chris1

Guys I need some help to figure a few things out, and while this is not TG specific, you guys have the knowledge to help. :hail:

I have a 383 that will be completed by the speed shop in a few weeks. Int. balanced Eagle guts, iron eagle 200s, GM 330hp 350 crate motor cam with 1.6 rockers. Should be in the ballpark of 400hp with gobs of torque.

The problem is this motor is going in the place of a 350 tbi with a 4l60E behind it. I'm not sure I want to guinney up my new motor for my initial efforts of fuel injection tuning tbi system capable of flowing over 200lb/hr of fuel. I would like to run with a carb for initiall break in and untill I figure out which way to go for the injection. How do I run a carburetor with my 7427pcm still in control of the transmission? And any advice on the best\easiest way to run things with fuel injection would be appreciated.

Thanks
Chris

11sORbust

Is this on a truck? I don't have the answer for you. My suggestion is to unhook the fuel injection totally and see how the PCM/transmission reacts. I would guess that if you have a vehicle speed sensor hooked up then it should perform OK. It's a great subject because I was wanting to try out the same exact thing and see if the PCM can be made to work like a stand alone trans controller. Please contact me if and when you try this.....


Tim

Grumpy

*Should be* only means if tuned to that level. You can tune it for less and use the stock TBI setup.

If the truck is currently running, then now is the time to strat learning to tune efi, rather then later.

About the only thing you can leave disconnected on the PCM and still use it as a tranny controller is the MAP signal. You need the TPS and CTS.

You might google and look at what some of the SS 454 guys are doing with the 7060. Might even think about a 4L8E.

11sORbust

What about the ignition? I think there is some rpm based routines going on...?

chris1

Thanks Grumpy,

What I want to do for safety sake is run a carburetor and begin my tuning experiments with the timing and the transmission shift points without having to worry about washing down the cylinders or cooking pistons. I don't know if I will stay with tbi, but if I do I will not stay with the stock tbi unit. Thats why I also asked for some ideas on what PCM/ injection I should run.

I thought I would still need the map sensor in the mix to measure load?

Chris

Grumpy

************************
About the only thing you can leave **disconnected** on the PCM and still use it as a tranny controller is the MAP signal.
************************

Grumpy

You can wash the cylinders just as easy with a carb (if not easier) then with TBI.
Have you searched for the SS 454 board(s)?.

The tranny doesn't use map, it uses TPS to form some delta TPS routines for various thresholds. The MAP is used for the engine management. Well, at least from what I've seen.

ben73

I have a 383 TBI with a 900cfm Holley 4bbl TB controlled by a 7747 ECM.

I am just about to swap the ECM for a 16168625 PCM from a '93/94 small block truck. Later on I intend to ditch the 700r4 for a 4L60e.

The 16168625 PCM looks like a nice unit. It has much bigger and better tables than the 7747. This is worth considering.

HaulnA$$

When you swap to the truck PCM, I recommend going to the 16196395/16197427 PCM from the '94-'95 trucks and suburbans, you can find them more easily. The $0D mask has more support (TunerPro) than $E6, is a little more versatile, and several of the BCC's are hacked as well. IMHO, this is a better choice. The 8192 baud rate of the TBI truck PCM's is a huge benefit too which I am sure was a factor in your decision for the swap. I have been working with this PCM for a couple of years now and I am very pleased with the results. I am in the process of building bench to run it on as I too will soon be swapping in a 383 with a 900 cfm Holley TBI. I found some 15 amp darlington driver transistors which I am going to install in the PCM along with some .05 ohm 3W current sense resistors to drive the 2 extra injectors. In theory, it should work great as long as the drivers don't build up too much heat. HTH

ben73

Thanks for the suggestion, but I've already got a '8625, and have it running on the bench and talking with datamaster. I have also spend a considerable amount of time creating a .ecu for use with tunerpro. I'll have a look at the PCM's you suggested, but I'm not inclined to change my plans at this stage..

HaulnA$$

Oh well. Just trying to be helpful. I'm sure you'll be happy with what you've got. Good luck.

ben73

I've looked into those PCM's and they probably would have been a little easier to use, mostly from the point of view that I would not have had to create my own .ecu file...
They seem very similar to the '8625, do you know of any significant difference?
If the 94/95 PCM supported cooling fan control ect, that would be a clear advantage.

Grim Reaper

Yeah, I helped tune a 94 Pickup running the $0D mask. It still had a memcal btw - 64K bin file sizes.

I would have to agree with you that this really is a nice PCM to convert to if you run TBI and want to run the 4L60E. I had a lot of fun playing with the shifting on the 4L60E. When my tranny goes, I am SERIOUSLY going to consider converting to the 4L60E.

If I could figure out a way to run my normal $8D code for the E-side, and retain the $0D for the tranny side. I would be a happy camper.

HaulnA$$

The transmission control stuff is a blast to play with. The good thing about this PCM is that it will control the 4L80E tranny and run the $31 mask ( 95 HD V-8 trucks) which has some decent Tranny control stuff it in. I don' think it would be too hard to run this PCM in a piggyback tranny controller mode either. There are many trucks running a TPI setup controlled by a '7730 with a piggyback '6395/'7427 tranny controller although I have never done this myself. There are also trucks using the TBI PCM to control MPFI setups (Edelbrock does it, although not very well). There is a CPI/PFI mode from the S-10 trucks and the synchronous to asynchronous injector firing stuff is based on constants. This is the way I'm gonna go after I get the 4 BBL TBI working well.

11sORbust

Have you disconnected the ignition to see how the transmission reacts without a DRP ?

Grim Reaper

That is the only route I can currently think of at this time. I would need some time to look at the code and configure the "least" amount of pins to the 6395/7427 so it could properly control the T-side of the bin, but not bother with the E-side.

I would be nice if the "E-Side" could properly control a Port Injected Setup. Bruce was telling one time about a "VIC" (variable injector controller) but the one I found seemed more for guys with banked port injected systems (like the 7730) and allowed you to 'trim' each injector. I couldn't get any info to show whether the VIC could convert a TBI signal to run port injection.

I actually thought the E-side had some nicer features than the $8D and could offer more control of the fueling. I also liked the $0Ds method of handling PE/WOT fueling. It uses "desired AFR" versus "% Change" in the $8D.

I didn't have enough time to keep playing (the friend who had the truck totalled it a few weeks later), but it looks like you could tune WOT independently of the main VE Table based on that "desired AFR" method of tuning WOT. Unlike the $8D, where a subsequent change to the main VE Table will have an affect on the WOT because fuel is added baed on "%Change". I wanted to play with this a little more to see if the $0D VE Tables were truly independent of the WOT Tables.

Grim Reaper

Oh, the ONLY downside the I could see to the $0D is I could see any way to 'trim' fueling based on a MAT reading. I don't know if TunerCat just doesn't have the "MAT Table" documented. Or, if there is not MAT table for trimming fuel.

chris1

Thank's guys

"Have you disconnected the ignition to see how the transmission reacts without a DRP ?"

No. I have not tried anything yet. But I would assume the transmission would not leave 1st gear without the signal. And I think I need the map hooked up for the pcm to control ignition.

"There are many trucks running a TPI setup controlled by a '7730 with a piggyback '6395/'7427 tranny controller although I have never done this myself."

Great Idea HaulnA$$!, What TPI system{s} could be made to fuel in the 400 to 450hp range with the least amount of work? I may just go the fuel injection route to start with if I know that the 7427 can be made to handle the transmission. I looked at the TCI website and they sell splitters for the TPS sensor and the distributor signal.

Chris

HaulnA$$

I'm not sure what you mean by "properly control a Port Injected Setup". If you are referring to injector timing, I believe the CPI/PFI code from the S-10 applications and the synchronous/asynchronous firing thresholds will handle this with a little tweaking. If you are referring to the P/H drivers controling saturated MPFI injectors, each driver can control 4 saturated injectors at a time without ever tripping the current sense of the P/H driver to put it in the lower current hold mode, even if it did, a slightly lower resistance sense resistor would fix this. 4 saturated injectors in parallel don't draw as much current as a single TBI P/H injector. This is how the Edelbrock TBI to MPFI conversion system works. It is in injector timing where they fall short. As for WOT fueling, the "WOT AFR vs RPM" table is definetly tied to the VE table. I wish it was independant but it's not. Lastly, there is MAT stuff throughout the code but the TBI trucks don't use a MAT sensor. I believe the V-6 CPI S-10 trucks do use a MAT sensor and I know the 4 cyl. MPFI ones do and this code is all included in the $0D mask.

SBNova

I have looked at all the tables in $OD- my friends van has that PCM and he needs to tweak it a little, but I feel I need to share my opinion of the 4L60e. I think it sucks. I have built numerous 2004r's and a few T-350's in my time. I had a 4L60e in my 97 Tahoe, and was greatly disappointed. From what I understand, the 4L60e uses a pulse width modulated lockup on the converter. what this does is "chatter" the lockup apply to engage more smoothly, creating more clutch dust in the tranny. It also overheats the converter, and wears the lockup bore in the valve body. There are kits to fix this stuff, made by Sonnex and TransGo. In my Tahoe at 90k miles there was clutch dust seriosly blocking passages. More so than what should have been there with that mileage, and I had the towing package, but never towed anything more than a 5x10 trailer.

I understand that these parameters seem adjustable by the tables in $OD, I just urge you guys to use caution with this transmission. I believe the trouble code I saw the most was P-1870 in my 1997. Do some searching, and figure out a way to overcome these problems before you lean too hard on a 4L60e.

Stevie

I'm running a 7730 for TPI and a 6395 piggybacked on for control of my 4l60e. Using the $OD on the PCM. I think the setup is great. And Im totally sold on the 4l60e tranny. Now I'm not pumping out tons of horsepower but having control of the shift points is a blast. You can get driveability just the way you like it.

The 6395 only needs TPS, Dist REF, and a VSS signal. Works fine.

Steve

11sORbust

How did you feed those signals to the 6395?

Grim Reaper

Thanks Steve. SBNova does bring up some good concerns.

SBNova, when you are discussing your experience with the 4L60E, are you speaking from a Heavy Duty version? The reason I say this, is I wouldn't expect a stock 700R4 to last either, but I have a number of friends that have had very good luck with their "built" 700R4. My thought was never to install a stock 4L60E, but a "heavy duty" version (say 500-600 HP).

Stevie

It's just a matter of paralleling each signal to both the ecm and pcm. The VSS was a little more work cause the 4l60e output is different than a VSS generator used on the typical 700r4 setup.

If anyone is interested, I'll post more info on it.

Steve

HaulnA$$

Agreed, a 4L60E in stock form isn't a performance transmission. These guys http://transmissioncenter.net/4L60E.htm seem to have all the bases covered. A friend with a '94 383 Suburban went through 2 rebuilt 4L60E's, then he used all the HD parts from these guys, rented all the proper tools and rebuilt it himself. He has since gone through two 10 bolt rear ends and the tranny is going strong. Needless to say he has now upgraded the diff.

11sORbust

how hard was that?

Stevie

ummmm, I'm not sure what you mean. For instance, the wiper of the throttle pos sensor now feeds the TPS signal input to ecm and pcm? Just added a jumper between the two.

Steve

Grim Reaper

Please do. I would also be interested in the problems you encountered with the VSS when converting to PCM.

11sORbust

For example, my friend had this zex nitrous box. It taps into the tps that way it can sense WOT. When that happened the box cuts off the return fuel line to add enough enrichment for nitrous. His car would act funny while the box was hooked up. Come to find out the zex box was pulling voltage from the tps signal, thus messing with the puter. So I figured what you are doing with the stand alone PCM trans controller would require something that prevented signal loss, cause it going to happen when you just tap into a line. You just spiced the wires in and it works fine? Of so then do you recall how you wired up the ignition? I second glenn on the vss..

SBNova

My 4L60e was stock, but so was the truck. In fact it was my wifes truck. I have a good understanding of transmissions, I wasnt trying to say it cant handle power, I was trying to advise of its poor lockup converter control. By cycling the converter, and doing this in more than just fourth gear, it kills itself. Im not talking about WOT, this applies to just normal driving- which is what we spend most of our time doing. When you build the 4L60e, just address the converter issues, or try to fix them in the eprom to avoid uneccessary lockups.

chris1

Thanks again guys for all the input!

I thought I had found a solution to getting a TPS signal from a carburetor, a product made by HGM Automotive and Electronics called Acculink. It just bolts to the far side of a carb with an adjustable linkage assemly, problem is they wont sell me one! it is only available with there complete Compushift TCU package.

Any ideas on the best way to get the TPS signal from a carburetor?

Chris

11sORbust

Use a computer controlled carb, it has a tps. I think it's 750 cfms and I don't see any reason you couldn't rework it for your combo. The computer will control the ignition and you'll have signals for trans to run..

chris1

What manufacturer and model carb are you referring to?

Thanks
Chris

11sORbust

GM made them on all the rwd v8 cars of the 80's. They phased out the carb in 88. I know because my formula ia an 87 and had a carb. You could pick one up in the boneyard for a song. Also grab the harness, distributor and ecm. Then you'll have a carb and all the signal wires to run everything. The CC carb harness uses a baro sensor, you might be able to delete that in the chip. The connector is the same as a map sensor. So you would just need to plug it in and cut the signal wire, then run it to the trans controller. The 86-87 firebird even has a electronic VSS..

Grim Reaper

Good point. I actually noticed that same thing with my 4L60/700R4...I hated how the TC would come on and off, while driving on rolling hills...and yes, I could see how it could "lock/unlock" itself to death...it almost drove me insane.

It was one of the FIRST things I addressed when I got into eprom burning. I forced it to stay lock after it reached my prefer speed.

About my biggest reservation is the cost of a built 4L60E compared to the 4L60/700R4. Most places have a "core charge" for the 4L60E. But no core charge for the 4L60/700R4. And even if you have a "core" for the 4L60E, it's still higher than most 4L60/700R4s without a core.

Stevie

Yep, I just spliced into the the signal wire from the TPS which already feeds the 7730 and fed it into the 6395 pcm TPS input. The pcm has a relatively high input impedance so it does not appreciably load down the signal.

On the ignition, I did the same thing using the distributor ref signal and the distributor ground. Spliced into the wires and routed them into the 6395 inputs.

The VSS is a bit more work. The 4l60e vss has a 40 tooth wheel inside which is sensed by a magnetic pickup. This signal goes to a DRAC module which is a separate little plastic box which splits the signal out for the pcm, speedo, cruise control, anti lock, etc. I used a spare output from the DRAC to feed the 7730 VSS input. Use pin B21 on the 7730 rather than the normal VSS input pin C2. This input is compatible with the output signal from the DRAC. You have to uncheck "mag speed sensor" in the bin because the signal is not an AC sinewave.

The 4l60e doesnt have a mechanical drive for a speedometer so you have to come up with an electronic speedo if you dont have one. There are some outfits that make a kit which lets the 4l60e drive a speedometer cable also.

Too much info?

Steve

Grim Reaper

No, great info! Thanks.

BTW, do you mean "B12" instead of "B21"?

Stevie

Nope, it's really B21. It's the optical input pin. Evidently many of the pinouts show it as not used. Somehow RBob knew about it.

Steve

Grim Reaper

Looking at the connectors per my 1991 Factory GM shop manual, there is no "B21" (by GM's numbering system) for the 7730. The Black 24 pin is A1-12 & B1-12, the Black 32 pin is C1-16 & D1-16 and the Green 32 is E1-16 & F1-16.

Are you sure you are not talking about a different ECM such as the 727 instead of the 7730?

Stevie

Dang, my bad.

I did mean the 727. The weather pak version of the 7730.

Steve

Grim Reaper

That's okay, I was wondering if my medications was causing holucinations.

I tracked down the a 727 to 7730 wiring conversion and B21 on the 727 equates to "C6" on the 7730 which is the VSS Optical input to use if converting from MAF to SD.

This may allow a 165 MAF user also to convert to 4L60E also since it appears you need to use the same VSS input on the 7730 as when you convert from the 165.

HaulnA$$

Which pin on the DRAC module did you get the spare output from?

Stevie

I used pin C14 to drive the ecm. C15 will work just as well, I used it for the speedometer though.

Steve

Grumpy

A who?

Grim Reaper

No spill czecher

chris1

With everyones help I now have an understanding of what it takes to get the 7427 PCM to run the transmission alone. My engine is going to be done next week and ready to install probably the next. The more thought I put into this project the more I am considering staying injected from the get go. I wish the Holley PCMs that come with there systems were lower priced! I sure would like to go with thier Stealth Ram setup. I can buy all of the hardware for it minus harness for a very reasonable price <$650, about what a decent intake and carburetor will run me. What factory ECM would you guys consider to piggy back with my 7427 to run the Stealth Ram?

Thanks
Chris

Grumpy

Might do some more investigating on the pcm. Isn't it Edelbrock that sells a BBC truck conversion for port?. I think it uses the stock pcm. You might cruise the SS454 truck boards for more info. (justa idea of where to start looking).

chris1

Thanks Grumpy,

It is Edelbrock who sells a BBC conversion for port along with a SBC conversion for port {my application} for use with TBI PCMs. It's a batch fire system utilizing the two injector drivers, and it is priced pretty close to what a true multiport setup would cost.

Grumpy

There was some info., floating around about doing Port with a TBI PCM, is why I mentioned looking further. Typically, TBI fires the injectors alternately on every DRP, while port fires them once per crank rotation. Either can use 2 injector drivers.

HaulnA$$

The 16197427 has CPI/PFI code built-in but I have yet to test it out, PCM bench under construction, but I have heard tell of this working to drive MPFI V-8 setups. This is the thread Grumpy was talking about https://www.thirdgen.org/techbb2/sho...hreadid=266523 . HTH