E85 poor cold start

[ta406]

Hello all. Novice tuner here looking for a little help. I have a 2013 ZL1 with a ported supercharger, BTR stage 3 cam, 5 inch intake, meth injection and headers. Earlier this spring I had my car professionally tuned by a reputable tuner. Car runs great on pump gas. I have recently added a flex fuel sensor and have been trying to get my E85 tune dialed in myself. So far the car runs great on E everywhere but cold starts. The car usually sputters and dies within a couple seconds of the first cold start attempt. On the second attempt, the car sputters again but will usually come to life withing a few seconds. I have attached my tune and a cold start log. Any help would be greatly appreciated.

[07GTS]

see if this helps

[ta406]

see if this helps

I'll give it a try in the morning. Thank you very much for the help!

[ta406]

see if this helps

Sorry for the late update but now the cold starts are great. Thank you very much!!!!!!!

[noobers8]

I?m in the same boat but with a 2012 CTS-V . I can?t open the files but what was changed to help with the cold start fueling ?

[GHuggins]

Main things he changed for this were injection timing when cold - he retarded it to 155 in the ect table and then cranking timing - it was trageting something around 1 degree when cold up to 6 degrees for the hotter temps and then tapered to the right up to 14ish degrees by 800 rpms. He also changed cluster outputs - I'm not sure on this one - perhaps he can tell us so I can learn and a very minor tweak to crank fuel later in the crank time.

[cammedcaddy]

I compared the files to see what was changed and what not. I "think" I got mine just by adding x1.5 more fuel into the cold start FA CRANK table as he did the OP. I havent changed anything else but needs to get colder so I can truly retest. Not sure if it helped or if it messed with anything else.

[07GTS]

try this one see how it goes, also your OL fueling tables are all commanding 1.0 as well as the IVT so ur not going to be starting well like that put the stock values back in and see what its like after that as well as my changes, my changes alone may not do much as u need enrichment for cold engine as not all fuel is being burnt so more has to be commanded in the OL tables, also the inj tip temp offset should have values in it to help hot starts, see how that goes

[07GTS]

Main things he changed for this were injection timing when cold - he retarded it to 155 in the ect table and then cranking timing - it was trageting something around 1 degree when cold up to 6 degrees for the hotter temps and then tapered to the right up to 14ish degrees by 800 rpms. He also changed cluster outputs - I'm not sure on this one - perhaps he can tell us so I can learn and a very minor tweak to crank fuel later in the crank time.

if a tune is scaled with the stoich then i reduce the cluster density by the same amount all it does is keeps the fuel usage values closer to factory, if u just double the stoich the fuel usage cluster values show about halve what they should be

[sgod1100]

I compared the files to see what was changed and what not. I "think" I got mine just by adding x1.5 more fuel into the cold start FA CRANK table as he did the OP. I havent changed anything else but needs to get colder so I can truly retest. Not sure if it helped or if it messed with anything else.

Pretty sure cranking spark was changed as well

[GHuggins]

if a tune is scaled with the stoich then i reduce the cluster density by the same amount all it does is keeps the fuel usage values closer to factory, if u just double the stoich the fuel usage cluster values show about halve what they should be

I didn't look at the tune that closely to see that it was scaled. Makes sense now. I always forget to do that part unless someone points out their fuel economy being way off and then the ol forehead slap moment - yeah....

[07GTS]

I didn't look at the tune that closely to see that it was scaled. Makes sense now. I always forget to do that part unless someone points out their fuel economy being way off and then the ol forehead slap moment - yeah....

ive got a feeling its not a straight divide tho but i think its close, if i get the time i was thinking of using a axillary pump and fill some fuel into a bucket and run the engine till it dies and then fill with exactly one litre and reset fuel used and run engine till it dies again and see if the fuel used is 1 litre and adjust to suit, ERM had a calculator for it back before but i dont think it ever worked right as the numbers were way different to a straight divide for scaling

[GHuggins]

ive got a feeling its not a straight divide tho but i think its close, if i get the time i was thinking of using a auxiliary pump and fill some fuel into a bucket and run the engine till it dies and then fill with exactly one litre and reset fuel used and run engine till it dies again and see if the fuel used is 1 litre and adjust to suit, ERM had a calculator for it back before but i dont think it ever worked right as the numbers were way different to a straight divide for scaling

I've always just divided it out too. The only way to get it 100% is to measure, reset and then drive and then divide out the difference back into it for each individual cell. Honestly they're usually 1mpg off from factory, so dividing out regularly just skews them, but gets them close enough to work. Then you have to factor in the fuel is always different in each part of the world or each county here in the US it seems most times, so it will always have a slightly different energy output and will burn more or less than other fuels at other locations, so again effects the numbers...