AudiWorld Forums - 1.8t Coil Pack Conversion for the Audi AAN 20vt (Photos and NOW hyperlinks!!)

1.8t Coil Pack Conversion for the Audi AAN Inline turbo 20 valve 5 cylinder

This conversion is intended as an alternative to the original equipment (OE) ignition system that uses two 3-channel power output stages (POSs) and five individual coils each with a replaceable sparkplug connector. The 1.8 t coil pack conversion works but there are no guarantees about improved performance or freedom from failures. The 1.8t coil packs have built-in POS units as well as coils and plug connectors. At the time of writing this, these 06B 905 115L coil packs were about $30 each. In comparison, the OE POSs were about $150 each (you need two) and the OE coils were about $115 each (you need five). So even if the 115L coil packs do fail every once and awhile, they are far less expensive than the original ignition system.

Before you start the installation you should have read the following:

The parts shopping list:

<a href="https://forums.audiworld.com/s4s6/msgs/83216.phtml">shopping list link"</a>

The assembled parts should look like this:

https://cimg6.ibsrv.net/gimg/www.aud...b327682b1.jpg"

The Pin-outs:

<a href="https://forums.audiworld.com/s4s6/msgs/83686.phtml">pin-out link</a>

You can also use this wiring diagram started by audiquatro75 and completed by spiralsmurf:

https://cimg1.ibsrv.net/gimg/www.aud...5cfc363610.jpg

(for a better version of this diagram go:

<a href="https://forums.audiworld.com/s4s6/msgs/85130.phtml">wiring diagram link</a>

or the URL at the bottom for spiralsmurf's post)

Once you have the parts and understand the pin-outs, you can proceed:

BEFORE YOU GO OUT TO THE CAR:

1. Load the 20 female pins into the 5, four-pin coil pack connectors. If you purchased the pins as the two-pin, yellow-wired pigtails, snip the wires in the middle before you load the pins. For me, the pins did not want to slip into the connectors as easily as I would have wanted. I had to push them in with a metal tool (from the rear) so the front of the pins were in the correct position. Add the red silicon wire sealant grommets. Once you are done, try a connector in a 115L coil pack. Try removing the connector (press down on the square bail and pull back).

2. Regenderize the Jetta tail light connectors as per the parts list. Load four male pins (and wires) into one and two pins in the other (in Positions 3 and 4). Add the red silicon wire sealant grommets.

The "before" picture is below (with one "regenderised" to male and the original one still female):

https://cimg7.ibsrv.net/gimg/www.aud...34baf413ab.jpg

The two completed regenderized connectors looked like this (note I added a fourth pin in position 2 for the POS ground after this photo):

https://cimg8.ibsrv.net/gimg/www.aud...f0678de554.jpg

3. Cut the wires on the two, 3-pin Jetta O2 sensor connectors so there is 12" to 14" of wire.

Here is a photo these two connectors after I added wire (I thought the wires were too short - they weren't):

https://cimg1.ibsrv.net/gimg/www.aud...e052583437.jpg

4. Trim and modify the 115L coil packs as shown in the photo below. You need to end up with a ribless band of silicon rubber about 6 to 8 mm high under the hard plastic part of the coil pack tube. The ridge on that hard plastic part of the coil pack tube needs to be removed (I used a Dremel and great care to ONLY take the ridge away). The bottom half of the square(ish) plastic box needs to be removed. Find a F5DP0R sparkplug. Practise pushing the 115L down onto the spark plug. It should go down far enough so the coil pack clips over the hex part of the spark plug.

The 115L on the left has been modified to fit the AAN; the one on the right is the way they come out of the box:

https://cimg0.ibsrv.net/gimg/www.aud...6a75cfea56.jpg

OUT AT THE CAR:

1. Remove the OE coil pack. Remove and save the four 5 mm hex socket bolts. Disconnect the coil pack from the two POS units and the two power connectors on the firewall and the single ground wire to the passenger side rear of the cam cover. Remove the coil pack gently and store in a safe place. If you follow these instructions, if need be you can go back to the OE system within 20 minutes if something seriously goes wrong with the coil pack conversion.

2. Check your spark plug torque. 22 lb-ft. Tighten only. Never back off and re-tighten. Do all five. (Two of mine were loose-ish).

3. Grab one of the trimmed 115L coil packs and pull the rubber ring you left down off the coil pack. Now try installing the coil pack down onto the spark plug. It should go down far enough that the top of the coil pack is about 1/4" (6 mm) below the top of the cam cover. You should hear the coil pack "snap" (click) onto the spark plug. Try this on another spark plug. Measure the distance down to from the cam cover. Remove the trial 115L and replace the rubber ring you removed a few minutes ago. Try installing the coil pack again. It should go down the same as before but you will not hear the click/snap because the rubber ring prevents the sound from leaving.

Here's a photo of trialling a trimmed 115L in Cylinder No. 1:

https://cimg5.ibsrv.net/gimg/www.aud...e77f7b1506.jpg

4. Coil pack orientation is a variable but you need to decide before you start the wiring. IF you do not use the snap-on caps to corral the wires coming out of the connectors, you can point the coil packs to the 7 o'clock position as shown in this photo (from Don Smith, the 2nd known person to do this conversion):

https://cimg2.ibsrv.net/gimg/www.aud...7b32a15048.jpg

However, if you do use the snap-on caps (which I recommend for neatness), then I found that the best orientation was as follows: No.1 (at the front) - 7 o'clock. No. 2, 3 and 4 - 10 o'clock and No.5 (at the rear of the engine) - 5 o'clock. Even with this, the a corner of the snap-on cap and the 115L itself need to be slightly trimmed on No. 1 and No. 5 to get a little clearance.

This second orientation, showing all twenty wires that you have to connect is shown below:

https://cimg9.ibsrv.net/gimg/www.aud...31c9bafefb.jpg

5. Once you have decided on the coil pack orientation, then you can start the wiring process. I left the coil packs in their respective holes, oriented as desired but NOT pushed all the way down (yet). This makes connecting the coil pack connectors easier.

6. You need to be methodical in doing the wiring, and remember to put the heat shrink over the wire at the correct time. Connections can be crimped or soldered. IF you are crimping, I recommend a racheting crimper (more power and more precision) AND using butt connectors that have built in heat sealant (which you activate like when you shrink heat shrink). The objective is a good mechanical connection with no chance of moisture problems.

7. I started with wiring all of the No. 1 pins on the coil packs to the switched power connectors (the Jetta 3-pin O2 sensor connectors installed into the metal connector rack on the firewall). I started at the front with Cylinder No.1 and moved towards the rear, planning how I was going to route the wires, as I went. Note: Because my No. 1 coil pack was pointed to 7 o'clock and I wanted to run the wires on the intake side of the cam cover well, those wires had to loop a bit around to get past coil pack No.2. Likewise, for No. 5, those wires had to loop around coil pack 4 (on the coil pack 3 side) and actually join the "harness" before coil pack No. 4 wires. Because I didn't think I could get a solder connection to the O2 sensor wires, I used crimped butt connectors. I think only cylinders 1 and 2 required extension wires. No. 3, 4 and 5 where direct connections between the pin pig-tail wires and the O2 sensor wires.

NOTE: Since doing this, I am wondering why each cylinder needs its own power wire. Another way to go MIGHT (YMMV) BE to run a single 12 or 14 gauge feeder wire from one fire wall connection and then "tee" into that wire with the Pin. No. 1 wires. This would result in fewer wires and less congestion in the wiring harness.

8. Then I did the Pin. No. 3 connections to the ECU wires. This is the one you really have to make sure that you don't make a mistake on. Study the Pin-out text again. You need to connect Pin. No. 3 of Coil Pack No. 1 to the green wire wire position (Pin 4) of the four pin regenderized Jetta taillight connector (stuck into the POS No. 1 (N122) connector with its boot pulled back so you can see the ECU wire colours and positions). Watch your wire routing again. Extend wires as required. Pin 3 Coil Pack 2 goes to the Violet Purple position (Pin 3 on the 4 pin Jetta taillight connector). Pin 3 Coil Pack 3 goes to the Black Grey position (Pin 1 on the 4 pin Jetta taillight connector). Pin 3 Coil Pack 4 goes to the Black Yellow position (Pin 4 on the other Jetta taillight connector (the one with only two pins) stuck into the POS No. 2 (N127) connector with its boot pulled back to expose the ECU wires). Pin 3 Coil Pack 5 goes to the Black White position on the second Jetta taillight connector (Pin 3 of 4).

9. For the coil pack POS ground, I used a single wire and T'd in the wires from Pin. 2 of the coil pack using solder and heat shrink. I did this by routing the a 14 gauge brown wire from around the firewall, along the intake side of the cam cover well. Coil Pack No. 1 was a straight "butt" type connection. For the other four connections, I routed the Pin 2 Coil Pack wire to where I thought I wanted the "T" connection to occur. Then I very carefully stripped off about 1/2" (13 mm) of the 14 gauge wire cover. I cut the yellow wire to the appropriate lenght and stripped off about 5/8" of insulation. Then I wrapped the exposed yellow wires around the open 14 gauge wire section and soldered them together. Then I cut a section of heat shrink about 1.5" long and slipped it over the 14 gauge wire from the firewall end and then over the connection I just made. The "T" becomes more of a "Y" but it works. Shrink the tubing (I used careful application of heat from my Weller soldering iron). Continue on with 3, 5 and 4 (remember my order) or whatever makes sense for your coil pack arrangement. The final connection is to Pin 2 of the 4- pin Jetta taillight connector - to the brown white wire position. (This wire ends up connected to the intake manifold ground terminal).

10. For the coil ground, Pin No. 4 on the coil pack connector, I followed the same procedure as with the POS grounds except the final terminal was a ring connector that goes under the same ground connection 5 mm hex socket bolt you removed to remove the OE coil pack ground.

11. The next thing is to snap all the four pin coil pact connectors into their respective coil packs and then push the modified coil packs down as far as you had measured when you first trialled their installation and heard the "click".

12. Tie wrap the Jetta taillight connectors into the ECU POS connectors. Check that all your tools are out of the engine bay and that there are no loose wires anywhere. At this point, the result should look something like this:

https://cimg0.ibsrv.net/gimg/www.aud...873c750615.jpg

13. Start the engine. It should start right up and run smoothly.(Mine did - Yay!!) If it doesn't stop the engine and recheck everything - a connection wasn't done correctly. Find it and fix it. Continue until the engine starts and runs fine. Then stop the engine

14. With the engine off but everything fine, corral the wires with the snap-on coil pack boots, 1/4" NYLON convoluted tubing fits right into these connectors (NOTE: DO NOT USE CHEAP POLYETHYLENE tubing - IT MELTS (BTDT)) See below:

https://cimg4.ibsrv.net/gimg/www.aud...a058bdbe61.jpg

The real shiny black plastic is where the plastic was melting.

To solve this (I hope), I removed the melted black PE loom and used Taylor Sho-tuf "Chrome" nylon convoluted tubing in various sizes and tie wraps to corral the wiring as much as possible. At the Jetta taillight connectors, I used red High Temp Silicon sealant to seal the end of the connectors. This is the current final product:

https://cimg3.ibsrv.net/gimg/www.aud...d3aaa69a5d.jpg

15. Keep a spare prepped coil pack in the trunk and enjoy.

Dave F. Oct. 3/05