can get solid info on this is greatly appreciated. Thanks.

 

What this guy said.

 

I was hoping more like official information from Honda affiliated sites but thanks anyway.

 

Right, that's why while setting the base timing the SCS connector is jumped (along with the rest of the procedure in the Helms) to ensure that the ECU is outputting a given ignition advance, so that you can make an accurate adjustment.

 

Sence you do this on EVERY OBD1 or 2 car, getting official info is a waste of time. You just have to know were the connector is. Your car will add or remove timing anyways, so it's pritty much a waste of time. Now if you have a tuning software like Hondata, Chrome ect, then it becomes VERY important.

 

OK. But just a side note wouldn't that be odd that if using non stock timing and the battery wears out, timing adjustment would have to be made afterwards after battery changeout?

Then again can resort to maintain 12V supply to the terminals whilst changing the battery.

Just a thought.

 

You are assuming the onboard computer has more intelligence than it does. It doesn't care what position the distributor is in, it goes by its ignition maps to advance and retard timing accordingly. When you move the distributor, you are changing the base timing. Ex. if your base timing is 12 deg. and the computer advances it 4 deg at a certain point, you have 16 deg of timing. If you change the base timing to 14 deg, and again the computer advances 4 deg, you now have 18 deg timing.

 

I know that too.

Anyhow, the manual says it so let it be. I'll look elsewhere.

Thanks anyway.

 

Yeah, that would be weird if it were true...which it isn't.