Hi all!
I am experiencing a random misfiring and loss of power mostly after downshift/deceleration. Once it starts misfiring, pressing the throttle will increase boost and injector duty on power fc commander, afr will go up, but rpm won't go up. After coming to a stop, the rpm will struggle at 100 rpm, and it will stall if I give it throttle. I was able to restart the car and everything went back to normal. The last time I tried it, I let it idle for 10-20 seconds to see if it will recover, and it did not and stalled after I pressed the throttle. I smelled something burning and opened the hood, and I could hear hissing sound and white smoke coming from underneath the intake manifold. I didn't see any leaking fluid or anything burning, just white smoke with burning rubber/plastic smell. The hissing sound and smoke went away after a while, and the car was running normal again after restarting the car.

The car has a brand new engine recently installed, bnr stage 1 turbo, new vaccum hoses/spark plugs/ignition coils/gaskets etc.
Recent work includes pwr intercooler, autoexe intake, power fc, wideband sensor, walbro fuel pump.

I noticed the symptom after the power fc install, though I didn't drive the car for more than 20 minutes before the install due to overboosting caused by the upgraded turbo, so I am not certain when it started.

I have checked TPS voltage and dashpot, and they seem to be working fine.


Update: I plug the stock ecu back in, drove for almost 2 hours, everything runs smoothly and normal. I checked the error code also and there is none. It's the power fc guys. Gotta check on the white smoke and hissing issue though.

 

not going to be an easy solution as everything you have described is all over the place. are you certain the power fc is good? if it is then i would say everything needs to come apart and checked again. injectors could also be a contributor but really, a lot is on the table. i would start with confirming the power fc is good as sometimes they go bad and cause all sorts of running issues. no smoke or burning smells lol but have to start somewhere.

 

White smoke is usually a sign of leaking coolant. How that relates to your stalling/misfire issues, I don't know. Have you had any coolant loss?

 

So, you have recently done A LOT of work on the car. The first thing I would suspect is human error while reinstalling everything.
There are literally hundreds of possible points of failure.

Did the problem actually start with the Power FC install, or did you only first notice it after installing it?

Did or will the car drive normally with the stock ECU? (assuming you are able to keep AFRs in a safe range)

Hissing and smoke means something is probably broken or not installed properly...

 

Power fc is brand new from Japan

 

No coolant loss. Smoke doesn’t smell sweet, smells like burning rubber.

 

let me swap back to stock ecu and check. It’s weird because it didn’t happen with the stock ecu

 

Did you cut the four wires on the harness when installing the PFC? This is a CYM right? US Spec car?

 

Yes it is. I depinned the 4 wires following dale clerks guide

 

I plugged the stock ecu back in, drove for almost 2 hours, everything runs smoothly and normal. I checked the error code also and there is none. It's the power fc guys. The base map on the power fc is freaking out intermittently with the mods I have I think. Gotta check on the white smoke and hissing issue though.

 

I take it you put the harness back to normal?
I would check to make sure it's not just an electrical issue caused by the harness mod.
The most likely culprit is some sort of short-circuit melting your harness....

I woudn't rush to blame the base map.

 

If it runs perfectly on a stock ecu, it will run fine on a stock pfc. I'm not sure what the correlation is here as to why you have what you have but something doesn't add up. You have the opposite of what is supposed to be the case here

 

Yep, I put everything back to normal.

I did the harness mod following DaleClark's guide, depinned the 4 connectors and put electrical tape around it. The chances of short-circuiting is low.

 

Yeah, it's weird.

I did find that the nagative battery terminal was too small, and the negative battery terminal was not attaching securely. But I don't think that's the issue.. I did not lose electrical power at the time.

 

I took some pics of the connector before I put them back in. Everything looks correct to me😓

 

My assumption was that something was shorting out in the engine bay.
I guess pulling wires on this side of the harness shouldn't cause a short, even if you unplugged the wrong thing.

Go ahead and try the PFC again and see if maybe it wasn't some weird fluke...or at least find out what the smoke is coming from!

 

Is it the correct version PFC?

Someone was having a difficult to explain issue, and it turned out PFC was receiving a faulty signal from one of the water temperature sensors.

Replacing the sensor fixed it.

I suppose the coolant feed to the throttle body has been deleted? If not, the hoses may be a source of coolant around the UIM.

On my rebuild someone forgot to tighten the worm (yes worm) clamps on those hoses.

Coolant was spraying everywhere.

 

Here’s a video of the smoke and hissing. I am planning to bring the car back to my builder after the new year to trouble shoot together for the white smoke and hissing. It only happened once, without any visible liquid leaks.. really hard for me to pinpoint.

 

nope, throttle body coolant line is still there. No sign of liquid leaks though. Maybe vaporized? But my water temp was around 90 ish at the time.
Yea

I do think I have the correct power fc version. It also has a new serial number that starts with FD3S7, which did not exist when Dale last updated his guide.

 

My understanding is that there may have been a second and a third update of the original pfc for each series, and that only the third updates were now available.

 

That video shows the coolant line to the back of the TB. There is also a brass "T" connector, that is not part of the OEM, but may have a reason to be there.

( I see worm clamps!)

Could that "T" be there as a source for a coolant temperature gauge?

 

That’s for the coolant temp sensor for aftermarket water temp gauge. I checked the connection and it was not leaking.


Yeah the worm clamp is not ideal, might consider changing that during the next coolant flush.

 

https://www.rx7club.com/power-fc-for...aster-1167351/

 

I had considered this, but the 8 bit and 16 bit plugs are totally different.

 

This video is almost totally useless, but I think it’s strange that the little tail of Teflon tape on your coolant line fitting is flapping like there’s something blowing on it. Your e-fan should not be blowing on that part of the engine.