I wonder about progressive dual TBI's - could it be done with 2 separate ECM's - separate TPS and maps for each?
I wonder about progressive dual TBI's - could it be done with 2 separate ECM's - separate TPS and maps for each?
I've seen some very interesting stuff over the years and I think a determined person could make the dual ecm solution work. But I'd prefer to stick with a single ecm to reduce the number of variables. Yes, pun intended.
Both ecm's would share the distributor, coolant temp sensor, ???
No modifications are necessary to run 4 injectors from a TBI PCM. I have a friend with two cars running stock (unmodified) '7060s, running home made 4 bbl throttle bodies made from pairs of GM throttle bodies. He simply wired the injectors in series pairs and has had ZERO trouble for years this way.
I agrre a single ECM solution is best.
Also progressive is not easily do-able with a stock GM ECM, since it has no provisions for progressive secondary injectors. If that's a must or highly desired a Megasquirt is what I'd recommend. The problem with trying to run progressive throttles without also running progressive injectors is that you will get a large amount of fuel puddling above the secondary throttle plates and then when they do open will cause a rich condition. This will not always happen at the same load or RPM, so it would be difficult to tune around, also if you stab the throttle let off and then right back into the throttle, you'd likely not get that excess fuel on the second stab, so that would cause a lean condition. Best to just keep the throttle linkage 1:1 for all throttle plates if you go with an ECM that's not capable of progressive injector control.
As a side note, I like the crossfire system. I have on eon my grandfather's '71 truck, running off a '7427 PCM, that is also controlling a 4L60E. :)
The man who says something is impossible, is usually interrupted by the man doing it.
Yes, shared sensors.
GM ran staged injectors on the ZR1 with an RPM triggered external driver module. It'd be interesting to scope the injector pattern if the VE is set to "0" for a range of cells as that approach to staging the injectors would work with multiple ecm's. And of course, if the code is acessible then it's possible to use custom code to zero injector output below a specific TPS.
The LT5 didn't use staged injectors, it used a set that could be switched on and off. And to switch them on and off the engine had to be off, and the switch turned with the ignition key, then restarted. All 16 injectors were AFAIK always on when the high power mode was engaged, just using a different VE table than the 8 injector mode.
The man who says something is impossible, is usually interrupted by the man doing it.
Actually I am fairly certain 1 project is correct. The switch disabled the secondary throttle plate (s) on the ZR1 but the secondary set of injectors and throttle only opened at higher rpms.Originally Posted by Six_Shooter
This seems like a mix n match of system info. LT5 TB had tiny primary blade and larger secondary blades. Also had primary / secondary runner combination. When secondaries were active, second set of 8 injectors came online. Activation was RPM and TPS based (I said RPM only). LT5 also came with "valet" key which would disable secondary operation. That system would prevent secondaries from opening and would prevent secondary injectors from operating. There are some descriptions, pictures, and maps for OEM TPS v RPM curve to activate secondaries on this page:The LT5 didn't use staged injectors, it used a set that could be switched on and off. And to switch them on and off the engine had to be off, and the switch turned with the ignition key, then restarted. All 16 injectors were AFAIK always on when the high power mode was engaged, just using a different VE table than the 8 injector mode.
http://www.corvetteactioncenter.com/...diagnosis.html
Damn Mercruiser engines. LT5 built by Mercury marine. total POS to work on. DIS under intake manifold made changing wires a bitch.
I work on Vettes all day and cringe when a ZR-1 drives up.
Posting Permissions
Reply With Quote
Bookmarks