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-   -   Power FC pfc with different injectors (https://www.rx7club.com/power-fc-forum-47/pfc-different-injectors-928411/)

stocky 10-27-10 12:02 PM

pfc with different injectors
 
after some advice ive got high impedance 850cc in the primary rail and low impedance 1590cc in the seconadry rail what do i need to do anything to the wiring for this to work properly as with the two pairs being difference resistances?
If so can someone go through what needs to be done or does anyone have a link?:scratch:

cewrx7r1 10-27-10 03:53 PM

If your 850s are stock, get rid of them as they are crap to tune.
Read other current thread on obsolete injetors.

For your secondaries; use a 3 ohm resistor in each one's circuit for 100% safety, or go down to 1 ohm for 99% safety, or use a FJO driver for best results.

blue87 10-27-10 09:37 PM

I agree the 850's aren't ideal, but they are a good stepping stone price wise until you can afford some more linear / controlable injectors. I am currently running 4 x 850's and it idles pig rich, but driveability is good and A/F control is not bad either. Like i said not ideal, but until you can afford a full set of ID's, rails, and FRP they are not a bad place to start...

stocky 10-28-10 02:52 AM

I've got a rising rate fpr and a kg parts secondary rail
for the resistors can they go in the engine bay just before the injector plug orwould they have to be traced back to inside the car?
I was Reading the obsolete injectors so at a later date i'll upgrade the primary rail and injectors

Banzai-Racing 10-28-10 05:38 AM

You can solder them in at the injector or the ECU. I prefer to install them at the ECU, this keeps them away from the heat and vibration of the engine bay.

The secondaries are wires 4X & 4Z

I have no problems achieving 13.0:1 AFR at 800-850rpm idle with the stock 850cc injectors in the primaries. The mechanical TB adjustments simply need to be set up properly

blue87 10-28-10 12:34 PM

Banzai are you able to achieve 13 to 1 with a pfc or are you using another ecm?

Banzai-Racing 10-28-10 02:46 PM

With the PFC, this is the PFC section after all. I can actually get it to 14-15 AFR, but obviously the car will not idle properly that lean. I never use negative lags either.

blue87 10-28-10 03:56 PM

That is good to know... Just purchased my fd this summer but haven't had the time to really give it tuning optimization yet just been fixing hardware things and made the tune a little more conservative here and there for safety. I never even bothered to look at the idle assuming it was a lost cause. I am running about 11:1 at idle now and targeted that for my cold ambient starts but I will look into my warm idle conditions more to clean her up a bit...

cewrx7r1 10-29-10 12:18 AM

Most engines that Kyle and I have tuned with 850 primaries had to use negative lag to lean them out using a base fuel pressure of 40PSI no matter what we did with timing or air.

Banzai-Racing 10-29-10 05:01 AM

It can't all be done from the laptop, you have to get into the engine bay and set up the TB properly. I use a base pressure of 40psi as well.

We have dozens and dozens of customers with 850 primaries all running perfect AFR's, I will take some video of the wideband and commander on the next car I set up and tune.

stocky 10-30-10 08:08 AM

ive just picked up a pair of resistors there 10w 3.3 ohms will they be the right ones i need?
the only 10w ones were 1ohm, 2.2ohm, 3.3ohm or higher

cewrx7r1 10-30-10 10:05 AM


Originally Posted by stocky (Post 10294857)
ive just picked up a pair of resistors there 10w 3.3 ohms will they be the right ones i need?
the only 10w ones were 1ohm, 2.2ohm, 3.3ohm or higher

They all will work, 2 or 3 are safer.


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