AFAccord
Well-Known Member
**WORK IN PROGRESS**
After seeing many incorrect or out-dated write-ups and receiving numerous private messages about converting to OBD1, I've decided to start my own write-up and hopefully continue to use it as a question and answer thread.
I have to start with a disclaimer. This write-up is assembled off my own experiences with my OBD1 conversion. I am not responsible for any problems you may incur while doing this conversion due to wrong or defective parts, negligence during installation, or any other act of God that may occur. If you experience any issues, feel free to post your questions here, but understand that I do have a life, and may not be able to respond immediately. There are others on this forum who are experienced with this conversion and may also provide valuable input to your questions.
---------------------------------------------------------------------------------------------------------------------------------------------------
As most of you know, the benefit of this conversion is the ability to tune your car. This is essential for anyone who is serious about getting the most out of their car.
For those of you with minor bolt-ons, tuning with a complete engine management can bring out 10-15whp from a good intake/exhaust/header setup.
For those of you who go a step further with aftermarket cams, custom exhaust, head work, etc, can see gains of 15-25whp in my experience.
And the rest of you who have boosted your cars, there is NO excuse not to have a complete engine management setup. 95% of you could put together a working OBD1 setup for less than half the cost of a FMU or piggyback system. It's all about control.
---------------------------------------------------------------------------------------------------------------------------------------------------
Parts needed:
Required parts:
First of all, let me clear any myths, and say that this conversion CAN BE COMPLETED with only a chipped ECU with a basemap, and an OBD2 to OBD1 conversion harness. This is the foundation of the swap. There are some adjustments that need to be made to make the car idle correctly, but once done, the car can be properly tuned and driven on a daily basis.
I've found that these parts can most easily be found online at reasonable prices. Most distributors offer an OBD1 ECU's that are already socketed, and come with a chip burned with a basemap on your choice of tuning software (ie. Crome, Uberdata, Hondata, eCtune, Neptune)
Some websites I've had good personal experiences with are Xenocron.com and Phearable.net.
Recommended parts:
---------------------------------------------------------------------------------------------------------------------------------------------------
Special Considerations:
For those of you with 2000-2002 Accords, your engine temp gauge will stop working after converting to OBD1. This is because of the gauge cluster of 2000+ models, which are designed to work off of a pulse width module (PWM) signal which pulses, instead of holding a steady voltage like OBD1 and pre 2000 models.
In order for your temp gauge to work, you can do one of two things.
1. Purchase a $70 ECT adapter module from Modifry Products which converts the steady voltage from and OBD1 ECU to a PWM signal.
2. Find yourself some spare "B" and "C" OBD2B ECU plugs with a few wires still pinned in, and repin them for only the power, ground, sensor ground, ECT in, and ECT out. Basically running the stock ECU for the sole purpose of converting the ECT signal. This is the poor man's fix (my favorite kind), and I'll go into more detail about how to perform it later.
---------------------------------------------------------------------------------------------------------------------------------------------------
Two-Step Launch Control with eCtune:
I've received some questions about the launch control features of OBD1. Many tuning softwares (<< is that even a word??) allow you to program a set RPM for a launch control when using an emulator (simulated EEPROM adapter that allows you to make adjustments live, without having to burn and install an EEPROM) or burn it to an EEPROM along with the current tune. eCtune and some others allow you to set infinitely variable launch control points when ever you want. Here's how it works...
The eCtune two-step feature is TPS activated, meaning when the ECU sees the throttle position sensor go above 95% throttle quickly, and the VSS shows less than 8mph, the ECU activates a rev-limiter at the RPM that the TPS threshold was reached. This rev limiter is held until one of two instances occur, either the throttle position goes below 10%, or the VSS goes above 8 mph. All variables such as minimum rpm for two-step engagement, TPS threshold to activate, TPS threshold to deactivate, whether it is fuel cut, ignition cut, or both, are adjustable when the tune is being performed. When you release the clutch and the car begins to roll, the tires only receive the maximum amount of torque generated at that rpm, in order to get you off the line without completely burning out.
In the video link below I provided captions to explain what is happening during the launch control process for you visual people. This video is NOT a good example of how to get off the line quickly, I was just having fun. Unless I'm using slicks and an LSD, I would never actually launch this high to get off the line quickly.
Two-Step Launch Control with Captions
After seeing many incorrect or out-dated write-ups and receiving numerous private messages about converting to OBD1, I've decided to start my own write-up and hopefully continue to use it as a question and answer thread.
I have to start with a disclaimer. This write-up is assembled off my own experiences with my OBD1 conversion. I am not responsible for any problems you may incur while doing this conversion due to wrong or defective parts, negligence during installation, or any other act of God that may occur. If you experience any issues, feel free to post your questions here, but understand that I do have a life, and may not be able to respond immediately. There are others on this forum who are experienced with this conversion and may also provide valuable input to your questions.
---------------------------------------------------------------------------------------------------------------------------------------------------
As most of you know, the benefit of this conversion is the ability to tune your car. This is essential for anyone who is serious about getting the most out of their car.
For those of you with minor bolt-ons, tuning with a complete engine management can bring out 10-15whp from a good intake/exhaust/header setup.
For those of you who go a step further with aftermarket cams, custom exhaust, head work, etc, can see gains of 15-25whp in my experience.
And the rest of you who have boosted your cars, there is NO excuse not to have a complete engine management setup. 95% of you could put together a working OBD1 setup for less than half the cost of a FMU or piggyback system. It's all about control.
---------------------------------------------------------------------------------------------------------------------------------------------------
Parts needed:
Required parts:
- OBD1 ECU with basemap for your car.
- OBD2B to OBD1 conversion harness
First of all, let me clear any myths, and say that this conversion CAN BE COMPLETED with only a chipped ECU with a basemap, and an OBD2 to OBD1 conversion harness. This is the foundation of the swap. There are some adjustments that need to be made to make the car idle correctly, but once done, the car can be properly tuned and driven on a daily basis.
I've found that these parts can most easily be found online at reasonable prices. Most distributors offer an OBD1 ECU's that are already socketed, and come with a chip burned with a basemap on your choice of tuning software (ie. Crome, Uberdata, Hondata, eCtune, Neptune)
Some websites I've had good personal experiences with are Xenocron.com and Phearable.net.
Recommended parts:
- 2-wire IACV
- 2-wire IACV plug
- Blacktrax IACV Adapter plate
---------------------------------------------------------------------------------------------------------------------------------------------------
Special Considerations:
For those of you with 2000-2002 Accords, your engine temp gauge will stop working after converting to OBD1. This is because of the gauge cluster of 2000+ models, which are designed to work off of a pulse width module (PWM) signal which pulses, instead of holding a steady voltage like OBD1 and pre 2000 models.
In order for your temp gauge to work, you can do one of two things.
1. Purchase a $70 ECT adapter module from Modifry Products which converts the steady voltage from and OBD1 ECU to a PWM signal.
2. Find yourself some spare "B" and "C" OBD2B ECU plugs with a few wires still pinned in, and repin them for only the power, ground, sensor ground, ECT in, and ECT out. Basically running the stock ECU for the sole purpose of converting the ECT signal. This is the poor man's fix (my favorite kind), and I'll go into more detail about how to perform it later.
---------------------------------------------------------------------------------------------------------------------------------------------------
Two-Step Launch Control with eCtune:
I've received some questions about the launch control features of OBD1. Many tuning softwares (<< is that even a word??) allow you to program a set RPM for a launch control when using an emulator (simulated EEPROM adapter that allows you to make adjustments live, without having to burn and install an EEPROM) or burn it to an EEPROM along with the current tune. eCtune and some others allow you to set infinitely variable launch control points when ever you want. Here's how it works...
The eCtune two-step feature is TPS activated, meaning when the ECU sees the throttle position sensor go above 95% throttle quickly, and the VSS shows less than 8mph, the ECU activates a rev-limiter at the RPM that the TPS threshold was reached. This rev limiter is held until one of two instances occur, either the throttle position goes below 10%, or the VSS goes above 8 mph. All variables such as minimum rpm for two-step engagement, TPS threshold to activate, TPS threshold to deactivate, whether it is fuel cut, ignition cut, or both, are adjustable when the tune is being performed. When you release the clutch and the car begins to roll, the tires only receive the maximum amount of torque generated at that rpm, in order to get you off the line without completely burning out.
In the video link below I provided captions to explain what is happening during the launch control process for you visual people. This video is NOT a good example of how to get off the line quickly, I was just having fun. Unless I'm using slicks and an LSD, I would never actually launch this high to get off the line quickly.
Two-Step Launch Control with Captions
Last edited:
