D16Y8 to D15B Engine Swap Issue


New Member
Yeah it took me and a friend months to figure that out..
So, what were the symptoms that led you to finding these "hole" differences?

I'll try switching the TPS/MAP sensor plugs first, the knock sensor "trick" second and plugging the holes third.

I'll update you when I find the cause.

Thanks Kevin & freak, for all your help!


Well-Known Member
It had a rough idle and ran a little rough too.. try spraying some brake cleaner across the top of the intake to see if it is leaking.. and the tps should have a red/blue , green/white and yellow/white wires on it..


New Member
Well guys, it turned out to be the four hole difference between the DB16Y8 manifold and the DB15 head was what caused the whole problem. In fact, the vacuum from the holes caused the manifold gasket to fail, so when I sprayed carb cleaner near it was very easily detectable...thanks freak. Ended up plugging the holes with wood "golf tees". I was gonna try aluminum tape, but if the vacuum caused the gasket to fail, figured it might punch through the tape. Also tried JB weld, but it didn't want to stick to well...guess I coulda roughed up the surfaces? I suppose if the "tees" don't last, I'll pull it off and mig weld the holes up, but for now it's doing the trick. Decided to (eventually) replace the obd2 (p2p) ecu with a (p08) obd1 with a conversion harness, to get rid of the cel instead of the knock sensor trick. The "trick" seems too "jerry riggish" for me to be comfortable with.

Anyway, thanks freak & kevin for all your help. Maybe this thread will be useful to someone else experiencing similar problems.


Well-Known Member
Hey no problem glad to help.. And you can use the aluminum tape or duck tape. Either one will work that is what my friend used and I did the same thing when I used a y8 intake manifold..


New Member
Kevin & Freak,
Just out of curiosity...
I was gonna run the car for a while as is, without changing the ecu, and monitor gas mileage. If gas mileage is sufficient, I was thinking of letting it go and just buying a code reader to check it every now and then for "other than knock" sensor codes.

What's your take on that approach?

Also, if this works out do you have any suggestions on mapping the current (p2p) ecu for the D15B engine? Right now, the vtec doesn't kick in till about 5700'ish, which makes little sense to me since I never let it run that high, i.e., I'd want the extra power around 4000 for it to do me any good. Can the p2p be chipped for that?

Guess ur thinkin if I'm gonna go to all that trouble, might as well get the programmed p08 ecu, eh?


Senior Member
It should run fine as long with the CEL; but you can do that piezo trick if you want the CEL gone.

P2P cannot be chipped/remapped. I'd also advise against lowering the VTEC engagement point(at least that low). VTEC is just "another cam" and chances are you'll lose power by lowering the engagement point(creating a dip in your powerband).

You can use P28; easier to get a hold of. P06 and P05 will work too if you add VTEC transistors.
Last edited:


New Member
Same issues here

My brother and I just finished the swap today. From d16y8 to d15b jdm three stage. Swapped intake exhaust manifold and dizzy from the y8 to the d15b. Car fired up and ran between 1600 and 1800. Few minutes passed as we were attempting to adjust the idle then idle started bouncing up and down. Kind of stuck at this point. Do you have any ideas on what the issue is?


Well-Known Member

The holes that are circled in red need to be sealed up I use aluminum tape or duct tape... If you did this check for any other vacuum leaks or air in the coolant system..


New Member
Was having same problem in my jdm d15b in my eg and all it was, was the plug next to the iacv was in the wrong spot so the iacv was not even working. Switch plugs and see if that fixes your idle. the plug to the right of iacv is the same as the iacv plug. Simple mistake, simple fix


New Member
vtec problem

i have the obd2 d15b in my 96 ex but didnt hook up the vtec yet cuz i dont knw how to and dont wanna slice and dice and be ass out i want to have my vtec runnin on my y8 cpu and wiring harness if any info plz help hit my email wit info


New Member
hey guys im new to the sight. all your info has been really helpful for my issue as well. today i bought a 97civic ex. found out he swapped the d16y8 with a d15b vtec (not the 3 stage) from attarco. car feels seems like its running rich (which i now know is because the p2p is looking for the crank signal). also seems like the engine is really restricted, like im not getting its full potential. this could be because the new clutch he put in needs to be adjusted really bad (doesnt catch until my foot is basically off the pedal) and i think its slipping.
my questions are.
1. is the p08 or the p28 better for the d15b?
2. can they both be chipped and which one is better for chipping?
3. a obd2 to obd1 conversion harness IS needed?
and 4. all i have to do is plug in the new ECU start the engine and go?