Hey guys, my Evo has not been boosting past 10psi or so. Checked all the vacuum lines and did boost leak and came up with nothing. Had a mechanic do some diagnostics on the fuel system and couldn’t find anything there either. I am not throwing any codes either.

car has bolts ons with e85 tune and a buschur mbc.

recently had an oil leak because of the valve cover gasket, but I did replace that and clean up the oil. When I got the car back from the gasket replacement is when I really noticed the problem. Tried to have the same shop diagnose it but they spent a lot of time unable to figure it out. The alternator was also failing so that was replaced at the same time.

any help is appreciated

 

sounds like its just on spring...

you got a boost controller that is not hooked up right or unplugged... or something.

 

no i checked all that. Looks like it’s the tune actually. Pump gas map is boosting just fine. I don’t understand though why the e85 map would be fine one day, then not good at all the next. I would say maybe bad batch of fuel but I went through two different tanks from two diff places and no difference. Will have to get an adjustment I guess

 

Does anyone know if you can run e85 on a gas tune without major problems. I know you couldn’t run gas on an e85 tune cuz it’s too aggressive. I’m starting to wonder if the tuner accidentally switched my maps

edit:
i realize my question sounded dumb. I’m just confused with whats going on. E85 is supposed to be my default map but it would explain that the tuner had switched the maps accidentally if the ecu reset after my alternator failure. Car ran fine at idle or low acceleration but boost would cut off at around 10 psi. Switched to what’s supposed to be the gas map and now it boosts just fine, idles just fine, and I am not showing knock. AFRs under wot is mid 11s. If that was really the gas map I don’t see how any of that would be possible.

 

glad you figured it out.

if you run E85 fuel with a gasoline map, you will be extreeeeeemmmly lean.

it was completely running out of fuel.

 

honestly I think the tunes are just all sorts of screwed up. Gonna get retuned for both maps

im getting a tune regardless but curious if anyone know if changing MBC brands warrants a retune. I wanna replace my buschur for a Hallman Pro

 

I actually did the exact same thing last year. I had a buschur MBC from about 2010 and it was hard to get boost dialed in. Switched to the hallman pro no re tune and works perfect. I love how smooth the adjustment is.