2005 VW Golf Loses Power/Runs Bad in the Heat

1st problem:

I have a 2005 VW Golf GL, automatic tranny, 2.0L 4-cyl that has some issues during long drives in hot weather. The 1st incident occurred when I was driving on the interstate in AZ w/the outside air temp around 100 degrees. It was a flat, desolate stretch of road and I had cruise control engaged as well as the A/C turned on. Suddenly it was as if someone had let off the gas pedal, as the car began quickly slowing down from 70 or 75 to maybe 40 or so. I turned off the cruise control & tried to increase back up to highway speed manually, but there was a long lag time before the engine kicked up again. I got it back up to full speed, then moments later it would kick down again unexpectedly as if I had taken my foot off the gas even though I hadn’t (and I was still not climbing any hills). The temp gauge was still normal, but I turned off the A/C just in case this was making an unnecessary drain on the engine. Still the car would behave in the same way. I took the next exit, let it rest a bit, then limped along @ a slow speed on the frontage road until the next town. Suspecting it was the MAF sensor, I had it cleaned @ a repair shop before heading back home. It ran normal for a little while during the drive back, but then the same issue.

Back in town, I replaced the whole MAF sensor, since I was told just cleaning it was a temp fix. By this time the outside air temp was cooler, & short drives to/from work went fine. However, the next time I tried taking the car on a long hot drive (from SoCal into NV), the same issue happened again! So maybe it wasn’t the MAF sensor afterall (unless the replacement was faulty?). Nevertheless, I took a wet washcloth & wrapped it around the sensor, & this seemed to do the trick to get me back home again. For now I am no longer going to risk taking this car on long hot trips until I can figure out what’s wrong w/it & how to fix it. I do plan to take it to a mechanic but wanted to see first if this rings any bells for people on this forum…??

2nd, (possibly related?) problem:

Today as I was coming home, the engine stalled when I tried to take off when the light turned green @ an intersection. I limped it to the other side, pulled over, & tried starting it up again. It started right away & then ran fine. I’d been low on gas but not so low that it should be an issue. I drove the rest of the way (on a highway) to a gas station (several miles) w/o A/C, no problem. I filled it up, did the washcloth trick once again in case that was related to the problem @ all, & drove the rest of the way home just fine. Battery is relatively new (about 2 yrs.) & alternator tested fine. Did not see any corrosion on a recent check of the battery posts. Outside air temp warm today, but not that bad…only mid-80s. Temp gauge read normal.

Thanks in advance for any help! :slight_smile:

My guess is that your fuel pump is going out. A failing fuel pump sometimes first acts up when it gets hot. In the first case, you said the outside temperature was high. In the second case, the low gas level meant there wasn’t much gas to help keep the pump cool. Have the fuel pressure tested.

Agreed wih lion9car about the fuel pump.