lawless

iTrader: (4)

My FD was recently (5K ago) rebuilt and was running great for a while. A few weeks ago it started having problems. I appeared to be electrical considering any wiring harness touched by the old owner was cold soldered and mangled. Slowly the car began intermittanly shutting down on one rotar. Once while driving, quickly came back on. Then the rest were on start up. We had trouble getting it to run on both rotars. Now, it only runs on one. I checked all of the electricals and fixed all of the crap the old owner had destroyed. The issue appears to be fuel. Fuel pressure is fine but it seems that the front primaries are not firing. Could this be a bad PFC or FJO? The signals seem ok. Is it normal for the ground to show 12V on the injectors? I know these peak and hold injectors open on something like a small amp signal. Has anyone ever seen anything like this? Im hoping its still electrical. Were going to do a compression check just in case. Any thoughts would be great.

Other questions:
Do spark plugs on rotaries simply stop firing or is there a chance that they wont fire under compression? Could the coils possibly appear to be firing but just weak and cause a weak spark or spark blow out?

I guess I just have an odd hunch that its not the fuel system. AFR's just show dead lean after start up so it appears to be not getting fuel. I just dont know if the wideband will register unburned fuel.

Is there a possiblity that my PFC could be bad? If we open it up, what should be looking for? How about a way to test it?

like I said, any input/guidance at this point would be fantastic. Thanks to all that reply

cptpain

iTrader: (1)

change plugs and wires
check ignition wiring
check coils

THEN check fuel system

Its very rare for a PFC to take a dump, but it has happened on rare occasions.


what are your mods?

juicyjosh

iTrader: (29)

lawless,

You might consider plugging in the stock ecu and looking for error codes. That would be the most logical next step, since the car itself will tell you what's wrong.

It's a slim possibility that the injector may be clogged, something that happened to me last year, but I only experienced that once within 6 years and 2 FDs. It's also a good idea to run a clean fuel filter.

It's highly unlikely that your Power FC failed, even with the bad wiring; it just doesn't happen. (It would have to be sent back to Japan to test it.)

Chad D.

iTrader: (2)

cptpain, is right.
my old fd did this.
easy fix, it is something you would do to further diagnose the car anyway imo, or like juicyjosh said, plug stock ecu in if you have it.
Hopefully is is not a "rare" problem. good luck.

lawless

iTrader: (4)

Its comforting to know that the PFC being bad is rare! The car has tons of mods. Here is a list of mods that matter when it comes to diagnosing the issue.

850 primaries, 1600 secondaries, FJO, Stainless lines, Supra pump, larger fuel rails.

Factory plug wires, coils, and new plugs now. HKS twin fire.

By passing the twin fire did nothing. Havent tried plugging in the factory ECU yet. Thats the next step. Signals look good to the injectors. All the crap from the injector harness was cut out. Could a bad crank angle sensor cause this? There was a wiring issue with that too. the wires were bare and grounding out. I suppose with the ECU plugged in, it should tell me everything thats wrong to include all the factory harness not being used cut out, such as all of the sensors that lay on top of the rotar housings for the vacuum system for the stock twins.

We're also going to pull the injectors out to see if they are clogged. Would fuel pressure still be at around 42 pounds with a bad fuel filter? That should destroy the fuel pressure. Ill post more after I plug in the factory ECU

lawless

iTrader: (4)

Ok so you australian guys obviously arent listening and for some reason, believe that everyone is an idiot. I have already replaced the plugs. EVERYTHING is working ignition wise for sure. It seems that the injectors are firing but one may be clogged. Less than 250 miles before this all began is when we did a compression check. Compression is still strong. Everything seems to be fine mechanically. Something is still wrong electronically.

Has anyone ever had their FJO injector driver go bad? We're getting 12V to the injectors and with a stethiscope (spelling?) we can hear the injectors firing but the car is still leaning way out like its getting no fuel. Could this be too much fuel that isnt atomizing like the injectors are "squirting" instead of spraying? (if that makes sence) I dont know if my wideband would register unburned fuel. I suppose it wouldn't so it would read as if it were not getting any.

Does that make sense? Or am I still an idiot that HAS to listen to you guys before I F something up seriously? Please, Im asking nicely and respectfully, dont treat everyone on here like they have no idea as to what they are doing. Im not very good at explaining things sometimes but I do know what im doing. I have been wreching and building cars for years. Not rotaries persay but many others, and every automobile is different which is why people specialize. This is my first rotary and I dont intend to break it. I intend to diagnose the issue before it turns into something worse as would I for any car... not just a rotary.

Back to the problems. I have not tried the factory ECU yet. I will grab my code reader and let you guys know what comes out of it... if it even runs on the factory ECU. lol

lawless

iTrader: (4)

Hey Mazda RE... YOU arent listening! SOMETHING else is the issue. Im WAY the **** ahead of what your are or have been trying to tell me to do! STOP ALREADY!!! Thanks but no thanks! Its hard enough for me to read what youre saying let alone deal with you treating me like a child! Everything I have been saying, you are now asking! Ill post again when I figure it out! Right now I have a regular job and have idiots to manage everyday!

snivley whiplash

iTrader: (4)

lawless,
now that you have new plugs installed, start it and run it for about one minute and pull the leading plugs and inspect them. if the plug is really wet it could be a open injector causinfg flooding on that rotor, if it is dry then I would look into injector clogging. you have been on the correct path to correct the problem and the injector pulce pattern is there, correct? Check the plugs for fuel sigh first. could just be injector problem that can be cured by notable injector repair shop.


hope this helps

lawless

iTrader: (4)

snivley whiplash... that is what we are working on now. We have gone over everything else. PFC seems to be good, FJO is good, twin fire is good, coils... new plugs and wires. All thats left is the injectors. The primaries are actually (according the previous owner) RC650s that rotary performance turned into 850s. I bet that those are the issue. One of those is clogged or something. Im going to check the fuel filter once more even though the fuel pressure is good, I just want to make sure there is no junk from the tank making its way through.

Ill post more if i find out anything else.

How would you recommend I test the actual spray of the injector? I can use a stethiscope to hear the injectors come on but I dont know if they are actually spraying. Thats where we are now. The plugs seem as if they are NOT getting fuel but the injectors are coming on. This is why we want to check the actual spray. Having not figured it out yet is making me worry.

lawless

iTrader: (4)

RE - We have had the manifold off many times correcting the wiring nightmare the previous owner made for us. We have corrected all of the wiring and cut out anything and everything not being used, ie, the factory connectors for all of the vacuum sensors for the stock twins. The area under the plenum has been rewired and everything is nice and pretty under there now. Electrically the ingition system and the fuel system are fixed. The next step is checking the injectors and having them flow tested. We should know more tomorrow. I will pull the plugs out and wind it over a few times to make sure no residual unburned fuel is in there. I think I have a set of 650s around in case my primaries are bad. I should be able to make it run right while my 850s are being rebuilt. Thanks for all of the help. Ill post more after tomorrow.

lawless

iTrader: (4)

Ok so its fuel for sure. When cranking with the injectors out, front primary does not fire. Front primary fires when plugged into the connector for rear primary. Conclusion... All injectors are fine. Here is the next issue:

FJO injector driver shows 12v on all connectors. We dont know how to measure the signal to actually fire the injectors. Electrically, we have everything fixed but is there a chance that the FJO has gone bad? It appears that the injector driver is not sending the signal to fire the other injector. Im sure grounding out some of the 12v hots on the injector driver fried it, or at least part of it. The electrical messes are fixed but we still have no signal firing primary front injector.

Any Ideas???

lawless

iTrader: (4)

So after more testing, the FJO injector driver has good input signals but the output signal on two injectors is bad. There is no output signal on half of the FJO. I guess its time for a new FJO. All the shorts that the previous owner created from horrid wiring caused the FJO to short out.

Anyone know where I can get a new FJO injector driver?

Nexxussian

I don't know where to get another FJO driver, especially here in town.

You mentioned getting the injectors flow tested, is there somewhere in town now that can do that?

bumpstart

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Type: sales and installation

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lawless

iTrader: (4)

yeah... everyone is out! We cant find one to save our lives!

bumpstart

consider lifting the cover off it and sniffing to find which darlington transistor is burned and raiding radio shack for another equiv and bridging any burned tracks

i have done similar with some earlier ECU's but it will all depend on if its darlington or IGBT driver and if there is an equiv still available

while it sounds daunting its actually fairly easy,, easier to an electronics service technician and usually only a handful of $$ to roll the dice if doing yourself

lawless

iTrader: (4)

Its a thought... I might give it a shot. We have rebuilt ECUs and other small boards before as well. Ill let you know what comes out of it. Meanwhile, if anyone knows someone that is parting out or selling theirs, Ill pay top dollar... reasonably. lol

lawless

iTrader: (4)

We did end up finding 6 FJO injector drivers. Been looking 24 hours a day. Full Blown Motorsports has 6, well now 5. I think these are the only ones in the entire US.

bumpstart

cool, fix

double check that wiring and establish what the cause was
potentially it could be a weak earth or insufficient cable that has been causing a heat issue
also think about twisting or shielding cables on the new install

it may pay to keep an eye out for those sorts of troubles

let us know how well that all goes for you

lawless

iTrader: (4)

Well the new FJO showed up today. Should be wiring it in today and hitting the key. As for the bad wiring... we have gone through the entire wiring harness now and fixed all of the bad grounds or any 12V hots grounding out. The wiring was a mess. Its crazy how bad it was. Ill let you guys know later if this solves it.

Attached is a picture of what the wiring looks like now. Everything red is all of the wiring the we had to fix. Red is the only color that we had. LOL! The turbo blanket is new as well. That should help keep the heat down.

Radial GT

iTrader: (16)

GASP!! Open intake runners!!

I also am dealing with a very chopped/very cooked wire harness. Yours looks great now. Hope you got it fixxed.

I thought we had short driving time in Minnesota with like 5 months of decent driving weather for sports cars. Alaska has got to be even shorter huh?

GoodfellaFD3S

iTrader: (213)

While youre in there, consider degreasing that engine bay, esp on the turbo side.

lawless

iTrader: (4)

The runners were left open only for the sake of taking a picture. There is much more wiring harness that we had to fix hidden further back as well as under the dash. Its pretty upsetting actually. It was a lot of work.

I dont have my 7 up here in Ak. Its in Texas. Hopefully if things go the way I want, I will be in florida with it for the next few years. I do have a modded speed3 up here though. Dry roads are fun in that thing!

The engine bay isnt as "greasy" as it appears. The factory color is red. Owner before me had it painted CW but only painted the bay with a raddle can. Thats where all that black comes from. The install after the rebuild scratched it all up. I will be doing the engine bay this coming winter. There is still much more that needs to be done first. Things like the oil filler neck didnt even have an O-ring so oil was spewing out everywhere. Ill post some pictures in a different thread of the rest of the build making the car "pretty".