Crossbow

It's a long story. Here's what happened:

Last month, I brought my '97 A4 2.8L to an independent shop (which specializes in German cars) for a complete 60k service, incuding timing belt replacement, water pump, alignment, etc.

Based on what I read in some of the posts here, I thought it'd also be beneficial to have a professional fuel system cleaning performed, so I opted for the 3M cleaning. (At a cost of ~$80.)

When I picked the car up, the idle was rough, and the engine had an uncharacteristic growling, rumbling sound. Soon thereafter, the "Check engine" light came on.

I brought it back. The problem was diagnosed as a faulty fuel injector. Cost for replacement: ~$250.

I left the shop, drove less than thirty miles, and the "Check engine" light came on again.

I drove back.

It took 17 hours of diagnostic time, but the problem was traced to a "leaky gasket on the fuel intake manifold", which caused loss of vacuum.

The shop cut me a break on their labor rate, but I still ended up paying ~$600. labor for the replacement of a $24. part.

My dilemna: Could the 3M fuel system treatment have caused this gasket to suddenly leak? I sure didn't have a vacuum leak BEFORE I brought it in for the service and fuel system cleaning.

I'd appreciate hearing from anyone who is familiar with the 3M cleaning procedure.

Crossbow

Auditude

manifold. they had to disconnect something on the maniford in order to meter the cleaner into it.

Crossbow

...the extra $900.* I've had to pay since my original 60k service was a direct result of something the garage botched during the fuel cleaning?

I already posed that question to the mechanic. They say "Absolutely not".

I'm not so sure.

Anyone else out there have any insights they can offer?

Crossbow

* - ~$250. for a fuel injector, which I'm beginning to suspect wasn't faulty after all, plus >$600. for the lengthy diagnosis that finally led to the replacement of the $24. gasket.

hurricanesteve

Where they just connect it to the fuel lines, hang the canister on the underside of the hood and let the car idle? If so, then they wouldn't have touched the manifold.

Regardless...this is why I will watch shops like a hawk once I'm out of warranty.

17 hours of diagnosis is ridiculous for an OBDII equipped car. The car would self-diagnose to a very narrow range of possible problems. (i.e. vacuum leak). Then it's just a matter of tracing it down.

Better call (1) 3M and (2) an audi dealer tech to see about that particular cleaning system to see if it is recommended for your car. If it is specifically NOT recommended, get a lawyer.

Crossbow

First, I think the 3M Fuel Cleaning System is a bit more involved than what you described. However, I'm not an expert, so I'm seeking knowledgeable input.

Second, regarding the 17-hour diagnosis: I was there in the beginning and watched myself as the diagnostic tool was used. All it said was "Misfire on Cylinder 3". Then it said nothing for a while. Then it said "Misfire on Cylinder 4". Then nothing again. It was very inconsistent, and not very revealing.

The mechanic suspected faulty oxygen sensor(s) or a faulty ECU. He even swapped an ECU from another A4 to no avail.

Why did it take 17 hours? Beats the crap out of me. I'm just trying to decide whether I should pursue legal action (which is why I'm so interested to know if the 3M Fuel System Cleaning application could have caused the vacuum leak), or whether I should just write it down to experience and forget about ever going back to that shop.

Crossbow

hurricanesteve

Their system IS the type that is simply patched into the fuel line. The fuel line is disconnected from the gas tank line and the can of 3M stuff runs the car.

No warnings about particular vehicles, tho'.

I've seen it done at oil change places (never the 3M brand, tho').

Crossbow

Cleaning his fuel system by connecting a can of solvent and letting his engine run directly off its contents?

Couldn't resist. The parallels were too remarkable.

Thanks again for your insights.

Crossbow