'94 low mileage (pre OBD II) power loss

[Espritman]

Our garage stored '94 with fewer than 20k miles, is suffering from a rough running/lack of power (maybe 50% initially) and further gradual reduction to the point that the car stalls within 3+- miles. It immediately restarts then goes through the same power loss symptoms. The distance traveled has been under 2,000 since purchased in late 2013. The car has run very nicely until 2 months ago.

So far, I've checked the plugs and coils. They appear to be in excellent condition. Having had a similar issue with my previous '94, I replaced the main relay. Although it fixed that car, it did not solve this one.

Prior to my purchasing it, the previous owner had stored it covered in his garage for 10+ years. In preparation for sale, he had Criswell Acura in Annapolis, MD "Do whatever it needs." That bill came to nearly $7,000 including filters, timing belt, battery, tires, etc.

It's been suggested that I check the fault codes, but i find no OBD port. Can codes be checked on this car?

ANY remedy suggestions will be welcomed.

Thank you!

 

[Elmonte]

http://www.nsxprime.com/wiki/Trouble_Codes

Cheers

 

[Old Guy]

Yes, there is a procedure for getting the trouble codes on Pre OBDII cars. It involves shorting the service check connector and then counting the flashes on the engine maintenance indicator light. Rather than try and describe the process, go to the Prime wiki and follow the links to the on-line service manuals. You need the section on fuel / emissions which gives you a list of the trouble codes and a good description of how to retrieve them.

However, if the MIL light is not lit up, chances are that you may not have a trouble code. Based upon your brief description, and the fact that the car restarts easily, I smell a fuel starvation problem or a fuel problem of some nature. Fuel starvation would not necessarily trigger a trouble code. You said that the car had major maintenance done prior to purchase. Review the repair invoice and confirm that the fuel filter was replaced. If no record of replacement exists, then you could safely do that because it is one of those things that should have been done at least once in the last 22 years - 20000 mi.

I think a fuel pressure test would be in order. If you test and the pressure comes out low (after you have replaced the fuel filter if it wasn't previously replaced), then check out the fuel pump and fuel pressure regulator. The service manual has the fuel pressure test procedure and the regulator test procedure. None of this is super difficult; but, you need the test equipment and tools and it can be a bit messy and potentially dangerous with the gas getting on to stuff when you disconnect fittings. If you don't want to deal with that a trip to a good service facility may be in order. If the pressure tests out low and the filter is new and the regulator passes the test procedure, then its kind of looking like a fuel pump issue. That is a major hassle which involves dropping the fuel tank. A good shop can do a fuel delivery test to confirm whether you have a fuel pump problem

If the fuel pressure and fuel delivery tests out OK, then it might be injectors; but, I am thinking not. What you describe does not really seem like an injector issue.

If the car was totally dormant for over 10 years, I would expect fuel system issues. If the tank and fuel system was drained, then the rubber bits in the fuel system tend to dry out and get hard. If the tank and fuel system was kept full, unless fuel stabilizer was added and the fuel changed out every 12 - 18 months, even though the NSX fuel system is sealed, fuel deterioration is likely to be an issue with nasty residues the result.

 

[nikey22]

Is there a CEL (Check Engine Light)?
Does it stall at idle?
when you say, "it immediately restarts" what does that mean? - Did you physically restart it, or did it just sputter and then come back to life..

Unfortunately OBD-I doesn't show faults related to misfires, this sounds like it could be a symptom of a bad igniter. Easy fix, easy access, relatively cheap part, and same for ALL years.
P.S. Old Guy's analysis is awesome and it could very well be fuel related, but you said you drove it for 2months, I'm assuming gasoline has been replaced at least once..

 

[Old Guy]

The igniter is just a pack of six power transistors that switch the ignition coils on command from the ECU. Except for rare temperature induced problems, power transistors tend to work or be permanently dead. You can have a case where one (or more) transistors / cylinders goes dead with the rest remaining operable; but, intermittent operation would be unusual. However, poor grounding of the igniter module can lead to flakey operation / weak ignition. Checking the grounding is pretty much a case of unbolting the igniter module and removing it and checking for corrosion or other bad stuff at the mounting points. I seem to recall an external ground wire on the module which should be checked. Other than being in a slightly awkward location, removal is pretty straightforward as suggested by nikey22.

 

[bj91nsx]

I believe it's a timing issue. That and check valve clearances. GL

Sent from my SM-G930T using Tapatalk