XFI & 160ln inj

[tom j]

What is the best base fuel pressure to run. Also the injector opening time.
I'm thinking a lower f/p, but I have also read about the inj. dribling instead of misting at a lower f/p.

 

[lazaris]

What is the best base fuel pressure to run. Also the injector opening time.
I'm thinking a lower f/p, but I have also read about the inj. dribling instead of misting at a lower f/p.

I use 1.3 for injector open time. 43psi base pressure. The more volts you have at idle seem to help for the heavy mass of the 160 inj.

 

[Chuck Leeper]

"dribling instead of misting at a lower f/p." Forget that...That injector has no "mist" to the spray. It's firehose time!

 

[tom j]

I cant seem to get my a/f up past 13.0 and my inj time is .7 and f/p is 42. If I change the ve table it just falls on it's face and dies. My thinking is that the inj don't like opening that small amount of time so maybe if I lower the f/p this will alow me to get it out of the ve table.

 

[Chuck Leeper]

.7m/s is not likely possible w/ that inj. As Laz has said, 1.3 is more like it.
Are you trying to idle in closed loop?

 

[tom j]

Yes, should I raise it above idle and let idle in open loop. As of now my high idle is 1000rpm and my low is 800rpm

 

[Dusty Bradford]

What is your VE #'s?

I had better luck with 50psi base and the 160's. If your VE #'s are very low (20 for example) lower your opening time by .1. Be aware you may have to raise your VE to 30, then lower the opening time.

This may not have any effect on the injector but it will give you more resolution on your fuel map. The extra resolution will make a single digit change on the VE table less dramatic.

 

[tom j]

My ve is in the range of 29-33 in the idle portion. Dusty you are saying go lower than the .7 and then raise the ve table. F/P raise? I have aslo seen that people are running a inj flow rate than what they actually have say with 160lb they are running 150 flow rate. Why are they doing that?

 

[Dusty Bradford]

Dusty you are saying go lower than the .7 and then raise the ve table.

Yes, if moving the VE table by 1 number makes too large of a change, you need more resolution. Lowering the opening time plays with the calculation. It usually requires increasing the VE #'s to get it all worked back out.

F/P raise?

Sometimes the 160's will have a better idle with a higher pressure. I'm not sure if it helps the spray pattern or what but it definately helped get the car more stable at idle.

I have aslo seen that people are running a inj flow rate than what they actually have say with 160lb they are running 150 flow rate. Why are they doing that?

I see 145# used as the flow rate. It's just another way of fudging the calculations to help the tuning. You can try it with your own car to see if it makes a noticeable change. Every car is different.

 

[Craig Smith]

What color are the tops on your injectors? Blue, brown, or white?

 

[tom j]

I believe they are white, recently bought from precision

 

[Craig Smith]

OK, at least they aren't the brown ones. The brown ones are really hard to control at low PW. The blue ones are the best but not so easy to get.

Bottom line is that you are at or near the minimum controllable PW for that injector. You can tweak VE, flow constants, and a/f all day long but it still comes down to that in the end. More timing at idle may help you out a little bit. Reducing pressure is the only way to get the PW up, but as discussed, you can't go much lower before atomization deteriorates to the point that combustion quality will suffer.

160s are tricky on a smaller engine. If you can get it to idle well at 13.0 AFR you're doing better than some folks already.

 

[tom j]

I was mistaken they are blue tops. Anyways this is what I did I dropped the f/p 4psi and it upped the a/f within range (14.5) but it was searching so I played with the timing and I ended up dropping it from 30deg to 27deg and idles great now this is in closed loop