95T running too rich, no ECU codes

[Stevon]

UPDATE:
Finaly got a code that makes sense out of the ECU besides the engine misfire ones. Code 64 is indicating that rear secondary O2 sensor has a problem and is not working. Would that make the car run erratic power cold and put the car in failsafe or limp mode?
The exhaust is very black too which shows cats aren't working fully. They are at temps of 512 and 479 degrees after a six mile highway run, seems too cold for good running cats. The cats are from the 1990 engine installed in this car. The secondary O2 sensors are resistors and O2 simulater units. Guess it's time for Pro Speed converters with bungs installed for real secondary O2 sensors.

I have just completed my five year project 1995 NSX T and putting the car on the road. First problem was gelled gas from sitting which destroyed the original fuel pump and another replacement pump in the tank. Cleaned tank out and replaced pump and gas, put some carb cleaner in fuel rail and ran the car. The car has power and idles and accelerates fine when hot. Problem is no power when accelerating cold, super lean, pops in intake manifold. When the engine warms up the problem suddenly goes away and check engine light comes on. Stored code is 71,72,73,74,75 and 76 "cylinder misfire". If you reset the ECU (pull clock fuse) and drive the car hot it drives fine and no codes are stored in the ECU. When getting the car smoged for registration, HC and CO2 are off the scale! needless to say it fails, here are the readings:
Test ______Rpm|%CO2|%O2|___ HC (PPM)___ | CO (%) |
_M1: 15 mph 2611 9.8 | 0.1 | MAX 85 Meas 296 | MAX 0.50 Meas 7.57|
_M2: 25 mph 2427 9.4 | 0.0 | MAX 50 Meas 303 | MAX 0.47 Meas 8.03|
I was wondering what to do because there are no codes to go by, bad injectors? Any sugestions?

Did some experiments today. Measured the cluster temperature sensor cold and hot, it is within specs. When starting the car cold it turns over and starts in 3 seconds and idles smooth. When pushing the accelerator pedal the rpm drops down and if you push it all the way the car will almost stall running extremely lean. After about 3 minutes you hear a click like a relay sound, check engine light comes on at the same second, then car accelerates normal with full power and no problems other than running rich for emissions. I’ll have to get a fuel pressure gauge to see what’s going on as a baseline.

Stephen

 

[pgilliam1]

My first guess would not be injectors. It might be oxygen sensors or coil packs. Since it runs good through the power band when it's hot, I would check those parts that can change after they heat up. I would also check the spark plugs as they can tell you what cylinders are having problems by the color or buildup.
Good Luck and Happy Motoring!

 

[Stevon]

PGilliam,

Thank you for the fast reply. The compression on all cylinders is within specs and pressures are close to each other. Pulling the plugs I see dry light brown insulator deposits and a faint sweet smell to them, no black carbon present. Engine codes are for all six cylinders misfiring. Coil packs, plugs, fuel pump, fuel filter and oxygen sensors are all brand new Acura parts. Did a major tuneup by taking out the engine and replacing all maintanence parts including T-belt, LMAs, clutch and oil seals. One issue is that the temperature sensor guage pegs full hot when turning the ignition switch on, even when cold so I'll try to fix that first. It's annoying and may be related to the problem, have to start somewhere! Idle is butter smooth cold or hot.

Stephen

My first guess would not be injectors. It might be oxygen sensors or coil packs. Since it runs good through the power band when it's hot, I would check those parts that can change after they heat up. I would also check the spark plugs as they can tell you what cylinders are having problems by the color or buildup.
Good Luck and Happy Motoring!

 

[pgilliam1]

Next I would check fuel pressure. The NSX has a 2 stage fuel pump that is controlled by a relay in the engine compartment. It is located above the fuel filter and can be straped out for testing (that allows the fuel pump to override the low/ilde to 4200 RPM setting and operate at full pressure). The presure should read around 40psi or slightly higher at idle. I installed a cheap fuel pressure guage on top of my fuel filter to check mine because the pump's a known failure on older NSXes. I also sent my injectors to RC Engineering for balancing and it helped my starting, but if yours idles and runs OK when hot I can't see that being the cause. Although they could definitely cause engine misses and may end up being your problem since you had fuel problems to begin with.
Good Luck and Happy Motoring!