Convertying Non-FFV to FFV (Flex Fuel Vehicle / E85)

[roosterk0031]

2007 Chevrolet HHR

Following his experiments I'm going to convert my Cobalt XFE (or really just enable) the FFV feature. After 5 years of owning a SG2, I finally figured out the xgage features so I can see Long Term Fuel trim, HP, A/F and Knock Retard. My test drive was with E10 LFT was around 3 most of my 15 mile drive. made 100 hp at 4,000 rpm, 0 knock retard, A/f 14.6.

I went and topped it off with almost 8 gallons of E85 making an E55 blend after just a few block LTF was in the 20's but it jumps all over(3-28). Didn't expect it to move around that much. A/F 14.6.

What I think will happen is the car will learn the new fuel and reset the LTF to 0 so that it doesn't throw a CEL with LFT exceeds 30 or so, I don't really know the % when it throw but in the past anything over E55 would throw a CEL.

Sometime next week I'm going to(pay someone one else to using EFIlive) turn on the FFV feature that is already in the ECU and make some small tweaks to the timing maps, maybe some tweakes to fueling.

Same year/engine/tranny HHR has the same everything but is a FFV so using it for a baseline. If it works well, then KT's Cobalt.

[ME_Andy]

Following... I'm interested in this as well.

[roosterk0031]

Took about 30 miles this morning to throw a CEL, P0171, LTFT seems to have stabilized at 28-29, but when stopping or coasting it drops to 2-3. A/F doesn't seem to change ever so going to investigate that a little more this weekend.

With E10 the HP went negative when DFCO, doesn't go negative with E55. Did a 3rd gear pull uphill, saw 102 hp at 4,000 rpm (55 mph) before shifting to 5th. HP is pretty slow to update so really the same as E10. Need at steeper hill or more weight in the car to make the pull take longer.

[ksa8907]

Originally Posted by roosterk0031

Took about 30 miles this morning to throw a CEL, P0171, LTFT seems to have stabilized at 28-29, but when stopping or coasting it drops to 2-3. A/F doesn't seem to change ever so going to investigate that a little more this weekend.

With E10 the HP went negative when DFCO, doesn't go negative with E55. Did a 3rd gear pull uphill, saw 102 hp at 4,000 rpm (55 mph) before shifting to 5th. HP is pretty slow to update so really the same as E10. Need at steeper hill or more weight in the car to make the pull take longer.

The hp being "measured" is simply calculating based on the weight of the vehicle and the rate of acceleration. Go down the hill next time and you'll gain 20 or 30 hp.

My point is the hp you are reporting is just a number that is only comparable to your car under those same conditions.



Im curious how this all works out for you. Im not at all familiar with efi live.

[roosterk0031]

Yep, I understand that as well, and even my MPG because I have different size tire than stock and don't account for it. I just found things to do with an old toy.

I thought it would have to use torque to calculate HP so without a load(going up hill) it won't make as much. I'll try down hill on the way home, it will take 1/2 the time so the SG2 probably won't keep up and I'll hit 55 and only see 50 hp I guess.

EFILive or HPTuners was trying to talk a friend more into it to buy HPtuners and cover half of it and have him tweak my cars. Cost about $650 and includes 8 credits I think, it takes 2 credits per my cars($50 each credit), it kind of a license deal, once it reads the VIN those credits are tied to the car. So to have someone without a unlimited tuner do it it's a min of $100 just for the license fees.

I think EFIlive license/credits are slightly more expensive, but that's a one time fee for as long as you own the car and use the same tuner. After that it's just the tuners time.

Going to double check my xgage setups later and try a few more, not sure if I used the GM specific a/f or one of the other10+ options.