My Wife's Beetle doesn't like ambient temps above 80! Help please

[mahatma171]

Well, I have inherited the care of an '01 New Beetle through marriage. This little girl runs great all winter long, and runs great now that its cooling down a little bit around these parts. However, she had attitude all summer long. Can't seem to figure it out. Symptoms are a general loss of power, surging, and a generic P0171 DTC. The turbo still spools and sounds really loud when its surging. Twice she lost all power and the EPC light came on, had to pull over and restart her. I recently changed plugs, air filter, cleaned the MAF and the throttle body. Wife says its happened every summer since like '08. Sometimes the turbo seems to kick in pretty hard under moderate acceleration, just from my own observation. I don't have time for any hide and seek right now so I thought I'd ask in the forum here. Any helpful hints would surely be appreciated. Thanks in advance.

[Design]

Are you using the right octane of fuel? I would recommend that you also take a hose and clean the dirt and dust out of the intercooler.

have you flushed your coolant? Ever change the timing belt, water pump, thermostat?

Do the fans work properly?

Here in North Texas we have had 60 days of above 100 degree temps. and I had to replace my fans two weeks ago. Hell, it rarely gets below 80 at night here.

Lots of easy things to look for.

JB

[MyOtherRidesAVette]

Based solely on other threads I have read, my thought would be the MAF sensor and it is somewhat confirmed by your P0171 code -

16555/P0171/000369 - Fuel Trim; Bank 1: System Too Lean

Possible Causes

• Mass Air Flow Sensor (G70) defective
• Intake System Leak(s)

Possible Solutions

• Check Mass Air Flow Sensor (G70)
• Check Fuel Pressure Regulation
• Check Fuel Pump
• Check Injectors
• Check Intake System for Leaks
• Check Exhaust System for Leaks
• Check Secondary Air System for Leaks
• Check Vacuum Pipes for Leaks

Special Notes

• Fuel Trim Info

Retrieved from "16555/P0171/000369 - Ross-Tech Wiki"

[psaboic]

Try a new MAF. If that does not work, I would start looking for any possibility of vapor lock in the fuel system (since it seems to do it only at high temps. Unplug the MAF and drive it for a couple days and see if it still has the temp problem

[mahatma171]

design... I will try cleaning the intercooler ASAP. I haven't flushed the coolant or touched the cooling system in any way. Haven't changed the timing belt either, that might be something I'll be interested in doing soon, seeing that she has 119,000 on the clock. The engine temps remain normal the whole time, around 180-185F I would say, confirmed by DTC scanner and my laser temp tool. The one thing I did notice from the DTC scanner is that the intake air temp will be around 130F or higher when she really starts messing up. The cooling fans work just fine. I must say that your fans got quite a workout in that kind of heat! Just wish this girl wouldn't be so heat sensitive.

Now, I have been telling my dear wife that this girl takes premium fuel. She had been using 87 previously when the prices went past $3 per gallon. Any comments on the effects of that would be appreciated.

Thank you also MyOtherRidesAVette and psaboic for your input. I was leaning that way as well, like I said I cleaned and reinstalled it. Works for me many times, but not always the answer. Obviously did nothing this time around. So let me go back and try a few of these suggestions. Thanks

[MyOtherRidesAVette]

By the book, the 1.8T is a premium engine, the 2.0 a regular, however, the VW comment on the 2.0 is that regular is okay, but premium is preferred and that the engine may perform better. Gasoline additives from the oil companies are different in the summer than the winter so this may be an indirect result also.

M.

[Smileybug]

Get that timing belt done ASAP!!! At 120k, you are long overdue! Common knowledge is 60-80k, but even the VW service schedule says 105k.