So i just purchased a 2001 WS6 A4 with 44,000 miles on it. Car is in amazing condition other then a few chips in the paint from being on the highway. It looks like the last owner took very good care of the car. Anyways, before I bought the car i did research on the engine. I found that the LS1s have piston slap. I was reading that every car varies on how loud the slap is. On mine it goes away a little bit when it is warm. Im just concerned that it could be a rod knock. I highly doubt it because of the condition of the car and low miles. Like I said before it looks like the last owner babied this baby. Can any one give me peace of mind? My first car i threw a rod and now every time i hear a ticking noise from the engine I freak out. Also anyone have any ideas how to improve the mpg in this beast? I was looking into a cold air intake system. AND yes I KNOW THIS IS A V8!!!! this baby was made to suck up gas car is stock by the way
Thanks guys!!!!

 

The piston slap that you refer to is usually associated with a cold start of the vehicle. That slap should normally go away within a couple minutes of warming up. If you're hearing something continuously when the car is warm, that may not be normal. Numerous LS-1's right off the showroom floor when new had this issue....even brand new Vettes. It's certainly not all LS-1's since the large majority of cars I've owned or test driven did not have the slap....or at least I couldn't hear it. A lot of M6's have obvious input shaft rotational noise from the engine under 2,000 rpm. You can hear this in the cabin coming from the shifter area. But, most are probably so minor that you can't hear anything short of applying a stethoscope. I'd get the noise checked out by a shop (or person) that is familiar with the LS-1. It might not even be engine related. If your noise is solely from the piston slap there will be plenty of owners on this site that should report identical conditions to yours.

As far as improving MPG the two biggest factors would be your rear end gear ratio and gunked up sensors in your air intake system. You can weaken your rear end gear ratio by 5-15% though that will take away some performance Opening up your intake and cleaning things up including the PCV valve could help. Check a couple spark plugs to ensure they are still in good shape after 44K miles. They probably haven't been changed and might not need to. Upgrading the spark plug wires is another option. Check/change the air filter. Some recommend upgrading to a K&N style. Having fresh drive train fluids can help a little. At 44K miles your car should be close to a 2nd auto trans fluid change, if not already done recently. A cold air intake system would help hp and mpg. Ensuring tire pressure is kept on the higher side will help, though again, performance will be affected. Better breathing exhaust system (header and exh pipes) is another answer but now your deviating from stock and increasing $$. Short of major mechanical changes you might only increase the hp by a couple of percent...something you might not notice by seat of the pants feel or even at the gas pump.

In the end, ensure the car is up to date on fluids and maintenance. Drive the car as you desire and don't fret too much about the mpg unless you're getting something woefully under the typical 17-22 mpg. I think I averaged about 18-20 mpg overall on my A4 when I had it from 2002-2009. I've had a dozen or so V8's (1985-2002) on all makes/models over the previous 30 years and 18-20 mpg is about where they all have ended up....and that includes 2 LT-1's and 2 LS-1's.

 

Sometimes piston slap will continue even after the engine is warmed up, when the outside temps are cool. My '02 was this way; it generally always had some amount of piston slap at idle any time the ambient temp was below about ~70°F, even once the engine was fully warmed up. Of my four LS1s, the 2002 was by far the worst in this regard, and the noise was consistent for the ~7 years and many 10s of thousands of miles that I drove it. The piston slap never resulted in any issues of any kind, just an annoying noise.

At 44k miles, I doubt the car is in need of spark plugs or O2 sensors, but it might need an MAF cleaning (especially if the car has ever had a K&N-type air filter). A dirty MAF can lead to several driveability issues including poor MPG. Front O2 sensors would be the other item that could have an equally large effect on MPG/driveability, but again I doubt you'd need those with such low mileage and no SES present.

There isn't much you can do to significantly improve MPG beyond making sure that everything is running as well as it can be. Modifications that allow the engine to breath easier might give you a slight bump at cruise, but as you make more power the fuel demands at WOT will increase. Weight reduction is something you can consider that will improve both MPG as well as acceleration.

 

Im doing a tune up before winter. Im looking to buy a SLP air box lid, cold air intake , and the smooth bellow. Get a little bit better mpg and power.

I just started my car and I can hear the ticking noise, and realized that the noise goes away when I bring up the rpm. Its only at a certain point though where it goes away. What could that be?
And in what ways could I cut weight on the car? Im also thinking about getting a different rear end
Thank you guys

 

This could definitely still be piston slap. Mine would go away completely as rpm increased, then come back at idle if the ambient temps were cool enough. Other things that could cause a tick that's influenced by rpm would be push rods, valves or lifters, but bent push rods and/or valves would be more common with an M6 trans (due to missed shifts/mechanical overrevs), and lifter tick isn't nearly as common as piston slap with the LS1s.

Weight reduction ranges from simple things like elimination of the jack/spare/floormats, to more complicated things like removal of insulation/padding, to major surgery such as modifying/deleting support brackets/braces and/or swapping for lighter weight aftermarket pieces, etc. You'll get a bunch of ideas if you do a search on this.

Not something I would ever worry about for a stock A4 car epscially with low miles/minimal wear. The A4s are much easier on the rear, and you'd have to try really hard to break it at stock power levels with street tires. Even with big stalls and internal engine mods, plus sticky tires, many of us have gotten long lives out of the stock rear behind an A4 trans (so long as you can keep wheel hop away). On the other hand, M6 guys have been known to break rear ends even at stock power levels.