Need Help With Vacuum Lines/Wiring! -Tip vs. Manual Transmission

bxtech · 02-07-2010, 10:38 AM

Hello all,

Currently working on an engine swap in a 2001 Carrera 4 with a manual transmission. The REPLACEMENT engine came from a car with a tiptronic transmission. One issue that I have a question on are the vacuum lines at the vacuum canister underneath the intake manifold.

-The engine that came out of the manual transmission car (The 2001 C4 -the car we are working on and keeping) has a 3 way vacuum line tee at the vacuum canister.

-The replacement engine that came out of the tiptronic car has a 4 way vacuum tee at the vacuum canister. The 4th vacuum "leg" goes to a Pierburg brand switch (with an electrical plug) and then another vacuum line comes off it and went all the way to the tail end of the tiptronic transmission. The electrical plug going to the Pierburg switch goes right into the engine wiring harness.

I am planning to just swap over the vacuum tees and lines, so that part is pretty simple.

My question is about the Pierburg vacuum switch and electrical plug. Should I just remove the switch and leave the plug unplugged? Will this cause any electrical or ECM problems once installed? I'd really hate to have to swap over the whole engine wiring harness.

Has anyone had any experience with this? I would imagine that someone out there has swapped over engines between a manual and tiptronic car before. Any advice and/or info would be greatly appreciated!

Thanks in advance!!

bxtech · 02-07-2010, 10:41 AM

Picture of the vacuum lines on the engine with the manual transmission with the 3 way tee:

bxtech · 02-07-2010, 10:45 AM

Picture of the vacuum lines on the engine with the tiptronic transmission with the 4 way tee and Pierburg vacuum switch. Please take note of the electrical plug that goes into the engine wiring harness:

Pacific996 · 02-07-2010, 01:48 PM

It's all up to how the ECU looks at the engine.
The manual trans ECU isn't looking for the extra input so it should work.
I guess the switches wiring is worked into the wiring harness bundle.

bxtech · 02-15-2010, 08:15 AM

Yes, the wiring/plug for the switch goes into the engine wiring harness. You'd have to cut it apart to remove it. I would imagine that it goes all the way up to the round body harness plug on the chassis.

I haven't checked pins at the body harness plugs, but I would imagine that maybe the particular pins are left blank for the tip vacuum switch on the manual transmission cars. I'm sure glad I'm not installing a manual trans engine into a tip car. I'd have to change engine wiring harnesses!

Wayne 962 · Wayne 962's Garage

I think that you can just remove that and plug it, and it won't affect anything or generate any codes. I assume you're using the old ECU?

-Wayne

bxtech · 03-06-2010, 09:44 AM

Thanks Wayne,

I have changed the vacuum lines, and have just left the switch unplugged. I am using the old ECU that is in my manual transmission car. The car is now on the road and seems to run fine. I did run into a CEL problem which turned out to be an O2 sensor and had nothing to do with this vacuum switch setup.

Thanks for the help! I really appreciate it! I don't know what I'd do without this forum!