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-   -   92 LT5 ecu ignition program and control (http://zr1.net/forum/showthread.php?t=28738)

Theg 01-31-2018 09:45 PM
Re: 92 LT5 ecu ignition program and control
 
1 Attachment(s)
Pic of the injector bosses intrusion into the port

Theg 01-31-2018 10:05 PM
Re: 92 LT5 ecu ignition program and control
 
1 Attachment(s)
Pic of custom pipes

XfireZ51 01-31-2018 11:30 PM
Re: 92 LT5 ecu ignition program and control
 
Quote:
Originally Posted by Theg (Post 273753)
I dont plan on modifying any internals . Only mods will be removal of the secondaries and pluging injector bosses and other vacuum ports etcetc.
I may look at removing the injector boss material from inside the port . Will look closer at that option once I get a good look at what material would need to be removed . Looking down the ports though I see a fair flow obstruction that may benefit performance if I can smooth them .
Also has custom headers.
W stock cams and headers, probably sufficient to use stock ignition map and perhaps add a few degrees.

Theg 01-31-2018 11:41 PM
Re: 92 LT5 ecu ignition program and control
 
Quote:
Originally Posted by XfireZ51 (Post 273761)
W stock cams and headers, probably sufficient to use stock ignition map and perhaps add a few degrees.
Do you think the ignition would still fire normally even if all fuelling side sensors are failing to send data to the ecu ?
Do you know if the knock sensor if left wired to the ecu would continue to help retard ignition if there was a condition of too much advance in the timing .

XfireZ51 01-31-2018 11:54 PM
Re: 92 LT5 ecu ignition program and control
 
If there’s knock, then the ECM will retard timing depending on the amount of retard defined in the calibration. Given that the ECM is calculating pulse width to control injectors, doubtful u can use the OEM ECU. A Holley Pro-Jection system may be a viable alternative.

Theg 02-01-2018 01:23 AM
Re: 92 LT5 ecu ignition program and control
 
Quote:
Originally Posted by XfireZ51 (Post 273763)
If there’s knock, then the ECM will retard timing depending on the amount of retard defined in the calibration. Given that the ECM is calculating pulse width to control injectors, doubtful u can use the OEM ECU. A Holley Pro-Jection system may be a viable alternative.
Just a bit confused now . Im unsure if you mean I cant use the stock ecu to run just timing and ignition control when Ive no sensors for fueling returning signals to the ecm .
Basic question is if I removed all injector wiring and map sensors ,TPS, 02 sensors, coolant temp etc etc but left ignition sensors like crank sensor and knock sensor would the ecm still carry out the ignition function when over the 400rpm ?

XfireZ51 02-01-2018 08:43 AM
Re: 92 LT5 ecu ignition program and control
 
Ignition is controlled by the ECM and is based on RPM x MAP. Without sensors, u have a bunch of codes. Whether the motor would even start is questionable. It certainly would be in “limp home” mode. What u are describing is using an ignition control system, so that’s what u should use.

XfireZ51 02-01-2018 01:43 PM
Re: 92 LT5 ecu ignition program and control
 
One other point about employing carbs sitting on top of the LT5 plenum. The plenum and injector housing was designed as a dry induction system for port fuel injection. Quite a few twists and turns in the journey of air from TB to combustion chamber. Runner length is quite long. I can see quite an issue with fuel coming out of suspension in the induction tract and dumping raw fuel onto the valves. Don't mean to rain on your parade, but I don't think its a very workable configuration.

Theg 02-01-2018 03:18 PM
Re: 92 LT5 ecu ignition program and control
 
Dam Id forgotten about the limp home factor .
Will do some more thinking.

tpepmeie 02-01-2018 07:00 PM
Re: 92 LT5 ecu ignition program and control
 
Quote:
Originally Posted by XfireZ51 (Post 273789)
One other point about employing carbs sitting on top of the LT5 plenum. The plenum and injector housing was designed as a dry induction system for port fuel injection. Quite a few twists and turns in the journey of air from TB to combustion chamber. Runner length is quite long. I can see quite an issue with fuel coming out of suspension in the induction tract and dumping raw fuel onto the valves. Don't mean to rain on your parade, but I don't think its a very workable configuration.
Easily the beacon of reality (BoR) award for this week. I agree with Dom, that setup -- carbs on top of the LT5 plenum doesn't seem ideal to me.

If you're going carbs, I'd do a custom tunnel ram fabricated manifold.


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