DOHC ZC OBD1 Conversion - Ignition Timing

s300 and SManager software questions & answers
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Spiffydudex
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Joined: Mon Jan 06, 2020 4:21 pm

DOHC ZC OBD1 Conversion - Ignition Timing

Post by Spiffydudex »

Hello All,

I am working to upgrade my DOHC ZC 3rd gen to OBD1. I have run into an issue with ignition timing.

Things I have done/Verified:
  • While OBD0 - Ignition timing was correct at -16BTDC. Car ran like a dream
    Crank and Cam are perfectly aligned.
    Purchased 2 TD43u distributors and have managed to replicate the issue.(Generic eBay and a Spectra unit)
OBD1 conversion:
  • Purchased and installed an OBD1 to OBD0 wiring harness.
    Pre-installed Hondata and set with a basemap for a D16A1
    Installed TD43u distributor.
The Problem
  • Set the S300 to timing mode.
    Timing set to 16
    With the distributor at full advance, ignition is at TDC 0 degrees when measured at the crank. I cant get enough advance out of the distributor.
I can set the timing on S300 to 30-32 and get the engine to run correctly, but that seems like a really bad way to do things.
I'm not really sure what else I need to/can do. Any help, guidance and advice would be much appreciated.

Thanks,
Andy

skaterguy1986
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Joined: Mon Jan 01, 2018 7:31 pm

Re: DOHC ZC OBD1 Conversion - Ignition Timing

Post by skaterguy1986 »

I've seen cheap aftermarket distributors that have poorly aligned trigger wheels inside that cause them to not be able to be set in time but I also have no experience with OBD0->OBD1 conversions and if there is something there that can cause this.

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Spunkster
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Re: DOHC ZC OBD1 Conversion - Ignition Timing

Post by Spunkster »

Are you using a dialback timing light, or a fixed timing light.

TTR
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Joined: Wed Mar 31, 2004 8:48 pm

Re: DOHC ZC OBD1 Conversion - Ignition Timing

Post by TTR »

Is the cam/crank timing correct?

Spiffydudex
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Re: DOHC ZC OBD1 Conversion - Ignition Timing

Post by Spiffydudex »

Spunkster wrote:
Mon Jan 27, 2020 10:07 am
Are you using a dialback timing light, or a fixed timing light.
Worked perfectly with the OBD0 setup. Timing light can be (and is) fixed at 0.0.
TTR wrote:
Mon Jan 27, 2020 3:45 pm
Is the cam/crank timing correct?

Cam and crank are in time. Original OBD0 dizzy was nearly dead center on adjustments.
skaterguy1986 wrote:
Mon Jan 27, 2020 8:45 am
I've seen cheap aftermarket distributors that have poorly aligned trigger wheels inside that cause them to not be able to be set in time but I also have no experience with OBD0->OBD1 conversions and if there is something there that can cause this.
That was my thought originally, hence the purchase of a second dizzy.


Further info: (I had some time to play around last night. :D)
In order to get the timing correct (or even close) I setup the dizzy in a central adjustment position. From the set timing window I have the timing set to 40 in order to get it close enough to 18btdc on the crank. From there I adjust the dizzy slightly advance to dial it in. Engine still feels slow to respond from idle, but it does sound much better(better combustion).

I also played with some of the tunes from the vault. They seemed about the same as the D16A1 basemap in terms of response and combustion.

I guess my main question, is this the correct approach in terms of ignition timing?

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Spunkster
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Re: DOHC ZC OBD1 Conversion - Ignition Timing

Post by Spunkster »

If it is a fixed timing light then it is showing the 0 position and not 16 degrees advanced as you are trying to get to.

Spiffydudex
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Joined: Mon Jan 06, 2020 4:21 pm

Re: DOHC ZC OBD1 Conversion - Ignition Timing

Post by Spiffydudex »

Spunkster wrote:
Tue Jan 28, 2020 12:14 pm
If it is a fixed timing light then it is showing the 0 position and not 16 degrees advanced as you are trying to get to.
From my understanding, with a original OBD1 engine/ecu with the timing light fixed at 0 and the Set Timing window set at 16, I should see the timing on the crank at (roughly) 16 BTDC and I should be able to get it correct with the software by advance/retard the dizzy.

With my car, I open the Set Timing and have it set at 16, with my timing light it appears that the ignition is almost 4 degree retard ATDC.

Due to the OBD0 -> OBD1 conversion (TD03u ->TD43u) and the purchasing of two TD43's, I don't think that the OBD1 dizzy internal timing is producing the same results as the OBD0 exhaust cam timings. Physically the TD43u mounts up perfectly and every internet forum etc states that it is the correct OBD1 dizzy. It's possible I got two bad units from different manufacturers, just seems unlikely. To me it seems like the timing is way off from the D16a1 and it may just be for the ZC engine.

I'm really scratching my head on this. Any thoughts?
I can get videos, although, I don't know how helpful they will be.

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