Hello!

I have a 1997 C4 Chassis A6 Avant Quattro that has 202K on the clock, and usually runs like a top. Recently, I've noticed a decrease in power/torque. I'm getting no warning lights, etc. I did (however) notice that the Boost Sensor appears to be damaged. The fitting that comes out of the bottom and attaches to the hose coming from the MAF appears cracked.

I have seen these buggers priced anywhere from $10-$330 all over the web. New, used, etc. Could this be the cause of my lack of power? Also, the car is now, for some reason getting acceptional mileage. Just filled up and got 122 miles and I'm still slightly above 3/4 tank. The gas guage is usually spot on too!

Anyway... Any information regarding the boost sensor and it's affect on performance, if faulty would be most appreciated!

Best regards,

Aaron

 

What engine is this? Is this car located in europe?

 

Nope... Right here in the Chicago 'Burbs. Car spent most of it's life in Indiana, then the NW 'Burbs when the owner moved. The car has the 2.8 litre 12 valve engine. A bit low on power, but really a sweet little mill. Just purrs along.

Thanks,

Aaron

 

Well, with a 2.8L you don't have any turbos so you definately won't have a BOOST sensor, since the car can't develop boost.
An old 2.8L with that amount of mileage i would cover the basics like doing a compression test and cylinder leak down test.

 

The component which I speak of clearly states that it's a boost sensor, and has the indicated partnumber embossed on it's case. The lower fitting appears to be cracked, which is the reason I took notice in the first place. The boost sensor in question is mounted on a bracket near the air filter box, and has a hose running towards the MAF area.

I'm aware that the old gal is a non-turbo, and am wondering if this particular component has something to do with vacuum or lowered air volumn pressure in relation to the intake, rather than something whcih would detect boost. There is a similar component on my Mercedes M119 V8 which, again, is not a turbo'd car, yet has a boost sensor as well. For the life of me though, I have't the foggiest what this bugger could be up to, as there are a plethora of other sensorts in the intake and plenum that can perform a similar function.

As for performance, the car feels just fine now. I wasn't aware of the specs of the engine, and expected more power. There are no leaks, no vibrations, missfires, or any other anomalies. Compression seems fine, as I had a car with poor compression due to worn rings, and in that instance oil consumption was epic. This car burns no oil, and according to an Audi driver friend of mine who used to sell these, drives pretty darn close to new.

So, the mystery continues! What's a boost sensor doing on a non turbo'd 2.8 12 valve engine? I'll try and take some pics tonight and post (for proof of it's existance).

Thanks again,

Aaron

 

Well if its located in the intake line i can only imagine its a MAP (mainifold absolute pressure) sensor. Which just reads the vacuum/pressure inside the intake system. Its not like a honda where it only uses a MAP sensor and no MAF, the audi uses both of them for engine management. So if the MAP sensor is bad, you most likely won't notice it much with a non turbo'ed car. In any case, if its damaged, i would replace it.

 

Hello,

I just snapped some pics of the component in question. As you can see, it is mounted to the outboard side of the air cleaner box. Weird thing is, my research is showing this part as a componnent from a 1.8T A4, not an A6. I wonder if it even belongs there, and is simply a "close enought fit".

Any other ideas?

Thanks again,

Aaron

 

i have a boost controller in my 1997 A4 1.8T Quattro and when ever it boosts past 9 pound it cuts, is there a sensor or anything i can take out to make it not cut ?