Holley EFi Piggyback
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From: Crossroads of America
Holley EFi Piggyback Just wondering if anyone piggybacked the stock ecu in general. Ls2 or ls3 setups.
I bought an aftermarket Pro Efi 128 setup an year back and sold it but I still got that piggyback harness laying around and am been thinking about hooking it up with Holley Efi current setup.
Any idea's of problems I could face? ProEfi have been doing it with twin turbo vette's it seems like its running fine.
I bought an aftermarket Pro Efi 128 setup an year back and sold it but I still got that piggyback harness laying around and am been thinking about hooking it up with Holley Efi current setup.
Any idea's of problems I could face? ProEfi have been doing it with twin turbo vette's it seems like its running fine.
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From: Crossroads of America
soundengineer I did search around, halltech guys seem to be doing it. I know for fact that Pro Efi did it years ago with corvette and still offer piggyback harness for many other applications.
Could you give me some insight why it isn't recommended or why I shouldn't try it.
soundengineer I did search around, halltech guys seem to be doing it. I know for fact that Pro Efi did it years ago with corvette and still offer piggyback harness for many other applications.
Could you give me some insight why it isn't recommended or why I shouldn't try it.
Could you give me some insight why it isn't recommended or why I shouldn't try it.
things like the crank sensor require special twisted and shielded cable as they are extremely susceptible to interference...
anything that splits using a 5v or 12v signal needs diodes to prevent any accidental stray voltage from backfeeding from one device or the other
not saying it will always happen....but some pieces just arent happy being split and some funny things can happen
grounds have to all go to 1 device...not both
this can cause issues(again...not always...) with the device that has no grounds from sensors
and sometimes the solution is isolation transformers...which can get costly to do it correctly
again....I'm not saying it isnt possible...
I'm just saying that there are some challenges to overcome, and it is not recommended.
this guy over on yellow bullet has tried it.....
he says in this post...
you need separate sensors to make the Holley Happy....meaning you cant split them to the holley and the stock ECU.
http://www.yellowbullet.com/forum/sh...51&postcount=7
he says in this post...
you need separate sensors to make the Holley Happy....meaning you cant split them to the holley and the stock ECU.
http://www.yellowbullet.com/forum/sh...51&postcount=7
I'm getting ready to do this.
Why would you need to split the IAT, ECT sensor for the stock ECU?
If you are going to piggy back it to keep the BCM and factory gauges happy and have the Holley control fuel/spark I can't see any reason the factory PCM needs to see anything except cam/crank.
Why would you need to split the IAT, ECT sensor for the stock ECU?
If you are going to piggy back it to keep the BCM and factory gauges happy and have the Holley control fuel/spark I can't see any reason the factory PCM needs to see anything except cam/crank.
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I'm getting ready to do this.
Why would you need to split the IAT, ECT sensor for the stock ECU?
If you are going to piggy back it to keep the BCM and factory gauges happy and have the Holley control fuel/spark I can't see any reason the factory PCM needs to see anything except cam/crank.
Why would you need to split the IAT, ECT sensor for the stock ECU?
If you are going to piggy back it to keep the BCM and factory gauges happy and have the Holley control fuel/spark I can't see any reason the factory PCM needs to see anything except cam/crank.
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Verdad Gallardo It's something that I can do "testing" on at work on my car.
I have an extra HP ECU and some wiring harness' laying around so I'm going to see how it goes.
I know the most important thing is getting the crank/cam sensors happy. I have a scope so I can play with a pot to find out the right pull down resistance to get/keep a good signal.
I've never piggy backed an aftermarket ECU to a stock ECU before, hence why I'm using my car for testing. I'm interested in seeing in what I do and don't need to keep the rest of the car working.
I have an extra HP ECU and some wiring harness' laying around so I'm going to see how it goes.
I know the most important thing is getting the crank/cam sensors happy. I have a scope so I can play with a pot to find out the right pull down resistance to get/keep a good signal.
I've never piggy backed an aftermarket ECU to a stock ECU before, hence why I'm using my car for testing. I'm interested in seeing in what I do and don't need to keep the rest of the car working.
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From: Norn Iron
I'm getting ready to do this.
Why would you need to split the IAT, ECT sensor for the stock ECU?
If you are going to piggy back it to keep the BCM and factory gauges happy and have the Holley control fuel/spark I can't see any reason the factory PCM needs to see anything except cam/crank.
Why would you need to split the IAT, ECT sensor for the stock ECU?
If you are going to piggy back it to keep the BCM and factory gauges happy and have the Holley control fuel/spark I can't see any reason the factory PCM needs to see anything except cam/crank.
No big deal, just add another sensor for the piggyback ecu.
Piggybacking isnt difficult...just do it.
Any powered 5v sensors, rarely is there an issue splitting these to two devices.
