I cant believe I'm posting this. My car is having its first problem in basically forever. I'm shocked

I have a 1992 JDM RHD automatic FD. Stock everything, stock ECU, stock boost. No performance mods whatsoever.

Description:On cold start up, it is running absolutely pig rich. I mean black smoke, bridgeport idle, wants to foul its plugs and die. I baby the throttle for 4-5 minutes until it clears up and clears the fuel out and warms up. Then it will idle at the factory 750rpm no problem at all, A/F seems really good at that point.

If I leave it idling for say 10-15 minutes, it may all of a sudden stumble, and choke down to 300rpm. The ECU seems to catch this, and brings it back to normal idle within 2-3 seconds. It then continues to idle perfectly.

If I drive it, *sometimes* under boost it will stutter and try to die. I let my foot off, and it comes good. Most other times, it will boost and rev to the buzzer, no problem. Out of 12 pulls in 2nd gear, it stuttered and died once, at 7psi, at 4000rpm. The rest of the runs were flawless.

If I go home and park the car and shut it down, I can come back in half an hour and when I attempt to start it, the car just winds over and does not attempt to fire. Black plumes of richness come out the exhaust during cranking. If I then do the de-flood procedure and put my foot hard on the accelerator during cranking, it will start up and idle fine.

What I've tried:

I put a new factory ECU in the car. This did nothing.

I changed all the spark plugs. This cleaned it up some, and reduced the rich-hard starting issues and eliminated stalling. Now it only stumbles but can catch itself and resume idling.

I pulled the UIM off and found the green check valve between the pressure tank and the primary side of the Y pipe was broken open in half. Replaced it. Idle seemed nicer.

Removed fuel tank and checked for debris. Very clean.

Removed fuel pump. Very good condition.

Verified fuel pressure.

Verified no blockages in fuel lines or rear fuel filter (what a job)

Eyeballed a lot of things. Shook a lot of wiring harnesses. Nothing appears out of place physically.

Compression is known to be good. It does not feel like a seal or blown engine issue. I can force the idle down to as low as 450rpm and it will hold that idle happily as long as I want it to. I have 17" Hg vacuum at idle also.

Could my leading coil pack be on its deathbed?

List of things I have yet to look at:

Map Sensor + inline filter.

oxygen sensor

PCV valve

Idle speed motor

Throttle cable tension adjustment

Hot wax rod operation

Dirty throttlebody

Brake booster check valve

Any electrical switches like neutral safety switch on trans failing

I attempted to put a wire across the diagnosis terminals in the diagnostics connector in the engine bay. I get no fault codes.

Spraying carb cleaner around the engine at idle gives no idle leaks.


Soooo.... Anyone want to have a stab at this one?

 

Update- It now drives and idles fine when at full temperature. Cant fault it once warmed up.

Only unresolved issue is the $%^&*ing super duper rich cold starts. It must be something in the start up/ fast idle choke system that is not working.

Starts up cold fine. Fast idles fine for the first minute. Then comes the glut of excess fuel. It braps and blows rich black fuel smoke out the back, and it wants to die under the excess fuel. I can accelerate it and it will slowly brap its way up to 3000rpm, and then after about 2 minutes, blam, it clears up and settles down to run fine.

If I can find out why its deciding to run so rich at start up, I can solve it.
I'm looking at the wax rod, Idle control motor, air bleed screw, etc...

 

you should try to pull the codes out of it. Engine Diagnostics

 

Thanks, but your engine diagnostics is for a USDM RX7. It does not work on the Japanese RX7 because we have no check engine light on the dash.

 

clink on the link, its for cars with no light on the dash.

 

Thanks, I did get to that solution in between being away from the forum, but your link has much more information than the link I found, so thanks

My question now is, if I get an LED that has an inbuilt resistor intended to be used in a 12 volt circuit, will it just work without needing to solder a resistor in one leg?

I am going to say yes? I am going to look for a suitable LED when I get home, hopefully I have one lying around somewhere. The only electronics parts place is 40km away and has odd opening hours :s

 

FIXED!!!

Code #9. Water thermosensor was dead.

Poor ECU didnt know water temps, and so cold starts were super rich, and then during driving, it would lose its water temp reading and it would stall out.

 

The link you provided only gives a few error codes. and I found this on fd3s.net

1 Ignition coil (trailing side)
2 Crank position NE sensor
3 Crank position G sensor
5 Knock sensor
8 Airflow meter (AFM)
9 Water thermosensor
10 Intake air thermosensor (AFM)
11 Intake air thermosensor (engine)
12 Throttle sensor - full range
13 Pressure sensor - intake manifold
14 Atmospheric pressure sensor (built in ECU)
15 oxygen sensor
17 Feedback system for O2 sensor
18 Throttle sensor - narrow range
20 Metering oil pump position sensor
23 Fuel thermosensor
25 Solenoid valve - pressure regulator control
26 metering oil pump stepper motor
27 Metering oil pump
28 Solenoid valve - EGR
29 Solenoid valve - EGR vent
30 Solenoid valve - split air bypass
31 solenoid valve - relief 1
32 Solenoid valve - switching
33 Solenoid valve - port air bypass
34 Solenoid valve -idle speed control (BAC)
37 Metering oil pump
38 Solenoid valve - accelerated warmup system and air supply valve
39 Solenoid valve - relief 2
40 Solenoid valve - purge control (auxilary port valve)
41 Solenoid valve - variable dynamic effect intake (VDI)
42 Solenoid valve - turbo precontrol
43 Solenoid valve - wastegate control
44 Solenoid valve - turbo control
45 Solenoid valve - charge control
46 Solenoid valve - charge relief control
50 Solenoid valve - double throttle control
51 Fuel pump relay
54 Air pump relay
65 Air conditioning signal
71 Injector - front secondary
73 Injector - rear secondary
76 Slip lockup signal
77 Torque reduced signal

Are these all the error codes for the FD?

I did the diagnostics test on my car because it also runs rich on a cold startup and at first it gave me 4 long flashes and 6 short, which on the list above is 46 (Solenoid valve - charge relief control) I then disconected my negative on the battery and waited about a minute and then reconnected it, tried the diagnostics test again and now the LED flashes only 4 long times, which is 40? (Solenoid valve - purge control (auxilary port valve))

Also after a WOT pull to 8000rpm it sometimes battles to idle and becomes very unresponsive and I got to play with the throttle to get it back up to stable revs. car idles nicely at +- 1300rpm and sometimes idles very rough at 750 and slowly goes back to +-1300?

Sorry for the thread jack..

Could someone please give me some feedback? Thanks.

 

I would say that idle stability problem could be related to an air leak (wants to idle fast, and idles rough when you try to lower the idle)

When it runs rich on cold start, how do you mean?

When I say my car ran rich at cold start, I mean big plumes of black filthy smoke everywhere, teary eyes and a brapping blown-rotor sort of idle and popping exhaust. It was basically as rich as it would go without stalling.

Try removing the pressure tank on top of the engine and having a good look under there for split hoses and leaks.

#46 Charge relief control solenoid is a pretty basic one. The solenoid is controlled by the ECU. It switches its ports to send vacuum to the charge control valve (plastic BOV looking object towards rear of engine, connected to Y pipe) which basically vents prespool charge of the secondary turbocharger until it comes online. The solenoid could be bad. It sends a signal to the small vacuum line on the top of the plastic BOV object, controlling its open or closed position.

The reason you didnt get the code 46 back again is because the car requires driving (until the secondary turbo comes in) to actuate that solenoid, and detect a problem. You probably have issues with your primary to secondary boost transition possibly.

#40 I have no idea. Purge control is not my area of study at the moment..

 

yeah those sensors go bad a lot. the funniest one i've seen was one where the sensor was broken, so it would alternate between shorted and open, so the car would alternately flood or get no fuel.

 

Thats exactly what my sensor was doing. It crumbled into plastic dust when I touched it. It was hanging on by very little, very brittle material.

Basically it would short out, and the car would randomly flood. And it was also going open circuit and the car would hit a bump and just stall and then crank and crank and go rich and fail to start.

I had to remove the strut bar, pressure tank on top of the engine, etc to get at the sensor. And then the big issue was that I didnt have any 19mm wrenches slim enough to get in there to crack the sensor off and unscrew it. I had to grind and bend a custom 19mm wrench especially to do the job.

There are two vacuum hoses and a water hose that run across & over the top of the sensor location. I chopped the vacuum hoses out and then replaced them with fresh vacuum hose at the end of the job. The water hose I gingerly removed.

There is also a wiring harness that runs across the top of the sensor location, and goes forward to the front of the thermostat housing, and plugs into the water level sensor and one other water sensor with a brown plug. I had to unplug those plugs and bend that harness away from where I was working.

Also, the large plastic Y pipe-to-intercooler flat boost crossover pipe had to be removed.

Replacement sensor is Tridon TCS032 or Fuel Miser brand, CCS21.

The dead sensor in question is in green in the photos below.





Happily, the car now runs perfectly A1 again. Drove it everywhere today.

*pulls up to stop at intersection*

Fiancee: "Is the car even running? I think its turned off or something. I cant hear the engine!"

Me: "Nope, its just running really well. Look, 850rpm on the tach. She's just smooth."




Because thats how well its running now. I think the coolant temp sensor must have been on the fritz for a few months. Its never idled so smoothly.