Oil Change = Check Engine Light

[Mac626]

I wanted to relate something that happened to me. First a brief background. We bought the 1998 TDI bug a couple of months ago. During the transaction, the dealer told us that he had just installed a new Mass Airflow Sensor but did not know when the oil had last been changed.

Last weekend I took it to the Kwik Kar Lube (a chain that's mostly in Texas) for an oil change. I took my own oil and they supplied the filter. I picked the car up later that day. Since I don't usually drive it I wasn't sure whether it was driving okay or not, but it didn't seem very 'peppy'. Anyway I took it home to my daughter. The next day she drove it about 15 miles and the Check Engine Light came on. She told me the car did not seem to be running right in that it lacked it's usual power.

I popped the hood and noticed that the screws used to hold down the air filter cover were sticking all the way out and the filter box was open about 1/2 inch or so (my receipt confirms Kwik Kar checked the air filter). I refitted the top and screwed it down. After about 4 starts, the car's perfomance improved and the Check Engine Light went out. Sigh of relief, right?

Not so fast. The car sat in the driveway for a couple of days (she does not drive every day). When she drove it next time the Check Engine Light came back on and the power loss was once again evident. I looked at the engine and could find no obvious problems. Today I sent it to a VW mechanic I found via word-of-mouth and he plans to pull the codes.

My guess is that the Mass Airflow Sensor is bad and that the period of time where it ran with the air filter canister open caused or contributed to it's demise. Kwik Kar doesn't seem very interested in taking any responsibility, so I will probably take them to small claims if the mechanic confirms my suspicions.

Anyway, I just wanted to get any opinions and at least let everyone know that you should always check to make sure the air filter can is back in place before you leave one of these 'full service' oil change places. I will never go back to one, I'll pay the extra few dollars to my mechanic.

[Mac626]

UPDATE:

Well, one week in the shop and $600 later the vehicle is back in my driveway.

This is a summary of what the mechanic told me. First, he indicated that the problem was very difficult to diagnose and was something he had not seen before. Even though this ocurred immediately after having the poorly executed oil change, he would not commit that it was the cause or a contributing factor (I got the impression he did not want to get involved in my dispute with the oil cahnge company).

The first thing he discovered wrong was a vacuum problem. Apparently there is a check valve that regulates vacumm between the brake booster and the turbocharger. The vacuum level was fine and the brake booster was working okay, but the turbo would not give any boost; therefore he diagnosed the check valve as bad and ordered a replacement.

After replacing the valve, the symptoms were the same. This time he determined that the brake booster was also bad. He replaced the booster and now everything seems to be fine. Plenty of boost for the brakes and the turbo, and the check engine light is finally off.

I still think the oil change debacle had somethign to do with this, but I don't seem to be able to prove it.

Anyway, be careful who you get to change your oil.