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Link G4 previous tune running rich

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I have a 98 Subaru STi Type RA with a link G4 installed. The vehicle came with a tune from a reputable tuner when I purchased the vehicle and worked perfectly.

I wanted to start learning how to tune and watched the efi fundamentals course and the road tuning courses and felt the confidence to begin tuning my car. I loaded link's base map and got the car to idle properly.

After I finished with setting the idle I reflashed the previous tune I was using. This tune now runs richer than before. Unfortunately the tune is password protected and I can't look in to see if anything is wrong.

Is there a calibration period for the link ecu after it gets flashed with a "new" tune or have I done something wrong?

Hi Jack,

No there is no "re-learning" period like you have with some OEM stratagies. A password protected map should operate exactly the same as it did before after re-loading it in.

I can only think of a couple of exceptions - the first would be if you had upgraded the ECU firmware in the meantime then there may a new table or something introduced that was not in the original map. The other exception would be if something mechanical was changed such as fuel pressure, exhaust, map sensor etc.

Hi Adam, thanks for the reply.

I kinda figured the fuel maps were set as they were and there wasn't a relearning period. I haven't switched anything with the car in the time I switched back and forth from the tunes so that's why my mind is so boggled on this issue.

Just to add to Adam's post, I've had this situation a few times with firmware updates. A table that's caught me out in the past is the introduction of the short pulse width adder table. When this table is added during the firmware update process it tends to be filled with garbage values which 'add' to the injector pulse width and hence make the engine run excessively rich. If you haven't made a firmware update or made any mechanical changes to the car then there's no real reason why the fuelling would change.

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