What Aftermarket ECM are you running??

**cailey37** · 07-19-2006, 04:11 PM

Was just wondering what aftermarket ECM people are running....I'm looking at the F.A.S.T XFI system but would like to see if anyone has one or another one and how they like it......

**sdonegan** · 07-27-2006, 03:40 PM

Since I have not found any useful aftermarket replacements for the stock 1998 LS1 computer I am building my own (I am an engineer motorhead with engine/electronics/programming expertise).

My first step has been to build a few devices to intercept the stock sensors - the first was the MAF. Nothing more than an analog to digital converter, micro-controller, and digital to analog converter - it spoofs the stock computer quite nicely :-)

At some point I will have a data logger that catches all the signals at the stock box - followed by adjusting things as desired. Final 'product' will be one which could replace the stock box - I may not go that far as I only am interested in the engine side of things and the stock computer does a ton of other things (car alarm etc). A simple 'interceptor' design may be where I stop.

My goals include using wideband O2 sensors and a technology called Ion Sensing to use the sparkplug itself as a sensor to deduce peak chamber pressure and adjust timing accordingly.

Far too much fun, and as I have a real job never enough time to prototype/test...

**turbotko** · 08-08-2006, 04:50 PM

Funny you mention Ion Sensing. BMW is using it on the S85 M5 engine. It's seems to be much more accurate than using a knock sensor.

**12secSS** · 08-10-2006, 12:15 PM

Although not compatible with 1998 ECMs, AEM is starting production of the EMS for 1999+ F-Bodies. I should be receiving mine very soon.

**sdonegan** · 09-05-2006, 07:01 PM

My first PCB (done by a fab, not by my own etching etc) will be ordered after I do a final eyeball on the layout tomorrow and then should be here in a short while. Given the tooling costs -vs- the per board costs I'll just do a run of 20 boards. It does the spoofing of the MAF sensor to the stock ECM - reads in the frequency, applies whatever % correction factor I wish and builds a new frequency output. The connectors are stock ones so it just fits :-) I bought a bunch of the standard GM male/female connectors for this purpose. Tests will be done on the car tomorrow with a frequency meter before/after the interceptor.

The same board has 5 analog to digital converters on it - so it can take the stock IAT, TPS, MAP, O2 Sensor(s) etc as inputs. And it has 8 digital outputs I have yet to find a use for but 'plumbed' on the board for giggles. The board is 1.5 inches by 3 inches :-) It is simply one of the 'fingers' of my distributed ECM spoofer... Board cost, per unit for parts is <20$ :-) I plumbed in a switch to allow the unit to be in passive/data logging mode or active spoofing mode. The board outputs RS-232 to a laptop. I believe the board has <10 components on it - the only 'expensive' one being a 6$ PIC Microntroller...

**sdonegan** · 09-06-2006, 02:02 PM

The board check exposed one little error which I corrected. The PCB order for 20 boards has been placed. Including components the boards raw cost will be ~13$ each.

The board does not only spoof the MAF/ECM - if a wide band O2 sensor is attached to one of the 5 available analog to digital converters and a 'goal' air/fuel ratio is entered it will adjust the MAF to ECM suitable to reach that goal. The only other sensor it needs to read/spoof to make this almost foolproof is the MAP sensor (the ECM uses tables and the MAP data to cross-check the MAF readings). The board has plenty of I/O left over to accomplish this.

**sdonegan** · 09-08-2006, 06:58 AM

Since Ion technology is a patented item, what I am building is a high voltage current measuring probe - what you connect it's output to is up to you.

The custom ordered DC to DC converter to supply 290V to the device under measurement arrived. Pricey but hopefully worth it. The PCB design is as final as it will get until I've put together a prototype probe. The design has a BNC connector for input and one for output as well as one for 12V DC (well I guess 13.8V) from a car battery/system.

You would use this, for testing current across a spark gap, by attaching high voltage cable to the spark gap/ground, with a couple of 20KV blocking diodes for those who like to run nice hot ignition systems, to the input BNC. The output BNC goes to an oscilloscope for your viewing pleasure (or to a high speed analog to digital converter if you want to play with the waveforms returned with a computer).

Enjoy

**sdonegan** · 09-17-2006, 12:30 PM

The proto boards arrived - I have stuffed and soldered the first one and will be testing it probably tomorrow. It has the capability to spoof/translate the MAF to ECM, input IAT, CT, TPS, O2, etc sensors (and spoof them as well) and drive an RS-232 line to a laptop for logging and a 4x40 LCD display - all on a board 1.25 X 3.0 inches in size :-)

At some point I may sell these for other motor/bit/electron head types :-)