I have 18, 000 miles on my 2005, S2000 ... From time to time I hear a POPPING

noise from under the vehicle ... It happens when in first or reverse. It sounds like

a loud BANG... ANY IDEAS what this could be? I read ther were recalls with

spark plugs of older s2000 ... Has anyone else had this problem?

Could this be a sprk plug problem???

PLEASSSSE Respond with any info ....

 

pop? need more details. back fire?

 

definitely sounds like drivetrain...

unless you could describe better...it could be anything at this point.

 

are you putting on the brakes when it happens? pop? clunk? i wonder if you are hearing the pads/calipers reset?

 

The loud noise happens once in a while ... it sounds as if it comes from underneith the

back of the car. It happens when I'm in first gear or reverse. The noise is so loud it

feels as though I ran over something ... could be a backfire or something. The several

times it happened, I started the car, let it warm up for a while and it happened while i

was backing out of the drive way, and another time when I was down the street in firts

gear.

 

This has happened to me a few times when I first started up my car on a cold day (really cold). I put it into reverse after like 45seconds of idling and I heard a loud POP. I stopped the car and went out to check because I thought I ran over something. Hasn't happened in awhile though.

 

How may miles do you have on your car? It happened a once or twice when my car had under 10, 000... but now at 18,000 it's happening more frequently ... and i only use the thing on weekends.

 

Tough to pinpoint, though could be one of a couple things:

The rear brake pads will rust to the rotors if the car is parked overnight, and even if you disengage the the parking brake, the first time you try to roll the car you'll get a loud "bang" when the pads release - it's harmless.

Second possibility is that it could be the transmission. A known behavior is that you coast up to a stop after pressing the clutch in, after downshifting, and then select first gear. The lay shaft is (nearly) instantly dragged down to whatever the engine RPM's are at idle, when it has just been spinning at a much higher velocity. This causes an audible "clunk" for some. This is also pretty harmless, though it may cause premature synchro wear and can be avoided by pausing in neutral before selecting first gear, or double clutching. Somebody else chime in if I butchered the explanation for this.

Then again, it could be something else... ymmv.

 

This one gets my vote. Particularly since the OP says it happens "once in a while". I suspect those occurrences coincide with the days that you put the S to bed while it's still wet (after washing, or after driving in the rain). Then the brake pads rust a bit and bonds them to the rotors. When you first move the car, that bond breaks and results in a loud pop. Seems that it's generally just the rears that are affected (maybe because the e-brake is set).

 

If you're getting this noise from a stop, then it's most likely the parking brake.
After sitting overnight, when it's cold.. or after a drive in the rain, the rust collects on the brakes and POPS when you disengage the parking brake and roll away.
Scared the living daylights out of me the first few times, until Billman explained it to me.