1992 240SX - Persistent codes 32 EGR and 34 Knock sensor

[qat727]

I have tried searching and located some threads with some similarities to my problems. After trying most of the suggested solutions with no luck, I decided I need more help.

Requisite background: The car is a 1992 240SX base 5 speed. Chassis has ~147k. Engine is a S14 KA24DE, supposedly with 104k. Transmission is from an 89, supposedly with 90k.

Parts replaced/modified: Emissions system has been removed, with the exception of the IACV, PCV, MAF, and O2 sensor. S14 upper intake runner installed to delete SCV's. Vacuum lines below manifold and behind head have been deleted, with all additional vacuum ports being blocked or routed to necessary equipment. New OEM coolant temperature sensor also installed.

Fuel rail including injectors were replaced with one from a S13 KA24DE. Knock sensor and harness were removed and visually inspected. No damage was seen on the sensor. The sensor came with the S14 KA24DE replacement engine. The harness showed some wear and was replaced with the harness from a S13 KA24DE. This change did not resolve the code 34 concern.

EGR has been completely removed. Pipe from exhaust manifold has been removed and plugged with a nickel. Cast iron mount on intake has been threaded and plugged with a pipe plug and thread sealant. The harness connections for the SCV and EGR solenoids were initially left disconnected and the solenoids were removed. Upon finding code 32 and reading a thread on NICO, a 100k ohm resistor was used to jumper the EGR harness plug. Code 32 persisted. Resistor was removed and a solenoid was added in its place. No vacuum lines were connected to the solenoid. Code 32 persisted and is ongoing.

Additional history of the concern: Prior to installation of replacement engine, the original KA24DE was rebuilt and occupied the engine bay. Persistent concerns with poor idle, jumping time, and fuel consumption were eventually traced to a faulty rebuild of the engine that eventually caused complete failure. With this engine, the emissions had been deleted as well. However, codes 32 and 34 were not present while it was running.

After the replacement engine was installed, codes 31, 32, and 34 were observed in conjunction with running rich and stumbling under acceleration. A replacement 02 sensor was installed and code 31 did not reappear. A different fuel rail and injectors were installed and resolved some of the hesitation concerns. Car still ran rich and threw codes 32 and 34. Aforementioned repair attempts followed with no success.

Latest issues and repair attempts: Poor fuel economy and hard cold starting were accompanied by a strong fuel smell outside vehicle at the rear. Diagnosed as a leaking fuel tank. Removed and patched 6 screw holes in the top of the tank. Pressure tested and held to ~15 PSI before cap released pressure. Tank reinstalled. Vent hose was and is routed to behind the driver side headlight and is open. Difficult to start immediately after tank was reinstalled, but have not had a chance to try to start cold again since fuel tank repair.

Idle was higher than spec. Per FSM and TSB instruction, timing was reset to 20* BTDC and idle was set to 700 RPM. Car did not hold lower idle and now idles between 750 and 800 RPM. Given the nature of 240SX's, this is satisfactory to me.

Current problems: The vehicle has a noticeable lack of power between 2,000 and 3,000 RPM. Below and above this range the vehicle acts normally. When the ECU is reset and the codes are cleared, this behavior is less noticeable. After approximately 10 minutes of driving, codes 32 and 34 reappear and the lack in power becomes more noticeable, gradually getting worse.

The vehicle runs rich constantly. Replacement of the O2 sensor and fuel injectors provided a noticeable improvement, however the exhaust still smells of unburnt fuel. Spark plugs are new NGK and show a black coloration consistent with running rich.

The combination of symptoms and the circumstances they occur under lead me to believe that whatever is causing the codes is causing the car to run rich and lose power.

My questions: Is there anything that could provide a false trigger for codes 32 and 34? What can be done to prevent code 32 from triggering, given the fact that the EGR is non-existent on this vehicle. Given the cost of a new knock sensor, is there a good way to test my various knock sensors to find one that is definitely good so I can eliminate that as a possible cause for code 34?

CLIFFS NOTES: Realizing I just presented everyone with a wall of text, here is my problem in simple terms.

My car consistently presents codes 32 and 34. The car has no EGR system installed. The knock sensor harness was replaced and prior to the engine replacement, the car did not throw either code, even without the EGR system.

Any suggestions on how to eliminate the codes and make my car stop running rich and losing power between 2-3k RPM's would be appreciated.

[qat727]

I drove the car extensively this evening, so I figured I'd report back. Difficulty with cold starting is still present, but is largely overcome by opening the throttle after cranking a few seconds.

The car is still running rich and still throwing codes 32 and 34. Fuel smell is gone from the inside and rear of the car and overall, the car seems to run a bit smoother, with the exception of the 2-3k RPM lag.

Today I procured the proper test equipment to perform a fuel leakdown test. I will perform the test as soon as possible and reply back with the results.

[qat727]

Bump. Surely someone has some suggestions.

[qat727]

Meh.... I gave up trying to fix it and sold the car. If the new owner wants to pursue a solution, I'll let him take up the torch.