This was my first summer with my 91 NSX. It had 36.5k on it when I purchased it. I did about 500 miles thus far.
I have done a number of repairs over the summer. A lot of deferred maintenance and replaced items that have failed or were failing due to age.
The latest project is to address the low power at low RPMs.
The car seems to lack torque and power in low RPMs until it gets to about 4,000 RPM. Also it does not fire up right away. It seems to crank longer than I would expect it to need to start. (not extreme, but my S2000 fires up super fast) Since I never had the car from new and have never driven one other than my own I have no frame of reference. It could be that this is how it normally is but, it does not seem right to me.
Reading other posts on this subject I see that the usual suspects are:
- Fuel Filter
- Fuel resistor
- Fuel pump
- O2 Sensors
I looked through the service records I got with the car and I see no evidence that that fuel filter or fuel pump have ever been changed.
The first thing I did after purchasing the car was to change the water pump, timing belt, spark plugs. [I have done many other things mostly unrelated to the engine. Clutch master, slave, ABS flush and unstick solenoids, gauge cluster repair (almost caught on fire), AC restoration and interior restoration like windows, broken trim etc.]
My plan is to start with some injector cleaner first. Also I will order a fuel filter. I don't see anywhere in the records it has ever been done.
In other threads I see references to by-passing the fuel pump resistor. I could use some advice on this. I assume that by-passing means putting a jumper on the following connector?
Doing this means that the fuel pump will run full power at all times? Then if I notice a boost in power. It could be the fuel pump or the resistor itself? The fuel pump does not have a lot of milage on it. But its old and has probably sat for long periods in between use.
The oxygen sensors
If they were failing wouldn't the check engine light come on? Or could they be failing but just not enough to trigger the code? Reading though other threads I have seen a debate on if they would cause this issue or not. In some threads I have seen replacing them fixing a similarly described problem.
The suggested test I see for this is unplugging them and running without them. By doing this the engine would default to a base program. I assume unplugging them will trigger the check engine light. I have a few questions on this:
- What is the easiest way to reach them to unplug them? Under the car or can it be done from the top?
- Is putting a jumper on the service connector and counting the flashes on the dash the only way to read the codes from the ECU?
If I needed to replace these sensors how hard are they to remove? I have seen examples where they needed to be heated up with a torch and a sensor socket to remove them. Is this the norm? My car has never been driven in the elements. The bolts connecting the muffler are very rusted though. I can't see the manifolds. I had no problem getting the sensors off my S2000. But they are in a super easy to access location. Seems like replacing the back O2 requires removing the muffler to access it.
Fuel pump
I ordered the fuel pressure gauge from SOS. I will follow the procedure to test in the service manual.
Any advice or suggestions would be much appreciated!
I have done a number of repairs over the summer. A lot of deferred maintenance and replaced items that have failed or were failing due to age.
The latest project is to address the low power at low RPMs.
The car seems to lack torque and power in low RPMs until it gets to about 4,000 RPM. Also it does not fire up right away. It seems to crank longer than I would expect it to need to start. (not extreme, but my S2000 fires up super fast) Since I never had the car from new and have never driven one other than my own I have no frame of reference. It could be that this is how it normally is but, it does not seem right to me.
Reading other posts on this subject I see that the usual suspects are:
- Fuel Filter
- Fuel resistor
- Fuel pump
- O2 Sensors
I looked through the service records I got with the car and I see no evidence that that fuel filter or fuel pump have ever been changed.
The first thing I did after purchasing the car was to change the water pump, timing belt, spark plugs. [I have done many other things mostly unrelated to the engine. Clutch master, slave, ABS flush and unstick solenoids, gauge cluster repair (almost caught on fire), AC restoration and interior restoration like windows, broken trim etc.]
My plan is to start with some injector cleaner first. Also I will order a fuel filter. I don't see anywhere in the records it has ever been done.
In other threads I see references to by-passing the fuel pump resistor. I could use some advice on this. I assume that by-passing means putting a jumper on the following connector?
Doing this means that the fuel pump will run full power at all times? Then if I notice a boost in power. It could be the fuel pump or the resistor itself? The fuel pump does not have a lot of milage on it. But its old and has probably sat for long periods in between use.
The oxygen sensors
If they were failing wouldn't the check engine light come on? Or could they be failing but just not enough to trigger the code? Reading though other threads I have seen a debate on if they would cause this issue or not. In some threads I have seen replacing them fixing a similarly described problem.
The suggested test I see for this is unplugging them and running without them. By doing this the engine would default to a base program. I assume unplugging them will trigger the check engine light. I have a few questions on this:
- What is the easiest way to reach them to unplug them? Under the car or can it be done from the top?
- Is putting a jumper on the service connector and counting the flashes on the dash the only way to read the codes from the ECU?
If I needed to replace these sensors how hard are they to remove? I have seen examples where they needed to be heated up with a torch and a sensor socket to remove them. Is this the norm? My car has never been driven in the elements. The bolts connecting the muffler are very rusted though. I can't see the manifolds. I had no problem getting the sensors off my S2000. But they are in a super easy to access location. Seems like replacing the back O2 requires removing the muffler to access it.
Fuel pump
I ordered the fuel pressure gauge from SOS. I will follow the procedure to test in the service manual.
Any advice or suggestions would be much appreciated!