Car stumbles below 3,000 RPM....no idea why.

[Meeyatch1]

So my little 1994 NSX must be mad at me for some reason, because it has cost me more time and money in the last 2 months than the last 2 years. It just turned 185,800 miles today, and for the past couple of days has had a nasty habit of stumbling when accelerating with the RPMS below the 2,500 - 3,000 RPM range. It is not throwing any codes now, but a few days ago threw a code '51' on me. I cleared it out, the code has never returned, and the car ran fine. Then while accelerating from a roll in 3rd gear at probably 2,000 RPM the car bogged down, so I shifted down to 2nd to accelerate away with a little stumbling still. The car has been doing this stumbling ever since. If I am above 3,000 RPM and floor it, it zips up to red line just like it should. I am baffled with where to start. The real pain is that I was going to register for NSXPO today (yes, I waited until the last day, I know), but now I am nervous to attempt to drive the thousands of miles with the car not 100% perfect.

Any help is appreciated. My buddy is just not running right.

 

[Meeyatch1]

Got it!! Since there were no codes on this, I started thinking like the car was human. What would make me gasp or stumble? Lack of fluids or air. I checked my service records (this is WHY you keep service records) and found that the fuel filter was not very old, but could not find anything on a recent air filter. I pulled the air filter and the bottom was BLACK!! So I swapped in a spare (yes, I keep cabinets and attic space full of spare NSX parts in inventory at home) and went for a drive and tried to bog it down like it did before, and the car runs fine. Needless to say, I sure hope that I got it right, and that was all. My buddy (my car) is happy now, and so am I.

 

[socold57]

congrats

 

[Coconut]

Sometimes its the most simplest things. I'm glad you solved the problem :smile:

 

[goldNSX]

Shame on you for neglecting your car.

 

[Briank]

I think your stumbling problem will come back. Are you still on the original fuel pump?

 

[goldNSX]

I think your stumbling problem will come back. Are you still on the original fuel pump?

Good point, I wanted to suggest that too as I ran into it myself but as the air filter was overdue I think the variety of possible faults is very, very wide.

 

[Meeyatch1]

I think your stumbling problem will come back. Are you still on the original fuel pump?

I think I am on the original pump, but not filter.

 

[docjohn]

fwiw Mitch my original fuel pump may be getting weak,my 96 has been giving me an intermitent lean code,and Larry B wants to measure fuel pressure.I've also thrown some techron fuel injector cleaner in the gas as per his suggestion.

 

[PHOEN$X]

Glad to hear you got it resolved, Mitch. See you at NSXPO?