Tune changed by itself??

[Tait72]

I have a budget drag car, tuned on FreeCrome. On my last visit to the track it felt slower and went two tenths slower. Brought it home and did a pull on the dyno and the tune had changed to really lean on the low cam and very rich on the high cam. Its retuned and I made more hp than ever but has anyone ever lost their tune or had it change on its own before??
It had gone from 206 to 181.

 

[Briansol]

simply impossible... it's a flash rom. it's physically written data to a chip.

i'd say, if anything, your motor changed. Perhaps something broke, a ring is leaking compression, a valve seal is going, etc etc
or, the temp changes with the weather since you tuned....
or, the fuel you are using now got water, junk/etc...

 

[Tait72]

That's weird I did a compression test and all good across the board, but not a leakdown, I tuned it again and it made 212whp so I don't think it is broken which leaves me with fuel.
See how it goes Friday night thx for the reply.

 

[newb]

Ive heard of cars running 3rd party engine management systems have this happen before. Never did see a solution come from it tho.

 

[Briansol]

the stock ecu has some margin of error to play with beyond the tune... based on reading the map, iat, etc etc, which implies the weather is the biggest factor. But most of it goes out the window on WOT...

what was the weather like when you tuned vs today?

 

[reikoshea]

If your TPS is not reading wide-open, your tune can change. I'd check the manual and make sure it's still in spec. That's the only logical reason I can come up with.

 

[Tait72]

Briansol: Hard to tell what the weather was like, was over a year ago just remember it being hot
Reikoshea: Tps was out marginally 4.67 a wot and was recalibrated.
Chatted with most of my car buddies and only one who had anything close to this was a Kswapped EL that lost its Hondata tune entirely when he brought it out of storage.
Anyways thx for replies and advice.

 

[Briansol]

I guess it's possible for a chip to lose data... but at that point, the car wouldn't even start.

 

[Tait72]

Wow car ran great, all is well with the ecu, and the tune. The engine is definitely not hurt.
Went 12.70@105. had never been faster than 13.06.