[s-cars] ping vs. rattle

[Phil Mische]

Detonation only occurs when the air-fuel mixture spontaneously combusts well
in advance of when it's supposed to - it only happens under load.  Therefore
if it's making the noise with no load (at idle) it's a rattle, not pinging.


 

If there was fuel starvation (kinked hose) it would ping like mad at WOT.

 

PJM

 

From: s-car-list-bounces at audifans.com
[mailto:s-car-list-bounces at audifans.com] On Behalf Of james McCarthy
Sent: Tuesday, January 25, 2011 3:38 PM
To: s-car-list at audifans.com
Subject: [s-cars] ping vs. rattle

 

Need the wisdom of the group.

So I'm starting to think I'm getting some pinging since replacing my fuel
pump (used a bosch OEM unit)... old pump was replaced as precaution 2 months
ago currently running RS2 turbo, MAF, injectors, EM and IA software. Not
100% convinced it started right after the pump swap but definitely not there
before.

Here are the symptoms -
At approximately 2800-3100 with moderate tip in of the throttle I get a loud
rattle (machine gun/ rattle snake) that I can sustain but starts to fade if
I hold it. Can also get to to occur at higher RPM but with less consistency.
Rarely hear it with WOT...

Can get it to occur with the car stationary in neutral (clutch in) but much
less severe (quieter).


No change in Peak boost smooth throttle with no hesitation even with WOT.

So I feel like I might have have had occasional backfire when letting of the
throttle complete and quickly after WOT (but that would be a symptom of
running rich correct???

No exhaust problems I can see (stroumng unit) BPV is forge unit and holds
vacuum. I actually pulled the cat/ center section off this weekend - no
rattle and the cat is perfect.

So I'm wondering of the "new unit" is a bit anemic??? - consider replacement
- but why would this come up now - running the same setup for 2 years (no
previous pinging).

If I go with the 005 or 044 - is the noise going to make me nuts?

Will dive back into the tank to make sure hose isn't kinked somehow...

No codes.

Any other thoughts?


     
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