? for duty cycle and PFS PMS
 

Can we just upgrade to bigger injectors? Is the computer compatible with them?

Logic tells me that the computer will just add the fuel, and the duty cycles will read lower, true? I am not sure where the computer gets the duty cycle info and if it is stock injector size dependent, know what I mean?
So will the reading still be accurate with bigger injectors?
And can we stay with the PMS and just upgrade the injectors?

Thanks guys,

Raj

You can add bigger injectors but getting to run correct is much harder. Anyhow if you have stock turbos the stock injectors are plenty. I made 354rwhp on stock fuel system.

Raj was actually asking for me. I'm planning on adding 1300cc secondaries and leave the stock 550 primaries. We were both wondering if the duty cycle was going to read correct on the larger secondaries. I know we can swap them out, but the questions is if it will read right.

Yeah the duty cylcle will read correct. You will be taking fuel out when you do the 1300cc injectors on the PMC unit.

This question was in regard to FDREY who will be upgrading his injectors on this computer soon.

My question about the injector duty has been answered, and I THINK.....Huffner = DontBeARikki...

Thanks for the answers Huffner.

Raj

From my understanding the problem with increasing the size of the secondaries is that the PMS is unable to change the rate a t which the secondaries come on line and so its hard to tune at the RPM/load cells that that is happening. Is that correct?
Mark

Yes, I have heard the same. The larger secondaries are way too hard to tune using our computer. I will let FDRey know....


but who hear has run larger secondaries with the PMS and tuned it correctly? What did the tuning entail?

Raj

I have 1300 secondaries and have had significant problems due to this (I believe) at about 3200 - 3700 RPM at part throttle. When I datalog my O2 voltage can drop to 0(!) before bouncing back up. Since it occurred around where the 3K stumble point I have grounded the bejezus out of the car - uim, ecu, downpipe, cat-back, alternator, battery - no change. The TPS has been adjusted to spec. I added fuel to the cells that appear lean without change. I spoke to Carlos Iglesias and he suggested that I might be way too rich and fooling the O2 sensor so as soon as I have a day off I will get half a tank of race gas, grit my teeth, lean the offending cells out and hope I get a smooth transition and not a POP!
Mark

Volunteering to be the gineapig, heh? More power to ya.

Mark, try running it with your O2 sensor disconnected on one of your runs. I think all these cars stumble at that rpm range when the O2 and PMS are hooked up. But, you have to rely on some other air/fuel guage.

Raj

I will try that in the AM. I was always leery of doing that but the result can't be any worse than what appears to happen when I run with the O2 sensor. I will be buying a wbo2 anyways. The issue is that EFI makes one now and Doug told me that there would be a patch to allow it to be datalogged on the interacq software but its at least $100 more than the tech edge. Decisions, decisions.
Mark

Just in case any other PMS users out there are considering using the EFI UEGO, the price is $549 and Doug said that the upgrade is not a given b/c they haven't figured out how to do it without a chip upgrade. They probably won't upgrade the chip since they no longer support the PMS. Oh well. Tech Edge here I come.
Mark

Well, I've decided to go with a Microtech, and get rid of the PMS. I sat down and looked at what I wanted out of my car (11 second daily driven street car), and decided that the PMS was not an option. So if anyone knows someone that might buy it off my hands please pm me.