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1989 Crx HF; DOHC swap in progress; mainly stock minus a few updates.
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Discussion Starter · #1 ·
hey everyone,
Just looking for a bit of confirm or deny here to make sure i got my **** straight.
just pulled the stock engine. built DOHC ZC going in. should have everything with it including trans (gotta untarp and double check since this projects been sitting for about a year)...
My knowledge is as follows (roughly);
-should mate to trans respectively but going to check all seals and probably get a new clutch.
-should bolt right in to existing engine mount locations.
-headers will bolt on but need port matching unless using ZC headers.
- have dizzy conversion plug (converting obd0 to obd1), but still need ecu conversion plug ;

" to run the engine as OBD1, you will need a OBD0 to OBD1 ECU conversion jumper harness along with the OBD1 ECU and OBD1 distributor, TD43U - the factory OBD1 DOHC ZC ECU is a P29 - you can use a P06 ECU, but it won't work very well - you can chip the P06 ECU to run the P29 fuel and ignition maps - if you use the P06 ECU, you will need to use a 4-wire O2 sensor - the P29 ECU uses a 1-wire O2 sensor - again, you would need to swap out the OBD1 injectors for OBD0 injectors or you can use the OBD1 injectors by removing the injector resistor box from the system - you would need to swap connectors at the distributor or purchase a distributor jumper

in either case, there are a couple of things that will need to be done with the wiring - you need to use the HF engine harness on the ZC - it will have one connector which went to the EGR valve that won't be used - the OBD1 engine has the cooling fan switch on the thermostat housing - the HF engine has the cooling fan switch on the back of the block next to the oil filter - you will need to swap a connector onto the cooling fan switch wires so that it will plug into the switch on the thermostat housing - the HF has the MAP sensor mounted on the firewall inside the black control box - the OBD1 ZC has the MAP on top of the throttle body - you will need to extend the wires for the MAP and install a connector so that it can be plugged into the MAP on the throttle body


you will also need 88-89 Integra upper radiator hose ".

-So basically a few connections to make sure the electronics hook up correctly, a radiator hose, and the correct or correctly chipped ecu and this thing should be back on the road again;
  • i have an extra engine harness, 3 ecu and a few other things.
  • my only question ecu wise is unless i have the p29 ecu is the vehicle going to run lean or rich?
  • any other tips for the conversion/swap i need to know since this is going in an HF and not DX or SI?

This is my first honda anything. worked on plenty of other things but not hondas. but got the old engine out yesterday so just trying to get my **** together because there is a million different posts and questions on this topic across the threads and forums from many different dates, Ive done a ****load of research and watched videos, and I'm just trying to get the dam thing back on the road (daily driver). i'll worry about axles, a different trans, and whatever else later. i would just prefer to get it done correctly so i dont have to worry about any wild issues comming up in the future (having to pull engine or replace again) once the swap is in that might lead to more frustration (damage to things because of incorrect fuel input or whatever else).

the reason for the swap is the bearings in the bottom of the stock engine got fried and i was told it's easier and more cost effective for the swap then to try to rebuild the stock engine. so here we are...:rolleyes::unsure:

Thanks for the time ladies and gents, again if I'm on the right track just a thumbs up will suffice; and if I'm way off any input is greatly appreciated.
 

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91 CRX SI
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To my knowledge everything you said seems to be on point. Since you are swapping into a Dx chassis and not an (HF/SI) you may need to do the MPFI conversion (if you haven't already) and also swapping out the fuel line on the fuel filter. Also if you're going obd1 don't forget to pick up a block off for the cam sensor.
 

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1989 Crx HF; DOHC swap in progress; mainly stock minus a few updates.
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7 Posts
Discussion Starter · #4 ·
Thanks for the replies. its been slow goings.
This swaps been sitting for 1.5 years, at the time i didnt even ask.... the gentleman who i bought the engine setup from had a rhd car he had bought and he said the only reason he pulled the engine was to put a b series in it. super clean. but alas it was 11 at night in virginia beach and i still had 5 hrs on the road to get back to home. so we chopped it up for a few in between him cleaning and me making sure the head and things wernt marred beyond use.... and once that was done we parted ways, i was mainly happy i had an engine that wasnt going to need a full rebuild as the first engine i bought had a fucked cam and some other issues. but at least now i have extra parts...
 

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1989 Crx HF; DOHC swap in progress; mainly stock minus a few updates.
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Discussion Starter · #5 ·
I'm going to continue to do some research....so i can help myself.

Chassis is 89 HF stock, non-mutilated. engine out and going into, so mpfi either came with the car or someone converted it... Still learning where all the sensors are on these things. although i have read about 6 different articles about OBD1 conversion and they all mention different things and multiple sensors that do or don't need to be changed depending...

Attached are some pictures i took of the engine today.. i honestly have no idea how to tell if its obd0/1 but tomorrow im going to de-grease the head again and try to find a date stamp. the only thing thats got me confused is some of the setup on this engine as you will see. its got a weird dizzy on it, or and a few other odds and ends that im not sure of what im looking at....again any input greatly appreciated. still learning about the honda stuff...

But on a lighter note. Today i got the engine bay clearned and degreased for the most part...lol its the small wins that count right haha
 

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1989 Crx HF; DOHC swap in progress; mainly stock minus a few updates.
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Discussion Starter · #6 ·
one other note for you all. the engine above came with a trans. any tips on how to identify what model its from (si, dx)? i was planning on bolting it to my hf trans and throwing in a new clutch to keep the mpgs good but if i can figure out the trans, i might just leave it together and not fiddle with it although that would probably mean having to buy another set of cv axles since i know the spline count is different for the hf compared to the other models... I'm like 75% sure its not a zc trans because it looks exactly similar to my hf one....
 

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The HF cars were all MPFI to start with; only the DX were DPFI. So no conversion needed.

There are stamped numbers on the trans, but I have heard conflicting reports on how reliable they are as to what gearing the transmission actually has.

There's a way to put the trans into gear and spin the input shaft 10 times and measure the output flange rotation, but I would have to search for a while (like in the FAQ posts here) to find that.

The HF came with a very tall geared transmission, which is good for fuel economy. Not so great for acceleration. The Si came with a much shorter-geared transmission, which is the other way around. The DX was in the middle. The ZC trans was not available in the US; it was geared similarly to the Si trans that we got, but I believe with lower gears and a taller ring and pinion ratio? (I could have that backwards.)

Anyway, I suggest looking at the list of threads stuck to the top of the listing here and in the General Discussions for anything that says "FAQ". Your answers will probably be there. :)

--DD
 
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the ZC transmission uses an intermediate shaft and larger axles - i doubt you have a ZC transmission, in which case your HF axles would work - the splines are only different at the hub end of the axle - that said, the HF axles aren't the best choice, but to use the DX/Si axles you would need to swap the front knuckles and hubs to ones from a 88-91 DX/Si/LX/EX

I can't tell from the pictures if the distributor is correct for the OBD0 DOHC ZC - the correct one would be the TD-03U which is the same as the distributor used on the 88-89 Acura Integra
 

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one other note for you all. the engine above came with a trans. any tips on how to identify what model its from (si, dx)? i was planning on bolting it to my hf trans and throwing in a new clutch to keep the mpgs good but if i can figure out the trans, i might just leave it together and not fiddle with it although that would probably mean having to buy another set of cv axles since i know the spline count is different for the hf compared to the other models... I'm like 75% sure its not a zc trans because it looks exactly similar to my hf one....
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going HF to ANYTHING ELSE get new spindles and axles for the front, HF was the only one to be weird and different size, so they wont fit unless you use the HF trans. to figure out which trans you have? put it in and figure it out by driving lol, best way... found out i have an LS trans in my B20b swap HF(it was sitting in my buddy's shop for a few years when we put it in so had no idea) glad it was the ls though... couldnt imagine having the gsr with the power my car has...
 

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1989 Crx HF; DOHC swap in progress; mainly stock minus a few updates.
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Discussion Starter · #15 ·
Sorry its taken me so long to respond. Thank you all so much for the input. its taken me a while and some finagling, but i got the wiring harness swapped over. i still have to swap the ecu, and make sure that the dizzy is correct, but other then that it was fairly easy given the info yall assisted with.

now its just swapping ecu, and managing the cooling far switch, MAP sensor, and the cylinder position sensor relocation. once those are done. i think i should be in the right area. i again have no idea of the state of the clutch, or the injectors. provided that the injectors are the ones that were in the engine (OBD0) and didn't get swapped along with the distributor by the guy who pulled it...i would assume once things are ran and adjusted, the clutch is checked, i should be able to get this thing back in and attempt to get it to run.
any tips on double checking things or small things to look out for after its all back together. i would hate to get to this point of completion get it bolted up and fry something because the dizzy, injectors, etc are incorrect, but i can look up the proper part numbers form the other sections and stickies.


since i've got the suspension pulled apart and am throwing on a set of tokiko blues that were with the engine when i picked it up (questionble at best, but i dont believe they're blown out)... any recommendations of bushing/tie rod end brands to use or not use when replacing them? otherwise i'll just get whatever is available from the local parts warehouse.

thanks again everyone.
 

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1989 Crx HF; DOHC swap in progress; mainly stock minus a few updates.
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Discussion Starter · #16 ·
Good morning/afternoon,
So, having transfered the harness over, here are some things i felt i would ask you about.
1) in the first two pictures, the latter of the 2 is pretty fuckd, is there i way to swap or fix? its on the zc engine,the working one is on the stock engine.
2) What are these two wires running from the distributor for? they're super long, 12-15 inches, but other then that i have no idea what theyre for or where they could go to unless its for one of the sensor relocations needed to convert.
3) as you can see i have 3-5 wires without a connecting plug. is there a easy way to pin these in or a better way? theyre not in the best shape.

thanks for the help. its greatly appraciated.
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1989 Crx HF; DOHC swap in progress; mainly stock minus a few updates.
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Discussion Starter · #17 ·
ANY HELP IS APPRECIATED. i guess i could just swap throttle-bodies? for the first two pictures; but as for the rest of the questions concerning the dizzy idk. thanks in advance ladies and gents.
 

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On the TPS, you can swap one and calibrate it. Or just get another Vehicle's TB.
as for the dist. Wires, you need to trace those wires to the point of origin.
you need to make sure the wiring used matches the ecu pins, different ecus use different locations for the sensors.

You need the wiring schematics for both the chassis and ecu, even if using a harnes convert plug you need to validate each pin. Some of those plugs are not 100% wired correctly for any given application.

I've rewired an OBD2 distributor to OBD1,
Havent started the car yet but each wire is used as per OBD1 wiring diagram.
I had to add a wire for the tachometer signal though(easy stuff).
 

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Awh man that's an OBD0 zc... ugh.. i went through this lol. worsttttttttttttt. it'll be alright. i have alllllll this junk. check FS post, you'll see some of it. I suggest convert to OBD1 and GET RID OF THOSE EXTRA SENSORS. MOAR COMPUTER CONTROL. Get a chipped and tuned ecu and get rid of the factory junk, it'll never run riht trying to mix and match stuff and it'll be faster and cost you less money. and you dont need expensive rywire this and that.... ****s been around forever, just get the conversion stuff you need and click it in. ZC in a crx is a lof of fun. They sound great too.
 
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