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Discussion Starter · #1 · (Edited)
I'm restoring a car that's been sitting outside for 10 years, more to see here: 1st gen CRX restoration project in stopmotion video

Everything on it is JDM. Has a first gen DOHC ZC out of a 1986 Integra that has been transplanted with intake and ignition off a '89 CRX, so a bit of a mongrel.
Runs OBD0, distributor TD03u [correction - some unknown distributor from a SOHC that's bolted on with adapter withou possibility to adjust], injectors with a resistor box, MAP sensor on firewall, standalone cam sensor, ECU is PM7.
It runs, but not great. Has a slight misfire on idle and produces a lot of carbon (soot) - the rear bumper is all stained black around the exhaust. Fuel economy is actually pretty good (38 MPG), but it just runs rough and stinks (no cat - I wanna put on one, but only after I sort out the soot issue)

I already did some mechanical refresh on the engine (new bearings, hone, rings, lapped valves, all new seals, new waterpump and timign belt)
I have a brand new O2 sensor (single wire), new sparkplugs and spakplug leads. Flushed the injectors with carb cleaner both ways, cleaned the IACV, put on new air filter.

My question - what should I do to make it run well and clean? What should I buy new (considering it's been sitting very long).
I like the idea of converting to OBD1, but after soem research, I think it just isn't possible with this engine because the timing of TD43U distributor is incompatible - can anyone confirm? (as described here with no resolution DOHC ZC OBD1 Conversion - Ignition Timing - Hondata )

If someone would be so kind to also recommend parts from RockAuto I could use (I live on a remote island and it's hard to get anything here)
Also what problems can I expect? I did a lot of googling, everyone online is super confident giving advice, but then in real world the OP has some weird issue and everybody gets quiet and the thread dies. Prefer to not end up like that, so maybe stick with OBD0?

TY all!
 

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Formerly weebeastie
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I build a lot of ZC's, so I say with a lot of experience, that you can easily tune it with OBD0 or OBD1. Either one works just fine. You will need a chipped OBD0 ECU to tune it with obd0. Those can still be found and you will need at least a chip burner. I have a good OBD0 tune for stock ZC's that is pretty spot on. You just need a chipped ECU and a chip burner to make that work. I'm assuming you're running a PM6 ECU in it right now?
 

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Discussion Starter · #3 · (Edited)
Soul Engineering, that sounds good, so really no reason to go to OBD1, it wouldn't gain me anything, is that correct?

So I'll probably just buy new OBD0 injectors, new dizzy cap and rotor.. what else goes bad with time, some sensors?

@ECU - I actually have a chipped PM7! Though no means to burn chips. I know a guy who used to do that in the 2000's, but his hardware no longer runs with current computers.
I'm guessing I'd have to buy this? 'BURN2 Chip Programmer' [BURN2] - $85.00 : Moates.Net
Or would perhaps this work? 15.0US $ |Pcb5 Multifunctional Programmer Willem Burner Eprom Flash Mcu Mainboard Bios Write - Instrument Parts & Accessories - AliExpress (this seems to require a computer with LPT printer port, oops. And it seems to be very fussy with million things to go wrong.. I think I should stick with unmodded ECUs
 

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Discussion Starter · #4 ·
Oh and since the OBD0 route is looking more viable, I should mention I have some codes (PM7 ECU):
17 - vehicle speed sensor
20 - electric load

I'm guessing 17 is because it's missing that signal? What do I look for, I assume it goes from the speedo in the cluster to ECU?
20 - no clue about this one

The check engine light comes on while cruising downhill (foot off throttle). It doesn't come on until that happens.
 

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Formerly weebeastie
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Yes, so likely the signal coming from the cluster is making the ECU think funny things. A chipped PM7 will work great. Now you just need a Burn2 and you're set. I have a BIN file in Tuner Express that you can burn to said chip. That's what I'd recommend doing. And it's a straight up, burn, install and run. It is a safe tune that does not require additional adjustment. But it will make a good difference in performance. Yes, the IAT sensor dies over time, rotor, cap, coil, spark plug wires (use NGK for these), Engine Coolant Temperature sensor. Just basic things that go bad. Also on the code 20 you likely have a faulty ELD circuit. Electric Load Displacement. It's common on these cars, and will likely require replacing the fuse box to fix that.
 

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Common with swaps to use the wrong fusebox that doesn't have the ELD circuit. Take a pic of the fusebox and i'll be able to tell you if it's there. With the VSS, check your speedo is working, and if its working fine check for continuity between the cluster and the ECU.

Neither of those codes should affect how it runs.

It's pretty common to have that sooty mess on your bumper from a car with no CAT, usually from condensation the exhaust holding unburnt particles and then blowing it out on the next startup.

What's your ignition timing like?

Check your vac lines are solid to your MAP sensor.
 

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Discussion Starter · #8 · (Edited)
EFB055, thanks m8, I had a look:
  • my speedo works, but I didn't check for connection to ECU - I'll look into it later and report back - thanks for the directions in the meanwhile!
  • I got no fusebox under the bonnet, only 3 simple fusible links with nothing around them
  • bumper is really stained a lot, and it didn't do this 10 years ago when it last ran, so it definitely isn't normal. And I forgot to mention, one sparkplug is black - that's probably the misfire on idle. At speed it runs well. But also, when I was rebuilding the engine, there was a lot of thick soft carbon buildup everywhere.

- ignition timing: funny you mentioned it - I think I was wrong about my distributor, I actually have some other one probably from a SOHC, because it's not fitting on factory holes, which also don't allow any adjustment. I talked to the guy who built this, and he says no adjustment is necessary because it all happend with electronics. He's an engineer and builds racecars, so I didn't question him - after all the car ran fine when he built it.. But maybe I should look into this more. I have no idea how to setup ignition timing, probably should learn that.
Motor vehicle Automotive tire Light Automotive exterior Gas


- vacuum line to MAP is brand new and tight!

- my under dash fusebox
Electrical wiring Computer hardware Gas Electrical supply Wire

I'm guessing this one is irrelevant and my car simply doesn't have ELD. You think I can try to transplant it, or there's really no benefit?


- Another symptom I forgot to mention - it's very jerky in low speed in 1st and 2nd gear. Going steady pace at slight throttle is near impossible, it either wants to brake or go forward. Doesn't stall, just jesrks me back and forth a lot. If I step on it it goes fine.
 

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EFB055, thanks m8, I had a look:
  • my speedo works, but I didn't check for connection to ECU - I'll look into it later and report back - thanks for the directions in the meanwhile!
  • I got no fusebox under the bonnet, only 3 simple fusible links with nothing around them
Ah, i realise now you're just using the ECU and not the rest of the harness from an ED. The PM7 will be looking for that ELD and your harness wont have it. It's not an issue, you'll just get that code.

  • bumper is really stained a lot, and it didn't do this 10 years ago when it last ran, so it definitely isn't normal. And I forgot to mention, one sparkplug is black - that's probably the misfire on idle. At speed it runs well. But also, when I was rebuilding the engine, there was a lot of thick soft carbon buildup everywhere.

- ignition timing: funny you mentioned it - I think I was wrong about my distributor, I actually have some other one probably from a SOHC, because it's not fitting on factory holes, which also don't allow any adjustment. I talked to the guy who built this, and he says no adjustment is necessary because it all happend with electronics. He's an engineer and builds racecars, so I didn't question him - after all the car ran fine when he built it.. But maybe I should look into this more. I have no idea how to setup ignition timing, probably should learn that.
Are there any markings on the dizzy? A code?

- vacuum line to MAP is brand new and tight!

- my under dash fusebox
I'm guessing this one is irrelevant and my car simply doesn't have ELD. You think I can try to transplant it, or there's really no benefit?


- Another symptom I forgot to mention - it's very jerky in low speed in 1st and 2nd gear. Going steady pace at slight throttle is near impossible, it either wants to brake or go forward. Doesn't stall, just jesrks me back and forth a lot. If I step on it it goes fine.
Check the TB operates smooth, check the TPS with a multimeter, check the throttle cable operation is smooth.

I know you mentioned you cleaned the injectors, but it'd be worth getting them flow tested if they were sitting for that long.

Check the lash is set correctly on your valves

If it's a stock ECU that you're using at the moment, you still need to adjust your timing (that's why the mounting points have slots for adjustment). Either way, throw a timing light on it and see where it's at.
 

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Discussion Starter · #11 ·
Quick Q - How about injectors - can I rebuild them at home, or should I straight up buy new ones? I saw some rebuild kits on RockAuto, but not sure if they actually replace the important bits.
I know definite answer woudl be to get them tested, I'm pretty sure proffesional testing would be more expensive than new injectors anyway.
 

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Quick Q - How about injectors - can I rebuild them at home, or should I straight up buy new ones? I saw some rebuild kits on RockAuto, but not sure if they actually replace the important bits.
I know definite answer woudl be to get them tested, I'm pretty sure proffesional testing would be more expensive than new injectors anyway.
I would honestly buy new, or send your old ones off to have them sonic cleaned and tested.
 
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