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Discussion Starter · #1 ·
Im new to this forum and have a question about my 2000 civic ex. The previous owner swapped it to a d16y5 and I know the vtec in these engines is supposed to engage around 3000 rpm. Instead it kicks in hard around 6000 rpm. I checked the vtec solenoid gasket and the cleaned the screen still the same problem. Oil levels are good just put in fresh oil. It has the correct ecu for the motor so I dont really know what it could be other than oil pump. Sorry if its an obvious answer im not super knowledgable on cars in general.
 

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'99 Civic EK1
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D16Y5 head comes with E-VTEC like D15Z6.
That kind of engine "kicks" arround 5500rpm and has econo mode until 2500-3000rpm (using his stock ECU)

If you wanna know when kicks vtec, you can pin the ECU with a led, and when it lights you will see it. I tested once and if you flat out will kick at 3000-3200 but you wont feel it. Its really progresive on evtec
 

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Discussion Starter · #3 ·
Yeah its styaing in econo mode until like 6200 when I floor it. Then all the power comes in for like 1000 rpm. So theres no mid range power at all
 

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93 Civic HB SI
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From the way you say you can feel VTEC engage, it seems like the circuit is functional, which is good.

Your avatar shows you as in the US, so a 2000 civic EX should have come with a D16Y8, which explains why you say VTEC engages at like 6K (spec is 5600 stock, close enough).

If the engine and head is a true Y5, meaning it operates in 12 valve mode until "VTEC" switches over to 16 valve, you need the Y5 ECU to change the VTEC-E crossover point, but that's not the only thing to consider here.

That engine came in the 1996-2000 civic HX. If you simply grab an HX ECU and plug it into your EX chassis, the HX ECU will throw catalytic converter codes when using the EX cat, as well as the lack of OEM wideband sensor present. The HX chassis is the "fuel efficient" version in USDM, and that ECU had special feedback mechanisms and emissions control devices (close head mounted cat, stock upstream wideband, EGR, etc) in place to play nice with the lean burn characteristics that it was tuned for.

If you don't have those emissions control devices installed, wired in properly and functional so that an HX ECU can actually monitor and use them, your in a tough spot. It'll run crappy and the CEL will always stay on.

Honestly, the easiest and cheapest way to:

A) get your power back,
B) not spend a fuck ton of money on emissions control devices on a 20 year old car
C) not have to buy an ECU

Would be to swap a Y8 head, intake and exhaust onto your Y5 block.

You could pull all of that at a pull a part for like $150 bucks, send it to a machine shop to cut it flat, do a valve job and install new valve stem seals for another $100 bucks, and get a head set, timing belt and waterpump from eBay or Amazon for another $80 bucks and swap it in the car over a weekend.

You'll have more performance, knock out a bunch of good preventative maintenance while your at it, and still be cheaper than getting an HX ECU.
 

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It has the correct ecu for the motor so I dont really know what it could be other than oil pump.
Are you SURE you have an HX ECU installed? VTEC changeover wouldn't be at 5600 rpm then...

1996-2000 HX = P2N (VTEC @2500 RPM)
1996-2000 EX = P2P (VTEC @5600 RPM)

The way you describe the crossover sounds like the Y5 is trying to run like a Y8 with a Y8 ECU.
 

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Discussion Starter · #7 ·
Shoot yeah your right it is the Ex ecu I mixed up the names of them. So would a z6 head work as well? Theres an aftermarket exhaust and headers and no CEL so would it be pretty plug and play if I found a good quality head? Thank you I probably never wouldve checked the ecu again since I was so sure it was the right one.
 

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Shoot yeah your right it is the Ex ecu I mixed up the names of them. So would a z6 head work as well? Theres an aftermarket exhaust and headers and no CEL so would it be pretty plug and play if I found a good quality head? Thank you I probably never wouldve checked the ecu again since I was so sure it was the right one.
It does. As long as you run the Z6 cam gear and the appropriate head bolts.

Pretty sure you'll use all D16Y bolts, but you'll need one D16Z bolt somewhere. There could be other nuances as well, I personally can't speak to all of them.

This swap has definitely been done before, there should be tons of write ups that go over all the particulars. Use the search!
 

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Swap to a d16y8 head. you will want the extra compression. ANd if you dont want the d16y5 head anymore, its worthwhile selling on the forums to someone who wants to kick off an economy build.
 

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Yeah its styaing in econo mode until like 6200 when I floor it. Then all the power comes in for like 1000 rpm. So theres no mid range power at all
This reminds me of the initial d episode when Bunta swaps in a new engine to the 86, and Takumi doesn't realize the new rev limit is 11,000 RPM and powerband is now from like 7000-11,000 haha.

When he's driving it initially, he feels the surge of power at like 7K, but shifts at 8K, and doesn't (yet) understand why its so much slower of a car compared to the old engine haha.

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Try revving the engine to 11,000 rpm and see if that fixes it :)
 

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Ok will do. Thanks
Yeah, the Y8 head will honestly be easier all said and done, less parts considerations. Plus youve already got an ECU and block ready to work with that head.

Y8 heads really are dime a dozen at any pull a part. Just make sure to grab the Y8 intake manifold! You'll be restricting that head with any other intake, especially if trying to run the Y5 intake haha.
 

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Likely it still has the Y8 stuff, as the Y5 intake manifold looks very similar to a Y8, with tiny throttle throat and smaller runners. Worst case, get the dremel out.
 

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Discussion Starter · #14 ·
Whats the easiest way to tell if it has the y8 intake manifold and yeah I agree after doing some research the y8 head would be much easier
 

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remove the throttlebody and measure the throat

I dont think the codes are different. If they are, it will be on the BACK of the plenum. Find #1 runner nearest driver, look behind.
 

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P2K is d16y8 by the way.

Plus d16y5 has EGR stuff on it
 
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