cruiserbrett

Hi,
I have read through alot of posts and while I found a ton of info, I couldnt find the answers I was looking for... so, here goes.

Working on a TBI conversion on a, ahem, 1975 Land Cruiser(4.2L I-6), and decided to look into the 7427 pcm as an option, since its apparently much better tuning wise.

Pinout changes and wiring issues are no problem, I can figure that out with the info on the site.

I have looked high and low for a manual tranny .bin file without any luck? do they exist? Preferably for a 4.3L and $0d mask? I would need another mask .xdf if I dont find one in $0d.

Since the cruiser is going to be used offroad, a feature I would love is an idle up function independant of the a/c(the cruiser has a/c so I would like the a/c idle up to work by adding about 100 rpm or so?) Is this possible? I read a post somehwere here that stated there may be a force idle up function? Can I set the force up RPM to say 1000 to increase alternator output with a switch on the dash?

I am planning on using Tunerpro(already downloaded and somewhat familiar), and got the $0d.xdf from the site uploaded.

I am interested in realtime emulation and looked over the moates site. Lots of info there, but I just dont know what is best for me... I have a pocket programmer 2, and a laptop with USB,parallel and serial ports, I made a rs232 ALDL link that worked fine with a 7730 ecm. My goal is to tune this to a point and burn a chip and thats it, so I would rather not spend $350 on the APU1. Already planning on a WB02 sensor(LC-1?) so I can tune more accurately. Would love to get the WB02 data into the ALDL stream but that is WAY over my head(would be like asking a monkey to fly the space shuttle)...

Thanks for your help!

-Brett Garland

DENN_SHAH

iTrader: (1)

im not real familiar with the 7427 ECM and OD.
i don't know if there is a $OD bin for a 4.3 or not.
but i think i've read here that you can change the A/C idle speed adder like you can in the 7730 with 8D, so a switch on the dash should work fine.
having a standard trans, you could possibly use the park input for the additional idle speed instead of the A/C adder.


because you already have a burner, i believe the Ostrich 2.0 will work great for your real time tuning and emulation needs.
the Ostrich also stores the bin so you don't need your laptop hooked up once you get the tune close unless your wanting to take a data log.

RBob

iTrader: (1)

I doubt that there is a stick trans calibration for the '7427 PCM. The reason is that during the time that PCM was used stick vehicles received the standard TBI ECM. No need for a PCM as it is for running both the engine and electronic transmission (auto).

If you do go with the '7427 PCM, look into how to disable the 'E' functionality. Should be able to do this by setting/clearing a flag to tell the code that a 700R4 is in place. And to run a TCC instead.

The reason for this would be to disable torque management functionality. If the PCM thinks it is shifting a 'E' trans whn it isn't, the tune could get funny real quick.

RBob.

w/t1500

I 've one $0D 4.3L m/t .bin for you
BDXR superceded by BJFD.

Sylvain

RBob

iTrader: (1)

Always an exception to the rule. I wonder why they used the PCM with the 4.3l trucks. Anyway, the BDXR calibration is listed for use in a '8625 PCM. while the BJFD is listed for use a '6395 PCM.

I've put a '7427 and a '6395 side by side and I can't see any difference between them at all. From what I can tell they are the exact same PCM with the exception of the number on the label.

The '8625 PCM is different from the '7427/'6395 PCM's. At least the PCB layout and so on. I guess the question is, are all three of these PCMs functionally the same? And do they have the same pinout to the harness connectors?

If they do then it would be easy to mix & match between the three of them.

RBob.

Fast355

iTrader: (2)

The only manual transmission trucks that came with the 7427 were 4.3s and 7.4s. They are out there.

There is a manual transmission option that overides the computer shift coding and enables the shift light.

The 4.3s and 7.4s ran the PCM because they ran Linear EGR valves.

Fast355

iTrader: (2)

8625 is pin for pin and has the same functionality. On the otherhand some of the un-used inputs for VSS and TSS are missing capacitors and resistors on some PCMs and others have them.

4.3/7.4 ran them for Linear EGR valve support.

RBob

iTrader: (1)

And it would have been easy for me to miss a few SMD caps and resistors. I'll need to take a closer look next time I have some opened up.

The C3 TBI ECMs don't have any extra ADC channels run out the connectors. Makes sense to use the PCM instead of a layout and code change on an ECM that is being phased out. Shoot, probably didn't have room for any extra code anyway. Thanks.

RBob.

93V8S10

http://www.fullsizechevy.com/forums/...ny-set-up.html

HTH

dimented24x7

iTrader: (2)

See my comments in bold.

dimented24x7

iTrader: (2)

You wouldnt be the first one to miss those caps and resistors I got burned by those too trying to use the auxilliary TOS inputs in my custom code. Since both of mine had all the needed hardware in place, I made the stupid assumption that all the others did as well. Found out the hard way that its not the case.

dimented24x7

iTrader: (2)

How much different are they? Both of the PCMs I have are 8625's that where running my modded $0D code. Wasn't aware that the 7727/6395 were different. All auxilliary inputs worked on my 8625's, so maybe those are the ones to go after in the yards.

RFmaster

I have one 8625 (BHAZ) and 7427 (BPRY) which I can take apart and do side by side comp under a microscope if need be, with photos. Any area of interest in particular???

//RF

cruiserbrett

Thanks for the help!!! I got the bin uploaded to tunerpro with the $0D.xdf, and looked over it.

Flags/Error codes are very generic. I dont have a bit breakdown of the specific codes, so I am shooting in the dark there. I need to do the following:

1. ensure manual transmission is selected(should be but want to double check)
2. select shift light option and set rpm?
3. disable EGR? best way?
4. disable trouble code for EGR and any tranny ones.


Couple other questions: looking at the tables, there is a near idle and off idle VE table. dont understand the difference, since there are two slightly different values for the same RPM/Load. take 1600 RPM and 40 KPA. One has 79% VE and the other 73%. seems wierd. I do see that there is increase resolution on the near idle table up to 1800 rpm, but since they are clearly not adders(would be 152% VE), how does the computer pick between the two potenitally different values?


Also, If I am using a 89 Astro van TB, with the stock injectors(45#/hr?) at stock 13 psi, what is the expected fuel pressure? I see its grams/sec, but is that at 13 psi like early TBI?



For spark control: Similar to 7747 ecm? Ie main spark table-initial-bias+coolant+egr+pe etc? any other that I missed or are not on the xdf?




Is the coolant subracted or added? Seems like added, since most normal operating temps coolant correction seem to have the same value as main spark bias, so they would cancel eachother?



Main spark open throttle vs closed throttle? Is that just part of a complex deceleration enleanment? What is the %TPS for the closed table to be activated? 2% or less? or is it a delta TPS lookup? Seems weird since there is a closed throttle column for 100KPA, which would be nearly 0 in vac. strange for a manual?



Would it be best to just duplicate the open throttle table for the closed throttle position table to start tuning? for better engine braking would I want to add spark compared to the open throttle table?




Also, is there a location I could find out what is the application for that broadcast code? So I can order a manual for say a "1995 blazer"???



I know these are basic questions, but I am still learning.

w/t1500

CalData Report 03-03-09

Search Keys:
Broadcast Code: BDXR

"BCC"= BDXR
"Year"= 1994
"Rel Date"= 12/16/92
"EPROM #"= 16189357
"ECM #"= 16168625
"PROM ID"= 9358
"SCAN ID"= 9425
"Platform"= C1
"Eng","Disp"= LB4 4.3L
"Trans"= MG5
"Trans Type"= manual

Sylvain

93V8S10

Try the xdf at the bottom, might help.

The near idle table is only used at idle. There's a constant for the entrance point to the off idle table, if you need to change it. I just set the RPM lines that match to the same value as the off idle table and calculate the others, but you can use different values if needed.

Ya, just duplicate the open throttle spark table works fine. You can add spark for engine braking, if needed, just up to you.

cruiserbrett

Wow. there is SO!!! much more there! Found the idle up parameters, so it will work automatically with a drop in voltage. Cool.



DRP and CCP? what do they stand for?






THANK YOU!!!

Fast355

iTrader: (2)

DRP = Distributer Reference Pulse

CCP = Charcoal Canister Purge

RBob

iTrader: (1)

I have the PCMs reversed. It is the '8625 & '6395 that use the same PCB. The '7427 uses a different PCB along with a different processor. Although the PCB is different it sure is hard to tell by looking at it.

The '8625/'6395 PCB has the same version numbers on them. While the '7427 has a different number along with the different uProc (different part number).

Later today/tomorrow I am going to take a better look for component differences. I left them on the bench as a reminder.

RBob.

junkcltr

iTrader: (1)

I am running the $0D in the 427 ECM with a stock GM 350ci target master replacement engine with a stock TPI unit on it. The trans. is a SM465 (4-speed w/granny low). I had to disable the spark correction function. It would pull a bunch of timing as engine load increased after shifting gears. You may want to take a look at dimented24x7's hac. It shows how the spark tables work when different options are set. Things like stick/auto and all the fuel modes.

dimented24x7

iTrader: (2)

Heres the hack for the $0D

RBob, Id definitely be interested in seeing what the differences are. Seems like GM always does weird stuff with the hardware.

gsjmtntman

Would love to know also before I button up my 6395 after MPFI mod!

cruiserbrett

Well, after scouring through countless astro vans and s10's, I was able to locate one! 16197427. I think they are popular around here since every vehicle I thought might have one was missing the ecm. except one newly dropped off astro van...Also got a DRAC, which brings me to my next question.Looking through the advanced $0D ecu file, I noticed that only under the 4l60e parameters was there a VSS ratio constant. Since I am running a manual tranny,and my choices of VSS are 2 pulse/rev DC, and 4 pulse AC, will I be able to make the PCM think its actually operating at the correct speed? Those two VSS are the only two available for toyota speedo cables...does the pcm need an ac signal?Does anyone have a link to the wiring pinouts and purposes of the drac wiring? Found the info on calibrating it and already installed a 7pin dip switch.

dimented24x7

iTrader: (2)

There are two main inputs for the PCMs VSS, both using DC pulsetrains. It retains reverse compatibility with the older systems/code in that it uses the older style VSS input on pin F13 (2K pulses/mile), as well as a secondary high frequency TOS (Transmission Output Speed) input on pin F12, which can be configured for pretty much anything. 2 pulse/rev or 12, or 40, or what have you. You can probably just wire up the VSS only since your not using an e-trans. From my recollection, the only place the TOS input is used when a manual is present is in the code for the shift light. If your not using a shift light, you can omit the output to the TOS and disable the error code.

dimented24x7

iTrader: (2)

To exand on what I said in the last post, you will need to calibrate the DRAC to convert the pulsetrain to 2000 pulses/mile and wire it to pin F13. Another way to think of it is that at 60 MPH, the PCM should recieve 2000 pulses in a minute. Now, the VSS signal from the stock speedo, I assume that is driven by the speedo cable? If thats the case, then you will need to know the ratio of the speedo gears in the toyota transmission. If you know that, along with the rear gear ratio and tire size, you can calculate what the conversion constant should be.

dimented24x7

iTrader: (2)

Also, with the stock GM DRAC from the truck (I assume thats what your reffering to), you will need to use an AC signal. If the VSS for your speedo can only produce 2 pulse/rev DC or 4 pulse/rev AC, you will need to use the 4 pulse/rev AC with the DRAC since its configured to work with a magnetic reluctor. If you can get a converter box of some sort, then the 2 pulse/rev DC signal could be used and scaled appropriately for the PCMs VSS input.

cruiserbrett

thank you!

the drac is an earlier one, from a 91ish blazer IIRC. So the drac requires an AC input and can output a DC signal to f13. Lucky casue I already have the 4pulse/per rev one from an old TPI swap I did. Fortunately toyota speedos are also calibrated to be 1000 revolutions per mile, so works out to 4000 pulses.


Getting more advanced: WB02ALDL output. More pure curiosity than something I will tackle immediately.

Wiring:Read through the board as much as I could and found I would need to use linear pintle position EGR input. that should be simple pin location.

ECM: changes in code? I am guessing by looking at the .ads that there are steps calculated by the ecm output to the .ads. How does the ECM get feedback from EGR position? linear potentiometer in EGR valve or does it calculate it by counting steps?

ALDL stream: modify .ads. now, the question is in there a constant(dFactor) by which I would multiply the analog voltage, or is the output of the LC-1 non linear and requires a lookup table?


dwItemType =1;
strItemComments =<Comments>;
bSeparator =0;
bVisible =1;
dwUniqueID =81;

btByteNumber =61;
btMessageNumber =1;
dwItemSizeBits =8;
dwOperation =0;
dFactor =1.000000; change to whatever the constant is needed
dOffset =0.000000; use if 0 AFR is actually outputing 1 volt for example
strItemTitle =Linear EGR Pintle Position RAW Counts; change to "=AFR;"
strUnitLabel =Counts; change to "=Ratio;"
dwAlarmHigh =255;
bAlarmHighENable =0;
dwAlarmLow =0;
bAlarmLowEnable =0;
iRangeHigh =255;
iRangeLow =0;
iLookupTableIndex =-1;

Please feel free to tell me I am offbase and need to stop. I am learn the best by doing something,so this might(in the future) be something I tackle.

Thanks!
-Brett

***EDIT: just looking through the $0D hack I need a better understanding of the code... Ouch.***

dimented24x7

iTrader: (2)

If the cable is 1000 rev/mile, then you can possibly sidestep the entire drac by simply using the 2 pulse/rev DC VSS for your speedo that you mentioned. That can be fed directly into the PCMs VSS input and will produce the needed 2k pulse/mile that the PCM expects to see.

dimented24x7

iTrader: (2)

There are two ways to handle the WB with the linear EGR. One way is to disable the EGR and simply use the linear EGR position input to read in the raw A/D counts and convert them externally. Fortunatly, the LC-1 is linear in its output, so a simple scalar conversion using the .ADS file is the easy way to go. The other way is to add a patch into the code to do the lookup internally, and transmit the actual AFR to the ALDL stream. This is only really required if the WB controller cant linearize the output.

In your case, you can just transmit the raw voltage by making a few tweaks to the PCM to disable the EGR and adding the linear EGR A/D position to the ALDL transmission table as you discussed. On the LC-1's side, you set up the output so that the A/D voltage equals the AFR x some scalar. Something like 0 volts = 0:1 AFR and 3.9 volts = 20:1 AFR. The 5 volt signal will be read as 0-255 by the A/D, so this will correspond to the AFR x 10, an easy external conversion.

cruiserbrett

That is even simpler. Just have to get that VSS. with regards to VSS, is one wire grounded, and the other pinned to correct PCM pin?

Last Q's for now:

Is it worth adding a MAT sensor and barometric pressure sensor? Truck has an intake manifold like an old slant 6 where there is lots of airflow around it and they generally take a long time to warm up? Also on the baro sensor, the usage of the land cruiser is going to be from sea level to over 10,000 feet, so thinking it might be worth toying with these?

dimented24x7

iTrader: (2)

Yes, you should be able to just wire the signal directly to the PCM. There are two considerations, though. First, the VSS is actually a switching type input. In other words, inside the PCM there is a resistor hooked to a 5 volt source. To trigger the input, the circuit providing the VSS pulses momentarily grounds the VSS pin to pull it to 0 volts, which then triggers the VSS counter within the PCM. You should verify that the DC VSS can do this. If not, a simple external switching transistor could be rigged up to do this. The second is that the circuit supplying the VSS signal must either share a ground with the PCM, or be on a good common ground. If there is a difference in potential between grounds, the VSS may not trigger properly.

As for the sensors, the MAT can help, but with a wetflow system, its very hard to predict what corrections are needed. This is because of the gas in the manifold. The gas itself evaporates under vacuum, which can lower the intake manifold and entering air charge temps quite a bit. Its a bit of a crapshoot when trying to correct for air temps since there is no simple way to model how the fuel will effect the air temp.

The PCM uses the MAP sensor to compensate for changes in baro. There is a pseudo-baro routine within the PCM. Basically, when the engine is at low RPMs and high throttle, the PCM assumes that the manifold is at or near full atmospheric pressure. The PCM then takes this reading to be the ambient baro. There is no additional baro input like some other computers have.

sylgeist

Hey I know this thread is a few months old, but I just stumbled across it. Lots of good info!

I have a question to throw out since I am in a similar situation. I have a 350/4L60E combo and I got a 7427 and harness from Howell. It is set up to use a DRAC obviously, but I was hoping to avoid that. I have Dakota gauges which takes the VSS and can output 2k or 4k output for the ECM. This lets me adjust the speedo for tire size and gear ratio without all the DRAC mess.

So the question is - there are two inputs on the ECM as talked about below (F12-TOS, and F13-VSS). Which one should I hook up and is there a problem only hooking one of them up? Or should they both be spliced to the same signal?

Since there is only one VSS I am confused how/why the DRAC would output two different signals to the ECM?

Thanks!

belaw

First let me apologize for re-opening an ancient thread, but it's spot on to my situation.

I need speed input for a '7429 PCM without using a DRAC/VSSB (I have a manual transmission without provisions for reluctor ring so a stock GM VSS isn't an option). I was planning on using the JTR 2-pulse sender input to pin F13, but that presents another problem; I'm using a Classic Instruments electronic speedometer, which requires a 16 pulse signal. I could pitch my current speedo sender and install a signal converter between the JTR pulse generator and the speedo, but I'm only the cost of the existing sender and the JTR replacment and also another $100 for the converter. That's why Dimented24x7's post caught my attention; if I can configure the PCM to accept a 16 pulse signal I can just use the speedometer sender I already have.

I know that the F12 input isn't necessary with a manual transmission so long as 2-pulse signal is input at F13, but is the opposite also true- can I use F12 as the sole speed input for engine control and exclude F13 input? If so, what's involved in reconfiguring my PCM ($0D mask) to accept a 16 pulse signal at F12? I spent some time looking through the definitions in TunerPro and couldn't come up with anything.

bnio

So if you have a manual transmission why do you need the speed input? The ecm only uses it for the pcm control of an automatic. I ran my maf only version $OD on the 427 ecm without the VSS for some time. If you still need it or want it poke around in the settings of the bin with tunerpro and see if there is something already there where you can set your pulses per rev.. I don't have time to look at it tonight I have to work in teh morning. I haven't messed around with these ecms for a while now so I am not up to speed like I used to be.

belaw

I'm looking for VSS control of the engine only obviously, but I understand that it is important particularly for the idle control parameters.

I did spend some time in TunerPro and didn't see anyplace where I could set the input pulse rate.

bnio

Vehicle speed sensor control of the engine only? I don't understand what you mean by this. The VSS does not control the engine. There is nothing vehicle speed dependant in unless there is some throttle follower table but this it would insignificant at the end of the day in real world use. Just adjust the throttle follower accordingly so the engine doesn't fall on its face and problem solved. So recap why do you want VSS for the engine????? How much tuning experience do you have? How much understanding of efi, programming and the physics of engine dynamics do you have as well? I need to gauge how technical to get about all this.

belaw

Fair questions. As a starting point, please understand that EFI/TBI is new territory to me and that factors heavily into my thinking.

Even with a manual transmission it is my understanding that VSS plays a significant role in controlling idle speed and air/fuel ratio. Just go into TunerPro, open the Parameter Finder and search "MPH" for a listing of VSS controlled engine functions. Now, I do recognize that I can get to the same place without a VSS using TPS; for example, I realize that you can reprogram the PCM to control which Spark / Fuel tables (Near Idle / Off Idle) are used based on TPS% rather than MPH. But that's not at all the same thing as saying that VSS plays no role in engine control.

But this is precisely where my inexperience comes into play. Stock programing bases certain engine operations parameters based on VSS input; while there may be more than one way to skin a cat, being a noob I'm much more comfortable "tuning" based on the VSS input data the PCM expects rather than "reprograming" those parameters to a TPS% control basis.

bnio

Well I will put it to you this way. My original definition for the maf only port injection $OD code I tested and still use had the MPH values all messed up. It was reporting all over the place so you would think it would cause havoc, but it didn't. I don't have time to write a detailed explanation but many times people split hairs over parameters and features that don't really influence anything. This is where you really need experience with the using the code or understand how the code is written to understand what it is doing. So at this point I would go ahead hook it up get it running and get some experience. If it doesn't work well then you now know how important it is. We can be here all day throwing ideas out there but nothing beats jumping and getting your hands dirty. Warning, I have not been tuning with this code for sometime now but from what I remember it should work just fine. And by the way AFR is never mph dependant. A throttle follower table I could see but vital engine operations will never be MPH dependant such as idle stall saver, AFR, ignition timing, etc.