-engine idle cycles from about 1500 to 1700 @ about 1 Hz
-Check Engine light on with NOK sensor listed as root cause

I've read various similar forums/threads suggesting I need an "OBD1 P08 ECU", and/or an "obd2a to obd1 ecu wiring harness conversion", but when I bought this engine from "Tigerautoparts.com" there was never any mention of having to change the ECU, or what year and/or type (obd1 vs 2) ecu that it was made with originally.

Any help would be greatly appreciated!

 

Sorry, forgot to mention...
The civic is a '99 ex coupe, D16Y8 original engine swapped with a D15B JDM engine from tigerautoparts.com.

 

Tiger wouldn't have mentioned that you need a different ECU. I'm guessing the engine is OBD2b if it lined up with your current harness without issues. If that is the case, that mean is has 2 vtec solenoids. If you swapped from a Y8, you have a knock sensor already wired, you might have just not hooked it up. There is a lot of info out there on the JDM D15B. The ECU meant for the OBD2 D15B is the P2J. Unfortunately, the P2J's for manual transmissions are very rare and expensive if you find one. A lot of people use the p72 ecu and map it for the engine.

There's a good amount of info on my thread here:
https://honda-tech.com/forums/honda-civic-del-sol-1992-2000-1/jdm-d15b-3-stage-p2j-ecu-egr-o2-sensor-wiring-checklist-pics-2802636/

 

Thanks dj!
First let me say, I had a local (reputable) auto shop do the engine swap for me, so I need to run all of this by them, i.e., harness lined up w/o issues, knock sensor hook up, etc.

...but I'm pretty sure the knock was hooked up, since the shop told me the error code was knock related. Apparently, they got the knock code to go away (I guess by resetting), but after running the engine for a little bit it came back.

Q's:
1) How do I find out the OBD status of old versus swap engine? Is it stamped somewhere?
2) When you say "map it (p72 ecu) for the engine", do you mean replacing current map sensor with a different one?...or is map adjustable? Please provide more info?

I definitely think it's map related, i.e., excessive air is getting into the manifold for some reason?...maybe IACV issues? Other threads suggest unplugging the IACV to see if it has any effect?

Sorry for all the dumb questions, I'm pretty ignorant when it comes to these high tech engines...I'm still living/eating/breathing in a carburetor world!

 

...just spoke with the shop owner who replaced the engine for me.

He tells me they had to replace the harness due to some lines that were inadvertently cut during the engine removal, so it has a new wire harness in there and it all matched up with existing ecu.

He thinks the high rpm might be due to a "stuck" IACV and said he will run some cleaner through there to see if it loosens it up. If not, he says it (IACV) will need to be replaced.

I'm wondering if I'm headed down a long/expensive road? Any additional thoughts?

 

IACV's are definitely a costly replacement if you have to pay for a new one. Search up vtec solenoid on google images and see if you have 1, 2, or none. That will help narrow down the year. Also, if you're using your current ECU, chances are its OBD2b. When I said map the ecu for the engine, I meant use a P72 ecu and chip it for the d15b. I'm not too savvy in that area but there's a lot of info out there if you look for it. It could be idling like that if the IACV is for an Auto and your car is Manual, or vice versa. You can always clean the IACV before replacing it, it's pretty easy to do.

 

dj, here's a pic of the same config I've got:

 

Also, upon unplugging the IACV, the engine idle rpm dropped to a "steady" 1200'ish.

On another forum, someone suggested that if there was no difference plugged/unplugged IACV then it is stuck and needs cleaning. Since there was a response, I assume the IACV is functional, but has the wrong ecu driving it? They suggested I get a P08 ecu with an obd1>obd2 harness conversion.

Assuming I need a P08 ecu, which is for a 92-95 D15B JDM (the engine I just swapped for), why are they suggesting an obd1>obd2 harness conversion? With a P08 ecu, everything should be obd1, right?

 

i'm sorry but what shop gives a customers car back with cel's and problems? sounds, and looks like, you bought an obd1 d15b vtec engine. i'm curious as to why they thought they had to cut your engine harness? it's fully un plugable from your old engine... to effectively get the knock sensor code to go away you'll need to wire up the knock sensor from your old motor onto your new one if you don't want to convert back to obd1.

as far as the iacv issues first make sure your coolant is fully topped off and bled properly. i had a lopey idle once when i didn't bleed my cooling system... if that's fine, you might have a small vacuum leak which is causing the engine to see extra air, and the iacv is trying to compensate for it. if that doesn't work, try swapping out the iacv for a known good one.

 

I'm not familiar with that ECU, but if it is OBD1, you'll need a conversion harness at the ECU down in the kick panel because your car is OBD2, and when they put a new harness in (I'm guessing OBD1), they must have left it OBD2 at the kick panel so it could plug into your current ECU.

Ok so you know your swap is a 92-95 D15B, that's good. I'm sure you can figure out the ECU you need for it by searching, you might have already found it's the P08?

With the IACV, check how many wires it has (2 or 3). Is your car a manual or auto?

 

Apparently, the shop isn't as reputable as I thought? I'm thinking he just plugged in the existing (ob2) harness to the sensors that came with the D15B vtec and started it up. Since there were no (major) issues figured he was done with it. I'll check the coolant level tomorrow, but based on other threads explaining similar circumstances, it really sounds like the issue is the ecu.

 

Yes, 92-95 D15B vtec 5-spd man tranny. Yes, P08 (http://hondaswap.com/reference-mater...cu-list-29129/) is the correct ECU. IACV = 2 wire. Also, according to the chart in the link provided the P2P (existing ecu) uses obd2, vs obd2b.

Someone mentioned to me there would be no issues using the P08 (obd1) ecu with an obd1>obd2 conversion + existing ob2 harness + D15B (obd1) vtec engine. However, that I should use the dizzy + injectors from the D16Y8...does that make sense?

Would it make more sense to just swap out the obd2 harness for an obd1? How much of a pain is it to swap harnesses?

 

OBD2 has OBD2a (96-98) and OBD2b (99-00). Your P2P is OBD2b. It will work well with your d15b if I'm correct.

I think the injectors from the y8 are the same as the d15b. If the d15b dizzy works then I wouldn't change.

It's running fine except for the idling right? I don't think you really need to change anything. Honestly, just get some carb cleaner and clean your IACV. It is very easy and even if it doesn't fix it, then you know for sure you need to replace it.

 

It's running fine, but I haven't verified gas mileage yet nor whether or not the vtec kicks in...plus I've got a constant CEL for knock.

Still leaning towards changing the ecu out, if for no other reason than that's the ecu made for the JDM D15B vtec.

Thanks DJ.