ecm piggy back (i searched) - Third Generation Forum

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ecm piggy back (i searched)
Monday, January 19, 2009 2:18 PM
hey guys i got my car to do a 3*00 swap im in the process of gathering parts. the car is a 97z my question is can some one give me a more detailed how to on piggy backing the 3400 ecm and the cav pcm to run the gauges. i.e. wat if ant sensors do i need to have muliples of or do i just splice into the existing sensors? any incite greatly apperciated.

Re: ecm piggy back (i searched)
Monday, January 19, 2009 3:01 PM
did you search on v6 swap sticky? only read it thru a couple of times but its pretty use ful plus there is links to other sites with use ful info
Re: ecm piggy back (i searched)
Monday, January 19, 2009 4:32 PM
i skimed it but ill give it another look
Re: ecm piggy back (i searched)
Monday, January 19, 2009 7:08 PM
It's been like 4 years since I did mine,-- depending on what harness you have, you need to have the engine (donor) run by itself, the cavi guages run off the "uart" ?? line from the j pcm- so it needs to operate too, but not for the injectors and such. -- oil press, water temp etc must be t'd with the old sensors added to the new engine. others have been able to run a 3 wire temp sensor and make it work, I just welded in a new bung in the bypass tube and used the old sensor. also, dont forget about the passlock system!! very important




Re: ecm piggy back (i searched)
Tuesday, January 20, 2009 12:14 PM
ray gardner wrote:hey guys i got my car to do a 3*00 swap im in the process of gathering parts. the car is a 97z my question is can some one give me a more detailed how to on piggy backing the 3400 ecm and the cav pcm to run the gauges. i.e. wat if ant sensors do i need to have muliples of or do i just splice into the existing sensors? any incite greatly apperciated.


I don't know how to piggyback to GM PCM's. Because both of them are going to want a speed sensor input.



Re: ecm piggy back (i searched)
Tuesday, January 20, 2009 2:22 PM
why does the v6 need a speed sensor input to operate-???




Re: ecm piggy back (i searched)
Tuesday, January 20, 2009 2:31 PM
i thought this has been done or has it just been discused
Re: ecm piggy back (i searched)
Tuesday, January 20, 2009 3:26 PM
i did it a long time ago






Re: ecm piggy back (i searched)
Tuesday, January 20, 2009 6:10 PM
just do autometer guages much easier, all the wires you need are under your dash



JBO since July 30, 2001
Re: ecm piggy back (i searched)
Tuesday, January 20, 2009 6:32 PM
im deleting the cav's engine harness and ecu and did u kick that mustangs ass
Re: ecm piggy back (i searched)
Tuesday, January 20, 2009 7:46 PM
if at all posable i would like to retain the stock gauges and i really cant aford to by 200$ of autometer gauges and get the car goin but it is my plan b.

Re: ecm piggy back (i searched)
Wednesday, January 21, 2009 3:52 AM
john beers aka thebondoman wrote:why does the v6 need a speed sensor input to operate-???


On new cars you get a CEL without a VSS being hooked up. Also the PCM's (for quite some time) at least on manual transmission cars will hold the idle speed a bit higher until you drop under a certain MPH (4mph or something of the sort). I'm not sure why they do this, just know that they do.





Re: ecm piggy back (i searched)
Wednesday, January 21, 2009 4:08 PM
john did you have a problem with vss or any sensor for that matter which ones needed multiples and were u able to splice any or mabey use a three wire temp sensor. if i could that would be awsome because i plan on using a 3500 and that uses a 3 wire sensor and is a pain to convert the bung to a 2 wire.
Re: ecm piggy back (i searched)
Wednesday, January 21, 2009 5:54 PM
now my brain hurts from thinking
I used a 01 grandprix engine, pcm, radiator and fan assembly // added a second temp sensor-jcar- onto the bypass coolant line- easy. ran a jumper from the gp pcm to the charge idiot light (under the hood), I added a main fuse and relay at the fuse box for a second fan. since the a/c is pcm controlled, I wired the a/c switch thru a relay to fool the gp pcm to turn it on--- all the wiring using relays was routed thru the j fuse /relay setup
i did not have any issues with the vss, had a 5sp. but I did have to change my fuel pump.
another very important item-- you must use an upgraded clutch. I had a stock 2.2 cluch,-- street driving was ok, but at the track it slipped at least half way down the track and gave me a slow 60ft time of 2.39
used the donor transducer and key to bypass the passlock system
hope this helps






Re: ecm piggy back (i searched)
Wednesday, January 21, 2009 6:03 PM
im prob gonna use like a stage 3 clutch. all this will prob be alot easyer wen i have both harness infron of me and i can go through them wire by wire and figure out wat im gonna use for wat. i plan on gettin the motor runnin on the G.A. ecm with the pass lock and auto codes removed and then ill tackle gettin the gauges to work. all this incite has gave me a good idea of wat i have to do but still kinda confusing the hell out of me. lol
Re: ecm piggy back (i searched)
Wednesday, January 21, 2009 6:22 PM
I would recommend having both gm service manuals- your vehicle and the donor - they have complete wiring and pinouts- includes colors, wire size and circuit id codes





Re: ecm piggy back (i searched)
Thursday, January 22, 2009 12:09 PM
yea im gonna get at least the hanyes manual and i have access to all data
Re: ecm piggy back (i searched)
Saturday, January 24, 2009 7:37 AM
ok im in the process of the piggy back as well but i disabled the speed limiter on the gtp ecm but will i need to run the vss through the cav ecm or gtp



my kill list:a geo metro and a mac semi wow did i kill that thing
Re: ecm piggy back (i searched)
Saturday, January 24, 2009 2:26 PM
the VSS is needed for the cav pcm to operate the speedo




Re: ecm piggy back (i searched)
Saturday, January 24, 2009 10:25 PM
thank you sure sorry for thread jacking



my kill list:a geo metro and a mac semi wow did i kill that thing
Re: ecm piggy back (i searched)
Sunday, January 25, 2009 9:34 PM
jacking is ok if it benefits all !!!





Re: ecm piggy back (i searched)
Sunday, January 25, 2009 10:07 PM
john beers aka thebondoman wrote:jacking is ok if it benefits all !!!


That's what she said...





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