Cause mine been descreen for about 3 years now and I have noticed recently a really back knock in the engine. Could be that the engine is getting old and has 150,000 on it, but I'm just trying to get some input. It's a 95 A4 with SLP CAI, PCM tunning, 1le elbow, slp LM exhaust and thats about it.

 

While not an advocate of descreened MAFs, I doubt that it is your current problem. Having said this about that, I would have it analysed ASAP and do run it until you resolve your knocking....JMHO

 

I haven't heard of it causing knock.

 

I had a similar problem with my car. Every once in a while I would get a random misfire through the intake (about twice a week). I also would get a bit of a knock that sounded like it was a hollow sound coming from the exhaust. I replaced the MAF and about a week later the problem went away. You could call it coinicidence, but I believe the car needed to 'learn' the new parameters.

 

De screening allows in more air and could make it run a tad leaner and thus the preignition "knock" if indeed that is the "knock".

 

ive had mine done for about 6 months now and have noticed no adverse effects.

 

Ok well maybe the knock is not from descreening the MAF. I just can't figure out what would cause the knock. I know it's not running lean and the PCM is programmed with the descreened MAF in mind. The car actually runs rich when going down the track cause at shift points black smoke puffs out the exhaust.

 

If removing the screen truly did increase air flow, the MAF sensor would pick it up, and the PCM would add the extra fuel. Even if the MAF didn't measure the (miniscule ) increase in air flow, the long term fuel corrections would have no trouble correcting for it. I doubt its running lean, and the "knock" he is describing sounds like it may be more like a bearing knock than detonation.

 

When you are running at the track you are in PE mode so it will run rich. It's totally different when you're driving on the street. Noticing a knock from the engine is bad. Is it a pinging sound when you are accelerating or is it a knocking noise coming from the engine all the time? If it's all the time you're in trouble.

 

It's coming from the engine bay and its really only noticeable at idle specially say stoped at a red light.

 

Does it knock in tune with the RPM? I think you should start saving your money for some sort of engine work

 

When it does knock yes it does in tune with the RPM. But it does it then stops then does it and then stops it's not constant and like I said only at idle.

 

Ya won't here spark knock at idle. May be a rocker or worse.

Injuneer,
Ya are right,that's why ya are the computer guru. I was thinking more of tip in fuel at the initial WOT.

 

what would be worse?

 

Bearings [rod/main]