Batch fire or bank fire?
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 8
From: Tampa Florida
Looking at the FSM diagrams we know that most years have a minimum of 2 drivers/controllers one for each bank.....this means that from what see the computer has the ability to fire each bank seperately....how the controllers are activated (opeed/closed) is done by the logic within the chip set. There is very small "time" difference (if any) in the fire sequences between the odd/even bank fire setup. I don't see any performance difference of the bank fire over a batch fire. I think we're splitting hairs over any performance differneces between the two. As far as the # O2 sensor differences...it depends on what the ECM/PCM chip logic is set up for.....it may adjust both injector bank pulse widths with just one value. A professional reputable "Tuner" that knows the ECM circuit(PCB) layouts/components and has a firm grip on the chip logic for each year model should be able to answer all these questions with very little effort. I'm kinda surprised that none of these "Tuners" have posted a comment yet.
Last edited by engle1147; Jan 30, 2009 at 12:06 PM. Reason: 1 n in tuner
Racer
Joined: Jun 2006
Posts: 408
Likes: 0
From: Elkton MD
Really good analysis
The FSM and other electrical circuit diagrams surely support the above conclusions regarding batch, bank and SFI modes of operation.
A caveat; the FSM sometimes does NOT reflect 'As Built' electronics but is only a functional representation. For example, the 1995 C60 A/C control head schematic shows a mechanical rotary switch that controls the A/C compressor on/off. To my great surprise (when diagnosing a 100% always on compressor) I found that control head has a bank of switching transistors (one of which was shorted). The 'As Built' device physically was nothing like what the FSM illustrated but was functionally identical.
Physical circuit observation or performance evaluation via "BLM" records may be necessary to figure out what's really there.
I don't mean to be negative at all regarding the great detective work here. Just trying to broaden the horizon.
EDIT If I could type faster, I'd have seen & acknowledged engle1147's input regarding tuners. Yes!
A caveat; the FSM sometimes does NOT reflect 'As Built' electronics but is only a functional representation. For example, the 1995 C60 A/C control head schematic shows a mechanical rotary switch that controls the A/C compressor on/off. To my great surprise (when diagnosing a 100% always on compressor) I found that control head has a bank of switching transistors (one of which was shorted). The 'As Built' device physically was nothing like what the FSM illustrated but was functionally identical.
Physical circuit observation or performance evaluation via "BLM" records may be necessary to figure out what's really there.
I don't mean to be negative at all regarding the great detective work here. Just trying to broaden the horizon.
EDIT If I could type faster, I'd have seen & acknowledged engle1147's input regarding tuners. Yes!
Last edited by IRAraid; Jan 30, 2009 at 09:32 AM.
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 8
From: Tampa Florida
The FSM and other electrical circuit diagrams surely support the above conclusions regarding batch, bank and SFI modes of operation.
A caveat; the FSM sometimes does NOT reflect 'As Built' electronics but is only a functional representation. For example, the 1995 C60 A/C control head schematic shows a mechanical rotary switch that controls the A/C compressor on/off. To my great surprise (when diagnosing a 100% always on compressor) I found that control head has a bank of switching transistors (one of which was shorted). The 'As Built' device physically was nothing like what the FSM illustrated but was functionally identical.
Physical circuit observation or performance evaluation via "BLM" records may be necessary to figure out what's really there.
I don't mean to be negative at all regarding the great detective work here. Just trying to broaden the horizon.
EDIT If I could type faster, I'd have seen & acknowledged engle1147's input regarding tuners. Yes!
A caveat; the FSM sometimes does NOT reflect 'As Built' electronics but is only a functional representation. For example, the 1995 C60 A/C control head schematic shows a mechanical rotary switch that controls the A/C compressor on/off. To my great surprise (when diagnosing a 100% always on compressor) I found that control head has a bank of switching transistors (one of which was shorted). The 'As Built' device physically was nothing like what the FSM illustrated but was functionally identical.
Physical circuit observation or performance evaluation via "BLM" records may be necessary to figure out what's really there.
I don't mean to be negative at all regarding the great detective work here. Just trying to broaden the horizon.
EDIT If I could type faster, I'd have seen & acknowledged engle1147's input regarding tuners. Yes!
All opinions are welcome...books can be wrong no doubt about it....we all know not to put dielectric grease between the ICM and the distributor case for heat transfer....as the early FSM suggest....use heatsink type paste instead. The diagrams of these "black box" ECM drawings are simplified for whatever the reason.....pcb and electronic components are often changed/altered frequently from revisions made by manufactures....or maybe just too much information there.
If someone has a 2 channel "o" scope they could hook it up slow it down and compare when the pulses occur for each bank....just thought a "Tuner" response might save us the time and trouble.
Last edited by engle1147; Jan 30, 2009 at 12:07 PM.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
The diagrams for 1986 and 1987 that engle1147 posted are not correct. The same 1227165 ECM was used from '86 through '89 and it has only one injector driver.
In my '86 the injector wires come into the ECM on pins D15 and D16. They are connected together inside the ECM and go to the single injector driver transistor.
In my '86 the injector wires come into the ECM on pins D15 and D16. They are connected together inside the ECM and go to the single injector driver transistor.
Last edited by Cliff Harris; Jul 23, 2013 at 03:41 AM.
Racer
Joined: Oct 2006
Posts: 438
Likes: 14
From: Tucson/Santa Paula AZ/CA
2017 C4 of Year Finalist
Cliff,
Thanks for resurrecting this ancient thread, I missed it the first time through. Just the fact that my '90 has a single BLM value tells me it's a Batch fired injection system. It's a lot like the 'drool' system used by my previous '61 Fuelie's Rochester Fuel injection. The new stuff is controlled by sensor feedback and the pulse width acts like the ratio lever in the Rochester system which was fully controlled by vacuum. I can certainly see why a matching set of injectors (both on flow and resistance) can make a huge difference in how the engine runs. Since the injector coils are all in parallel, the resistance seen by the ECM is less than the lowest resistance of the individual injector coils.
Mick
PS Don't let the Gestopo DMV see your Avatar, it's tag is expired.
Thanks for resurrecting this ancient thread, I missed it the first time through. Just the fact that my '90 has a single BLM value tells me it's a Batch fired injection system. It's a lot like the 'drool' system used by my previous '61 Fuelie's Rochester Fuel injection. The new stuff is controlled by sensor feedback and the pulse width acts like the ratio lever in the Rochester system which was fully controlled by vacuum. I can certainly see why a matching set of injectors (both on flow and resistance) can make a huge difference in how the engine runs. Since the injector coils are all in parallel, the resistance seen by the ECM is less than the lowest resistance of the individual injector coils.
Mick
PS Don't let the Gestopo DMV see your Avatar, it's tag is expired.
