erichackett

ok so here's the deal. i bought am EM1 (2000 civic si) with a ls vtec in it. i decided i didnt like the ls vtec and am going back to the original b16a2 block. the computer that was in the car is a p05 that is chipped. thats the extent i know about the ecu in the car. but the cars timing was advanced. my question is, was it advanced to counter the larger displacement of the b18a block? or was it possibly advance because the timing on the ECU differs from what that motor should run.

due to not knowing the extent of the mods done on that ecu, my friend gave me a p28 ecu (i think) and he said it was a jdm ecu and all stock.. i opened it up and sure enough it is stock.

can any one tell me what to do? the supposed p28 ecu on the side reads: 37820-PR3-J50

will that run my b16a2? and if so can i set the engine up to original timing specs?

PS i dont think it is a JDM Ecu because its not square. its a rectangle like the usdm ones. any information would be greatly appreciated.

JDM_SOHC

it's not a P28 if it says PR3, it's a PR3 (that's the ECU code), and a PR3 is an OBD0 ecu so it won't work without conversion harness...

erichackett

ok but the ecu does not match up to the factory harness. are u sure it is from an em1 because ive read several things saying that it is from a single cam pre obd vtec

JDM_SOHC

You're right, my bad... I had a brain fart, PR3 is from a B16 powered OBD-0 vehicle... I got a bit confused on the first part of your post... So let's clear the smoke, if you have an EM1 and you're running a P05 ECU, than my guess is you car was converted to OBD1 right..?? If that's the case a P28 will work for you since that's OBD-1, but that ecu you have now that says PR3 is not OBD-1 thats OBD-0...

erichackett

yes i figured that out now that its an obd-0.

a few questions. can i run my car with that P05 ecu? and also i do not know if the ecu could affect the way i have to set up the timing. because when i got it it was an LS/VTEC. and the timing was advanced. was it advanced because of the change of block or because of the ecu?

JDM_SOHC

Hmmm, well not knowing how the P05 was chipped kinda sucks... When chipping/tuning ECU's there's usually an option for advance/retarded timing and all depending on the motor setup, would tell whether or not to advance or retard the timing... I ran my LS/V with a chipped p72 (obd1 gsr ecu) and I left the timing settings as they were, and just advanced my dizzy 1-2 degrees... Timing advancements are usually made because of the head not the block...

erichackett

the head is completely stock except i was told it had skunk 2 valve springs... could that effect it? and my dizzy timing was advanced. so when i reassemble it should i still advance it or start it at stock and then go from there?

erichackett

also i just started a short build thread...
https://honda-tech.com/forums/honda-civic-del-sol-1992-2000-1/build-thread-si-2794927/

JDM_SOHC

Valve springs have nothing to do with timing, just gives you more ability for higher rev's... And when assembling things that deal with timing and all that, I always start from stock points and work it until it's where it should be...

erichackett

ok so would u guess then that it was advanced because of the ECU? of if u advance timing in the ecu would you not advance it on the dizzy?

also is it a good idea to just stick with that ecu?

JDM_SOHC

I mean maybe i'm a bit biased, but I always like to stick with whats known to work... If you have an LS/V setup, I'd go with a stock Vtec ECU... And yeah my guess would be they advanced it to make up for what the ECU couldn't do, but again that's just assuming that timing wasn't tethered with when that P05 was chipped... Rule of thumb, if you ever buy something from someone and told something, assume the opposite is always possible...

erichackett

well im getting away from the LS/V. im going back to factory motor. and sorry i worded that question wrong. what i mean to say was if the ECU timing has been adjusted, would you adjust the dizzy?

erichackett

and if you lived around here id give you that LS block for free. lol

JDM_SOHC

That's respectable, sometimes havin power over performance isn't really worth it... My LSV hatch would blow the doors off my old em1 setup, but to each his own... And if the ECU was adjusted, than I'd put the dizzy timing where it should be at TDC specs... If it doesn't run right that way than I'd start to mess with it...

erichackett

ok sounds good on that..

i run pretty rich, would upgrading spark plugs help that? if so any suggestions on plugs?

JDM_SOHC

I always go with NGK's with stock gapping and never run less than 8.5mm wires..

dpetro1

ok enough with all the obd0 stuff. there is absolutely no point in running that pr3 in your car so give it back to your friend.

if you are going back to completely stock then get the stock ecu, p2t.

if you are planning on tuning later than keep your chipped ecu and have it mapped for the b16a2.

once the ecu is finished, make sure your cam timing is correct. then set the dizzy to 16* btdc and call it a day. no need to advance/retard the dizzy in any way, if your get tuned the tuner can set timing values on the map.

dpetro1

how do you know that you run rich? do you have a wideband on the car? if not then you are just guessing.

also, spark plugs no effect on the amount of fuel being delivered to the engine. they simply ignite the fuel so changing plugs will not correct a rich condition. but to answer your question you should run ngk bkr6e-11 plugs, stock# 2756

erichackett

im not planning on running that pr3. and i have no money for a tune lol. so i was asking if i can used that chipped ecu with my stock motor

erichackett

i know im running rich because i have a autometer air/fuel ration gauge

dpetro1

yes you can run the chipped ecu but the chip needs to be programmed with the stock b16a2 map. contact a local tuner or online dealer and see if they can burn the map onto the chip for you.

94EG8

Some PR3s are OBD0, some are OBD1. I'm guessing the OP has the OBD1 version. It also appears to have originally been for an automatic. Its definately JDM. Not all JDM ECUs are square. A chipped and converted P05 should work just fine as well. Once the ECU is converted and chipped it really doesn't matter what it was for originally.