D16Y8 to D15B Engine Swap Issue

dhudge

New Member
No the p08 is a obd1 ecu. And it won't matter if the motor and harness is obd2 it will still work...
Sorry for more stupid questions hondafreak, guess I'm just hard-headed and I want to make sure I got this right:

1) I need an obd1>obd2 harness conversion in order to use the existing obd2 harness with the P08 (obd1) ecu, correct?
2) When you said "it won't matter if the motor and harness is obd2 it will still work"...I thought, based on previous conversations, you said (& according to http://hondaswap.com/reference-mater...cu-list-29129/) the D15B JDM is obd1? If so, are there any issues with the obd1 engine utilizing the obd2 harness?
 

hondafreak513

Well-Known Member
1)Yes
2)No there won't be any issues using the obd2 harness just use the y8 dizzy and injectors..
do you have a obd1 harness?
 

dhudge

New Member
1)Yes
2)No there won't be any issues using the obd2 harness just use the y8 dizzy and injectors..
do you have a obd1 harness?
o $hit, the D15B dizzy & injectors won't work?
It's running now with the P2P ecu and obd2 harness?!?!

...no, I don't have an obd1 harness.
 

K2e2vin

Senior Member
You don't need to swap to an OBD1 harness...your car is OBD2.

Don't need to swap distributors; they both have the same sensors(at the Y8 doesn't have the CKP sensor); where did they wire the CKP sensor anyways? JDM D15B doesn't have it on the crank like the D16Y8. You can add it though by swapping to the Y8's oil pump.

What I think you should do: check the TPS and MAP sensor before continuing. Or, swap over the D16Y8 throttle body if it's known to be good. Also, no codes?
 

hondafreak513

Well-Known Member
You don't need to swap to an OBD1 harness...your car is OBD2.

Don't need to swap distributors; they both have the same sensors(at the Y8 doesn't have the CKP sensor); where did they wire the CKP sensor anyways? JDM D15B doesn't have it on the crank like the D16Y8. You can add it though by swapping to the Y8's oil pump.

What I think you should do: check the TPS and MAP sensor before continuing. Or, swap over the D16Y8 throttle body if it's known to be good. Also, no codes?
This too but you can run the obd1 ecu with the motor setup for obd2.. I ran a p06 in a 99 civic with a d16y7, ran fine no problems..
 

dhudge

New Member
You don't need to swap to an OBD1 harness...your car is OBD2.

Don't need to swap distributors; they both have the same sensors(at the Y8 doesn't have the CKP sensor); where did they wire the CKP sensor anyways? JDM D15B doesn't have it on the crank like the D16Y8. You can add it though by swapping to the Y8's oil pump.

What I think you should do: check the TPS and MAP sensor before continuing. Or, swap over the D16Y8 throttle body if it's known to be good. Also, no codes?
Don't know the code, but shop says the CEL = knock
...but there may be other codes they haven't disclosed. I don't know what the shop did with CKP?

One question...
Why do all that, i.e., TPS, MAP, oil pump, throttle body, etc., when it would all be taken care of by swapping for P08 ecu...the one that's made for this engine???
 

K2e2vin

Senior Member
Swapping ECU does not solve sensor issues. ECU processes inputs from the sensors to meter fuel and time ignition. Feed it bad information, it will incorrectly meter fuel and time ignition. 88-00 Civics all use the same TPS and MAP sensor ranges(DPFI TPS just operates backwards).

JDM D15B VTEC doesn't have anywhere to hook up a knock sensor; while the stock D16Y8 ECU looks for one.

TPS and MAP issues are unrelated to the ECU function. If they output a bad/incorrect signal, or no signal, then the ECU will not compensate correctly. I've personally had a couple TPS go bad(and one MAP); either the range was out of whack, didn't output correct min/max voltage, or simply just needed to be adjust. A functioning TPS or MAP sensor that is outputting incorrect information will not throw a CEL. This is what I recommend you check first.

CKP sensor; this is the only thing I'd have to check into but it's related to wiring also. I know the 96-00 Civics use a crank sensor on the crankshaft, but I don't know if it still has it in the distributor. And if so, how is it wired. Again, this is directly related to wiring.

This is like being handicap due to severed nerves in your spine; a brain transplant in the same body would still result in being handicap even though it's a new brain.
 
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dhudge

New Member
Sorry Kevin, but you lost me on 95% of what you said. The one thing you wrote that struck a chord is this...

JDM D15B VTEC doesn't have anywhere to hook up a knock sensor; while the stock D16Y8 ECU looks for one.
I'm certainly not the sharpest "tool in the shed", but what makes sense to me is if I replace the existing D16Y8 ecu (P2P) with the the ecu that is made for the D15B (P08) then there can't be any misinformation for it (P08 ecu) to process because it was made for the engine (& sensors on that engine) that it is receiving info from, correct???

...or am I missing something?
 

K2e2vin

Senior Member
I'm saying to check the TPS and MAP sensor because even if you switch ECU and those sensors are outputting incorrect signals, it still wouldn't run right.

Pretty much any D16 ECU would be able to run a D15B VTEC "fine", hence why I believe you have issues somewhere else too.
 

dhudge

New Member
I'm saying to check the TPS and MAP sensor because even if you switch ECU and those sensors are outputting incorrect signals, it still wouldn't run right.

Pretty much any D16 ECU would be able to run a D15B VTEC "fine", hence why I believe you have issues somewhere else too.
Okay, it's sinkin in what you are saying, but other's have said that the ecu's do process the signals differently, i.e., the D15B doesn't have a knock sensor, right? So with the D16Y8 ecu not getting a knock signal, would that somehow affect the way the engine is behaving?
 

K2e2vin

Senior Member
It may affect it from a performance stand-point(throw it into limp mode); but this is not at the point where it feels like it's going to buckle and stall. The ECUs process signal the same, but knock sensor is an "add-on". If it detects knock it just pulls timing.

The TPS and MAP sensor affect the engine more so than the knock sensor. Those sensors are constantly monitored and how the ECU keeps up with load measurements. I keep telling you to check these because it's pretty easy to do and known to cause problems exactly like what you're experiencing.
 
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dhudge

New Member
...I keep telling you to check these because it's pretty easy to do and known to cause problems exactly like what you're experiencing.
And I thank you for that! I'm not a guy looking to race or hot rod this civic...just want to get the swap engine to function properly at the least cost.

Please note, the buckling/stall-like circumstance only occurs when I put a lload on it below the current idle rpm, i.e., when i shift into 2nd at or below ~1500...once I get above that rpm this behavior goes away. Thought I'd mention this in case there was any misunderstanding.

Sorry for being so technically challenged, but what's your recommendation for "checking TPS & MAP" sensors?...replacement?
 

K2e2vin

Senior Member
The TPS can be checked with a multimeter(turn the car on and the range should be something like .5v closed and .45v fully open). For the MAP I recommend just swapping that or the whole throttle body assembly from your D16Y8(the TPS is on by rivets and the MAP is mounted on the throttle body also).
 

dhudge

New Member
The TPS can be checked with a multimeter(turn the car on and the range should be something like .5v closed and .45v fully open). For the MAP I recommend just swapping that or the whole throttle body assembly from your D16Y8(the TPS is on by rivets and the MAP is mounted on the throttle body also).
Okay, I have an update...a rather embarrassing one!

I just now found out from the shop that the D15B intake manifold and throttle body assembly was all swapped (for the D16Y8 assembly) at the time of the engine swap. I don't know if I'm more embarrased about starting this thread with the wrong infor, or more pissed about not be told all that was done at the shop during the swap.

Okay, so now we know the TPS & MAP sensors should be okay, since they were okay prior to the engine swap. Here are some thoughts I have:

Is there a difference in MAP & TPS sensors for the D15 versus the D16 engines due to there difference in displacement?

Since the D15B does not have a knock sensor and the P2P (obd2) ecu is looking for it, how do I get rid of the cel?

(Damn...it would have been a whole lot easier if the shop would have just replaced the p2p ecu for a p08!!!)
 

hondafreak513

Well-Known Member
And hope they blocked of the vacuum hole in the center of the intake.. This will cause a problem if they didn't then you will need to take off the intake and use a strong type of tape or something to block off the vacuum hole in the intake..
 

hondafreak513

Well-Known Member
Intake_port1.jpg

The holes circled in red need to be blocked off when put on a different motor, they will cause a vacuum leak and could be your problem..
 
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