I'm preparing to install a Holley Commander 950 MPFI on my 502 and I am sure that I am going to have a ton of questions.

Here's my first question.

Can I use a stock fuel sending unit with the factory type return line?

If not, has anyone used the Moroso fuel neck that has the return line in it that you have to cut the filler neck?

Or? Any other suggestions for a return line spot in the tank?

I've been looking at the DSE tank with the internal pump. Man, that's a nice unit, but, not quite what I had in mind cost wise.

Thanks in advance for the replies!

One more question.

Where is the best place to find the Pro 3.0 software and cable for the ECU interface?

I see that Summit has it. Pricing seems...reasonable, but, I'm always looking for a better deal.

We have two cars with this system and just think they are great , both cars have rock valley tanks with the holley pumps inside . Jody here suggested putting our return lines off to the side rather than having the bubbles being stirred up right at the pump . We installed ares on the passenger side of the tank about an inch from the bottom so it doesn't flow in and cause aeration .If you want to ask more questions i could pm you my number and you could call me .
Mark.

have fun with your new system!

As far as the s/w for your laptop, I'm sure a number of us could email it to you.

The commander 950 has to be flashed with the v3 firmware. This can only be done by Holley. I think they charge $75 to do it. The member I bought my used system from talked them into doing it for free.

The cable is a standard 9 pin serial. My laptop only has usb ports, so I'll be using a usb to 9 pin cable I picked up at a computer store (tigerdirect) it comes with driver software that lets me asign it to "be" a particular serial port.

One of these days I'll need to cable it up and power up the controller and see if my laptop will talk to it, but I've used this cable for some pretty wierd stuff without a problem. I just tell it to be com1 and even really old dos s/w running in a command prompt box on xp has been happy with it.

I'll be using a stock (3/8") sender / pickup, with an additional 3/8" return line welded in. We'll see how it works. Trying to use the oem 5/16" vapor connection will be a problem. I tried that on my last one, it was unable to dump enough fuel to maintain the correct pressure at idle, car ran stinky rich till Doug at Holley told me to run a bigger return.

The cable is a standard 9 pin serial. My laptop only has usb ports, so I'll be using a usb to 9 pin cable I picked up at a computer store (tigerdirect) it comes with driver software that lets me asign it to "be" a particular serial port.

Per Holley, some serial to usb cables do not work well and cause strange things to happen. The preferred method is to connect to serial, but not all laptops have a serial port. If I could only remember the "bad" brands and "good" brands.....Damned brain turning to mush....:clonk:

Per Holley, some serial to usb cables do not work well and cause strange things to happen. The preferred method is to connect to serial, but not all laptops have a serial port. If I could only remember the "bad" brands and "good" brands.....Damned brain turning to mush....:clonk:
Very true.

The one that I have is from "sabrent", it's tigerdirect part # M501-1032

I haven't verified it with the c950 s/w yet, but I'm VERY confident it will work. I use it to run a diagnostic program which, according to the manufaturer, must use com1, and must run on DOS, not a dos window in windows. works fine in a dos window with this cable.

I'll take a look at the rock valley fuel tank, but, I was kind of hoping to use my current fuel tank and sending unit.

Any comments on the fuel line diameter? I was told that the reason that the motor would not run well before with the super charger was because it needed a 1/2" fuel line. At what horsepower level does a car need a 1/2" fuel line?

Oh, and is a 3/8" return line too big?

My plan is still to get the motor running without the supercharger, and then eventully put the supercharger on.

I tried talking to my c950 saturday, without success. Laptop is running Vista and using the cable described above.

At some point I'm gonna try straight serial into a desktop pc. If that works, I'll try from an xp laptop, and go on from there.

I have the question also posted on chevytalk, hoping to hear from DougF soon.

The return really should be the same size line as the supply. A few years ago, I tried doing one using a stock 3/8 sender as the supply, and the stock 1/4" vapor line as the return. It did NOT work, the system was unable to bypass enough fuel to control the pressure at idle.

I'll take a look at the rock valley fuel tank, but, I was kind of hoping to use my current fuel tank and sending unit.

Any comments on the fuel line diameter? I was told that the reason that the motor would not run well before with the super charger was because it needed a 1/2" fuel line. At what horsepower level does a car need a 1/2" fuel line?

Oh, and is a 3/8" return line too big?

I have run 3/8 supply and 3/8 return in all (three total) of my EFI cars. Try the stock tank/sender and see how it works, it can't hurt and it doesn't cost much. You have to run fuel lines regardless, worst case if it doesn't work out you can swap the tank later.

I have zero experience with forced induction or high horsepower applications so I will be of no help in deciding what fuel line size to use.



I tried talking to my c950 saturday, without success. Laptop is running Vista and using the cable described above.

At some point I'm gonna try straight serial into a desktop pc. If that works, I'll try from an xp laptop, and go on from there.

I have the question also posted on chevytalk, hoping to hear from DougF soon.

All I have ever done (while using a USB/serial cable) is looked in the device manager to determine what COM it is assigned to. Once I determined that I changed the COM setting in the C950 software to match. There have been times when I have had it assigned to a certain COM and then unplugged the cable or restarted the machine and it quite communicating. I just had to change the COM setting in the software to match what the computer said it was assigned to.

my usb cable worked with an xp machine, it seems vista is the problem.
When I connect the cable, the new hardware wizard says it's a "prologic"

I don't know what HP your engine will have buy my BB is about 640 and I run 3/8 everywhere and have no pressure drop at WOT.

EFI and carb line sizing is different due to the pressure.

If you go large anywhere, go big on the inlet of the pump. I run 3/8 on mine there even, but have a good gravity feed.

I'd run 700 HP with 3/8 and ideally a -8 feed to the pump.

I know the fuel systems people say -10, etc, but I think that is overkill on EFI.

Take a look at what some of the 2000+ HP EFI drag cars run. A lot of -8.

I'm starting with an engine that's 502 HP and then adding MPFI and a Pro Charger.

What do you guys think? Is 700 HP possible?

I agree that going to 1/2" line for the fuel supply is quite large, which was one of the reasons for the post.

Thanks for all the replies!

700 is easy , i have a 427 small block and i'm adding a F1 and intercooler i'm looking for around 750 at the rear wheels , i'm running the holley comander 950 MPFI with 65 lb fuel injectors , we are also going to run a water injection with methonol and water .
Mark.

you'll get 700 at the crank on 3 lb boost!
I think you'll be revising your expectations upward, substantially.

When I was running my Commander 950 pro I bought a Dell lap top off of Ebay. I cant remember the specific model number but could get it pretty easy if you want it. I went with this model as it had a serial port and being a older model it was pretty cheap. Do you have the wide band conversion? That really made a difference for me. I also ran the Holley inline pump with no problems, I also used the factory lines 3/8's for the inlet and 1/4 for the return. We tried diffent USB to Serial connectors and found one that worked on a friends lap top but it was running XP and not Vista. I ended up buying one as borrowing his was a pain, and using my desk unit was not a option. I have a extra contoller that has the 950 Pro hardware on it if your interested. The reason I got rid of the Holley was I'm installing a LS7 now.

haha, I just love your cast-offs, Mike, but another member fixed me up with the complete system, f/w 3.6 pro.

My new autometer wideband gauge has an output for the ECM, I'll just have to match up the voltage tables, then should be good to go.

I'm not giving up on the usb cable / vista thing quite yet, gotta be something that will work.

Jim,
LOL, No I have a complete Holley 950 MPI with a wide band 2 ECU's for a small block, heck its still mounted on the 350, Thats another thing I just realized I need to pull out all of the wiring for it.... I'm never going to get that LS7 in there. The ECU's might be with 3.6 Pro I know its something Pro...... Been a while since I have messed with it. Its for a small block though. I have a friend whos a computer junkie who has told me those USB to Serial adapters are hit and miss, they may work on one computer and not another. Allot he says has to do with the performance of the computer?? I dont know but he did show me where it would work on his, but not my older Dell. The other advantage I found on having a dedicated lap top for the Holley was you dont have to worrry about that computer getting a virus and loosing everything or just going to crap. It was nice in that respect, I didnt have to ever worry about the kids doing something to my Holley computer, I had all of my saved programs right there ready to go. BTW I'm still waiting on my GW rear springs but the car is in storage waiting for sometime to get back on it so their not picking up any milage....LOL

lmao Mike! I really don't want to know that I coulda gotten your castoff mpi for (if history is any indicator) the same or less than I paid for the TBI!...

Thanks. bud!

you'll get 700 at the crank on 3 lb boost!
I think you'll be revising your expectations upward, substantially.

I meant to say 700 hp at the rear wheels is what I was hoping for.

I actually had a chance to drive a Dick Harrell Super Car ('02 Camaro with 650 at the rear wheels) last year. I had to get out of it in second gear because it caught me a little off guard.:o

Anyway, I'm hoping to get a second (and third, and fourth)..) chance to try something with that much power again.:yes:

BTW, the Dick Harrell car is still cool.

I have a extra contoller that has the 950 Pro hardware on it if your interested. The reason I got rid of the Holley was I'm installing a LS7 now.

Laptop?

Does anyone have a Holley Commander 950 map file for a stock ZZ502?

IIRC its in Holleys Pro proram files as a base map. I think thats the base I used for my 406. The lap top I ended up buying was a Dell Inspiron 600M it has a serial port and plenty of power, its cheap, and its a Dell dude.

I did end up finding finding a base map "50242PPH.950".

I guess what I am wondering is if that was based on a modified ZZ502(different heads or anything like that).

I was able to verify that I do have 42PPH injectors, so, this prolly gets me closer than some people have to start out with.

Thanks for the recomendation on the laptop. I'll take a looks and see if I can find one.

Thanks for the replies!

That is for a bigger cam and 50-80 more HP.

I'd try it and expect to have to add more fuel at idle due to your higher vacuum and most likely have to lean it out at WOT.

That is for a bigger cam and 50-80 more HP.

I'd try it and expect to have to add more fuel at idle due to your higher vacuum and most likely have to lean it out at WOT.

This is exactly the feedback that I was looking for. Thanks Doug!

FWIW I spoke to Holley Tech support today about the fuel return line.

I was wondering about using a factory type sending unit that has the dual line (since I plan to keep the stock gas tank).

I was told that it is okay to use a 5/16" return line as long as the return line pressure does not exceed 4-5 Lb of pressure (after the regulator).

Any comments on this?

I used the factory 69 camaro dual port sending unit on my 67 camaro which works great, I first tried the moroso 'nipple in the neck' it made too many fumes, it probably would have been OK if I would have run a hose down into the bottom of the tank from the nipple in the neck. my 950comp is serialed into my onboard 1.7mhz 2nd computer in my glove box. It works sweet with a 10.5" touchscreen in the dash for 'on the fly' tuning....and gps,tv tuner,internet,dvd's,mp3s....all on the touchscreen
http://a714.ac-images.myspacecdn.com/images01/93/l_e30c309f890a4c2d0ec60f63132eb161.jpg

one more pic
http://a855.ac-images.myspacecdn.com/images01/125/l_a93a422faa2563959d27eabfc1ba887e.jpg

Well, it's been a while since I originally posted this thread, but, I finally got to hear the motor run for the first time today.

I used the 50242pph file that was in Holley's software, and it didn't run good at all. Very, very rich.

Unfortunately, I now have bigger problems than the tuning of the MPFI system.

It's either a case of "where did that little washer go?" or... I don't really know.:(

I now have a lower end knock that I have to take care of.

BTW, anyone got any recommended upgrades to the engine while I have it apart? I've heard that a camshaft swap in these motors makes a big difference. But, I don't want to give up driveability.

Fortunately, I was planning on yanking the motor back out this winter anyhow, but, not for that reason. Oh well.

Is it feasible that a malfunction such as an injector sticking could have saturated the cylinder and taken out a rod?

I am also questioning the wiring to the injectors. When I got this system, I had to take it apart to clean up the intake. The problem is that I am not sure if the injectors were possibly wired wrong and the system is trying to inject fuel into the wrong cylinders at the wrong time. How can I double check this?

Additionally, this motor did have a supercharger on it at one time. How can I verify if I have a 1 bar or 2 bar map sensor?

I doubt that the injectors being rich could effect a bearing, tho it could wash the rings.

Did you check your return line pressure?
It really is vital to do that. You said you were gonna use the stock vapor return on a 69 sender. I think that line is 1.4", and 1/4" is not big enough. If your return pressure is too high the motor will be stinky rich, especially at idle and cruise. You won't be able to tune it out.

The holley is a batch fire system, fires each bank of 4 every other revolution. It would not matter if the injector wires were mixed up.

I've heard what you've heard, a lil more cam will really wake that engine up. But if the engine has a history... including a blower, are you sure the stock cam is still in it?

The map sensor should be a stock GM part. Type the part number into GMpartsdirect and see what comes up?

Sorry to hear about your knock. I hope it's minor.

Did you check your return line pressure?
It really is vital to do that. You said you were gonna use the stock vapor return on a 69 sender. I think that line is 1.4", and 1/4" is not big enough. If your return pressure is too high the motor will be stinky rich, especially at idle and cruise. You won't be able to tune it out.

I ended up running a 3/8" return line into the tank as Lee suggested. It is directed away from the pickup.


The holley is a batch fire system, fires each bank of 4 every other revolution. It would not matter if the injector wires were mixed up.

This is good to know. I wasn't sure if it had specific injectors that it was pulsing based on the cycle of the cylinders.


I've heard what you've heard, a lil more cam will really wake that engine up. But if the engine has a history... including a blower, are you sure the stock cam is still in it?

I've been around this motor since it was brand new, so, I am sure that this is the original cam.


The map sensor should be a stock GM part. Type the part number into GMpartsdirect and see what comes up?

There are no distinguishable GM (8 digit) part numbers on it. All I can find on it is "229". I'm gonna do some research on this to see if I can match up a Holley number with this #. Like I said, this is the only number on it. We actually tried a map sensor out of our tow vehicle (7.4L TBI) to see if it would have any effect. Didn't change much.

Sorry to hear about your knock. I hope it's minor.

Me too!

I am confident in saying that I have not "memorized" the book for this system (yet). I think for the most part it's going to be a matter of learning as I go...without doing damage!

Thanks Jim.

1: Fuel pressure
2: Idle speed and mixture & timing
3: tune main fuel map using various steady state / assorted load & rpm tests.
3 1/2: More timing
4: fancy stuff... See DougF for details.

Hi Jamie, if you go on holley.com website you can download the complete instruction manual.Also all the part numbers you need on the software new version 3.0 and they have base maps so you can load THEM . Part numpers for the map sensor.
If you send your ecm they will also flash it back in 3 days.

The map sensor i got from holley has these numbers on it G127-6289 on the bottom.
Holley maps sensors.

Map 538-24 stock
Map 538-13 up to 14.7psi
Map 538-23 up to 29.4psi

I have installed lot of these holley 950 commander EFIs
If you need the software i got it,
they come in floppy discs with the base maps.

Or if you want you send me your 950 ECM i can flash it for you WITH BASE MAP TO GET YOU RUNNING.
Any questions let me know.
610-461-5033 c\p INC.
Paul.

1: Fuel pressure
The gauge is reading 45 PSI.
2: Idle speed and mixture & timing
Which is done via the programming. Correct?
3: tune main fuel map using various steady state / assorted load & rpm tests.
This is going to take more studying of the installation / tuning manual on my part, but, can you elaborate a little further?
3 1/2: More timing
I'm glad you mentioned this. So here's the question. My 502 should be set at 8 degrees initial timing. I assume that this still stands true for the installation of this system as well. Correct? We can't seem to get enough adjustment on the timing to get what we want!
4: fancy stuff... See DougF for details.
I'll do that. Thanks!

Hi Jamie, if you go on holley.com website you can download the complete instruction manual.
Thanks. I have the manual. Just haven't mastered the content quite yet.

Also all the part numbers you need on the software new version 3.0 and they have base maps so you can load THEM . I got the new software from another TC member, loaded it on a PC, and was able to upload "50242PPH.950" into my PCM. As I understand it, this is a little much for my motor since mine is a stock ZZ502. I think that this program is for a little bigger cam.

Part numpers for the map sensor. The only readable number on the MAP sensor that I have is "229".

If you send your ecm they will also flash it back in 3 days. I'm curious. What's the difference between me uploading the new program that I mentioned above and flashing the PCM?

The map sensor i got from holley has these numbers on it G127-6289 on the bottom.
Holley maps sensors.
Map 538-24 stock
Map 538-13 up to 14.7psi
Map 538-23 up to 29.4psi
None of these numbers match what I have. I think I need to research this a little more. Maybe just buy another one to eliminate any question.

I have installed lot of these holley 950 commander EFIs. If you need the software i got it, they come in floppy discs with the base maps. Yep, got the software. But thanks!

Or if you want you send me your 950 ECM i can flash it for you WITH BASE MAP TO GET YOU RUNNING. Any questions let me know. I love this site. Everyone is so willing to help out!

Jamie,
Flashing and installing your software is the same.
Set your timing 10 deg that is what the 502 likes MAKE SURE IT MATCHES YOUR reading on the ign map at that RPM.
What size injectors do you have?
A ZZ 502 has a nice lopey cam IT WILL IDLE ROUGH!

Jim - I verifiied that my return line fuel pressure is less than 3#. This was done by taking installing a 0-10 mechanical fuel pressure gauge in the return line system at the fuel rail after the regulator. In case anyone is wondering, this is only temporary.

Collingdale - My timing is set at 10 degrees on the motor, but, I need to verify that this is synced with the PCM.

Understandably, the programming is in question, but, I'm gonna take a look at the MAP sensor to make sure that it is the right one (1 Bar versus 2 Bar) before I get into the programming.

I have 42 PPH injectors.

The gauge is reading 45 PSI.
Good, 45 psi supply, less than 5 return, at idle, is your basic for getting it all right.

Which is done via the programming. Correct?
Both programming and hardware. Physically, you need to set static timing, and the idle stop screw on the throttle body. Programming wise, you are looking at the cells she is idling in on the main fuel table (map vs rpm) both in neutral and in gear (if automatic) You are also looking at the IAC motor settings. There's some tricks here that I don't recall very well, good info in the efi forum on chevytalk.

This is going to take more studying of the installation / tuning manual on my part, but, can you elaborate a little further?
What I've done is start at "steady state" that is, various combinations of contant speed / load, mostly at low rpm's to get the basics on the fuel map right, then progress to accelerating at various map levels, that is to accelerate so that the rpm's are increasing but the map is not. A run at 10" of vacuum, then one at 8", then 6" etc. Datalogging can help here.

I've always done this in closed loop, and keyed on the O2 comp # to determine what I need to change. O2 comp shows whether the computer is adding or subtracting fuel to maintain the target AFR. 100% = computer is doing nothing, > 100% = computer is subtracting= fuel, < 100% = computer is adding fuel. You want the computer to be subtracting a lil fuel all the time.

If you have narrow band O2, the "target AFR" is always 14.7. If you have wideband, the target is whatever numbers you program into the AFR table.

I'm glad you mentioned this. So here's the question. My 502 should be set at 8 degrees initial timing. I assume that this still stands true for the installation of this system as well. Correct? We can't seem to get enough adjustment on the timing to get what we want!

Let's not make any assumptions on timing. That 8 degree number is an arbitrary value out of GM's manual for that engine, and is only designed to keep people out of trouble. It's a very small number, and most motors will want considerebly more.

Just as an example, my currently carbed 383 likes 18 degrees starting (initial), 36 degrees idling with no load (initial plus vacuum) 50 degrees plus cruising (2000 rpm, 20" of vacuum) and 34 degrees at full power (initial + mechanical @ WOT 0" of vac, rpm aboive 3500)

All of this is easily and fully controlled in the timing tables of the C950.

Another cool trick is the "idle spark control" checkbox, under the spark menu. Idle spark control allows the ECM to control the idle by changing the timing, it throws in more advance if the rpm's drop at idle, pulls advance if rpm's rise. This can happen MUCH faster than the IAC motor can move, so it will respond quicker when you put an auto trans car in gear, or when an A/C compressor kicks on. The C950 must be in "advanced mode" to enable this and a host of other cool things.

Modifiers: are the very last things you look at. ALL your initial tuning should be done with the engine completely up to temp and the modifiers at their default setting.

In the modifiers menu, you can mess with things relating to air and coolant temp.
I also think of the acceleration enrichment as a modifiers, and that's why I suggest using "steady state" runs to tune the fuel map, that procedure keeps all these modifiers out of play, until you are ready to fine tune them.

The fuel startup table is a whole nother big thing. You can handle ANYTHING relating to starting and keeping the engine running here, but again, you don't want to mess with it untill you have the basic done.

To me, this is all some seriously fun stuff. The C950 gives us instant control over dozens of things that effect how our engines run under any imaginable condition, and gives us THOUSANDS of datapoints we can change.

To compare, a carb gives us 6, and a conventional old style ignition 5.

I'm no where near the expert I'd like to be on this. I've tuned ONE C950 system from scratch, it was years ago, and a narrow band system without datalogging or timing control. Since then, I've read a lot, and I've learned from helping others and talking to others.

When I do my system this winter and spring, it WILL be heavily discussed here, every milestone and mistake laid out for all to see.

In the meantime, I'd love to hear from more people here on this whole subject.

Until then, there is a LOT of serious expertise over at Chevytalk, DougF, DeltaT, Zwede, and several others have both knowledge and experience with these systems. I wish they'd come here more often, but their home is there.

Finally (sorry for another long post!) I'll give you this:

The C950 is a good system, and it can be tuned to work very well on ANY engine, mild to wildest.

Base maps are just that, "BASE". Do not expect to load "the right" base map and drive off into the sunset. The base maps are designed to get you running safely. They are rich, and they are conservative. A "properly tuned" engine is right on the ragged edge, but NEVER over it. Under every condition, you get the most power and highest efficiency with as much timing and as little fuel as it can stand. Getting there with your system is at least half the fun, to me.

the first time you do a full tune with a system like this, you will learn so much about "what your engine wants and needs" and "how every engine works" that you will be humbled, and you will know that you knew no where near as much as you think you did before the tune.

Always remmember to save any changes you make on the efi on a disc or the computer because the 950 holley is famous for loosing its memory.
Read your instruction book carefully.
The pro 950 HOLLEY is better than the old version because it has the wide band capabilities to add to it.I don't know which one you got.
Always tune conservative is my philosophy, and your motor will last a very long time.

Not meaning to hijack the thread but how do you communicate with Vista? My old laptop died I picked up a new one and low and behold not only was there not a serial port (I bought a serial to USB) but the damn laptop wouldnt talk to the 950? Now what buy a old laptop?

There is a guy on Chevytalk that has it working, but I haven't pried the secret out of him yet.

I put XP on my vista laptop, dual boot. It's kinda tricky, research it first.

There is a thread here on this very subject!

Check your com port selection as there are 4 on the 950 C and you need to go my on your vista computer then pic device manager and you will see the bus drivers and make sure it communicates.My friend showed me how, but that is all i remmember.I hope that helps you.

I posted this same information on Chevytalk.

I have been successful in getting my Vista Laptop to communicate with my C950.

I used a Dynex USB to serial adapter and downloaded the drivers from the Dynex site. One important thing that I think I did was to download and install the actual drivers for this cable from the Dynex website.

I ended up changing the run mode from Windows Xp to Windows 95.

One thing that I found is that I had to get the 950 software to recognize the correct comm port.

After trying three (Comm 1, 2, 3) I was finally able to get Comm 4 to work!

I am using a Sony Vaio N365B laptop with Windows Vista. I also have a Toshiba Satellite that I am going to try to hook up since it's a little older and won't matter to me as much if it gets banged up a little.

Oh, I also was able to get the Data logging to work. I'd like to see if there is anyone interested in looking at my log file.

Let me know if anyone has any questions. I'm sure I have taken more information away from this site than I have given!