Trouble with injector scaling for e85.

[ziggo0]

I put in a set of PTE 1000's today. Fuel pressure is 43.5psi, Walbro 255 in tank. Drained the tank down to empty, ran the car until it died on 93oct. Put in 5 gallons of e85 and the fun began.

I'm using a 95 eprom and Tunerpro/SAFC for tuning. I know the deadtime for my injectors according to ECMTuning is 450usec - however I've found that 220us works better for me - is that ok? According to Ceddy's article - I changed my deadtime around until my idle fuel trims were correct.

After this it was time to set my global injector scaling. Injectors actually flow 940cc so I used that number instead of 1000cc. 940 x 0.67 = 630cc - using this number as my global correction resulted in so much fuel it damn near hydro-locked my engine . So far I'm at 700cc and it's starting on it's own but a bit rich - I'm about to move to 750cc and see how that works out as my part throttle/cruise is very VERY rich.

My overall question is - is setting 750cc instead of 630cc normal? Can the e85 in this area actually be more like e70? Thanks for any advice/comments/suggestions - I'm always on.

 

[bastarddsm]

I usually use the 66% like you did. Also, you can't set the deadtime without having the global set right. Finally, have you messed with the fuel map? Make all the non boost areas 14.7:1, and the boost areas 12:1, then tune from there. DO you have the AFC zeroed out? Are you sure you have the right address for the global scalar? its esay to mess up the offsets. As a test set the rev limiter down to 2500, and see if it works.

 

[ziggo0]

The addresses are correct as I'm using Ceddys BIN/XDF and Tunerpro (for now). I wound up doing some research on my injectors and most have found 315 to 345us for the deadtime is perfect - I settled with 330. I have to set my global as 800cc injectors instead of 630cc which I should...that is what confuses me. Could it be left over 93oct I couldn't get out richening up my e85 tank?

Also - what do you mean by by set all non-boosted areas to 14.7? Wouldn't that mess up my part throttle/cruise? I'm having an odd hesitation with it now that I'm on e85 and am curious to try that...

 

[the_mork]

Certainly your e85 could be more like e70. E85 mixtures change based on a volatility index for your region and the time of the year. Northern stations in winter will sell e70 as e85. You also can certainly have some 93 oct in your tank in fact I would suspect that there really is a fair amount.

Bastarddsm is completely correct that deadtimes need to be calibrated after injector size. Start with a good guess at deadtimes as it seems you've done and get the car to being close to right for injector sizing near idle then carefully drive it into boost. Basically you'll want to adjust injector size until you are as close as possible to your fuel map numbers equaling your wideband readings when you are out of closed loop. When you are in closed loop then your car ignores the fuel map (to some degree it still uses them but this is more complicated than this post covers) so it isn't useful to try to match these numbers. This is the reason why Bastarddsm has suggested changing all off-boost areas to 14.7 since the car doesn't read these in a way that you care about and having a cell significantly away from 14.7 when the car is in closed loop can mess with your fuel trims and confuse you. I personally don't do that but many others do it and it is a successful way to manage tuning.

WOT=injector size tuning
idle/cruise=deadtime tuning

In that order (once the car is safe to hit boost)

Your problem with a hesitation probably has a lot to do with not getting enough fuel on tip in which can be fixed by increasing what I would call Asynch_vs_TPS_Delta but I have no idea what the variable is called in tunerpro. Basically it is a variable that controls how much fuel is asynchronously added based on how much throttle changes over a short period of time.

Why do you have the SAFC in the car anyway? Tunerpro will do much more for you at a much finer adjustment level than the SAFC so you might as well sell it and pocket the money.

 

[MIdsm]

I haven't used e85 yet but my math seems to support that you would need to enter close to 75% of the injector's actual size.

If you have 750cc injectors and want to add 1/3 more fuel due to e85 you would need to get 1000cc injectors in order to run e85 but enter 750cc.

750+(750/3) = 750 + 250 = 1000

750/1000=.75

If you have 450cc injectors and you want to add 1/3 more gas then you would use 600cc injectors. 450+150=600 450/600=.75

Therefore, if you would like to run e85 on a set injectors you would have to enter 75% of the injector's flow rate into the ecu.

Good luck.