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e85/91 Tunes

EFI Tuning Fundamentals

Discussion and questions related to the course EFI Tuning Fundamentals


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I don’t know if this is the right place to ask this so I apologize in advance.

I tried running e85 on my e85 tune but my car doesn’t want to start. So I reflashed it back to my 91 tune and the car drives totally fine. No Knock or weird timing. Has any experianced such a thing. Before changing my tunes I ran the e85 for about 20miles to make sure my 91 bas was out my lines completely.

Hi Ricardo, can you provide some more information around this problem? What is the car and ECU? Has the ECU been properly tuned for E85? Or are you saying you flashed back your 91 tune and ran the car properly on E85? One of the factors that needs a lot of work on E85 is the cold start and cranking enrichment so it's possible the issue is around this. Give us some more background and i'll try and help you more.

2013 Scion Frs. The device im using to flash the ecu is the hks flash editor comes pre-loaded with 2 maps. RON91 and E85. I wanted to give my FRS a go on E85. Since I don't have a flex fuel kit I made sure to completely run the car dry of 93 pump gas and then added E85 octane to my car. After I put the E85 in the vehicle I drove about 20 miles under 3k RPM to be sure that the car had strictly E85 and to make sure that the E85 had reached the lines. I proceeded to reflash the ecu with the E85 tune and could not get the car to start. After many failed attempts to get the car started on the E85 tune with the E85 octane in the car, I then reflashed the ecu back to the RON 91 tune. After the car adjusted it self with the E85 with the RON 91 tune I drove my FRS around with no problem. What confuses me is the fact the vehicle started and was driven with a tune that was meant for pump gas but the actual E85 tune doesn't want to work with the required octane. Zero knocks and timing, A/F was fine as well. Could it be that E85 Tune is bad?