I pulled off the UIM the other day to install the SakeBomb ignition upgrade and update the rats nest with new silicone — and then I saw fuel pooling on top of the block — pretty bad. Anyway, I plan to pull the injectors and inspect everything (regulator and dampener). I am curious where you guys are sending off injectors to be refurbished or where people recommend to get new injectors. The only place I have seen that sells the stock replacements is Atkins (pretty expensive). I plan on keeping the car mostly stock so I have no need for larger injectors — but happy to hear thoughts otherwise. I have been running a Power FC since 2004 with just a base map on it. The car is mostly stock. Any advice or direction will be super appreciated.

 

An injector upgrade can be justified as preventative maintenance. With the power fc, you can go simplified sequential and make space for top feed rails. 1050 primary and 1300 secondaries is all you would need for what you want. If you're taking it apart, full send. Only use injector dynamics

Dale Clark has had some not so great experience with trying to refurbish stock injectors. Hopefully he chimes in. My vote is for swapping it out. Take advantage of the non stock ecu.

 

I would not recommend larger injectors if keeping the PFC. You can get it to work but depending on the sizing you will have issues idling (PFC min pulse width) and the injector transition (uneven fueling between pri/sec runner). It definitely can work, but without a modern ECU there are drawbacks. I would lean towards getting refurbished or new injectors stock injectors if you don't plan to do a bunch of other work. Especially if you don't want to dive deep into tuning and tweaking the PFC yourself. Its more or less an unlocked stock ECU, so functionality is limited. It suits best for lightly modified cars and I would draw the line at different injectors.

 

Thank you for the advice. I am heavily leaning towards stock injectors and torn between having mine refurbished or buying new. I will know more once I have the time to go back and pull everything off to inspect it and see where the leak is actually coming from.

I also need to do the research on what else I should change while I am there (diffusers, o-rings, etc…). It would be awesome if a company sold a kit to update/rebuild the fuel system.

 

none of this is true. Not a word. The only agreeable part is the power fc being an unlocked stock ecu.

 

Pull the UIM off and keep the fuel system intact. Then run the fuel pump through the diagnostic connector to see if you can spot it. As far as the injectors. I think it really depends on the mileage. I've had great luck having them cleaned when they are under 90K miles. I have not had any cleaned with higher mileage but I have not had any failures on the sets that I have had cleaned over the past 20 years. There have been a few cases where people have had injectors rebuilt and thought they would "stick open" only for me to tear into it and find harness damage causing them to stick open so inspect your connectors and harness very well while you are in there. No doubt its going to be crunchy. If it looks like somebody has been in there and you see physical damage, then you may also want to consider new since you don't know what has been done in the past.

 

Fuel pooling is probably the Fuel Pulsation Dampener. Get the kit from Ray Crowe.

Send the injectors out to RC Fuel Injection for a cleaning and rebuild.

 

Might want to also change the fuel filter as well.

 

Not trying to sound rude, but…. WHAT? 🤣🤣🤣🤣

 

Minimum injector pulse width on a PFC is 1.8ms, not small by any means. On injectors larger than the stock 550cc, you will be forced to raise the idle and it will still be richer than it should. 700CCs will idle around ~11.0 AFR (with fuel pump relay). For the injector transition point you only have two points to modify, the high transition point and the minimum secondary injector pulse width. You cannot control primary and secondary injectors individually. PFC will just divide fuel map value across the two injectors depending on the hysteresis transition point. You absolutely can get larger injectors to work with a PFC, but there are compromises with the control due to the 90's hardware. Its an inherently compromised setup, and if you don't need the extra fueling it is not worth spending the extra money.

 

While the means of implementation may be true, the actual results you state are in fact not. You do not have a grasp of how to use a power fc. This is actual misinformation. Do not assert such information any further to anyone ever please.

Without a great deal of effort, you can get an all stock car to run better on a power fc than the stock ecu to include a perfect transition in both boost and fueling. The same can be said for a lot of other set ups as well.

The power fc will work and has worked great for many years and Mr. Borg has only brought it to newer heights. This ecu will be relevant so long as there are FDs on the road.

 

I dont know where you are getting your information from but thats very inaccurate

for over a decade i was running 725/2000s and my idle at 12.5afr and 900 rpm did not skip a beat. I updated my whole system so took everything off my car, installed everything on another fd, it still runs exactly the same to this day.

on an AP engineering pfc for the FC. I have put together the same injector setup with a similar turbo and its been running perfectly for 15 years

 

I'm not a PowerFC expert, but I've heard other people say that the new software (FC Tweak or PFC Master) from Xavier Borg has helped with drivability and fuel tuning on bigger injectors. I think there must be good reasons side-feed injectors never caught on. Cars designed before the RX7 used top-feed injectors, and cars designed after the RX7 used top-feed injectors. When other communities like Toyota or Nissan owners modify cars that originally had side-feed injectors, they switch them out for top-feed injectors also.

 

Side feeds are more compact and of course have some serviceability and functionality drawbacks. Give and take I guess 🤔

 

Is Ryan is back?

 

Thanks everyone for all of the advice. I really appreciate it. I had some time to do a little more on the project yesterday. I took out the rats nest and exposed both rails. I did not see a smoking gun per se but the dampener does look cleaner than the rest of the system which could indicate leaking. The pic below is from yesterday. My plan as of right now is to order new pulsation dampener, regulator, new diffusers for the primaries (may as well while I am in here) and replace all the fuel hoses. Any recommendations or thoughts on anything else while I am here? I am tempted to delete some emission stuff while I am in here but concerned that may have some unintended consequences. My interest in deleting emission is really just to simplify and cleanup.

 

Do not replace the damper. Delete it. There are threads here on how to do it. A new one is needlessly expensive and serves no discernable function just like the AST.

You can delete everything that has nothing to do with the sequential system with no consequences. You will use the simplified sequential diagram in the thread with the vacuum diagrams.

Get your injectors serviced if you are not going to upgrade your fuel system. You are as close to them as you will ever be. InjectorsRX or boostlab will be able to handle it.

 

Thanks man — I will search the forum for the dampener delete. It is expensive and I am interested in simplifying as mush as possible while still enjoying the sequential set up.

and thanks for the recommendations on servicing the injectors. I checked out both businesses and will go with Boostlab. I went ahead and filled out the work request and will put my injectors in the mail this week. Fingers crossed they clean up and flow well again.

While they are out of the car, I will see what emission components I can take off. They look easy enough to take off and cap — any concerns with the computer throwing codes?

 

Power fc doesn't have trouble codes. Follow the simplified sequential diagram and delete everything that doesn't have to do with the sequential operation if sequential is what you desire.

 

Update — I took the fuel rails off and took the injectors out. The secondaries and the secondary rail looked great. The primary injectors looked okay but the primary rail was really nasty, especially on one of the inlets. I am sending the injectors to Boost Lab this week to have them cleaned and flow-tested. Pics below.

Secondary rail. Nice and clean.

Set looks good. Sending off in the mail to have them cleaned and flow-tested.

Both holes for the primaries were more dirty than the holes for the secondaries.

The primaries again. Not sure why the hole on the left is so gross.

 

Looks like the injector seals were bad. That could also explain the fuel on top of the motor. The whole engine in general and all components look like they have been getting a slight mist of liquid and dirt/dust is sticking to everything. I would clean everything very well while you have it exposed. It is much easier to trace leaks if you start clean.

 

I have a box of FD (I believe) injectors. How do I tell which ones are FD stock injectors? Any ideas? I'm building up an engine.

 

my stock injectors have “Denso” written on the side on the upper plastic portion. I hope this helps. Pic below.

 

For those that are interested, I sent the injectors off and received this report from Boost Lab. I am actually impressed the injectors performed so well, given their age. Plus, it is peace of mind to know they do not leak and deliver the fuel I need for my application. I should get them back in the mail next week and be able to start putting it all back together. While the car is apart, I will also start on the simplified sequential journey to simplify as much as I can.

 

So I tested these injectors with a 9v battery to see if they still ‘click’ meaning they aren’t stuck. They were cleaned a while ago. I’m told the solvent used can make them sticky. Besides slamming them on a 2x4, what else could I do to ‘unstick’ them. 3 out of 4 don’t click.