Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

The Computor Says it's OK

I recently did the 100.000 tune up on my 04 Passat 4 cylinder turbo. Water pump, timing belt, etc, cars runs better than new.

However…when I crank the car up first thing in the morning the exhaust is so bad you can’t stand near the car even outside without being overwhelmed by exhaust fumes.

The dealer says the computer controls all the settings and the computer says the exhaust is OK.

Guess if the computer breathed it might have a different opinion.

The engine needs to use an extra rich mixture of fuel to run smoothly when cold, especially the extra cold mornings of winter. The colder it is, the more rich the fuel mixture needs to be until the engine warms up. This causes the exhaust to be extra potent and look very smokey. Both dissipate as the car warms up. This is completely normal.

For the first 100,000 miles the car did NOT have a rich exhaust, only after the tune up.

What about the computer says the exhaust is ok? There are, for example, exhaust analyzers. Then there are scantools that don’t really do much in terms of measuring exhaust. One would just look at what the O2 sensors say about the exhaust. One might also look at fuel trim values.

Find out exactly what the dealer used to say that “he computer says the exhaust is OK”.

That’s the problem I’m taking about, the dealer stated that the computer sets the controls and if the computer says it’s OK then there is nothing the dealer can do about the rich exhaust.

The dealer said that once the computer fixes the setting the dealer cannot change the settings.

 [b]  [i] the tune up[/i][/b]  

 What was included in the "Turn Up"?  

 What "codes"  did the car's computer have?  (they should be in the format [P1234]

Ok - that’s silly.

Yes, the computer controls the fuel / air mix. But the mix can be too rich or to lean for various reasons. If its bad enough the computer will set an error code. Is your check engine light on? But just b/c things haven’t hit the point where the computer sets a code doesn’t mean that all is well.

Ask around for a reputable local, independent shop and get a 2nd opinion. Dealer shops don’t know anything any better than any other good shop. In fact, they often don’t want to be bothered with minor issues.

Before this “tune up” (and it would be nice to know what was in the tune up) how did the car run while it was cold? Did it idle nice and smooth at cold start? Maybe it is now normal and wasn’t normal before.

There may be a leaky injector causing excessive fuel to gather in the cylinders while the car is parked for a period of time.