Hey guys I just changed plugs from factory stock to a set of Beru Ultras...because they were supposed to be a lower temp range than the stock plugs...I've chipped and am trying to exterminate a very mild ping.<p>Here's the problem, I think the plugs I got are actually hotter...you can tell just by looking at them right?<p>The stock plugs I pulled today were Bosch here are all the numbers off the plug F7LTCR then Germany then 101000051AA then R1 the 871<p>I don't have any of the numbers on the Beru's cause they are in the head of my car :) but here's the problem. I though colder plugs have more of the electrode covered in ceramic than hotter plugs do. When I look at the Bosch plugs I just pulled there is about 1/8 inch of uncovered electrode the Beru's I just put in have about 3/16 inch maybe a tich more uncovered electrode...I thought this would be the hotter of the two plugs..am I right?<p>If it's true that the longer insulator means it has a colder plug operating point then I'm putting the stock ones back in and taking the Beru's back...maybe they gave me the wrong plugs. BTW the stock plugs are pretty clean and only have 5280 miles on them so I can just put em' back in right???? Or do I have to get a new set?

You cannot tell always, due to the difference in design. Your theory can work on plugs of the same mfg. and design.<p>I don't know your exact circumstances, but I cured my ping with Bosch Platinums that were a range colder, plus being a slightly different design. Check the archives for part no's.<p>Do you still have the ping/??

The problem is I think I hear less ping now...not that it's been bad at all since I had the timing set back a tad. I can't hear it at all in first but sometimes I'll get 4 to 5 minute clatter sounds when I've got the pedal slammed to floor in second on occasion. The problem is it's hard to tell the car is even pinging..you have to have the stereo off...AC and Blower off and the window down, otherwise you simply won't hear it. So I guess this could mean a few things. The ping isn't that bad so don't worry. Or it's worse than I think because I have a 99 and it has a pretty beefy hood mat on it which supresses the sound of the motor.<p>So I guess there is no standard method by which to read the temp range of a plug..i.e. a mark like 1 2 3 or something like that???

Since the 1.8T has antiknock sensors, how can you hear engine knock? The sensors should stop knocking long before you hear it. Verrrry interesting,.

Basically the ECU has a map for the timing of the motor, this map if you'd like to envision it is a 16 by 16 matrix of values...a few of them support advance and most of them support retard. The car supposedly starts out in some nominal position in the matrix which should work for most fuel and boost variables. The ECU sits there and listens to it's two knock sensors and when it detects a knock or ping that is above an acceptable threshold the car will step over one value to the right and down one value in the matrix...in this case it would mean less timing and fuel (?) then it listens again...if it doesn't hear a knock or ping it will try to move one to the left and up one, more timing more fuel (i.e. more power / performance) Basically the car is constantly moving around within this map trying to keep performance up but knock and ping in check.<p>Here's what happens in some chipped cars. In the course of design chip tuners often make use of timing in order to make more power and low end torque...in this case as nearly all others they advance it, which gives way to knock and ping if left unchecked. So imagine now you're driving your chipped 1.8T down the road and you romp it...it starts to ping a little the knock sensors pick it up and move over one step in the matrix...you're still flooring it and the car is still pinging because the one step it took was not enough timing retard to halt the ping...so the car tries again and moves over another step...it's now two steps below what it was at before you started to romp on the pedal...well this isn't quite enough retard either so it moves again...ect...ect. If I recall correctly there are 12 retard steps and 4 for advance (could be off..but it does jive with the 16 by 16 map) anyhow the car will keep moving through the map until it hits the end of the range...I don't know what happens then..maybe the check engine light who knows. The point is that the engine management software was unable to eliminate the ping because there is some delay in moving through the map and you may let off the pedal before it ever gets a chance to land on a value that would have stopped the ping, get it?<p>Anyhow so one of the ways to fix it is to permanently set the timing back (permanent power loss I suppose) or to change the step size in the matrix...suppose stock was 1.5 degrees per step and now if you make it 3.0 degrees per step it should be able to arrive at a timing that won't knock in half the time of the stock map.<p>Of course this only addresses problems that are tied to ignition advance. A plug that is running to hot will cause the car to ping and there is Jack **** the car can do about it because fuel is going into the cylinder and the intake valves close piston moves up and BAM the hot plug causes the gas to ignite w/o a spark forcing the piston in the opposite direction putting intense force on the connecting rods, crank shaft, pins ect...ect.<p>Anyhow I'm sooo not an authority on this stuff but this is how I understand it...someone please enlighten me if I'm off this is how it was explained to me.<br>