Volkswagen Passat Forum banner

The Easiest Way To Find Vacuum Leak on 1.8T Passat

149K views 91 replies 23 participants last post by  Steve in Chicago 
#1 ·
What is the best way to find out the source of the leak on 1.8T Passat?
The car idles funny like it's going to die but drives just fine.
Thanks!
 
#5 ·
Unplug the electrical connectors to it. If the car suddenly idles better, that's probably the culprit.

I've mentioned before, an easy way to check for vacuum leaks is to take a propane torch and crack the gas valve open a little. As the car idles, run the tip of the torch around the hoses, joins, gaskets, etc... anywhere a leak could be. If the idle suddenly surges, then you've found a leak.
 
#6 ·
Thanks guys, I'm going to check on the MAF later.

here's the codes that came up:

12 Faults Found:

16840 - EVAP System: Very Small Leak Detected
***********P0456 - 001 - Upper Limit Exceeded - Intermittent

17536 - Fuel Trim: Bank 1 (Mult): System too Lean
***********P1128 - 001 - Upper Limit Exceeded

16555 - Fuel Trim: System Too Lean: Bank 1
***********P0171 - 001 - Upper Limit Exceeded

17519 - Oxygen (Lambda) Sensor Regulation: Bank 1: System too Lean
***********P1111 - 002 - Lower Limit Exceeded

16684 - Random/Multiple Cylinder Misfire Detected
***********P0300 - 001 - Upper Limit Exceeded

16685 - Cylinder 1 Misfire Detected
***********P0301 - 001 - Upper Limit Exceeded

16687 - Cylinder 3 Misfire Detected
***********P0303 - 001 - Upper Limit Exceeded

16688 - Cylinder 4 Misfire Detected
***********P0304 - 001 - Upper Limit Exceeded - Intermittent

16686 - Cylinder 2 Misfire Detected
***********P0302 - 001 - Upper Limit Exceeded

16891 - Idle Control System RPM Higher than Expected.
***********P0507 - 001 - Upper Limit Exceeded - Intermittent

17705 - Pressure Drop between Turbo and Throttle Valve (check D.V.!)
***********P1297 - 001 - Upper Limit Exceeded

17544 - Fuel Trim: Bank 1 (Add): System too Lean
***********P1136 - 001 - Upper Limit Exceeded
 
#24 ·
I had 16840, replacing the gas tank cap fixed it.

17536/16555 came up because my MAF was dirty. I went and bought some CRC electronics cleaner and cleaned it. Slipped it back in and went away. However, now my MAF is having issues again, so I am replacing it. Found it for under $60 on eBay.
 
#16 ·
Ok so the replacement pipe didn't help. I'm still getting this code that is causing all cylinders misfired.

17705 - Pressure Drop between Turbo and Throttle Valve (check D.V.!)
***********P1297 - 001 - Upper Limit Exceeded

Any idea next part I should look into?

Also in block 002, all last 3 readings seem higher than the limit.
 
#17 ·
You can make your own pressure tester from plumbing PVC at Home Depot or the like. I have one that I made. I also searched and see that there are at least two sites that have a how to for making one. Basically I disconnect my Air box and plug the pressure fitting into that. I don't have the time to type it all right now but you get the hint. Put an air hose on the fitting and turn the compressor up to about 25 psi. Look for any leaks. you'll find them. Unless it's electrical. Good luck.
 
#20 ·
Have you checked the diverter valve? If it's leaking (passing air) you won't catch that with a boost leak tester.

The noise in the video could be a number of things. One of those things it might be is air passing through a hole/cut/split in a hose and making a humming noise. A ruptured Diverter Valve diaphragm may also hum, but I don't know if you'd get that at idle.

Best advice so far was the suggestion to make a boost leak tester and see what shows up.

As for the propane trick, that's something I used to use all the time on older engines. On these newer computer controlled and idle stabilized engine systems, it doesn't work as well. The engine has to be running super lean beyond the ECM's ability to compensate before you see any change in idle. If it isn't that far out of whack, the computer will compensate and when the propane is added, the computer stops compensating. You may not detect any change in idle because the system responds so quickly. So in other words, if the propane trick fails to pinpoint a leak, that does not mean you still don't have a leak. It just means the ECM can compensate for the leak faster than the propane trick can point it out.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top