Intermittant knocking/Pinging/Valve Train Noise

[DrewA]

This is for a stock 91 NSX with service (belts, etc) done one year ago. There are 85,000 miles on the car.

I've been getting intermittant, what sounds like knocking/pinging/valve train, noise under load for the past month or so. It comes and goes but is either there for the entire drive or good for the entire drive. Drive to work and have the noise. Drive home and it is fine. The car accelerates better when the noise is not present. I did notice that when I disconnect the battery everything seems to reset and the noise is not present for a number of days then it appears to come back.

I suspect something electrical like maybe the crank sensor, ECU,etc.

Ther are no CEL.

Has anyone else experienced this? Its not bad but something, somewhere is not correct.

Drew Altemara

 

[RON98]

Hey Drew

Valve train number usually comes when the car is cool and oil is still thick and not circulating well.

it should go away when the car warms up unless the valves need adjusting.

if its knocking, usually an gas issue.

have you tired a different kind of gas?

if you thihnk its a crank sensor issue, i would run the test according to factory nsx manual.

Happy motoring.

Rob

 

[DrewA]

Ron,

I looked in the service manual but could not find the crank sensor test. Could you point me in the right direction?

Drew

 

[Larry Bastanza]

Hi Drew,

I hope all is well with you. My first question is when the key is in the on position(engine off) is the CEL lit during the bulb test cycle?

Regards,
LarryB

 

[DrewA]

Yes Larry, when the key is in the on position (engine off) the orange/yellow check engine light on the top left dash illimunates for approximately 3 seconds then turns off.

The car is running fine right now.

I did take a Sears timing light to it. I assume the static advance mark is the one that appears to be once colored red with 3 marks; plus minus 2 deg.

Though I get a lot of bounce the red mark averages/appears several deg to the left (counterclockwise} of the pointer.

I find it hard to believe the timing is off but would like to check.

I was reading in the service manual that the timing can be adjusted.

Where is the main control module located that contains the timing adjustment?

I'm use to stuff that has a lot of carbs, points ,mechanical advance. I'm going to get above my pay grade real quick here.

Regards,

Drew Altemara