NO PC - Mega Squirt/Mega Tune, never ending issues Options

[Scott S]

Hi All -
Does anyne have a megasquirt/megatune FI set up that actually works... at altitude?

My brother has been building a big bodied audi S-4 for thre years. As of today the car has less than 1000 miles on it over that time. The car is blisteringly fast - it dynos between 550 and 600hp at the crank. However the megatune management system is so unreliable/unstable that the car will run great for an hour, then start doing things like randomly shut itself down, or drop a cylinder for no reason. The guy who is the go to guy back east actually reccommended that he set his idle to 1500+ rpm's to keep the car from stalling when the AC is turned on. Other than that, the usual response is just to wait for the next upgrade. The mechainic who is doing the build is fantastic and just as pissed as any one over the issue.

The lower elevation guys have no issues, it only seems to be affecting those at higher altitudes. Its like they never tested the system anywhere above sea level.

There have been a few threads on the MS system on our board, but even after searching, I could not find where anyone was ever beyond the point of "well, there are some issues, but I will work them out later". Just curious if anyone has actually successfully installed a fully operational system.

Thanks - sorry for the book...
Scott S

[jcd914]

Scott,
I have no MS experience but I do have "big bodied Audi S-4" experience, if you mean 1992-94 S4s (95 S6 is same car different name). I have a 93. These are the 5cyl 20valve turbo cars.
These cars have problems with the ignition coils and the ignition modules that drive the coils. Mine, it takes a while before the coil (1 of 5) starts dropping out and I am not sure which one it is. Since they are hard wired to the harness and all 5 are mounted on a cover over the spark plugs you can't just unplug 1 and plug in a new 1 to test. I tested the ignition modules by swapping them into my A6, 1 at a time. S4s use 2 of the A6 modules.

There is a tuner shop in Davis CA that knows these cars very well, www.2Bennett.com. They have always been helpful and friendly to me.

Most of the Audi tuners seem to modify the programming in the OE ECU, it does require a different MAP sensor in the ECU to go up much in boost. I think Audi used a separate Baro pressure sensor for altitude comp from the sensor in the ECU. I was reading where MS used the same sensor for both and just use the initial value (before start up) for altitude comp.

I hope he can get the issues worked out soon, my S4 is fast (for a 4 door lux sedan) at the stock 230HP I can only imagine what 500-600 would be like.

Jim