Improving engine block ground?

[MousieAudi]

Without the engine running, all my gauges on Megatune indicate correctly and steadily. As soon as I start the engine though, everything using the engine ground (CLT, MAT, O2) jumps around erratically. The RPM and MAP read steadilly at all times. I had my MS grounded inside the car at first, but the gauges were bouncing around horribly. I relocated the MS ground to the engine block, and it made a big difference, but the readings are still too unsteady for me to do any tuning. I can relocate the ground for the MAT sensor off the block, but the CLT and O2 sensors are grounded through their respective threads. Any ideas on how to improve the grounding between the engine and the rest of the car? Would running an additional bonding cable to the firewall make any difference? Any other methods? Thanks.

[ptegler]

ALL of your sensor grounds need to return to a COMMON point very near the MS box itself. Any heavy currents running down your chassis/battery/engine ground wires will mess with the small signals of the sensors. The only other option is to run extra ground wires right to each sensor. Entwine the ground wire around each sensor feed wire, and terminate them very near the ground wires of the MS box connector.

btdt

Paul Tegler
ptegler@cablespeed.com (ptegler@cablespeed.com)
www.teglerizer.com

----- Original Message -----
From: MousieAudi (twigmouse@gmail.com)
To: megasquirt-wiring@msefi.com (megasquirt-wiring@msefi.com)
Sent: Wednesday, January 24, 2007 10:45 PM
Subject: Improving engine block ground?


Without the engine running, all my gauges on Megatune indicate correctly and steadily. As soon as I start the engine though, everything using the engine ground (CLT, MAT, O2) jumps around erratically. The RPM and MAP read steadilly at all times. I had my MS grounded inside the car at first, but the gauges were bouncing around horribly. I relocated the MS ground to the engine block, and it made a big difference, but the readings are still too unsteady for me to do any tuning. I can relocate the ground for the MAT sensor off the block, but the CLT and O2 sensors are grounded through their respective threads. Any ideas on how to improve the grounding between the engine and the rest of the car? Would running an additional bonding cable to the firewall make any difference? Any other methods? Thanks.

[DCU1976]

http://forum.sounddomain.com/forum/ulti ... =007801;p=

Good Luck.