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Can tunes go bad?


glgraham_2000

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I have had a 2005 Legacy GT since it was pretty much brand new. I have had my Cobb AP installed with a custom stage 2 tune from TDC since the begining. Going on 90k miles with the tune. I have 110k miles now and all the sudden, the car will not start sometimes. I would have to reset the ECU with the Cobb AP to get the car to start. Over time, that stopped working and I had to wait 15 to 30 minutes until it would start after reseting the ECU. I took it to the dealer and they said there must be something wrong with the tune. I have had the same tune for 90k. How all the sudden does it go bad?

 

I decided to uninstall the the Cobb AP to run the factory tune to see what happens. The problem went away. Drove around with the factory tune for a few days and it started everytime. Besides the CEL comming on due to my exhaust mods and removal of sensors, the car ran perfect.

 

I decided to reinstall the Cobb AP and my custom Stage 2 TDC tune. After the install, I have not had a single problem for the last week.

 

How does that happen? Does the computer start rejecting a tune after 90K?

 

Any ideas?

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my guess is that its unrelated to the tune, could be a simple ground wire that needs to be cleaned causing a bad connection. Tunes are not gonna wear out or go bad unless the ECU bricks. It sounds like some sort of electrical issue though in the ignition system. How is your battery?
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In my line of business with servers/computers and software development, code just doesn't stop working with out something else not changing. Like a hardware problem causing the code to not function properly or not function as intended. Something usually changes or another variable in the equation changes. So I just need to find out what hardware is not functioning properly. The dealer is of course blaming it on the map/tune from the Cobb AP. I personally think it just needs a tune up. New plugs, etc. I'll get a tune-up and see if it runs better. Has not had one in 110k. :-)
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Yep, 110k on the original plugs. Not bad. :-) Dealers and mechanics kept telling me not to change them unless your having a problem. Have not had a single problem until the last month. Yes, I have done all the other routine maintenance, timing, and all other belts, among just about everything else it seems.

 

Another thing I am hearing and can't seem to find in the manual is when to change the gas filter. Again, I am hearing from mechanics and dealers, for our LGT don't mess with it unless your having a problem as it is part of the fuel pump, mounted in the gas tank and was design to be a lifetime filter. That still sounds odd to me.

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  • 2 weeks later...
So I got new plugs installed by the dealer last week. So it can't be that. Just happened again today. Went a whole week with out a problem. Got in the car today for lunch, drove 30 seconds across the street. had lunch for 30 min., car would not start. I have even reset the ECU with the COBB AP 4 times and it will not start. My next step is to uninstall the COBB AP like last time to see if that works again.
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