MicroSquirt.com read only forum (Jan.15,2018)

I am having a problem. I have used the built in calculator for required fuel. I really dont know for sure what my engine output is but its a 2300 8V (1970's) with very big vlaves and a 300 degree cam so over 180 - 220 BHP is unlikely. I get a value for required fuel of 14.4 (7.2 ) *2 squirts.
My parameters are:

2300CC
4 cylinders
270cc / min (25.7Lbs)
14.7 AFR


The weird part is that my VE values on the 100KPA line are up to 220%. I cannot believe this is true. I have a permanent fuel pressure guage on my fuel rail and the pressure holds at 43psi as it should be. I'm having tuning problems generally but the WOT stuff works quite well but anything below WOT gets really hard to tune. I think the clue is in my silly VE vlaues on the top line but I am struggling to put two and two together and come up with a plan!

I experimented today with the VE table generator and found whatever silly values I input it always caps out at 125 (ish). Would I be right in thinking that whatever values I put in over this number actually make no difference. I just sense something fundamental is wrong with my setup. There is no way my home made 2300CC is making enough power to need this much fuel. If it was I would not be writing this post!!

I only discovered yesterday when my EGO died that there was something weird going on. It was telling me that the AFR at WOT was a nice 11.9 and I had been tuning around that even though the engine just didnt seem happy. When it died I had fuel problems as the MAP increased so since I had to get somewhere I just bumped up the REQ Fuel until it was at least driveable when I put the hammer down, by the time I was running OK at WOT I had increased the fuel by 4 (yes 4 not 0.4) the car went like a rocket at WOT. The entire range below WOT was hopelessly rich but my suspicion was confirmed that all is not well.

I'm not really sure what the question is after all of this but I guess to keep it simple,

1 Are we sure the req fuel generator is right ( I suspect the answer is YES)
2 Is there a point at which upping VE values in the table cease to have any effect.
3 Has anyone else had problems with an LC1 being wildly innacurate as if mine is right I need an AFR approaching 8:1 to get maximum power.

Note the MSQ is before I added +4 to the required fuel.

MS 2 672b CODE

Jon

1 Are we sure the req fuel generator is right ( I suspect the answer is YES)

Jon,

Yes, the req-fuel generator is correct.

2 Is there a point at which upping VE values in the table cease to have any effect.

Yes, under at least two conditions:

- the fuel system can no longer supply the volume of fuel required (too small a fuel pump, too small supply line, clogged filter, lines kinked, insuffcient power to pump, etc.), or

- the injector duty cycle has reached 100%.

3 Has anyone else had problems with an LC1 being wildly innacurate as if mine is right I need an AFR approaching 8:1 to get maximum power.

I can't comment on that, but a number of people are reporting that they have trouble getting the LC-1 configuration right (apperntly is in not trivial).

Lance.

Lance,

it was the pump! It was rated well in excess of what I need but maybe I ran it dry once to often and killed it. I noticed on a warm start it was making an noise that just didn't sound right. Also had MAP damping problems as the noise on the MAP was big enough to cause bin hopping between 98 and 100KPA. I really went mad on the MAP damping, both with restrictors and a MAP damping factor of 15 and now it's much better. Running V2.684 on MS2 now and it all seems OK. Cant burn anything without losing comms but thats not a big hassle and may be my USB serial port convertor. Some comments and logs here. http://www.msefi.com/viewtopic.php?t=19972

The TPS problem has got to be worth looking at IMHO.

Jon