Will my computer reject boost?

[3100rettaracer]

i'd be an L body. i dunno i think the 93 3.1 W body sound promising. i'll se what i can do....

injectors....any suggestions guy?
well after that stuff i'm home free!.....oh wait.... i have ABSOULULY NO CLUE ON HOW TO HACK A GM COMP OR CHIP!!!!

[Fierofiend]

Hey guys, would the 3100 run on a 6869 Computer??

Thats what I'm running on my boosted fiero. Its been reprogrammed for a 2BAR map sensor, and it runs a knock sensor (with an added ANRZ ESC module)

Just curious if the newer gen engine would run on this computer......

[SappySE107]

im sure it would, but it may not be SFI anymore. Other than that, if it ran port injected 60V6, then it will run a 3100 no problem.

[3100rettaracer]

well...what do i need 4 that? and BTW that fiero looks so bad ass!!!!! i love it!

[BrianC72bgt]

Newbie to the board. I'm in the midst of a camaro 3.4 swap into a 72 MGB-gt and stage two will be a diy twin turbo effort. 3100rettaracer, you need to do lots of research, not just some guy said... blah, blah, blah that's the way to build a large bomb that happens to look like an engine, not a well tuned reliable huffer.

BASIC theory an engine is an air pump. It SUCKS it in, mixes in the correct amount of fuel, burns it up, and spits it out. All of the stock sensors and computer controls expect the car to remain stock. Bwahhhahhhahahhah! It may have a MAF or an MAP or a little swingy flapper thingie in the airbox(old bosch stuff and others). This sensor tells the stock computer how much AIR is being ingested into the engine and it knows how much fuel to mix with exactly that much AIR. Most of these sensors are for atmospheric engines (not turbo or super charged). And the stock ECU has a table of the exact amount of fuel and timing to give the engine for any ANTICIPATED situation. But now you are going well far beyond what the manufacturer planned for, outside the realm of the standard calibration, because your car is getting A LOT more air, so it needs A LOT more fuel (and pull some ignition timing on boost). This combination of A LOT more air and fuel in the CORRECT amounts gets you A LOT more power. Get the amounts wrong and you have a BOMB.

There is a correct ratio for the amount of air and the amount of fuel the engine gets to run well - not too rich and not too lean. Too rich and the engine is boggy and gives lots of black smoke out the tail and the fuel economy sucks - not that we care too much about fuel economy or we would be talking about solar powered bicycles and not big honkin turbos. Too lean (not enough fuel) and the engine gets HOT then it gets HOTTER, then the edges of the combustion chamber glow RED HOT, and then along comes an unsuspecting fuel/air mixture, passing the intake valve, minding its own business, waiting for the spark plug to ignite so the power will be generated AFTER top dead center (the spark plug needs a head start so it fires before TDC because things are moving really really fast) But the fuel mixture is thinking, "Damn it is really freaking hot in here right now, and screw it I'm not waiting for the spark plug which is triggered by some fancy computer thinking it knows when I should begin to combust, Hell, I'm gonna blow right now. So it does, BEFORE the piston gets over the top of the stroke. So it is trying to push the piston and the rod and the crankshaft backwards in the opposite direction they are all currently moving in. The fast moving parts are not happy. They tell you by making a "Knock" sound. Knock Knock. Who's There? Pissed off reciprocating parts that are gonna get all blown backwards to sh%# by some leaned out really hot pre-igniting mixture if you don't get enough fuel in here, cool the mixture and pull back the timing RIGHT NOW. A tenth of a second later knock knock knock KA-freaking-BOOOOMM. Too late. Broken rod, hole in piston, bent valves, tweaked crank....big paperweight. So to sum up, winging it not a good idea, Lean Mixture under boost with improper timing control...bad cheetah...very bad.

A turbo engine's intake doesn't just SUCK in air like an atmo engine, the air gets PUMPED in. So you need a MAP sensor that can measure air pressures BEYOND atmospheric pressure. 16 years old? High School? How much air pressure is there at sea level? 14.7 psi (also referred to as 1 bar). A 2 bar sensor measures up to 14.7 psi above sealevel. When everyone talks about boost, like 6 pounds, they really mean 6 additional pounds of boost above sea level.

So, how do you get more fuel into the engine when the boost is on? Well, just having the right MAP sensor is not enough, because the computer also needs to know that it is running a turbo charged engine which has altogether different fuel and ignition maps for various engine speeds and loads. The computer then tells the Fuel Injectors how long they should stay open to give enough fuel. The amount of time the fuel injectors stay open is referred to as the duty cycle. If you use stock injectors, even with a TURBO mapped computer, you will eventually exceed the injectors duty cycle. They willl be open all of the time on boost and this still won't be enough fuel to maintain, say, a 12:1 ratio. Then the engine starts running lean, then it gets really HOT...see above...KaBoooom! Solution, get larger injectors. But since they are larger, they flow more. Therefore at idle, they need to stay open for LESS time to flow the same correct amount of fuel as the stock injectors. So if you took your stock calibration and just added bigger injectors, there might be enough fuel at top end under boost but at lower speeds off boost the engine would be an overly rich pig that probably wouldn't run at all.

An AFPR is a half assed way of doing things on an all out motor. A regular fuel pressure regulator is just a valve that opens when it sees a certain amount of pressure at the fuel rail. The stock regualtor opens at... say 45psi...give or take some vaccum assist. An adjustable fuel pressure regulator, sensing boost, stays closed and allows the fuel pressure in the fuel rail to rise at a fixed rate..maybe 10psi for every one pound of turbo boost. So at 6psi of turbo boost you've got about 100 psi of pressure on the fuel rail assuming the pump can sustain 100 psi. This would be swell if fuelling requirements were linear and increased pressure on the rail caused a proportional increase in fuel injector flow...not the case, but close enough in a system with modest boost plans of maybe 6 or 8 psi MAX..and even then..no guarantees. An AFPR doesn't adjust the amount of time the injectors stay open, the duty cycle, they just increase pressure in the hope that that will be enough and correct at all times. So you DO NOT NEED and AFPR if you get the correct sized Injectors and the correct computer map to run them properly. An AFPR is a cheaper alternative to a standalone aftermarket ECU. Folks using AFPRs might also employ other band-aids like an MSD turbo ignition controller that will intercept the factory timing signal when you are on boost and pull a preset amount that you can program in. Again this stuff is not necessary if you've got a properly re-programmed factory ecu.

Spend $20 and buy Corky Bell's book, Maximum Boost and read it cover to cover a couple of times. Then go to this site and read all of it including:

http://www.gmpcm.com/phpBB2/viewtopic.php?t=39

Then talk to..I think his name is Mick a board administrator and tell him about your proposed setup. He has got a Turboed Fiero, I think. Maybe he would sell you a copy of his EPROM if your configuration was exactly identical in every way to his, but I doubt it. What he will give you for free is some great insight and tuning tips on how to reburn eeproms to recalibrate your old ecu box to run the turbo grand prix code with the appropriate tweaks. The bits to burn the eeproms and the software to do it might set you back $300. If he ECU and the harness cost more than $100 from a junkyard, ask them to kiss you first.

You don't have big piles of money, but you do have lots and lots of time. Use it, teach yourself, and learn patience grasshopper otherwise....KaBOOOOOOM! Bwahhahahahahahahahhahah

[xxrollin]

How about useing checkvalves between the engine and the map sensors. Guys running hondas back in the day did this all the time. If you put a vacuum gage to the engine at idle, there will be vacuum, but as the throttle is cracked open and the revs increase, vacuum drops to zero. I know it works out fine on a honda, this guy down the road from me is running the vortech FMU to increase fuel pressure. Hes only running 8psi. No problems after 2 years now. It doesnt have a MAF so no need to worry about those. Oh, if it did, I herd you can put it in front of the turbo and a check valve at the MAP and it will run good.

[SappySE107]

You still have to deal with spark if you checkvalve it (ghetto imo). THe MSD-DIS 4 wont help unless you run a constant boost at the same RPM every time, which I don't see happening. I dont know how you would go about spark if you checkvalve the engine and then run a fuel computer alone.

[BrianC72bgt]

As I mentioned in my previous rant, an FMU or a rising rate fuel regulator with a bigger pump or extra injectors triggered at boost or any other low cost hodge podge of plumbing can give you OK fuelling to a point...maybe 8 psi...and as for ignition timing, you can use a turbo timing control box, not an expensive MSD-DIS4, but another MSD product which receives a boost signal and then pulls a pre-programmed amount of timing for every pound of boost it sees. Fellow by the name of Dick Bipes also makes a similar gizmo. And it absolutely will work. It becomes a hodge podge of intercepts and workarounds, and I have a tremendous degree of respect for anyone who can make it all work and run well. While costlier up front, I think a Haltech E6K or E6X or E6GM, second hand oversized injectors and a DIY intercooler give you much more tuning and performance potentialdown the road. That said 8 psi is nothing to sneeze at and will totally transform the car. It all depends on what your ultimate goals are.

But back to the original thread. Do your homework. Read Corky Bell's Maximum Boost until you understand it, make a plan and then junkyard scrounge and improvise like crazy.

Good Luck,

Brian C

72 MGB-GT w/ injected 3.4 V6 in progress
90 Miata w/ DIY Turbo

[RacerX11]

The MSD boost Timing Controller will not work with the DIS system. You will need the DIS-4 to get it to work.

Marty

[BrianC72bgt]

I stand corrected. Are their any other mfrs. that produce a pull-timing-on-boost-box that will work other than an MSD DIS4? Anyway, this is all the more reason to start thinking about an integrated solution with a reprogrammed stock ecu or and aftermarket ecu. The price isn't that much more by the time you are all done.

Of course, if you have lots of time but little money, cobble away.

Brian C

[xxrollin]

I dont know of anyone else making an ignition box for GM type dis ignitions other than MSD. I would look into Electromotive and see if they have something that will tie in to the factory harness and use GM's integrated crank trigger. But you'd probably be better off getting the whole deal. Its all money, and if you cheap it out here thinking you'll save money, you'll probably spend more money than the next that'll get the whole deal. Haltech is probably the cheapest ECU available, I'm using a FAST Bank to Bank system originally meant for a turbo regal, $1850, and I like it alot. I have no experience with Haltech or there software, so I cant compare side by side, but as a first time user, the ignition was by far the hardest to figure out. Everything else was label'd with all connecters attached. I'm going to run my MSD Dis-4 into the system just to use it, I dunno....... I might sell it along with the DIS BTM, anyone want to make an offer..........

[Maetrix66]

Hey fierofiend, the stock 2.8 fiero ECM runs with a distributor, right??
Not sure how the computer with DIS will interact with a car/engine with a distributor. They may not want to play nice. It may work fine, obviously the fuel side would work, just not sure if part of the harness will need to reworked to include the DIS, since the 3.1 and 3X00 engines do not have a distributor.

[grandprix34]

could someone tuning with an FMU be able to use this Ben?

http://www.splitsec.com/products/tmc1/tmc1ds.htm

[grandprix34]

what about this one?

Description:

The FTC1 Fuel/Timing Calibrator provides precise calibration of fuel and timing retard. It is most often used when naturally aspirated engines are converted to forced induction. The fuel calibration range supports conversion to larger injectors. The timing control section is used to map timing retard to avoid detonation under boost.

Through a serial interface, the FTC1 can be programmed by a laptop computer running the Split Second R4 software. The software provides three dimensional mapping of the MAP and timing retard signal. The MAP value output is determined by the active cell value. The active cell is determined by absolute pressure measured by the internal sensor and RPM.

The FTC1 comes in many different versions. It must be ordered for a specific model of vehicle. Some versions have an internal 2.5 bar MAP sensor which can replace the stock one bar MAP sensor. Other versions operate in voltage mode and are driven off of the stock MAF sensor.

The calibration of the FTC1 is done through a serial interface, which is active while in operation. The R4 software runs on Windows 95/98NT/2000. The software provides real time display of RPM, manifold pressure, and cell value. The R4 software is the same software that is used to program the AIC1 and PSC1. A variety of editing tools ease the task of setting up an initial map and quickly fine tuning for optimum performance.

Features:

Two three-dimensional map tables defined by absolute pressure and RPM
Avoids fault codes due to excess flow readings
Compatible with 2 and 4 stroke engines from 1 to 12 cylinders
Laptop adjustable
Two modes for either direct output or signal modification
Can retard ignition timing by up to 20 degrees
Transient surge and battery reversal protection

Connection Information:

Because the FTC1 is offered in so many configurations, it is not possible to show a typical connection. Please refer to the installation instructions for a specific model for more information.

Software:

The FTC1 is programmed with the R4 Fuel Controller Software. When the software is launched an identification screen will appear that says Split Second. After four seconds, the maim menu will appear. If this is a new application, select File then New Customer to create a new customer. Type in the customer name and save. The default location for customer names is My Documents. When you return to the main screen, select File and Open Customer to open the customer file that you just created. Once the customer is open, the Maps, View, Options and Help tabs become active. Whenever you write new data to the FTC1, all settings and mapping will automatically be saved under the current customer name. You can fill in the various fields such as name, address etc. if you like.

Connections:

Select the proper com port for the serial connector on your computer. Connect the FTC1 to the computer using a 9-pin serial cable. The cable must have a male plug on one end and a female on the other. Once the serial cable is plugged in and the FTC1 is powered up, you may connect to the FTC1 by selecting the Connect to ECU icon. Once communication has been established with the ECU, the Real Time pull down becomes active.

Programming:

Refer to the R4 data sheet for specific information on how to use the R4 software. Use the Options pull down and Systems Settings option to select either the Vacuum/Pressure, or voltage mode and Programmable Signal Conditioner. Use the Options pull down and Engine Settings to select the number of cylinders of the engine. Use the Maps pull down to access the map tables. There are two map tables in the R4 program. Table A is normally used to program fuel and table B is used to program timing retard.

In the vacuum/pressure mode, the FTC1 is calibrated to read throughout the vacuum region and up to 16 PSI of boost. The vacuum and pressure readings are based on sea level conditions. As you move up in elevation and atmospheric pressure goes down, the ambient pressure reading will move down into the vacuum reading.

The number entered into the cells on the fuel map represent either the actual output voltage (direct mode) or the amount that the input voltage is offset (signal modify mode). The number entered in the cell can range from 0.0 to 20.0. The step size in both modes is 25mV. Example outputs are shown on the following table. The signal modify mode is recommended for most engine management applications.

This table shows the output voltage for direct and signal modify modes of operation. Note that there are 200 cell values. Only 20 are shown for simplicity.

Cell Value Mode
Direct Signal Modify
0 0.0 -2.5
1 1.25 -2.25
2 0.5 -2.0
3 0.75 -1.75
4 1.0 -1.5
5 1.25 -1.25
6 1.5 -1.0
7 1.75 -0.75
8 2.0 -0.5
9 2.25 -0.25
10 2.5 0.0
11 2.75 0.25
12 3.0 0.5
13 3.25 0.75
14 3.5 1.0
15 3.75 1.25
16 4.0 1.50
17 4.25 1.75
18 4.5 2.0
19 4.75 2.25
20 5.0 2.5

The number entered into the timing map indicates the timing retard in degrees. The value can range from zero to 20.0. The maps for both fuel and timing are overlay maps that are applied on top of the maps in the stock ECU. It is recommended that large jumps in value from one cell to the next are avoided.

You can click and drag to highlight an area of cells. Once highlighted, you can use the icons across the top of the window to fill all the selected cells with a value. For example, in the direct mode, if you fill the selected cells with the value 10, whenever the manifold pressure and RPM match one of those cell locations, the output voltage will be 2.5V.

A highlighted area of cells can also be changed by a percentage by using the Change By button. To increase a highlighted area of cells by 10 percent for example, select the cells, click on the Change By button and enter 10. To reduce by 50 percent, enter ?50.

You can also fill a range of cells with values that are interpolated from the end points. This works over a row, column or 2-dimensional area. To fill values over a two dimensional area, fill the four corners of the area with cell values. Then click and drag to select the area encompassed by those corner cells. Click on the Auto Fill button. The software will calculate and fill the correct values for all highlighted cells.

Once the maps are set up, you can write to the ECU in the FTC1. To write to the ECU, the ignition must be on so that the PSC1 is powered up. The engine must be off so that tach pulses are not present during programming. To write to the ECU press the Write Data to the ECU button. The operation of writing the data will also save the configuration and map information in the current file that is open. You can also upload from the ECU using the Read Data From the ECU button. You can then save or modify the data.

Operation:

Once the data is loaded into the FTC1, the engine can be started. From the main screen, the Real Time pull down can be used to observe a variety of operating parameters. The All option brings up a window that displays boost pressure and RPM as well as cell value and duty cycle for both A and B channels. The All window can be enlarged to full screen size to make it easy to read while working on the engine. The RPM and Pressure options display analog gauges that show those parameters. The All, RPM and Pressure options can all be displayed simultaneously.

Electrical Characteristics:

PARAMETER CONDITIONS MIN TYP MAX UNITS
Supply Voltage BATT+ to BATT- 12 13.5 15 V
Supply Current Into BATT+ terminal 25 mA
Tach threshold Normal operation 2.5 V
Tach Hysteresis Normal operation 0.5 V
Vacuum/Boost On vacuum/boost hose 0 2.5 Bar
MAP output Steady state source current 0.1 mA
Direct Output Steady state source current 10 mA
Modify Output Steady state source current 10 mA



Mechanical Characteristics:

[kanchou]

would such a setup need a turbo timer? Is it only oil cooled?