What can cause a car to run poorly and blow black smoke even at idle and hit a wall at 3500-4000 rpms even out of gear?

Bad MAP sensor? Temp sensors? Throttle sensor? Bad ECU? Power FC settings? Too much fuel pressure? Not enough fuel?

 

Lots of things. What have you checked so far? You've posted a lot of threads so it's obvious you've been chasing something but go ahead and consolidate everything you've checked so we can figure out what you haven't checked yet.

Matt

 

First if you have a powerfc commander pull up the sensor check screen and see if anything is highlighted.

not completely the same but I had an issue hitting a wall and blowing black under light load, ended up being the ignitor.

 

I'm gonna have to borrow or buy a commander but I was hoping to get the car running before I spent too much more money on it.

The ignitor and not the coils?

 

Engine:
-I get loud compression pulses all around and it starts easily as long as the plugs are new and the engine isn't flooded. I get black smoke (probably a mix of oil and fuel) and the engine tends to shut itself off after about 5-10 minutes due to the plugs getting fouled with fuel/oil. It won't rev past 4000.

-At first it seemed like only one rotor was firing but now it seems both are, but it still won't rev past 4000 and probably won't make enough power to even drive.

-Vacuum numbers at idle are very low.


Fuel:
-Fuel tank was probably near empty before I added 30L of 100 octane.

-I switched out the primary injectors to known good ones to make sure one wasn't clogged.

-I pulled the rails and checked that the primary injectors were spraying fuel (they were). I hooked up one of the primary connectors to the rear secondary injector just to be sure it wasn't clogged. The harness is too short to do this with the front primary.

-I confirmed the colors of the injector/sensor wires to make sure they weren't in the wrong place. I pulled the pump to make sure the tank wasn't rusted. I also confirmed it was running. I also pull the return line to make sure fuel was flowing (it was).

Ignition:
-I bought new wires (old ones were out of spec) but I can't say it really helped that much. New plugs will start the engine almost immediately but get fouled quickly.

-I borrowed some coils and ignition harness. The coils were out of order for some reason (they were the same order as a Zenki FD [T1 L T2] instead of the order of Chuuki FD [T1 T2 L]). Fixed that and confirmed the wiring was OK, but it still won't drive right.

Other:

I noticed at one point I unplugged the fuel pump and started the engine, and it started running at 2000 RPMs, which is kind of weird...

It has a SARD FPR which I think I will try to bypass to see what happens, as well as replace the fuel filter. I suspect there too much fuel?

Car is single turbo and has no cat or emissions.

 

What year is your fd? Do you have the black box or 93-95 solenoids?

 

It's a JDM Ver. 4 (96). I don't have any solenoids at all since it's a single turbo.

 

Also, pinching the MAP sensor doesn't seem to make any difference. It should make the car run crappier, should it not?

For some reason the car keeps running for over a minute after I pull the pump's plug, and at 2,000 RPM for some reason.

 

So when you pull the fuel pump plug does it shoot right up to 2k or slowly go up?

Does it run smoother after unplugging the pump?

Leaky injectors or excessive fuel pressure would be things to check.

You mentioned the car is single turbo? What secondary injectors?
Was it tuned by you or purchased tuned?

 

It shoots straight to 2,000 RPMs and runs for more than a minute (I did it this morning to release the fuel pressure). Which is super weird, no? It doesn't idle this high when the pump is running. It idles at something like 500.

I would say it actually does run smoother and has much less black smoke. Still a more than I would want, even for a track car.

One of the injectors I borrowed is very, very slightly leaky due to a cracked pintle cap. I will be getting my originals cleaned as soon as I can at least get it running respectably.

Yeah, I'm thinking maybe the SARD FPR (installed downstream of the stock one) might have the fuel pressure jacked up too high at idle. Being rich shouldn't keep it from revving past 4,000 though, I wouldn't think.

The injectors are stock and the pump is SARD.

I bought it like this.

It was already tuned.

The bizarre thing is that I put a 30 liters (about half a tank) in it, and I just found out the tank was almost empty. I haven't idled it for more than 30 minutes since getting it running. At least not personally.

I plan on bypassing the FPR to see if that changes anything.

 

Yeh definetely wayyyyy overfueling, which actually will cause it to hit a wall, once it gets so much fuel that it starts to blow out the spark/not combust effectively.

You've pulled both fuel rails and ran the pump and watched for injector leakage?If not start with just the secondary since it's significantly easier to access and has the larger injectors.

I would say back the aftermarket fpr right off but i don't know if your tune would have been done at a pressure higher than stock. Definitely bypass the SARD fpr if you can, if it's still the same start looking at the injectors as stated above.

 

I pulled the rails primarily to make sure they were firing.

I immediately saw fuel pooling in one of the primary injectors, but it wouldn't actually drip, the pintles would just stay wet all the time.

I didn't notice any dripping with the secondaries.

Overfueling might also explain why it gets flooded so quickly.

Yeah, I'm 90% sure it was tuned with the FPR at higher pressures (I don't think you're going to make 350 flywheel HP with stock injectors at stock pressures). But obviously the pressure is higher than it should be.

When I pulled the FPR off, I barely got any gas from the IN side, but I got quite a bit of gas from the OUT side (the return line). I originally pulled the pump to make sure the fuel gauge floater wasn't caught on something (nope, the tank was basically just empty)

 

Sooooo... Anyone know an appropriate fuel pressure setting for a TD06-25 at 0.8 Bar (about 12 PSI) making 350 flywheel HP with stock injectors and a 3" (ish) straight pipe?

 

First off, there is NO reason to run two fuel pressure regulators. That's going to be part of the problem.

Fuel pressure should really be a fixed thing. Whatever the stock spec is, you're good. A fuel pressure regulator has a vacuum line going to it to alter the pressure up and down so it's always variable based on vacuum and boost. So, for every pound of boost, you get another pound of fuel pressure. This isn't to give more fuel, it's to keep the pressure differential right.

Think about it - let's say you had 35psi of boost in the intake manifold, and 35 psi of fuel pressure. Would any fuel squirt out? No. The pressure is the same, so no fuel would go in. That's why the fuel pressure rises with boost and drops with vacuum.

Old school way of getting more fuel in the engine was to increase fuel pressure. There were also rising rate fuel pressure regulators that would ramp up the pressure increase with boost, so instead of a 1:1 ratio, it would be 2:1 or more. Now, with modern programmable EFI and proper fuel injectors, you don't need to do that.

I'm not sure what the factory FPR is good up to, but at your boost level it would have no problems maintaining proper fuel pressure.

Dale

 

For all I know the shop that installed the turbo back in the day may have disabled the stock FPR, since the car apparently ran fine before it was mothballed (or wasn't), so to speak. Fuel seems to flow right through the stock rails and back through the return line when the pump is on.

I just assumed the aftermarket AFR was to increase the fuel delivery capability of the stock injectors.

I suspect most of the gas I used was just cranking the car over and over and over again. In that case, where the hell did it all go? I surely haven't blown 7-8 gallons out of the spark plug holes as mist. Fuel can't drain into the oil in a rotary, I assume.

 

Let's just say I am using the stock FPR and run 25psi boost, the fuel pressure raises up past 60psi so it can keep up fine.

 

It does drain into the oil, substantially actually, might wanna do an oil change before you start it again. Pull the dipstick you should be able to smell it right away.

I imagine this car was built some time ago? Was a pretty common thing to just boost the fuel pressure on stock injectors for more flow, especially in japan from what i've seen. You don't have a fuel pressure gauge do you?
If not plumb one in, even a cheapo is good just to see what's going on.

Now trying to determine what pressure it was tuned at isn't so easy, my first step would be to find someone with a datalogit and pull the map off the power fc and compare it to a stock map, see if it's got lower injector on time when the engine is in vacuum. If it does it probably means the fuel pressure is increased over stock, if the vacuum map looks like a stock map chances are it's at stock fuel pressure.

 

It's a good thing I used some (expensive) oil I got for free (from HKS).

Yeah, but apparently the turbo kit and intercooler doesn't have all that many miles on it. The problem is that it hasn't been driven in about 4-5 years. It has about 60,000 miles but I suspect most of them were pretty hard miles.

I bypassed the FPR and the car runs much better now. Although now it wants to idle at 2,000...

I hope it isn't just that there's no more fuel in the tank and I'm getting the same effect as pulling the pump's plug. Gonna have to go buy more gas... Still haven't checked if it will rev, since the tank is almost empty, and I don't want neighbors complaining again.

The smoke has almost completely cleared up and I'm finally getting respectable vacuum numbers, although that's probably just because it's idling so high.

I suspect if I get it retuned it will clear up.

 

Filled it back up and now it idles (a little lumpy) at 750.

 

It will rev past 4,000 now but not smoothly. I wonder what I should check before trying to drive it to the tuner?

 

How long of a drive?

Assuming you have good oil pressure, it's not overheating, and the oil is staying fairly fuel free driving out of boost to the tuner should be ok.

Since it's a single turbo staying out of boost should be easy.

New plugs and an oil change are a good idea for any tune.

 

About 20 minutes.

I just found that the main engine ground (the big engine block ground) may have been loosely bolted on, with an M6 no less. I cleaned the terminal and the surface of a nearby M8 hole and bolted it down. I wouldn't guess this will make too much of a difference, but I'm not going to test it since I've already got complaints from neighbors... haha

 

Tuner doesn't want to touch the settings until I can nail down all the issues...

 

With the stock fpr I run my car with Bathurst sp hitachi twin at 550+Hp on 20psi boost, and my secondary injectors have been jetted to 1400cc from 850 and I run a 460lph Walbro fuel pump .

As for your problem , it's very common for oem fpr to fail after 10+ years .

But then again if your haven't got a good earth to engine then the coils won't discharge the current properly .

But most times it's the fpr , the fuel pressure on idle should be 30psi and will no vacuum to it (36psi , static)


If you go for sard fpr it's more work for fitment and no gain.

 

What is the typical failure mode? High fuel pressure? Seems like they would design it to fail safe instead of fail deadly.

I just wish I had a copy of the JDM Ver. 4 FSM. They used to sell pirated copies online for insane prices but I'd just assume buy a real one for that much...