Note: The FPR needs to have connected vacuum "on" to function properly. So check the vacuum lines and the controlling solenoid.

The FPR itself seldom fails, but it does happen. If the vacuum is "off" the FPR closes (at least partially) and this may cause your injectors to flood.

Also the fuel surge damper at the front (back?) of the injector rail has a little rubber plug that can disappear. Need to check that as well.

https://buyee.jp/item/yahoo/auction/...uggest_history

Version four harness. This might be a good investment., especially if yours is substantially missing. Expected landed cost to be as much as $150 more than bid amount.

It says Engine harness, but it is the Emissions Harness (but may also include the Engine Harness crank position sensors are there). The emoissions harness has a tail that goes back to the transmissoin for back-up light sensors, etc. Rare to have that tail still there (it usually gets sawed off.)

Condition looks very good. New are about $1500.

https://buyee.jp/item/yahoo/auction/...uggest_history

Buyee has a shipping restriction on it, but likely they will lift it. (If you hit the ask button)

https://buyee.jp/item/yahoo/auction/...uggest_history

Here is what a FPR looks like. You can get a vacuum test gun from the car part store. Apply vacuum it should open up.

(Shop manual actually has the Tech blowing on it.)

https://buyee.jp/item/yahoo/auction/...uggest_history

Version 4 MAP sensor. Always good to have a spare.

(Actually I grabbed this one just now.)

[It seems the seller in the above links "powergroup" is parting out a Version 4 at the moment. Powergroup is chain of car wreckers across Japan. They usually price items to move fast. So when a car comes in you might get a flurry of sales from that particular car.]

Thank you! This is alot of info but I always appreciate it. Going to take another look at vacuum lines and see if I can find something weird in there.
Would you recommend plugging in my PFC once I have the appropriate tune to see if I can see what sensor is malfunctioning?

https://buyee.jp/item/yahoo/auction/...uggest_history

This is likely the same as your ecu. Please refer to the pic of the innards. You want to see nice clean circuit boards. If your ecu is fried, it might smell burnt, even from the outside.

Sorry to bomb you with this stuff. It is just that this one seller has pics of a lot of Version 4 stuff to share.

Most of the ecu I have opened up appear very robust and clean, but sometimes the corrosion is obvious.

https://cimg8.ibsrv.net/gimg/www.rx7...3ea23d314b.jpg
Beauty. Look for popped capacitor tops, corroded circuits......

No worries! I honestly need all the help I can get. Banzai racing is the nearest shop, but it's a 2 hour drive and I need to trailer my car there and I want to try and fix this on my own first. 3 weeks in at the moment.

Check out the link to the powergroup YAJ site. Sort by "Mazda rx7 rx-7 Fd3s". It is instructive on the costs of items you may need. (Such as injectors.)

Do you recommend I swap in my power fc to see if I can get readings from the sensors?

Please note that a PowerFC intended for Version 1-3 FDs is not readily compatible with Version 4-6 FDs. Most of the wiring can be converted over pin-for-pin and V4+ sensors are largely the same as V1-3 in terms of electrical measurements, but a few things like the Fan Control System is where the waters get a bit murky. Also, you can bring up live data on the PowerFC's Commander handheld controller.

Before you condemn the ECU, can you give us a recap of what the current issue(s) are? The grounds you showed in pictures recently don't look exactly great, but they don't look like the trailer harness on my Expedition before I rebuilt it. To make a long story short, only the insulation was left in a few wires and the actual copper poured out as a blue powder.

Corrosion is starting to set in as it is exposed bare copper. It might skew readings a bit (higher than normal resistance to ground, so voltage goes UP), but I don't think it would just "nope" out entirely. Of course, resistance measurements will verify what's going on either way.

You have checked codes and should be able to trust the results.

If , like I suspect, a lot of the system has been removed, you need to address what you are going to do before plugging in a power FC.

There are specific power FC for each version so you have to match. Also, I believe Apexi may have updated the various power FC across the various versions.

Note Versions 1~3 of the stock ecu were 8 bit and subsequent ecu were 16 bit.

There is, I am told ,a power FC support group you can join by subscription. They can give you all the guidance you need and even show how to hook up the power FC to a laptop. They provide (or sell) software that automatically tunes your power FC to your particular set-up (or lack thereof, haha).. I have not gone that far yet, but it is likely worth looking into.

New power FC are not cheap. Used one's may have problems. Probably good ones turn up for about $800.

Google Apexi Power FC and find their site. They should list which of their models match which version of FD.

Be mindful that checking vacuum lines often results in solenoid nipples breaking off (particularly the green twin solenoid). So you need to have a plan to replace broken solenoids.

Likewise if you still have a rat box, a broken nipple on a rat box is a sad thing.

Use a a pike to loosen the hose tip, a proper hose puller and some dish soap (or liquid wrench). Twist the hose off gently.

But before that , listen to hear any vacuum leaks.

Another alternative is to have a shop do a smoke test. They hook up a device to your air intakes and pump in smoke. Any system leaks will hopefully show up.

(They will.)

I bought in this Version 4 harness tonight. This is substantially what your complete emissions harness should look like. The clump of connectors in the middle (orange, Blue, green, white, etc.) hook up to the rat box as marked by the colour coded dots.

If they are not there, they may have been deleted.

https://cimg5.ibsrv.net/gimg/www.rx7...c09cf57fa6.jpg
Version 4 Emissions Harness (possibly with subharnesses).

Work around your vacuum hoses very carefully. Sitting on light cover not recommended.

https://cimg1.ibsrv.net/gimg/www.rx7...b5551add89.jpg


Rat Box "in situ" with harness hooked up.
https://cimg6.ibsrv.net/gimg/www.rx7...553bd6956e.jpg

I'll go through the vacuum lines one more time, and I do have photos of me in the engine bay haha but I'm mainly kneel on the core support.
I appreciate all the help in getting my car on the road.
Could you link where you found the manual for the version 4, I can't seem to get anything when I search for it.

With a Version 4 (Series 7) FD, you'll not only need the 12/1995 Maintenance Supplement and Wiring Diagram Supplement, but all previous manuals too. Look closely in the pics Redbul posted and you'll see what he is using is a combined PDF that's nearly 4000 pages long and none of it is in English or searchable. Cue up Megalovania from Undertale, you're gonna have a bad time.

If it's the one I'm thinking of, it's also locked with two passwords. Took me a few days to crack it and split it back into the original books. Makes it a bit more human-compatible that way. This is one time where making the homework as easy as possible should be priority #1.

If all else fails, I'm ~5hrs away in St Louis. I may have some time starting tomorrow, once I get this Japanese VIN Database sorted out. Sifting through 50,000+ VIN numbers to get production numbers, fun times...:lol:

Watch out for manual download sites with Russian URL. You may get what you want, but they may get what you have,

The "laujesse" pdf is searchable, alright, one page at a time.

Btw: I am getting back from a friend a Version 4 ecu.

The "laujesse" pdf.

https://cimg2.ibsrv.net/gimg/www.rx7...ddf0ed687e.jpg

https://cimg7.ibsrv.net/gimg/www.rx7...fb1467b578.png

For the lower lines, how do I reach them? Remove the under tray and jack the vehicle up?

Nope. The diagram is not to scale or reflective of the actual instalation. Most of the stuff, if it is still there, is tucked under the UIM or can be accessed by removing the upper air pipes, or both.

Have a new Uim/LIM gasket (about $16) ready for when you lift off the UIM.

If you still have the twin (green) solenoid mounted to the front of the UIM, remove it carefully, without (at first) attempting to disconnet the four vacuum lines sproutlng from it.

If, and when, you do remove those vacuum lines, make sure to mark the locations well.

Having said all that, there are a few things you might have to access from below.

https://cdnyauction.buyee.jp/images....pbrtg35133.jpg

This is a fantastic resource. They often get bid up to $800.

It is a bit used, but then you won't mind using it.

Cornerstone of any manual collection.

https://buyee.jp/item/yahoo/auction/...uggest_history

Buy as a curiousity just to study it. Or to harvest the good solenoids.

This seller has about 10 for sale.

If I could spare the money, I'd grab it and put together a guide for rebuilding them.

Or you could translate the section out of the change manual. It seems pretty detailed.

The parts catalogue seems much better than the FSM for showing the proper scale and location of the vacuum hoses.
https://cimg5.ibsrv.net/gimg/www.rx7...1e96e270bf.jpg


Catalogue AJFA06-00

Ya know, I kinda like some downtime between projects. Especially after datamining the ENTIRE production run from September 1985 to August 2002 :nod:

83925 FCs + 52505 FDs = Data for 136,430 vehicles.