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I replaced my honda civic d15z4 engine with a d16A.

Apparently, VTEC engages at 5500rpm on these engines.

My car is still practically standard, I'm not sure if it does switch over, if it does, the sound is very subtle, but I'm not sure that the place I bought the engine from gave my mechanic a matching ECU (I'm not sure whether I would need the same ECU to run this engine in my car)

So my question is, will the VTEC switch over happen without the PBB-J61 ECU that the d16A was released with?

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3 Answers 3

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VTEC - Variable Timing and Lift Electronic Control

VTEC requires the ability to understand the state of the environment and motor in order to change the valve timing.

Various sensors from oxygen, engine rpm, barometric pressure, engine temperature, air temperature, oil pressure, throttle position effect the the various timing events of a VTEC engine.

  • spark
  • fuel shot
  • cam timing

All of these inputs effect how and when the ECU will control oil pressure to effect cam profiles at various rpm's.

The ECU for the correct motor is necessary in order for the VTEC system to function properly.

There are model years and series that have overlap in which an engine may perform reasonably with a different model year engine but it is highly recomended that ECU match the year and model for which it is designed. The ECU will require the matching harness as well as there are additional input sensors on VTEC engines.

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  • will the VTEC switch over happen if I put ANY SOHC VTEC ECU in my car? during my search I've found this info, but thanks. Just need the question answered before I look for best practice though. I just need vtec right now (;_;)
    – pythonian29033
    Commented May 20, 2015 at 15:25
  • I don't want to represent using the wrong ECU with a particular motor and say it will work or should work or........I don't want to make claims like that. Best solution is to buy the right ECU for the VTEC. I can't know the answer to that question. Will ANY SOHC ECU work with your motor? Dude, that's a one helluva reach on that question. I don't know how anyone could truly know unless they deal with that on a daily basis. no points for my answer? :( bummer.....
    – DucatiKiller
    Commented May 20, 2015 at 15:46
  • I work for points :)
    – DucatiKiller
    Commented May 21, 2015 at 7:08
  • ok, 10 pts for effort, but technically you're making me wanna ask more questions now
    – pythonian29033
    Commented May 21, 2015 at 7:37
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    Based on the discussions I have had with folks on mods for my car (Subaru, not Honda, but I feel this will be similar) you need an ECU specific to your engine, or for aftermarket ECU's, one which can be set up for your engine.
    – Rory Alsop
    Commented May 21, 2015 at 9:05
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Yes you will need a compatible ECU for your new engine. The ECU reads multiple signals from your engine and will change your camshafts timing accordingly. When your engine gets high rpm, your valve timings should be adapted to get the VTEC boost.

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  • hey thanks for answering so quickly man but will any SOHC vtec ECU work? Cos the engine was imported from europe I think and they never shipped cars with d16A engines into South Africa where I'm from, so it's gonna be hard, if even possible, to find the matching code ECU locally
    – pythonian29033
    Commented May 20, 2015 at 12:59
  • You also need to make sure you've got the proper wiring harness, so those extra signals the ECU uses will get to where they need to go. If you don't have it, chances are your new ECU will simply throw codes and refuse to start.
    – TMN
    Commented May 20, 2015 at 18:24
  • thanks, don't worry though, I'm going to have one of the local honda racecar tuning mechanics work on it, so he'll know what he's doing, but it's best to know these things anyways you know? that way you can look up the prices and you know you're not being ripped off
    – pythonian29033
    Commented May 21, 2015 at 7:39
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Any VTEC ECU should work as long as the VTEC solenoid is connected and wired to the ECU. I have a 94 integra with a B18C1 (DOHC VTEC). When I bought the car it had an ECU for a SOHC VTEC engine. VTEC would still engage. You might be able to test it with a test light on the pigtail for the VTEC Solenoid.

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    If you have the DOHC engine and an SOHC ECU you will not get one of the cams to change it's profile. There would not be a sensor or an actuator for one of the cams. You might 'feel' the VTEC kicking in but only on one side, intake or exhaust....but not both. It's just not possible.
    – DucatiKiller
    Commented May 21, 2015 at 21:31
  • My DOHC engine only has one VTEC actuator on the exhaust cam. Its a 94, so this was in the early days of VTEC. I never said it was optimal, the car ran MUCH better with the correct ECU.
    – rpmerf
    Commented May 22, 2015 at 12:24
  • so @DucatiKiller you reckon dohc ecu on a dohc vtec and sohc ecu on a sohc vtec should work?
    – pythonian29033
    Commented Dec 12, 2016 at 9:16
  • I know much more about these things these days. . .obviously. if you had a programmable sohc ecu you could tune it to work properly on dohc, but without any changes obviously dohc ecu wouldn't have restricted fuel flow
    – pythonian29033
    Commented Apr 22, 2020 at 17:13

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