Fitech EFI Rpm Noise Solved

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superchargeddrt

superchargeddrt

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After considerable issues with the dreaded RPM noise fault code and the engine just shutting off for no apparent reason I have a solution. I had to route all of my Fitech wiring away from any high voltage ignition wires (particularly the magnetic pickup coil wire). I also wrapped the pickup wire with aluminum foil and the coiled bare stainless steel wire around the foil and finally wrapped it all in a wire covering to make it look better. I then grounded the end of the wire connected to the foil from the connector to the throttle body to one of the throttle body mounting studs. The other end of the the connector to the distributor is grounded to the distributor with a screw running up through an unused threaded hole. Additionally I made a metal shield to go around the pickup coil inside of the distributor. This is held in place by the coil mounting screws. So far this is idling great with no fault codes. I couldn't drive it yet because of bad weather but I will post another video soon.

Here's the video link. I hope that this helps.
 
Here's a picture of the pickup coil shield.
20170429_134653.jpg
 
Now all I have to do is figure out how to setup the timing for both advance as well as retard. I don't have a clue yet but I will let you guys know when I find out. If anyone knows how to set this up please feel free to post.
 
By the way excuse the little air cleaner. That is on there because I couldn't use my dropped base with the straight fittings. I am going to put my dropped base and scoop seal back on as soon as I can get it out of my loft.(Dart is sitting right where I need to put the ladder so it has to be moved.
 
I'm not tryin to say "I told you so" but there is plenty of this kind of problem out there. One way I used to create braid shield.........and you can buy shield separate.........is to carefully strip the outer jacket of some coax cable. Not TV cable, usually, but CB/ radio feedline, RG-58/ 59, RG-8 etc. You can "bunch" the braid up by pushing it to make it larger to thread the wire, then smooth / stretch it out.

There was on guy had an MSD interfere with a Mopar voltage regulator. Stuff like MSD is particularly troublesome because there is so much power there
 
67Dart273 said:
I'm not tryin to say "I told you so" but there is plenty of this kind of problem out there. One way I used to create braid shield.........and you can buy shield separate.........is to carefully strip the outer jacket of some coax cable. Not TV cable, usually, but CB/ radio feedline, RG-58/ 59, RG-8 etc. You can "bunch" the braid up by pushing it to make it larger to thread the wire, then smooth / stretch it out.
Yes you are correct. We used a piece of braided steel covering on my buddy Larry's 1988 D150 (see the T for 2 thread). We had one heck of a time with RPM noise with both of the systems. Larry's set every code in the book.

There was on guy had an MSD interfere with a Mopar voltage regulator. Stuff like MSD is particularly troublesome because there is so much power there
Click to expand...
 
Good call on the shielded wiring. Every low amp ac circuit is supposed to be shielded from noise as much as possible. The pickup coil (Hall effect, variable reluctor, etc) doesn't necessarily need to be shielded but the wiring is a must because wiring acts as an antenna and electrical noise (starter, coil, msd, plug wires, overhead power lines, radio freqs) will alter the ac signal and give you crazy rpm/cam/crank timing readings. Not what we want with a boosted V8.

Megasquirt made it hard for me and I faught it til i finally realized i needed a pull-up resistor in line with the pickup.
 
T56MaxTorq said:
The pickup coil (Hall effect, variable reluctor, etc) doesn't necessarily need to be shielded but the wiring is a must because wiring acts as an antenna
Click to expand...

There is also a strategy with BALANCED circuits. Old copper phone lines, and the old TV twinlead are examples of this. Because the wiring is (supposed to be) balanced, it picks up noise equally in both conductors, and this actually causes a cancelling effect.

If you remember TV twinlead, you twisted it....this was to help maintain balance and aid in cancelling noise. Even old telegraph/ telco wires were twisted to maintain balance, AND IN FACT THAT is how ethernet cable works--------CAT-5..

Here is a twist in a telegraph/ telco line. It is for one reason........to maintain balance and to cancel noise

244832088.jpg


It is recommended to twist wiring such as the Mopar ECU pickup. This actually may not be as effective in this case, because one leg of the pickup circuit is actually grounded in the ECU. Nevertheless it helps form a shield. This low current "signal" wiring should not only be run away from powerful circuits, especially ignition, but near a "ground plane" that is the firewall
 
They do this same thing on 1939 data link connectors on the trucks I works on. All the data wires are twisted for shielding, like 67dart273 said.
 
70wayfarer said:
cool car. how do you rate the fitech set up.
Click to expand...
Thanks,
The Fitech setup works well but it is not plug and play (nor is any other FI setup) The basic settings will get you up and running but you are going to have to do some of the tuning yourself. Also you are going to have to shield some of the wiring to avoid the RPM noise error. There is a lot of help here on this forum. PM me if I can help.
 
superchargeddrt said:
Thanks,
The Fitech setup works well but it is not plug and play (nor is any other FI setup) The basic settings will get you up and running but you are going to have to do some of the tuning yourself. Also you are going to have to shield some of the wiring to avoid the RPM noise error. There is a lot of help here on this forum. PM me if I can help.
Click to expand...

I had a similar RPM noise issue with a Mega Squirt install, massive interference would not allow the motor to start / run.
the MS 3 Pro harness that attached to my distributor leads, I am using a locked lean burn distributor, had foil grounded insulation inside of the wire bundle, I found an EMI / RF article that stated there are times when grounded fol is not enough, and the fix is to add woven wire shielding over the foil.
and that was my fix for the RF interference. For the EMI side I moved the main engine block ground from the cylinder head to one of the starter mounting studs and all was good.
below is a link with additional info

After Market ECU's and EMI interference - Slant Six Forum

also the woven wire sheathing is available in wire size diameters, 1/8, 1/4, 3/8 ,,, for not much money, I think I paid $9.50 shipped for 10 feet of 1/4 inch diameter braided wire sheathing. Got mine from Electriduct e bay store
also, whether it is foil or woven wire, only ground one end of the shield.
 
grimreaper said:
With RPM noise being the known issue it is, I wonder why FItech doesn't provide the units with shielded wire?
Click to expand...

I have had NO problems with any of this stuff with my fast 2.0 f.i. system, from day one !.
It has worked flawlessly so far-------------all I`ve had to do is lean it out from the initial start up self learning, and go to hotter plugs.
May need more timing in it too, but is super easy on the handheld.
 
grimreaper said:
With RPM noise being the known issue it is, I wonder why FItech doesn't provide the units with shielded wire?
Click to expand...

FI is not the only one. I bought and started to build a "from scratch" harness for the Holley HP computer. But the diagram does not properly document shields. I have a Holley harness that "upgrades" the old Holley TBI / Commander 950 to an HP computer. Finally unwrapped enough of it to determine where the in-harness splice / interconnects actually exist, and what wires are shielded.

This is a **** problem. Holley should have done a MUCH better job documenting this. And it would have taken their schematic drawing guy about 10 more minutes to properly "fix."
 
My personal opinion is,
The RF interference issue is unique to every install. It really depends upon what devices are generating noise and where they are in relation to the signal wires. With each aftermarket kit being a custom install, the manufacturer can’t protect for every issue. With that said, and living through diagnosing and resolving a RF issue, I agree the FI suppliers could do a better job of providing ideas for resolution when a RF issue does occur
 
My Sniper system doesn't have these issues.
Maybe I just got lucky.
 
I've done about 12 systems professionally at this point. I've had 2 with an issue. Overall, these systems are pretty well engineered. In the reality, many of the people who are installing them really aren't capable.
 
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