does this happen to anyone else? once out of every 3 or 4 times i am accelerating in 3rd or 4th gear i will get a random IGN pickup of 16000rpms while datalogging (to verify)
BDC informed me that its because of shady IGN wiring so i'll rewire it, but exactly what should i make sure not to do when rewiring to make sure it doesnt happen again?

 

Only two causes...
1) RFI
2) Gain set to high.

#1 can be not enough shielding, improper wiring, too much high-power RF in your area.


-Ted

 

Ground the sheilding of the cas harness directly to the cas cover screw and it will go away...Max

 

I though you were to only ground it once and at the computer side.

I compared the stock cas wire and the haltech one and it's not even close in construction quality.

They stock one is FAR superior. It has a woven ground that surrounds the 4 wires and each of the 4 wires are larger and has thicker sheilding.

Next time I will try to run as much as the stock wires as i possibly can.

 

I don't know where that rule came from, but I had the same problem reported by Jacobcartmill when I first put in my haltech, the first experiment I tried was grounding the shielding at the cas end, and that was it...max

 

"If the Engine Speed reading is erratic, the trigger (crank or cam signal) is most likely picking
up ignition noise from incorrect plugs or leads, electrical noise from cooling fans, starter
motor, alternator or other electrical devices in the vehicle. Ensure that the trigger signal wire is properly shielded and that the shield is not grounded at the sensor end."

That was taken from the haltech manual.

 

hmm. well guess what, they are wrong......

 

ok







think of the ground as a lightning rod like on the house.

You don't run the wire all the way to the bottom of the house and ground it to the roof so the lighting can go through the house. If grounded independantly it will pick up any interference (aka lightning) and route it away from the sensor (house). This is obviously not 100 accurate but best example I could come up with (electromagnetics was my lowest grade in college and it shows )

 

Sesshoumaru,
you have both right. the OEM CAS wiring is far superior and should be retained and used in place of the Haltech supplied part. this was a suggestion made many years ago by the tech guys at Haltech in Australia. Also the shielding should be grounded on one end only. to ensure a good path to ground it is best to use the end that is connected to the body shell as the path through the engine is not always the most direct. This setup has worked for me and I have never had any wiring or RF related ignition problems. Also be sure to solder(no crimp connections) all ignition connections.

 

Grounding both sides of the shield is asking for trouble...
It's called a "Faraday Cage".
If you do this, it tends to cause more headaches than solve them.
Ground it only on one side.

I've seen when both ends of the shielding gets grounded, and the CAS signal get all fucked.


-Ted

 

I looked through my haltech manual and couldn't find any reference to not grounding both sides, all I could find is that it says" ensure that the trigger wire is shielded and properly grounded"...Lightning bolts and obscure electrical theories asided, grounding the cas end fixes the problem, both ends of my harness are grounded, I have probably 30 megs worth of datalogs with no Cas variations or ignition related hickups since doing it...
Here is my post from over 2 years ago where all the experts showed up with the answer.. and yes I am being sarcastic..
https://www.rx7club.com/forum/showth...&highlight=cas

 

ok

 

I think that grounding both sides will probably not give you any trouble with one exception. If you ground it to the engine and the engine is acutally carrying a very slight voltage, then you're going to be looking at a current flow through the wire. The point of that wire is to give the shielding used in the wire the ability to ground out the magnetic fields that are being generated by electricity flowing from other devices. If all you're worried about is the magnetic fields enducing current on the wiring grounding both ends should not be a problem if you just make sure that you're grounding to something that is not going to be offering any voltage difference. This is just what I figure, but if I'm wrong somoene please let me know.

 

RETed, We agree! First time for everything!
Do not ground the sensor side of the wire, the faraday cage effect will cause greif.

 

Sometimes I have tach twitches, I can feel it in the car also, so I guess its a "hickup". I had to cut the CAS wires a while back, I used crimp connectors, so Im missing about 3" of shielding around the 4 wires.
If I were to go back and solder the wires, what should I use to shield the 4 exposed wires with?