2003 Volkswagen Jetta GLS Lagging

Maintenance/Repairs
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1

I have an automatic 2003 Volkswagen Jetta GLS with 138,000 miles on it. I bought her four years ago with 91,000 miles. Right after I got her, I noticed that she’ll jump a little when when she’s cold (i.e. ease on the gas for the first few miles until she drives more smoothly). Looking around the web, this seems to be fairly common and most forums say that it shouldn’t be a cause for any alarm.

More recently though, she’s started to lag when I accelerate right around the RPMs where she should be shifting. For example, increase to about 3000 RPM, then it feels like a second of free fall, then she’ll catch up and be just fine.

I took her into a shop to get it looked at about 3 weeks ago - initial thought had been maybe an issue with the transmission fluid (did a flush back in 2014 / 110k miles). The mechanic refused to do the flush until I had the catalytic converter and downstream O2 sensor replaced. The previous owner had installed a modification to the sensor and the wires had got too close to the converter and melted. We noticed the check engine light about a year ago and had it looked at, but the mechanic then said it wasn’t a huge issue and was really only going to affect our gas mileage so we held off. Since this mechanic was fairly certain that this was causing our issue, we went ahead and had the repairs made. No luck. Haven’t had a chance to take her back to the shop, but I figured I’d ask to see if we were at least on the right track.

Second issue. My wife and I share this car, and her commute is significantly further than mine. She says that four times over the past two months the car has shut itself off when it comes to a stop. Not a common occurrence given the amount of driving we do, but enough to be concerning.

I’ve had regular oil changes and kept up with the routine maintenance over the past four years (new spark plugs, air filters, etc.). Just got a fuel system flush with the catalytic converter repair three weeks ago. Haven’t changed the battery since I bought her, but every time we get the oil changed they check it and say it’s good.

Appreciate any and all help!

2

You symptom sounds more like a transmission problem than an engine/exhaust system problem to me. Your mechanic is probably right to want to eliminate any known diagnostic codes before starting down the transmission path though. That’s to your own benefit.

But since the O2 sensor didn’t fix the symptom best to be off to the local transmission shop for a diagnostic. It could be something simple like a broken electrical connector, or more expensive but still not that big of deal, a faulty trans solenoid. Or a problematic lock up torque converter solenoid.

I wouldn’t recommend a flush procedure for this symptom unless it includes dropping the pan, cleaning it, and replacing the filter with a new one. Provided that is all possible on your car of course.

About your wife’s problem of the engine shutting off, it could be a faulty ignition switch. Try driving the car with just the one key in the ignition, no dangling key chains. If the problem goes away, it’s probably the ignition switch.