T-leg Piggyback ECU R&D

IronMonkeyL255 · Post by **IronMonkeyL255** » Mon Jun 05, 2006 4:43 am

Very detailed.

Project_Legacy · Post by **Project_Legacy** » Mon Jun 05, 2006 5:00 pm

i cant wait for this!

free5ty1e · Post by **free5ty1e** » Mon Jun 05, 2006 5:45 pm

I want my shop.... working out of a hotel room is not very productive.

I've got a reservation for a week-long rental of a huge Caterpillar 420 front-end loader / backhoe to clear and level my new 2-acre lot, and will be able to begin building the real shop there. This new land is already surveyed, has a clear title, and has power lines just two blocks away. The old land was in an area that had all kinds of survey problems and we just couldn't get anything done there.

I can't wait to have a real workshop again!!

Post by **Legacy777** » Mon Jun 05, 2006 6:57 pm

I really wonder if the comments he mentioned about unshielded wire could be a cause for some of my issues with the extension harness I have the PP hooked up to.

free5ty1e · Post by **free5ty1e** » Mon Jun 05, 2006 7:41 pm

Josh,

I've definately found that every signal you want to run somewhere has to be in it's own, separately-shielded wire (not sharing a shield with other signals) to avoid signal bleeding. Also, if the PP doesn't buffer it's inputs, you'd need an op-amp at each point you're taking a signal from (unless you grab them from the ECU, where they should already be buffered)...

Post by **Legacy777** » Tue Jun 06, 2006 2:44 am

Hmm....does the shielded wire need to be grounded?

I do not know if the PP buffers inputs. It is something I can ask. Can you provide a little more detail so I can intelligently ask the question and provide feedback if asked a question?

Thanks

Post by **Legacy777** » Tue Jun 06, 2006 2:47 am

Other question is regarding the harness Vikash made.
http://www.main.experiencetherave.com:8 ... fectpower/

Do you think having the wiring the way it is could be causing some of my issues?

free5ty1e · Post by **free5ty1e** » Tue Jun 06, 2006 4:41 am

Yep, the shields of each signal wire should be grounded to the chassis somewheres.

Since you're taking those signals from the ECU though, it probably wouldn't be an issue. If you were taking the signals from the actual sensors themselves and running cables through the firewall then shielding would be a good idea.

To guarantee that connecting the signals to additional inputs doesn't draw the signal levels down at all, each signal should optimally have an op-amp in line for protection. May or may not be necessary depending on the hardware they used, may or may not be necessary on the LegacEBC but I'll probably do it anyway to ensure that sort of thing won't be an issue.

Post by **Legacy777** » Thu Jun 08, 2006 3:49 am

I am tapping off that harness near/right at the ECU for the PP leads. So you don't think that harness or the PP wiring needs to be shielded?

free5ty1e · Post by **free5ty1e** » Thu Jun 08, 2006 4:16 pm

I wouldn't think so, no. The leads aren't very long, are they? If you're moving signals any more than a few feet there will be some drop, not sure how much would be acceptable in this application.

I might be wrong though - I still haven't used any signals directly from the ECU so I don't have direct experience just yet. I hate not having my shop yet

I suppose if you've got a digital voltmeter so you can see small changes, you can measure each signal in relation to ground with the key on (engine off so they don't fluctuate) at the ECU and at the PP, and see if there are any noticable differences. That might give us some clue as to which signals are problematic, if any.

aspect · Post by **aspect** » Tue Sep 05, 2006 9:50 am

bump

beatersubi · Post by **beatersubi** » Wed Mar 14, 2007 4:03 am

are there any updates on the legaCU or the legaEBC? this thead can't be dead. it is what inspired me to join here.

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T-leg Piggyback ECU R&D