Spark plug fouling

[twobjshelbys]

Originally Posted by eschaider

I actually think the Accel DFI units that Roush used before the FAST units were even worse.

The Accel unit was an early powerful system (I'd compare it's complexity to the MoTeC unit) but without ANY learning capability. It had a few tunes that would get the engine running but "tuning" it required you to visit all of the tables. They even offered a course on how to do it. The hardest table to do was the one they didn't complete - the altitude table which REALLY matters when starting at 5000' and going to 10K+' as I did. The default table from Accel was flat, so no compensation was done and the result was that it ran rich. The accel system is powerful, but requires much more knowledge to set up and a dyno do do it. They had gotten one of the overlooked aspects of the 8-stack and that is that at low RPMs with the throttle bodies barely open the fuel injectors fire but do not get adequate air flow to properly mix and the engine actually runs rich which is counterintuitive. I don't know if the FAST or any of the other self-learning systems do actually understand that aspect of that particular config.

[eschaider]

From my limited experience with the DFI system (I never owned one, but almost did), everything you say rings old and painful bells. The altitude table (I thought they had another name for it) is right at the front of the pain parade. I requested MAF support and was informed at the time it was coming but not yet available because speed density was better and easier to use.

I never was impressed with the tunability of the system. All the tables appeared to be there but it always seemed like a preproduction version of the tuning software. At the time I looked at them they were telling me they had a Ve estimator coming that would build a Ve table for you so you did not need to. I never saw it.

There were other tuning aids that were either unavailable or required interaction with an as yet unreleased sister software tool to work. I wouldn't say I liked the system and I did not buy it because of that along with many other whoopses they seemed to suffer.


p.s. At the time it was complex, especially for a first timer and appears to be so even today