Engine Ping or Knock

[Michael Dennison]

Hi guys - you know I wouldn't Ping from Knock if it jumped up and bit me. But every so often, going back a number of years, I get (let's call it) a bout of Pinging. Most often on uphill acceleration, but sometimes on the flat. Whenever it crops up the dealer (most often Kelley Infiniti in the Boston area who are, on the whole, great to work with) smiles that patient smile, dumps in some concoction, and tells me to go away. It comes, it goes, then it comes again. Of late it's back with avengeance. No matter how much Sunoco 94 I use, and I always use 93 minimum, there is no relief. Anyone have any ideas or suggestions??

[sijoko]

What year and mileage is your car? How hard do you drive it? Also what condition are the fuel pump and fuel filter in?

[Michael Dennison]

It's a 95Q with about 112k miles. Fuel pump was replaced 2 yrs ago but not sure about the filter.

[911/Q45]

Knock sensors OK?

[Michael Dennison]

Good question. Don't know but that gives me something to check out.

[maxnix]

How long since you had a rail flush? Replaced fuel pump? Fuel filter?

[MY92Q]

I have a 92 Q and I thought I had an engine knock or ping, it turned out to be a loose speedo cable on the firewall ratteling around and or a broken fastener on the left shock tower holding an ABS line. Hope this helps.

[Chally]

It doesn't have a speedo cable in the 95's so it will be in the engine.

We have had a serious problem in Australia with Pinging, as teh fuel suppliers have been caugh mixing fuels, causing the fuel to be diluted.If the fuel is of poor quality, you need to find another station to fill up from.

Get a consult on the car & find what problems come up, but also, make sure that the terminals on the CAS & MAF are clean + find someone to do a Carbon Clean on your engine. A company called Chemplex has a product that does a great job, but you need someone to administer it for you, as you need a special machine to do the job.

I did it on my 94 Q45 & my cold start idle now works properly. Seeing as it never worked since I owned the car, I didn't know any different, but no the engine is sweet & no knock!

[Michael Dennison]

Ok, so my profile does say I am a novice so my apologies for the questions, but ... what's a rail flush, a CAS and an MAF. I may not know much but my mind is a sponge. Thanks.

[PalmerWMD]

rail flush:

Is when you attach a bottle of petroleum based detergent (like seafoam or B&G) to your fuel rails and run it thru your injectors pure.Clean out injectors pretty well, extending their lifetime.

CAS: crank angle sensor, see where your cam are at, to direct teh firing of the plugs

MAF: Mass Air Flow Sensor, check how much air (oxygen) your car is ingesting, this is used by ECU to regulate leaness/richness of mixture

Fred...