ZeroBanger

Hey everyone..I have done alot of searching but still a bit unclear. Mods are in sig. I was realizing that I have only been boosting 10 LBS of boost at the track and want to get to 12-13.

I started monitoring my INJ duty cycle. So far it it 65 pct. I don't have an a/f gauge in my car, so I am curious what I should monitor to make sure my car is ok. For instance, if I stay at a low injector duty pct, is that enough? I know this question is vague but my concern is over boosting,etc.

I do know my car run rich to begin with, I do plan to use atleast partial race fuel at the track, too.

Currently I monitor air temp, e-rev (I like to see my max rev after a run), water temp and injduty.

What should I monitor and what should my readings be?

thanks

david

Snook

iTrader: (12)

nm I have no clue why you are only boosting to 10psi
I didn't notice you have a high flow cat at first

ttpowerd

you should be able to boost 12 psi safely on stock injectors and fuel pump. After this I would upgrade. Of course every car is different. Just watch your inj duty and make sure you are tuned for that high of boost.

Mahjik

iTrader: (1)

I doubt that running 13 PSI is going to overwork your injectors. Your duty cycles may be high, but that's not necessarily bad, it just means that you don't have much room to increase performance without upgrading your fuel system.

I kind of agree with Wade in which as long as your injectors are flowing well, what harm is it with them staying on verses switching on/off.

ZeroBanger

I guess you misunderstood....

I can make my car bost 15 if i want. I have been keeping it at 10. I was running what appears to be 12-13 PSI on my boost gauge. My INJ Duty cycle hit 65.

My question is, is 65 bad? If my injectors are flowing fine while I am at 13 PSI, do I need to worry? Or are injectors only part of the things I need to be concerned about?

Maybe I am not clear. Thanks for you help!

david

es

I wouldn't worry about any duty cycle under 90%.

ZeroBanger

Ok, so to clarify, as long as my duty cycle is under 90 pct, the amount of boost I am running , knock level and other readings are not important?

Thanks!

David

amp

iTrader: (50)

are you noticing 65% inj under load @ 12-13psi ?

ZeroBanger

not sure, that was the Maximum stetting that the injectors hit. I was at 12+ psi at times. Its difficult to watch my boost gauge, the road and the power FC at same time! My maximum rpm was 5200.

amp

iTrader: (50)

i was in the upper 90s under full load at 10psi...

es

Woa! OK, your EVERYTHING is important. Boost, Inj duty, Exh temp, O2, RPM... Just because the inj duty is good that doesn't mean your safe. Too low of an inj duty could easily mean your running a lean tune & will detonate the motor.

Now, that being said. You need to run all the way to redline, because as the engine spins faster more air is moving through the engine, and the inj duty cycle is raised to maintain the optimal safe A/F ratio.

I thought 60's sounded low, now I know it's because you weren't taking the thing to redline.

ZeroBanger

so what is optimal on the injectory duty? Also, there is no way to check the exhaust temp through power fc, right?

thanks so much!

David

skunks

There is no way for you to tell what the exhaust gas temp. is from the PowerFC and even though there was a way, it would not be accurate. I suggest you don't use the stock O2 sensor for the A/F ratio, get on a dyno and use a wideband! Check Wade's site out for the injector duty cycle and staging rpms.

BTW: I think its anything under 85% duty cycle is safe.

Good luck

P.S. Wade's site is http://www.newwave.net/~flanham/wlanham/

You duty cycle does seem to fall with in the stock map setting for the PowerFC although this tells you nothing about the A/F ratio.

ZeroBanger

Thanks, I did they dyno about two weeks ago, they found the more I upped my boost the more rich my car ran. it was tuned by a rotary shop, I just want to know how much boost I can run!!!

I plan on using racing gas anyway and only running 13+ lbs at the track, so I hope it will be safe.

RecKleSs

You didn't look through the PFC manual very well did you?
With the Commander you can view the peak on all the settings. Take your car out and do the following steps.
1. Drive the car
2. Push the Up button on the Commander
3. You should notice that the screen looks frozen; none of the numbers are moving. At this point it shows you the peak on all the things that it monitors.
4. To clear it push the right button
5. It should look normal again.

To see your max inj duty cycle drive the car really hard. For example, put it in 3rd gear and floor it until redline. Now you can just put it into neutral and push up on the Commander. You should see the peak on all the functions. Most likely you will be around 80 to 90% @ 11 psi on your inj's. You can leave the screen to show the peak as long as you want. When you want to clear it and have it back to normal, push the right button.

These steps will help you and everyone else determine if you are at your peak on the inj.

Tip: Drive your FD at night, since the weather is colder, which will be safer for these test runs.

2. Increase the boost slowly. You don't want to run 13 psi the first time you do the test run.

3. Try to stay under 90% duty cycle.

4. Most likely your car will be safe under 14 psi, because your inj are stock.

ZeroBanger

Actually I read the manual. Its you that mis read my post! I said I have the peak settings, that 65 pct injector duty was my peak (by 5200 rpm) but I do appreciate your post. I will check this out. Im doing alot of drag racing and don't want to *** it up.

RX7Elmo

65 percent duty at even stock boost is way too low. My duty is around 80-85% at 10-11psi. If your peak duty really is 65%, i'd say somethign is wrong there. And i dont' understand how more boost means more rich?? It should be the other way around.

Also be careful testing the car at night. I have a front mount and at night, i can guarantee you the car runs considerably leaner at night, yet of course faster. I of course account for that on my ecu.

Danny

ZeroBanger

It does get more rich with more boost. My power FC was programmed to do that.

I don't know about the duty cycle I have not had chance to test it 100 pct yet.

RX7Elmo

I'm sorry i didn't clarify. What i meant is say that you have one fuel/timing map and you run it at 10psi. If you up the boost to say 13psi and use that same map, your mixture will be leaner. That is what i meant.

maxcooper

You need to run to redline under boost to get a duty cycle peak reading that people will be able to comment on. Duty cycle increases with RPM even if you are flowing the same amount of air and fuel in a given cycle because the cycle gets shorter.

You will flow more fuel under more boost because you'll be in a cell in the fuel map that has a higher injector pulse width. But it could actually be richer or leaner than at lower boost because the fuel requirements change. If they out-pace in the increase in the fuel map, you will be running leaner. If the increased requirements are less than the increase in fuel from the map, you will be running richer. It could run richer up to 12.9 psi and then all of a sudden run lean above 13 psi because they are all individual cells in the map (well, I am not sure exactly what the boudaries are, but you will move from cell to cell as the boost goes up or down, or RPM changes, etc.).

-Max