[Diy_efi] Re: Problem with cam mounted optical trigger sensor and RFI

Thu Apr 6 09:36:04 UTC 2006

Thank you to those who have sent some advice.

  First I ran better sheilded cable, replaced the condensor and ran a new engine earth cable. This seemed to tone down the noise but it was still there.

  I then replaced the solid core spark leads I was using for some stock suppression cable. This made a huge difference and problem seemed to be gone. I replaced the standard coil with the CDI ignition. The car started for the first time on the CDI ignion but there was intermitted noise on the signal causing problems once again.

  I reverted back to the coil and thought I'd do some tuning. After a while of running everything seemed fine. I was stopping and starting the engine as I was mapping. At one stage I went to start the car again and the problem was back worse than ever! Now it won't even start as the noise is messing the signal badly.

  This is a very frustrating problem. Obviously something is amiss and I am starting to suspect the grounding system. Perhaps a ground loop? very annoying, very random

  Damian

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Today's Topics:

1. RE: Swaping 1225550 crossfire with 1227747 (correction)
(Chuck Kahler)
2. Problem with cam mounted optical trigger sensor and RFI
(Damian Long)
3. Re: Problem with cam mounted optical trigger sensor and RFI
(Torbj?rn Forsman)
4. Re: Problem with cam mounted optical trigger sensor and RFI
(Charles Slack)

----------------------------------------------------------------------

Message: 1
Date: Sat, 01 Apr 2006 17:40:07 -0800
From: "Chuck Kahler" 
Subject: [Diy_efi] RE: Swaping 1225550 crossfire with 1227747
(correction)
To: 
Message-ID: 
Content-Type: text/plain; charset="iso-8859-1"

Just wanted to let the forum know I finished the ECM swap out and it worked
great, started right up and ran fine.

Thanks for all the help various folks gave me along the way.

Only one question remains; initially when the engine first started up the
idle was high about 1800 rpm and as the engine warmed up the idle stepped
down to about 700, which was great. Now the idle stays high at about 1800
rpm even after the car is driven around. .

Any suggestions as to what could be going on here.

Thanks,
Chuck

------------------------------

Message: 2
Date: Sun, 2 Apr 2006 20:16:33 +1000 (EST)
From: Damian Long 
Subject: [Diy_efi] Problem with cam mounted optical trigger sensor and
RFI
To: diy_efi at diy-efi.org
Message-ID: <20060402101633.3010.qmail at web50312.mail.yahoo.com>
Content-Type: text/plain; charset=iso-8859-1

Hello,

I am installing a Walbro TDD ecu. It uses a motronic style 60-2 wheel. I have cam mounted this wheel. Basically what I have done is removed the standard cam mounted trigger disk (found inside the distributor) and replaced it with a custom disk. 
The sensor used to read the disk is a common standard Mitsubishi optical sensor that is found in the likes of Hyundai Excels, Nissans and Mazdas. I am using a sensor from an Nissan SR20 engine.
What is happening is that everything works fine from a cold engine. The ecu reads the signal perfectly and the engine runs great. As soon as the engine gets warm it seems like the sensor (or wires) gets some RF interferance from the high tension leads. The rpm reading goes nuts like 54000rpm and ecu obviously complains. At first I thought maybe a broken sensor as I have seen these have problems before when they get hot but the problem seems very dependant on how and where I run the wires to the sensor. Also if I connect a high power CDI ignition the problem is 10 fold. It does it from cold or hot. This leads me to believe it is not a broken sensor and the temperature has something to do with letting the RFI in.
Looking at the signal going into the ecu on an oscilliscope there is a nice square wave even when the strange RPM begin to happen. I don't totally understand why this is. It could be the RFI is causing the circuit inside the optical sensor to send false triggers (there is a small conditioning circuit inside the optical sensor).
All help appreciated.

Oh and Matt, if you are reading this. I live right near you. I am in Wollongong. I have seen your AFR gauges in a friends car. I like them and may buy one. 

cheers
Damian

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------------------------------

Message: 3
Date: Sun, 02 Apr 2006 12:37:21 +0200
From: Torbj?rn Forsman 
Subject: Re: [Diy_efi] Problem with cam mounted optical trigger sensor
and RFI
To: diy_efi at diy-efi.org
Message-ID: <442FA961.6030708 at gengas.nu>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Try using screened wiring between the ECU and the sensor. Ground the 
screen at some suitable ground pin of the ECU (some general signal 
ground, ground for the screened cable to the O2 sensor or something) and 
let the screen be unconnected at the sensor.

Another thing that might be worth trying is to low pass filter the 
signal from the sensor, in case there is some high frequency content 
from the ignition impulses overlaid on it. Probably, there is already 
some sort of filtering in the ECU but you might need a lower cut-off 
frequency.

Best regards

Torbj?rn Forsman

Damian Long wrote:
> Hello,
> 
> I am installing a Walbro TDD ecu. It uses a motronic style 60-2 wheel. I have cam mounted this wheel. Basically what I have done is removed the standard cam mounted trigger disk (found inside the distributor) and replaced it with a custom disk. 
> The sensor used to read the disk is a common standard Mitsubishi optical sensor that is found in the likes of Hyundai Excels, Nissans and Mazdas. I am using a sensor from an Nissan SR20 engine.
> What is happening is that everything works fine from a cold engine. The ecu reads the signal perfectly and the engine runs great. As soon as the engine gets warm it seems like the sensor (or wires) gets some RF interferance from the high tension leads. The rpm reading goes nuts like 54000rpm and ecu obviously complains. At first I thought maybe a broken sensor as I have seen these have problems before when they get hot but the problem seems very dependant on how and where I run the wires to the sensor. Also if I connect a high power CDI ignition the problem is 10 fold. It does it from cold or hot. This leads me to believe it is not a broken sensor and the temperature has something to do with letting the RFI in.
> Looking at the signal going into the ecu on an oscilliscope there is a nice square wave even when the strange RPM begin to happen. I don't totally understand why this is. It could be the RFI is causing the circuit inside the optical sensor to send false triggers (there is a small conditioning circuit inside the optical sensor).
> All help appreciated.
> 
> Oh and Matt, if you are reading this. I live right near you. I am in Wollongong. I have seen your AFR gauges in a friends car. I like them and may buy one. 
> 
> cheers
> Damian
> 
> 
> ---------------------------------
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> Messenger: Make free PC-to-PC calls to your friends overseas. 
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> Diy_efi mailing list
> Diy_efi at diy-efi.org
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> 

------------------------------

Message: 4
Date: Sun, 02 Apr 2006 11:35:16 -0500
From: Charles Slack 
Subject: Re: [Diy_efi] Problem with cam mounted optical trigger sensor
and RFI
To: diy_efi at diy-efi.org
Message-ID: <442FFD44.2080808 at arlut.utexas.edu>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Damian, Looks like you may be having RFI running back through the DC 
supply lines.
Put a large capacitor say 500 Uf @25 VDC and a small cap ( 0.01 uf @ 25 
VDC) across
the dc power leads to the CDI ignition module. You can try a 0.01 uf 
@100Vdc as
a HF bypass across the pick up leads, and across the incoming air temp 
sensor.
My 2 cents.
Charlie Slack
Austin, TX

Damian Long wrote:

>Hello,
> 
> I am installing a Walbro TDD ecu. It uses a motronic style 60-2 wheel. I have cam mounted this wheel. Basically what I have done is removed the standard cam mounted trigger disk (found inside the distributor) and replaced it with a custom disk. 
> The sensor used to read the disk is a common standard Mitsubishi optical sensor that is found in the likes of Hyundai Excels, Nissans and Mazdas. I am using a sensor from an Nissan SR20 engine.
> What is happening is that everything works fine from a cold engine. The ecu reads the signal perfectly and the engine runs great. As soon as the engine gets warm it seems like the sensor (or wires) gets some RF interferance from the high tension leads. The rpm reading goes nuts like 54000rpm and ecu obviously complains. At first I thought maybe a broken sensor as I have seen these have problems before when they get hot but the problem seems very dependant on how and where I run the wires to the sensor. Also if I connect a high power CDI ignition the problem is 10 fold. It does it from cold or hot. This leads me to believe it is not a broken sensor and the temperature has something to do with letting the RFI in.
> Looking at the signal going into the ecu on an oscilliscope there is a nice square wave even when the strange RPM begin to happen. I don't totally understand why this is. It could be the RFI is causing the circuit inside the optical sensor to send false triggers (there is a small conditioning circuit inside the optical sensor).
> All help appreciated.
> 
> Oh and Matt, if you are reading this. I live right near you. I am in Wollongong. I have seen your AFR gauges in a friends car. I like them and may buy one. 
> 
> cheers
> Damian
>
> 
>---------------------------------
>On Yahoo!7
> Messenger: Make free PC-to-PC calls to your friends overseas. 
>_______________________________________________
>Diy_efi mailing list
>Diy_efi at diy-efi.org
>http://lists.diy-efi.org/mailman/listinfo/diy_efi
>
> 
>

------------------------------

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