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| ECM upgrade (1227730) for stock 2.8 (Page 101/107) |
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Darth Fiero
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JUL 26, 01:14 AM
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| quote | Originally posted by sleevePAPA:
AXXD?
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No, AXYC. But same difference.
I know it should. It does in the Corvette applications (although different ECM architecture). I'll get back to this later (see my next post).
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For cylinder select, there is also a bit that needs to be turned off iirc. I will check and get back to you a little later. |
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I think I figured it out. Looking at an $8D disassembly/hack I have, there is a check done by the ECM for the Code 41 diagnostic which also needs to be changed.
The main "Number of Cylinders" constant is at address $0009, and here are the possible settings:
4 = $80 (decimal = 128)
6 = $C0 (decimal = 192)
8 = $00 (decimal = 0)
The code 41 Cylinder Select Diagnostic is located at address $0293, and here are the possible settings:
8 CYL = $00 (decimal = 0)
6 CYL = $08 (decimal = 8)
4 CYL = $10 (decimal = 16)
TBI = $18 (decimal = 24)[This message has been edited by Darth Fiero (edited 07-26-2013).]
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Darth Fiero
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JUL 26, 01:27 AM
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I downloaded a pinout comparison chart from the Ludis webpage some time ago that showed the hardware comparison between the 1227730/1227749 and 1227727 ECMs. For those of you who aren't familiar with these ECMs, the 1227727 ECM is a sealed unit that is designed to be mounted in the engine compartment and it has 4 square connectors. The 1227730/1227749 is an in-car mounted ECM (much like the stock Fiero V6 unit) only it has 3 connectors. All of these ECMs will run the same code mask programming. Anyway, using the chart and looking at the 90-91 Corvette TPI pinout charts, here is what I have found crosses over to the 1227730/1227749 ECMs:
(1227730 ECM pins)
*BC9 - A/C Clutch Status Input
BD3 - A/C Request Input
*BD12 - Fan2 Request (A/C Pressure Switch) Input
*BD14 - 4th Gear Switch Input
*BD16 - Park/Neutral Switch Input
*GE8 - Fan1 Relay Control Output
*GF1 - Upshift Lamp Control Output (MT & AT)
GF3 - A/C Clutch Relay Control Output
GF5 - 1-4 SkipShift Lamp Control Output
*GF6 - AT TCC Solenoid or MT 1-4 SkipShift Solenoid Control Output
GF8 - Fan2 Relay Control Output
GF12 - Engine Oil Temp Sensor Signal Input (0-5v analog)
* = Only ones used by F-Body V8 TPI (90-92)
All listed above are used by the Y-Body TPI (90-91)[This message has been edited by Darth Fiero (edited 07-26-2013).]
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sleevePAPA
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JUL 26, 09:03 AM
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Just checked, 08 set at 0x293work for cyl error qual.
For some reason i cant remember, i had to splice D3 and C9 together to enable a/c relay
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Darth Fiero
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JUL 26, 09:56 PM
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| quote | Originally posted by sleevePAPA:
Just checked, 08 set at 0x293work for cyl error qual.
For some reason i cant remember, i had to splice D3 and C9 together to enable a/c relay |
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BD3 is A/C request input. When the ECM sees 12v + power on this input, it *should* command the A/C relay on.
BUT, it will not acknowledge the A/C clutch is engaged until it sees 12v + power on BC9 since this is the A/C clutch status input.
I have not tested this yet so I don't know if this is indeed the case or if you are correct and, for some reason, both BD3 and BC9 need to get 12v + power before this ECM will enable the A/C relay output. Maybe I will play with this next week.
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fieroluke
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AUG 02, 06:04 AM
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| quote | Originally posted by Darth Fiero:
A/C PRESSURE SENSORS:
The $A1 code mask requires a 3-wire A/C pressure sensor be installed on the hi-side of the A/C system
GM used these 3-wire A/C pressure sensors on R12 and R134a systems. 1991-92 W-body GM cars with the 3.1L V6 had R12 and a sensor for or from one of these cars will have the R12 threads.
All 1994-newer GM cars and trucks used R-134a so a 3-wire A/C pressure sensor from any of these vehicles will have R-134a specific threads. You can have an R-134a pressure sensor fitting welded into a set of existing A/C lines if your welder knows what he or she is doing.
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Okay, I am currently running DarthFiero's 0x88 mask with my distributor 2.8, and I'd like to upgrade to DIS soon, it looks like I have to deal with this A/C issue.
I have a few questions:
- isn't there a 3-wire sensor that fits in place of the hi-pressure switch on the compressor? Do both hi pressure switch and sensor need to be retained? If the hi pressure switch can be deleted, it would be possible to make an adapter on a lathe that fits into the compressor port that has a R134a thread...
- Where does one get a R134a pressure sensor fitting? Is that a common part? Could that be welded to the A/C line next to the service port?
- The 0x88 mask should ignore the signal, so it should be possible to install the sensor with my current (non-DIS 0x88) setup?
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Darth Fiero
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AUG 02, 11:37 PM
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| quote | Originally posted by fieroluke:
Okay, I am currently running DarthFiero's 0x88 mask with my distributor 2.8, and I'd like to upgrade to DIS soon, it looks like I have to deal with this A/C issue.
I have a few questions:
- isn't there a 3-wire sensor that fits in place of the hi-pressure switch on the compressor? Do both hi pressure switch and sensor need to be retained? If the hi pressure switch can be deleted, it would be possible to make an adapter on a lathe that fits into the compressor port that has a R134a thread...
- Where does one get a R134a pressure sensor fitting? Is that a common part? Could that be welded to the A/C line next to the service port?
- The 0x88 mask should ignore the signal, so it should be possible to install the sensor with my current (non-DIS 0x88) setup?
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I have never seen a 3-wire A/C pressure SENSOR that will install directly into the back of an A/C compressor. But if anyone knows of one, I would be very interested in getting the part number.
Once you have a 3-wire A/C pressure sensor installed & wired up to the 7730 ECM and have the 7730 ECM controlling the A/C clutch relay, you do not need the stock Fiero A/C hi-pressure cut-out switch that mounts on the back of the stock Fiero A/C compressor. The 7730 ECM / 3-wire A/C pressure sensor will monitor A/C hi-side pressure and will disable A/C clutch operation if pressure gets too high.
GM did make a 3-wire A/C pressure sensor with the same threads (R12) as the hi-side test port that's on the stock Fiero A/C line up in the front trunk compartment. These were used on 1993-older GM W-Body cars. These sensors will screw right onto the stock Fiero hi-side pressure test port. The catch is the Fiero fitting was not machined to accept an o-ring to seal this type of sensor. I have been able to get these sensors to install and seal on these fittings but I usually have to stack 2 o-rings onto the fitting, discharge the system, pull the system into a vacuum, then install the sensor. Trying to do this on a charged system without it blowing out the o-rings before you get the sensor fully seated is next to impossible.
You can get R134a pressure sensor fittings (and matching pressure sensors) at the junkyard. Look for 96-newer W-body cars; should be pretty common. A good pair of side cuts will easily cut thru the aluminum line on both sides of the fitting so you can get the fitting off.[This message has been edited by Darth Fiero (edited 08-02-2013).]
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chetw77cruiser
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AUG 03, 12:16 PM
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Darth Fiero, if you want any help with the $8D code mask, let me know. I have been working with that code since 98 on everything from a 79 Dodge Omni, 77 Toyota Landcruiser, 72 Chevelle, and of course my 86 GT before the v6 converted to a v5. I even had this code working with a DIS system. I found the $8D code to be very versatile once you get your mind wrapped around it.
Chet W.
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sleevePAPA
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AUG 03, 02:11 PM
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| quote | Originally posted by chetw77cruiser:
Darth Fiero, if you want any help with the $8D code mask, let me know. I have been working with that code since 98 on everything from a 79 Dodge Omni, 77 Toyota Landcruiser, 72 Chevelle, and of course my 86 GT before the v6 converted to a v5. I even had this code working with a DIS system. I found the $8D code to be very versatile once you get your mind wrapped around it.
Chet W. |
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Good to know! Only real complaint I have with it is the fuel control modifier when EGR is active and the MAT counts table. Masks like $A1 and $88 seem to have higher resolution (EGR DC vs. VE) while $8D uses a partial pressure modifier. My studies into code hacking has stalled due to other priorities but I wanted to modify and resolve a few issues(IMO) like the MAT counts vs MAT table to work better with an IAT. Also wanted to add(for sh!ts n giggles) a spark cut routine(2step).
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Darth Fiero
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AUG 06, 02:53 PM
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| quote | Originally posted by chetw77cruiser:
Darth Fiero, if you want any help with the $8D code mask, let me know. I have been working with that code since 98 on everything from a 79 Dodge Omni, 77 Toyota Landcruiser, 72 Chevelle, and of course my 86 GT before the v6 converted to a v5. I even had this code working with a DIS system. I found the $8D code to be very versatile once you get your mind wrapped around it.
Chet W. |
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I appreciate the offer for help. But I too have been working with this code mask for as long as you have although 99% of my use with it was working with healthy V8 builds. I have little previous experience using it with a V6 and none with DIS, so maybe that is where you can help. I was looking over the $8D disassembly I have and could not find any coil dwell tables defined in it. What (if anything) has to be changed in order to make the $8D mask work with DIS?
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Darth Fiero
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AUG 06, 10:11 PM
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I connected the A/C "request" wire coming from the Fiero HVAC control panel to ECM pin BD3 - A/C request input. Then I connected ECM pin GF3 - A/C Clutch Relay Control Output to the Fiero A/C relay.
Result : No A/C clutch operation with HVAC selected to turn A/C on. No idle increase, no radiator fan tuning on.
I then tied ECM pin BC9 - A/C Clutch Status Input in with the BD3 - A/C request input wire and still no A/C clutch engagement (because the ECM didn't activate the A/C clutch relay); but I did get a raised idle and the radiator fan kicked on.
All this while still using the 305 TPI F-body base tune. I would assume it will work with the Corvette $8D base tune but I'm not going to mess with it on this car because I would need to spend a ton of time copying all my fuel and spark tables (as well as other settings) over to a Corvette tune and I really don't have time to mess with it right now. The A/C works without ECM control and there's really little point to changing that in this kind of application (stock 2.8).
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