hey guys, im a relatively new member of the evo family and i have a question. i recently bought a 2010 X gsr that was tastefully modified with all ams parts (intake, uicp, front mount ic, licp, widemouth dp, tp, and turbo back) when i picked up the car the salesman had put pump gas in it and at wot it would seriously break up and sputter, it was rather violent and i was concerned as to what was happening to cause this, also at idle the rpms would fluctuate from almost dying out all the way up to 1500-2000rpm. i bought an accessport and installed a 91 octane map to it and now it runs absolutely perfect. when i was installing the map the ap informed me that the car had a 3rd party tune on it. i have been trying to get in contact with the previous owner to find out who had tuned it or if it was a pump gas tune or an e-85 tune but becaust of privacy issues the dealer cant give me his name/number and he hasnt called them back yet. do you think that the symptoms (decent driveability on normal driving but at wot it would violently sputter and break up) point to the possibility of it being originally tuned for e-85? any information or thoughts on this situation would be greatly appreciated.

 

My guess would be the salesman put 86 octane in it

 

I had thought that as well so I ran it as close to empty as I could and re filled with 91 octane which is as good as it gets around me unless you go for e-85 and it cleaned up quite a bit but it would still do it every once in a while under wot, and this continued even after 2 tanks, and the idle was still fluctuating but I figured that must have been the tune or something

 

Why do you suspect it was tuned for E85? Normally for E85 you would use a higher flowing fuel pump and larger injectors and then the car would be tuned for it. If your car does have those things, the OTS map will not be right. You will either have to put the stock pump / injectors back, but a cheaper alternative is to get it custom tuned or to work with a e-tuner.

 

It's not necessarily that I suspected an e-85 set up I just couldn't figure out why it was breaking up like that even after the higher grade gas was used, I did some research but I don't have the car right now as it is in the shop waiting for jacks transmission to get my t-case back so I figured I would enlist the help of the evolutionm community ha. And I do plan on doing some data logs and working with an e-tuner once I get it back home and try to fine tune it a wee bit, I do appreciate all the help since this is my first turbo car and I'm kind of learning as I go. Thanks.