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Discussion Starter #1
Hey all, I have a 89 crx hf, came with the b6, that motor blew so I swapped it for the b2 dpfi. The issues I had with the b6 are the same issues I'm having now. So what I've done so far is, I swapped the b2, converted it to mpfi with the intake manifold and injectors from the b6, I tried using zc injectors but they weren't working right, I also have a zc throttle body installed as well. Now here's what's going on, the motor was proven to run perfect and was maintenenced so I know the motor isn't bad, I think it might be my ecu. The issues are, and keep in mind they are they same issues the b6 had. I can't go past 4000 rpms, and the iac is still bad, that is probably my own fault for not replacing it but I have sprayed it out. I changed the throttle bodies to the zc's in hope that it would fix the tps and allow me to go past 4000 rpm. Now I think it's my ecu and the parts I'm using. Right now it runs kind of like cap and there's a coolant port on the bottom of the left hand side of the manifold and one off the thermostat literally right next to each other and I have no idea what they're for. So what my question is, is there a different manifold I should use? What injectors? change ecu Also? What can I do to use the parts I already have? Why couldn't the zc injectors work? I'm in a rush to get this fixed being as I have to be out of my place in 7 days and have limited money so I'm hoping someone could side me on this real fast. Thanks!

Also for a note, all parts are from 89s the motor is from a 89 wagovan, the injectors and throttle body are from the zc in the 89 crx hf, they are all in my 89 hf, I'm using the b6 mani from my 89s old motor. my ecu is the pm8, the ecu for the b2 is pm5 Which I have but haven't tried out yet, I tried using a pr4 which I know came from a b18b, and it idled at 2200 didn't bounce in idle, but wouldn't go past 3300 rpm.
 

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swapping ONLY the engine should have been fine. It would have run lean when beating on it, but should be 90% okay.

If you want it working right, do your maintenance.

You cannot just swap injectors, the ecu does NOT know what size its running.

OR you can swap your old head onto the B2 block and deal with the slightly lower compression, and loss of only a few horsepower overall
 

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Discussion Starter #3
That really didn't help at all. I converted that motor to mpfi from dpfi because you can't do shit with dpfi. That motor has been serviced and I plan on continuing to service it, there's no reason to swap heads. And I realize you can't just use any injectors I was looking for an answer from someone that knew what they were talking about And knew from knowledge a d15b2 mpfi conversion and how to do it right.
 

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BATSLOMAN GIVES NO FUCKS.
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why not swap ecu's and see if it fixes itself? too much logic? easier to come in here and play 21 questions?
 

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Um he has engine building knowledge only wished by some, you on the other hand cant search AND know nothing. Check his name and see his posts, he has built more then just a dumb opinion, again unlike you.

I would help but your response is pretty much making me wanna just post this link and say, "search n00b, and clean up the tude, or we will just spit you out of here."

http://www.d-series.org/forums/naturally-aspirated/101303-d15b2-mpfi.html

That post has your answers or can lead you to them by learning, you could have found it an not offended me, again you chose the latter.
 

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BATSLOMAN GIVES NO FUCKS.
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I was going to post links, but didn't feel like spoon feeding. so I gave him a red dot instead and little bit of logic
 

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Discussion Starter #7
Alright, Im just going to apologize for the earlier reply that was a dick reply yes, I'm stressing out cause I have to be out of my apartment in 6 days and the crx has just been sitting there for a couple months and I don't know where I'm putting it. So I'm sorry, noob status I get it my bad. Apologies go to everyone that replied.
 

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Discussion Starter #8
I've also tried one other ecu which stopped my idling issue but wouldnt pass 3300rpm, I'm gonna try the b2s ecu tonight and see what happens. Lately some people have said to try the a6 mani, injectors and ecu. I was considering the z6 head intake ecu and injectors and wire up vtec. Idk.
 

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I dont understand your issue. your HF is mpfi from the factory.

if you only swapped the motor, you would still be running fine.

If issues arise, its most likely related to old sensors, the IACV out of spec (loose or very dirty), wiring chaffing somewhere on the chassis, bad grounds.

My rule for most engine problems, especially hondas, is to check any and all grounds. Unbolt, clean, rebolt.

Harbor Freight sells a small box of copper washers. They are generally used for brakelines and such, but I scuff them up and use them as ground bolt helpers. The copper will crush slightly and make a super good connection!

Problem can also be a weak ass fuel system. Make sure the fuel filter has been changed in the last 4-5 years

88 91 Honda CRX HF D15B6 Fuel Injectors Best Upgrade for More MPG's OBD0 OBD1 | eBay

new injectors will not hurt, and will actually help with the d15b2 motor being in there. These eBay injectors tend to be a little bit anyways.


I could really care less if someone has a dick reply or such, we are frustrated at times, so no worries.

But we just need users to be a bit more clear on what they are targeting, with random problems, previous maintenance helps a lot.


Most of the time, issues are resulting in a step missed doing something, or something coming loose, or simply a bad sensor.
 

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On an extra note, track down teh original ecu, or one for 88-89 crx hf's

wiring does not match upto SI's as far as I remeber (wiring diagrams online to double check)

a d15b2 ecu will NOT WORK!!! wiring to injectors is different, as the DPFI has only 2 injectors, a low rpm injector, and a mid/high rpm injector that turns on after a certain rpm. you will find it stalls or shuts off randomly any time after 3k rpm
 

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BATSLOMAN GIVES NO FUCKS.
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making some sense. rep when I can ^^
 

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Discussion Starter #12
Ok yeah I see what your saying, maybe I haven't worded things correctly.

The hf I got came with mpfi. I had the d15b6.

I swapped the d15b2 in and converted from dpfi to mpfi using the b6 intake manifold with injectors.

I have not checked the fuel filter.

I'm using the pm8 ecu.

Engine won't go past 4000 rpms. That was why I had changed my throttle body from the b6 to the zc, thinking it was the tps sensor also to go with the 74mm size I believe? Instead of the original size.

The b2 is running the exact same as my b6.

I'm using Mobile version to reply so I'm just going to submit this re read what you commented then reply again.
 

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Discussion Starter #13
The pm8 is the original ecu I had with the hf also. Is it a known good ecu? I'm not sure lol.

That's what lead me to believe maybe it's the ecu that's causing these problems being as my original motor and new motor are now both running the same.

I will look into new injectors and replacing the fuel filter.

Speaking in a broke perspective (money wise) I can get injectors from junkyards in town. Its a lot easier for me being as I don't have to pay to get in and injectors are dirt cheap used, so should I look for b6 injectors in the junkyards?

On another note b6s are hard to come by where I'm at, and I figured the iac is probably hit it's point, I've already tried cleaning it out, I don't know if you can take them apart or not to fix them but basically I can deal with the bouncing idle I'm just worried about finding the injectors In a yard. Is there a different model d15 I could pull from or d16 And use those on my setup?
 

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Look up the injector size and whether they are saturated or peak and hold type. mystery time...

Dont grab parts til you know you need them.

MPFI makes it a bit easier to test fuel pressure.

Might also want to yank your spark plugs out and make sure they are gapped properly, maybe shit aint firing properly.



There is only so much we can do across the internet.

For now you can unplug the idle helpers and just use idle adjustment screw. counterclockwise should raise rpms, clockwise (tight) shoul;d lower rpms.

I suggest backing it out completely and making sure its clean and actually will allow air to pass, as the passages can get clogged up.

Id adjust it for 1k rpms warm, so a cold start doesnt sit there and require throttle to stay running


I did forget that you mentioned a coolant hose missing between the thermostat and intake manifold. it looks like a tweaked U shape, and just lets coolant bypass a shut thermostat, so hotspots are reduced. THere should also be another small hose that goes to your heater core. I forget if the HF has extra hoses, as they might have a coolant-cooled oil filter base
 

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Discussion Starter #15
Ok so a quick update, I swapped ecus, I'm using the pm6 si ecu, it's running the motor way better then before. Idling high so gotta fix that, but I have a coolant port from the thermostat, and bottom left hand side of the intake manifold. Which goes to the second port of the iac, and what do I do about the other port (thermostat or intake) do I plug it? There's no where else to run a coolant line. should I put the 3 together? Or?
 

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check your car and a 90 civic dx

Honda Parts Catalog Store | Wholesale Parts | Honda Parts Store

view the coolant parts diagrams and make sure you also check the prices underneath (to see which ones the diagram is actually using)

this is a parts website, but the pictures are very accurate as far as parts used. I use this as a tool to figure this sortof thing out


Get familiar with the diagrams, then check your car out yourself.


I dont remember if the HF hardpipe would have had two nipples or 3 on the thermostat. ALso I dont remember firmly if the HF hardpipe was different than the B2 hardpipe (between thermostat and waterpump)
 

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Discussion Starter #17
So after check diagrams, the b6 had two ports on the hardpipe, the b2 has one Closets to the thermostat itself. The b6 had one close to the water pump and the thermo. I'm supposed to route the iacs first port (closest to the plug) to the port closest to the water pump, and the second port on the iac runs to the port under the throttle body. From what I was understanding. But since I have the b2s hardpipe, and only one port, should I run the port from the hard pipe to the first port on the iac? Then what should I do with the port on the intake?
 
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