jimboc88

i have a quick question that i am not sure about. i have a 96 civic ex with a d16y8 engine. well had a d16y8. i swapped it for a d16y5 engine bcuz the block is bad on the original d16y8 engine. so my question is do i have to replace the ECU for a hx model?? i mean i just switched the engine but i still have the same tranny and intake maifold but just the block and the head are from a hx civic a d16y5.

HondaPartsHero

If you want it to run properly yes. What about the head on the original engine is is good? You can just swap that onto the HX block. Otherwise you have to do some wiring and sensor work to get it to work with the HX ECU.

jimboc88

I think it is. What would happen if i run my civic like that? With the d16y5 engine an a d16y8 ECU? so if i change the ex head into the hx block il be good??

HondaPartsHero

Not really sure how the hx will run with that ecu. Yeah y8 head on the y5 block bolts right up.

craiglewis22

I want to jump in here because I'm in the middle of a D16y5 Stock rebuild, I bought a 99 HX from a Kid who drove it with no oil in it...and I want to know what makes the Economy version of Vtec in the HX any different from a standard D16 VTEC like the EX? Is it just all in the ECU?

apexi_rsx

ecu and head are different. the hx head has roller rocker style valvetrain. the ecu is different as well and i believe runs a 3 wire iacv. the hx head has smaller ports then the y8 . u would be better off running a y8 head and y8 ecu to make it easier. the mpg difference will only be slightly better with the hx but barely noticable.

Ghetto Civic HX

To the OP and craiglewis22: The EX's ECU has vtec set around 5k while the HX's is around 3k. USE THE HX ECU.

The EX's vtec is similar to the b-series in that it's performance oriented. the HX's vtec-e is meant for fuel economy. When the HX is not in vtec-e it's running on 12 valves with only one of the intake valves per cylinder open.

craiglewis22

cool thanks!

milkwasabadidea

id use the y5 block and the y8 head and use the stock ex ECU.... assuming the head is usable.... that would probably be your best bet if you dont want to run into any problems with the motor or smog

jimboc88

i have a question. im running my 96 civic ex model with a y5 engine and a y8 ECU . where can i buy the adapters to make the ecu of a hx model fit my connections of my ex civic? and will affect anything if i just run it like that w/o changing the ecu?

jimboc88

oh and i also have the y8 intake manifold and stock headers. is that bad for the engine?

Wrona

http://www.hamotorsports.com/obd2atoobd2b.html you should probably change the ECU to get the full potential of the motor of its MPG saving

jimboc88

oh and where could i buy a hx ecu and harness, cuz im pretty sure mines wont fit on the hx ecu

Wrona

idk craigslist online the marketplace depends if you buy a 96 ecu from an HX it will be thesame if it is 99-00 HX it will be OBD2B which i posted the jumper harness

Wrona

i dont understand why r u asking to use the EX or HX ecu if they already told u in this thread https://honda-tech.com/forums/showthread.php?t=2980759

jimboc88

and will there be any difference between the 99-00 ecu from the 96?

Kista20

Actually all 96-00 hx's are obd2a, I have both a 97 and 99. The main differences between the y8 & y5 is the cylinder head, egr, 5 wire o2 sensor, ecu and the cat. If you can find one in a junkyard somewhere you could get the wiring harness and ecu and perhaps anything else you would need.

HondaPartsHero

Its not simply a plug and play event. You'll need to wire up the 5/7 wire O2 if your vehicle is 5 speed. If you don't have the HX O2 its about $300 dollars if I remember correctly. Also you'll need to wire up the EGR valve. But seriously why did you start another thread? I thought you were going to just use the Y8 head on the Y5 block? I'm confused.

craiglewis22

this crank is junk and I cannot get into market place yet to see if anyone's got a cheap D16 shortblock forsale. any resources for used honda stuff in Phx AZ?

craiglewis22

I need 5 posts to 'graduate' so here goes

sumocivic

Ok I know I'm a little late but I have the some problem only I'm getting rid of my y5 head and intake manifold trying to see if I need to repin the hx harness for my ex ecu any help would be great (oh sorry for jumping in on your post)

ThiRteeN

If you end up using the Y8 head and Y5 block, you have to get the knock sensor off the Y8 block and put it on the 5

Mahalaleel

I'm doing a similar thing. I'm trying to put a d16y5 from 1997 into a 1999 d16y8's place. Would I just need a wiring harness and ECU for it to drop in and bolt up, or would I have to do some splicing, and sensor purchasing...

Hybrid96EK

Th thread is loaded with false information. Let me clarify a few points.

Only the auto hx's have a three wire iacv. It's mounted to the bottom on the throttle body. The manual uses a two wire on the back of the manifold.

The y8 and y5 head CASTING is identical. Therefore the ports are not smaller like someone mentioned. They are the same size.

All 96-00 hx's were obd2a.. This has already been clarified.

The auto hx's used a standard 4 wire o2, the manuals had the 5 wire o2. It's not $300 either, but if you want one, I've got one for $250 shipped!

Hx runs as a 12 valve engine at lower rpm. Vtec enables the other 4 valves making it a 16 valve engine at that point. The egr is used to heat the intake charge when in lean burn mode.

People who bag on the hx engine are te ones who don't know crap about it. It's only 12hp shy of the y8. Your not going to notice much of a difference if coupled to the same transmission. These engines can easily get 40+ mpg in manual form. Seen the price of gas recently? 12hp doesn't seem like much considering the savings you could see.

Mahalaleel

Thank you for those clarifications. What do you think would be more cost effective: Transferring parts from an overheated D16Y8 to the D16Y5 block (replacing all gaskets and hoping that the heads and other parts weren't damaged)

OR

Dropping the running d16y5 into the coupe body and splicing, dicing, and doing whatever it takes to get it running.

?