1999 Honda Civic lx d16y8 swap


New Member
Jan 14, 2022
1992 Honda Accord lx (h swap) 1999 Honda civic lx (d16y8)
I have this 1999 Honda civic lx that’s a 99, I swapped the d16y8 in place of the old y7. I’m using a 98 p2p ecu with a conversion harness, here’s the predicament I’m in. It runs good on the y7 ecu, but the second I hook up the y8 ecu through the jumper it’s idles fine on start up but after no more than 30 seconds the idle slowly climbs to 2000rpm then misfires audibly then the rpm drops back down, when driving it’s jerky and is slow to accelerate, not to mention it sounding like sh*t. I have the vtec pressure switch and vtec solenoid wired up as well as the knock sensor. Anyone know what’s going on? (Cel is on I don’t have a code reader so not sure what for, cel is also on with the y7 Ecu


Active Member
Mar 2, 2010
Just an FYI... this forum is based in Europe and mainly for the JDM EK9 Civic Type R, with a few other Honda Type R vehicles... none of which came with D series engines.
honda-tech.com would be a much better forum to ask this question in, especially if you're in the US and it's regarding a USDM model Civic and engines. And searching before you post is also a better plan. You're likely to find your issue and answer already posted.

Also, inexpensive OBD readers are readily available from Amazon, Walmart, Harbor Freight, etc. One would be a great first step towards diagnosing anything that prompts a check engine light. If you don't want to or can't afford one many auto parts stores offer free scanning, such as Autozone and O'reilly Auto Parts.


Jordan 258
Oct 11, 2013
Civic Jordan 258
probably your harness or the tune on the ecu.

AFAIK the only difference is the inclusion of VTEC and a knock sensor on the y8 as opposed to the y7