" by using a cheap Laptop , a ROMulator II, " and an upgrade for your TunerCat > you " can change the 'chip' information as you " drive > forget 'burning' a new chip outside " the ECM. you would want to burn a chip ultimately, when you get all the values tweaked, so you don't have to run around with the notebook and romulator spaghetti floating around. ---------- Andrew Hay the genius nature internet rambler is to see what all have seen adh@xxxxxxxxxxxxxxxxx and think what none thought ++ Ok - There was another section on the site for 'Flash Chip' installing & burning which is a 'nuther animal entirely, but not the one that makes the correction to the Factory unit - In Real Time -. Also, Craig Moates 'version' requires 'chip burning' . Including the URL to his methodology in this article blurs the mind set. For the Real Time process, unless I'm missing the boat, you plug in the laptop equipped with the Tunercat software and Romulator II program to your GM ECM, put the vehicle thru its' paces, make your corrections, double check, hit save and unplug from the ECM. Here is the Quote: \\\\\\\\\\\\\\\\\\\\\\\ In the 5 years I have been involved in GM EFI, the number one obstacle to making GM EFI user friendly was the process of having to make numerous calibration chips to tune a system. Well making chips to tune GM EFI is now history. There are new products on the market enabling instantaneous changes to a GM EFI calibration with the engine running. This allows immediate analysis of the engine response to the change which in turn allows immediate correction of the calibration. These products and the WINALDL program are revolutionary in the GM EFI world. On a recent weekend, I had the opportunity to tune two EFI vehicles with my laptop. The first was a l969 4-cylinder Ford Escort for which I had built a GM EFI kit. The second was a l988 Chevy truck with a twin turbo-equipped 350 engine. To tune the Escort, I purchased a Romulator II from www.xtronics.com and purchased Tunercat's (www.TunerCat.com) RT (realtime) software upgrade. Xtronics and TunerCat collaborated to create a system that, in theory, is supposed to allow realtime tuning of GM EFI, which means that no chips are burned to make calibration changes. The Romulator device mimics a GM EFI chip and allows the "chip" contents to be changed while driving with a laptop. To my amazement, it worked! Not only did it work, it worked better than my expectations. I could slide a mixture control parameter across my laptop screen and immediately see the engine respond to the changes. For ex., I adjusted the idle mixture and watched the map sensor value drop to a minimum. This is the same procedure as adjusting for the highest vacuum with carb idle mixture screws, but without having to so much as raise the hood of the car. In my DIY manual, I will describe the procedures used to tune a GM ECM with a RT Tuning setup. Also, checkout Craig Moates site (www.moates.net) for alternative products. Craig's AUTOPROM does emulation, ALDL data logging, and chip buring all in one package. On the Chevy truck, I used Accel's Gen VII DFI software. My customer had already installed and run his truck with this system. I spent a couple of days struggling with this setup. Let me just say here that GM EFI with the Realtime Tuning software beats Accel's DFI setup hands down! An interesting bit of info is that using a Romulator with a pre-1996 GM ECM, you can edit the calibration while driving. The newer GM PCMs use on-board flash chips which means the calibration can't be changed while driving. So the older ECMs with a Romulator are actually better technology than the newer ones, which is good because the older ECMs can be retrofit on older engines whereas the new PCMs can't be retrofit easily. ++ Bt