chillex8:


Now, am telling you I have done it both ways back to back. With optimal engine management.

I suppose when Honda built 2 different ECU's for the J30 and J35, they simply did it for the fun of it, with no logic or direction they just wanted to spend a small fortune. It's a known fact that manufacturers WILL retain as much of the same parts as possible, to make them interchangeable across the board. And keep costs down.

0.5 cents saved per component may not sound like a lot. Then consider when 13 million units are produced, then that small saving becomes a billionaire's ransom.

Out of interest, how did you actually measure "optimal engine management", apart from driving these cars?

chillex8:


Replacing J30 with J35 is POSSIBLE.

Its done everywhere, consciously and otherwise.

I have replaced j35 with J30 on my personal Van.. Its still serving the current owner.

I have also slapped in a complete J30 engine and transmission into a 1999 honda odyssey.

Same harness.

Same ECU.

It was a plug and play.

And it worked.

This is HONDA.

Siena:


Bro, I'm not saying a J35 motor won't run with a J30 ECU.

It will. But it will NOT operate at its optimum. If you're happy to have a can that drives, without bothering about fuel, ignition and timing maps, then it's a good swap. One thing is certain - the J35 will NOT produce the same power with a J30 ECU.

Contrary to what you posted, the ECU's are NOT the same. Different part numbers, as can be expected. Both these engines have different camshafts, so the duration and timing WILL be different. So will the fuel requirements, the injectors will be bigger on the J35, and the pulse duration (duty cycle) will be wider.

In summary:

Running a J35 on a J30 ECU will result in under-fuelling, lean-running, hot-running and detonation. In extreme cases, resulting in damage to the piston crowns, burnt-out exhaust valves, and damaged spark plugs. Damaged spark plugs could end up with the electrodes breaking off, and dropping into the cylinders. The result? Scored cylinder bores, and excessive oil consumption.

Running a J30 on a J35 ECU will result in over-fuelling, hesitance at low to medium throttle openings. In extreme cases, resulting in bore wash and gasoline-diluted oil, eventually leading to premature piston ring and bore wear, and damaged crankshaft journals due to gasoline-diluted oil.

disloman:
good job.slap 4 urself.This will b my last reply to all ur bullsh1t u've bn posting here.I'm nt blog trained mechanic.Where i work taught mi 3 principles to work with n those principles av helped me alot.
1.Use n replace part with exact n original spare parts
2.never to outsmart d manufacturer
3.Always ask questions.
U said u did this,u did that.That's good 4 u.Had a car which a mech like urs changed d engine frm K24 to K20.D engine works but d rpm high.What's d cause?foolishness.i doubt if u avn't removed d engine light frm d dashboard permanently.we knw pple like u.wish i knw u d more but....................

disloman:
good job.slap 4 urself.This will b my last reply to all ur bullsh1t u've bn posting here.I'm nt blog trained mechanic.Where i work taught mi 3 principles to work with n those principles av helped me alot.
1.Use n replace part with exact n original spare parts
2.never to outsmart d manufacturer
3.Always ask questions.
U said u did this,u did that.That's good 4 u.Had a car which a mech like urs changed d engine frm K24 to K20.D engine works but d rpm high.What's d cause?foolishness.i doubt if u avn't removed d engine light frm d dashboard permanently.we knw pple like u.wish i knw u d more but....................