keffinrx7

Hi all,

I have a really tough one that I can't get figured out. I posted on the general tech forum with no luck and have narrowed it down to what I think is the PFC not sending a spark signal to the ignitor. I have spent weeks trying to get a spark with no success. Was running great when I bought it, I go to clean and secure some things under the intake and replace the fuel lines and now no spark. After reading tons of threads and the entire service manual some of the telling symptoms are NO TACH MOVEMENT during crank, fans usually turn on with ignition, engine will crank fine with good compression and fuel. No spark!

List of relevant upgrades:
PFC PFC3S2 (missing the commander which I just ordered - hopefully helps me here)
Recent rebuild with streetport
Sequential turbos converted to non-sequential
Automatic transmission converted to manual

What I've tried so far:
Checked all fuses a thousand times
It's not just a flooding issue
replaced spark plugs
Checked power/ignition to PFC
Replaced coils and pigtail to coils
Replaced CAS - has good continuity to the ECU
Tested every connection I can think of - all good
Checked power to igniter
Replaced igniter

Any and all help will be much appreciated before I take it to a shop! I have a hard time finding info on how to test certain things (ex. Power to the coils, how to test the pulse coming from the CAS, where exactly the tach gets its pulse from and why it won't bump during start, etc.).

I think they are on to something here but no conclusion at the end of the thread.

Thx a ton for reading,
Kevin

keffinrx7

Ok I went out and purchased a brand new universal OLED Commander for my PFC, plug it in and it is saying "communication error." Do I have a bad PFC now?

Kevin

Banzai-Racing

iTrader: (11)

Sounds like you left the grounds loose on the engine.

cewrx7r1

iTrader: (2)

Normally if all is working well, and then you did maintenance or mods: and now it does not work.
It is operator error!

You need to go over all the work areas you messed with.

keffinrx7

I double checked my work and grounds 10+ times, had a mechanic come out and do the same - no change. I took it into a shop yesterday so we will see. You're right usually it is the simplest thing, I will reply what it is when/if they figure it out!

My guess is the engine/emissions harness that plugs into the ECU is bad...

keffinrx7

Update: The shop that is woking on it here in CO ar design - fabrication perfected home page Thinks it is either the engine wiring harness or the ECU itself. Since the PFC powers up and the commander just shows "communication error" I agree that it must be the harness. So I am about to purchase an aftermarket harness here: http://www.rywire.com/product-p/13b-milspec.htm. This harness looks much more simplified and eliminates all the connections that can go awry for all the unnecessary emissions solenoids.

Does this sound like a good idea or does anyone have experience with these aftermarket harnesses? My concerns are that it I will buy one for a manual transmission but it's plugging into a car that was originally an auto (now converted to MT). What are your thoughts - the harness is non-refundable???

Thank you,
Kevin

keffinrx7

Additionally does anyone know if this harness Mil-spec Tucked 13B Harness (FD3S/Rx7) can be utilized for a non-sequentional setup (factory turbos). They are telling me it is made for a single turbo conversion so just want to be sure it will have the connections to run both factory turbos still...

Thank you,
Kevin

cewrx7r1

iTrader: (2)

How old is the harness? The original harnesses became junk after about 7-10 years if you lived in the hot states. That is why some shops require a new harness on engine rebuilds. That happened to mine and a few cars I have worked on.

My new harness from 1999 is still in good condition today when compared to the original one from 92 when replaced in 1999. 15 years as compared to 7 years.

keffinrx7

The existing harness is in pretty bad shape, I hope swapping to this will fix my problem. RyWire is telling me that the above harness if for single turbo applications, however mine has the factory turbos and have been through the non-sequential conversion. I can't seem to figure out how the turbos kick on if both the turbo pre-control and turbo control solenoids have been eliminated with this conversion. Anyone know as the above harness only has one turbo control. Having a hard time wrapping my head around this one...

Thx,
Kevin

lOOkatme

iTrader: (19)

I have a rywire harness on my single turbo car. The harness is a good harness and I haven't had any problems with mine.

The non-seq shouldn't need anything driving the turbo's to come on? The turbo's should be active based off the wastegate being closed and exhaust flow. I had non-seq turbo's on mine and that is how they worked on mine.

Most of the solenoids from my understanding are vacuum driven, not harness driven but I am single turbo and I never had a sequential turbo system.

The one downside to the rywire harness is you lose your IAC wire, so you have to operate without it.

If you need someone to tune your car, let me know.

keffinrx7

Thanks lOOkatme, that is helpful. The problem I ran into with the RyWire harness is you have to tell them that your car was an AT to MT conversion, then they will build the harness accordingly. There is one connector that plugs into the dash harness that is specific to AT FD's. So after figuring this out I have to ship them back their harness with my original OEM harness and they are going to rebuild it for me - hopefully no charge.

I did notice when it ran that it had a fluctuating idle and I think the IAC valve has been removed/capped anyway. Is there a fix to the fluctuating idle? I would be interested in a tune during the spring and it's good to see you are from CO too. I was going to wait for the Rotary Performance guy from TX to come up to the Man Cave this spring as I hear he is an amazing tuner but...

keffinrx7

Update: We have replaced the engine harness with the custom one from RyWire - which is a fantastic harness BTW. Not only is it much higher quality and labeled at every end they were able to customize it for me to plug into my AT dash harness & still plug into the PFC & MT plugs (you must tell them this and ship them your old OEM harness in order for them to modify in this fashion). The only modification we had to do was loop the neutral swtich wiring in the dash harness so the car would crank (or of course hook the correct wire up to the clutch switch if you want to do it right). I am also hoping this makes my reverse lights work too - but yet to find out. I would highly recommend this harness for a car that has an AT to MT conversion and either a single turbo setup or the factory non-sequential modification.

That being said I STILL HAVE NO SPARK!!! The Commander on my PFC still shows "communication error" and all the same symptoms as before. I am going to borrow a working PFC from a friend and see if that is the issue...

Kevin

Johnny Kommavongsa

iTrader: (13)

sucks that the harness didnt fix your issue. My guess is you have a bad ecu.

tt7hvn

iTrader: (5)

I'll put my .02 cents in: The stock FD grounding scheme is garbage; it's just insufficient.

I'd install more grounds. A larger gauge from the battery direct to chassis instead of how the stock wiring is ran. And install more grounds from the engine to chassis. Also apply dielectric grease to your grounding points.

I was having a couple of electrical issues and no kidding, doing these little things, cured them all.

keffinrx7

Ok we figured it out - it was the ECU. I must have blown it when attempting to clean and repair the engine harness. So after replacing the engine harness and the PFC I now have it up and running again. For future reference always disconnect the battery when doing electronic repairs - DUH!! - $2000 lesson.

Good news is the engine harness needed replacing anyway & I have an extra commander and a newer model PFC. Now to get it tunned again.

Thx,
Kevin

lOOkatme

iTrader: (19)

I tune powerFC's and am located in CO. I do street tuning.

PM if interested.