So i have a 1999 audi a4 1.8t quattro. I will be driving along at a steady speed and for some reason the car will lurch forward or loose a little power. It is not shifting just usually at a constant speed and rpm. Sometimes at stoplights my idle will fall really low and bounce back up. What could cause this?

 

Anyone? Help??

 

Do you have a check engine light? It'd be worthwhile to scan for codes regardless. I'm wondering if you're having transmission issues rather than engine problems. If you scan with VagCom you can check for trans codes as well. If your trans is acting up you could see such issues - faulty shifts can cause the lurch, slippage can cause the hesitation, and a failure to properly downshift can cause it to almost stall.

 

There are a number of things that could cause this problem. Dying MAF sensor. Dirty throttle body. Engine Coolant Temperature Sensor. Vacuum leak.

Like ImTheDevil said, get the car scanned for codes to rule out as much as you can. You may have a code or multiple codes stored without getting a CEL.

 

i took it down to a german engine shop and they ran diagnostic. No codes showed up. They cleaned out my throttle body and replaced my jets and cleaned my fuel system. I left the shop and the problem continued. Low idle and then it would die at stop lights???

 

i took it down to a german engine shop and they ran diagnostic. No codes showed up. They cleaned out my throttle body and replaced my jets and cleaned my fuel system. I left the shop and the problem continued. Low idle and then it would die at stop lights??? Could it have something to do with the thermostat

 

sounds like a misfire....check the coilpacks...look for boost leaks....check the plugs make sure they are gapped correctly

 

If it starts back up with no problems after dying, it's definitely an air/fuel mixture problem. Since you didn't have any codes, the MAF is probably OK. So you probably have either a lazy O2 sensor or an engine coolant temp sensor (ECTS) that's going bad. The ECTS is pretty easy to replace and not too expensive. I would start by replacing it. The ECTS tells the ECU when the car is warm and commonly cause the car to run too rich when they go bad. This makes the car die at idle.

 

Sounds good i will try and replace that. Should i replace the theromostat while im in there? Is it easy to do? As far as the ECTS, is this the correct part? http://catalog.worldpac.com/ibusines...r+Temp.+Sensor

 

so i finally had a code show up.

Error code P0103

Mass or volume air flow circuit high input

would that be my mass air flow sensor??