CM5Falco

Hello Honda-tech!

I'm having a couple of issues with my 4DR ek.
First off, i swapped my d16y8 for A Jap spec D15B.
When I swapped my motor i don't really remember which intake manifold I used (due to it being a while back).
So after the swap was completed when i cranked the motor, the car started, but when idleing it rev's up and down as if it were leaking air! also when i drive it i cannot pass the 5200 RPM mark.
just wanting some opinions on why that is and how i can fix it!
I'm pretty sure i have to just swap the manifold just not sure which one to get.
I was also thinking it might be the ECU but not really sure.

if you've had this issue before please comment below and let me know how you got around it!

Thanks guys!

CX-Adam

Is it surging right away or after it warms up? Don't buy a new manifold. The manifold is not the problem.

CM5Falco

It starts right after it gets warmed up! It idles fine cold

CM5Falco

do you think it could be the ECU?

mk378

Generally when you do this swap you want to re-use all the manifolds wiring and controls that came with the car, and just change the engine itself (block + head).

Do you have the proper IACV? USDM auto EX uses 3-wire, manual EX 2-wire.

Make sure the cooling system is completely full. Park on a level surface or facing uphill, then take the radiator cap off when cold.

CM5Falco

I mad sure to put all the original parts back on, the only thing is I think my IACV might be the issue. Any ways to test that? Also when I disconnect the IACV the car comes to a lower idle (around 1k) but it Bogs during low RPM's. I thought it might of been a ECU issue so I tried a non vtec ECU, but it didn't help.

mk378

"Bogs at low rpm" is not an idle related problem. Have you set the spark timing? If it does not come in near the middle of the adjustment range the cam timing may be off.

CM5Falco

I did what you said with the cooling system and it stopped the fluxuating idle! Now the only thing is that it idles very high (2500 RPM) and I still can't seem to pass 5200 RPM's.

Jimi Hondrix

Clean throttle body very well. Search for vacuum leaks. IAVC gasket can flatten out and draw in air.

.If it's a Vtec engine then make sure the Vtec solenoid is connected to wiring harness. Also, check oil level..low oil could cause Vtec to not operate properly.
Might want to pull Vtec solenoid and clean the screen (part of gasket).

CM5Falco

I actually forgot to mention it's a non VTEC motor!

mk378

Non VTEC engine will require changing to non VTEC ECU. Otherwise it will find VTEC does not work and throw a code and impose a rev limit the first time you try to go to VTEC rpm.

If you have a 2 wire IACV, unplug it and see if the idle drops to lower than normal or stays high. This test does not work on 3 wire IACVs.

CM5Falco

i switched over to a "P2E" which is the non vtec version of the computer I have and it idles at 1500 RPM's now but it won't allow me past 2500 RPM's

mk378

Non-VTEC ECU then requires you to have a 3 wire IACV and rewire for it.

Can't rev over 3000 is almost always the timing belt being one tooth out of time. Have you set the spark timing?