send a copy of your ROM to the email in my sig, we'll take a look. that timing is pretty low there at peak load.

 

I was going to say the same thing.. I can imagine going up a hill, rolling on the throttle at lower RPM and the car feeling like a 120hp turd.

 

Yeah, you've got a lot of timing on the top end, but nothing on the low end. I bet it would feel like a different car with all the torque you could gain by adding some timing.

 

Another thing that can cause misfires is your spark plugs comming a bit loose from the extreme temperature cycles in the winter. I just had this issue and I retightened them and problem was remedied. Having said that this was ignition sputter, so if you are hitting a hard cut like a compressor surge or a fuel cut then this wouldn't apply. I have had the loose spark plug issue more than once. You have to be careful not to overtighten them though as the head is aluminum. .015 gap is a bit too close probably, I would widen that up to around .020.

 

Extemely low timing will cause misfires that can register as knock. You appear to have taken more timing out and compounded the problem.

 

There's also an 11 degree change between cells (100-120 loads), which is normally considered a no-no in proper tuning.

 

Thanks alot for the input guys. So this looks more like i'm hitting fuel cut then.
I also notice those timing numbers jumped so bad, but figured that I haven't had much tuning experience to dare to change too many things.

I just took a tuning class at EFI university and according to my calculations, my car probably needs bigger injectors and fuel pump.
My car made 465whp which translates to about 530bhp.
Using BSFC of .65 *1.3 (30% more fuel for E85), I need 447.85 lbs/hr of fuel
so 1 cylinder will need roughly 112lbs/hr of fuel which translates to 1142cc/min.
And that is at 100% duty cycle. I would need 1344cc/min to get 85% duty cycle.
Anyone can confirm this calculations?

I am currently on RC 1000cc/min with single 255lbs/hr pump as my tuner recommended.
Now that I learned about tuning myself, I figure that I may run low on fuel. What do you guys think?

 

Kinda switching topics a bit, but I run 1150cc injectors, an in tank walbro 255, and an inline bosch 044 and run out of injector around 530whp on e85. You might be able to hit 465whp with just a single fuel pump, but you are pushing it for sure. If I were you, I would upgrade your fuel pump situation before your injectors. Also jumping 11 degrees from one cell to another is definitely a whoopsy. I think the max I jump is like 2 or 3 degrees, I would have to look to confirm.

*Update* 3.9 degrees is my max jump and the average is more around what I said 2 to 3 in the steep areas.

 

Have a pro tune your car. Up the boost cut/limit. As stated before, the transitions from cell to cell are very drastic and will cause knock by such huge dips /increases.

After 2 pages did you fix the issue by upping the limit?

 

Depends on what type of dyno you were on and what AFR's you want. Doing calculations with BSFC, you're totally guessing on BSFC so it's not really going to be accurate; the BSFC you ended up using is probably way too high IMO. You should be able to figure out how much fuel you need just by using airflow and AFR.

I did 414awhp/459torque on RC750's @ 28psi of boost falling to 22 at peak hp (5600rpms); (and 370hp on a Dyno Dynamics). I then got it to hold 28psi all the way up, and I never saw any sign of running out of fuel.


If you are fuel cutting, you need to adjust the fuel cut up or remove it. Bigger injectors don't change fuel cut; fuel cut is based on airflow.

 

You tune timing in 1/10ths of a degree?

 

Holy Smokes. After seeing the timing map for E85. Needs a little work. That Sahara desert section near peak load is not helping any. Someone will get you on the right track.

 

Looking at the map in detail, the boost cut is disabled. If it were 465 on a dynojet I have seen 490 with the 1000s going static out the top. If the 255 is not modded it will flow less. We need a log or 3 to see exactly whats going on. If we knew where 2 byte load was going that would help. Too many variables at this time to make a 100% accurate decision, however its obvious that some stuff needs addressed. There are some good E85 timing maps up. I posted one awhile ago for a 475whp e85 car on a 57 trim. At 28psi it was knock free and not near MBT. That car was also on 1200s and the IDC were only 83% on the EvoScan scale (it goes to 115% not the normal 80-100%).

 

I use an AEM.

 

Do you have a Sun Hyperforce by chance?