Months have passed...
Work has been on and off...
Cell phones full of pictures, destroyed...
Now the final installment of the Audi saga!!
WARNING STUPID LONG ARTICLE
Last time you were with me I had finally finished assembly on the cylinder head. With some help from my friends, I got the head into place and bolted er dahn.
The next step was to rebuild what I could of the mechanical injectors before install. To do this is an involved and much under-documented process of which I shall outline to the best of my rememberings as I did this in October sometime.
I started out by soaking the injectors in a bath of the finest solvent and fuel system enhancer money can buy from the great Zone of Auto, Seafoam.
Pictured are the 5 injectors for the car submerged in the seafoam after sitting for about 3 weeks. I had previously removed the caps or hats from the ends of the injectors to ensure a more thorough steeping in the solvent. After removing the injectors from their baths, I was left with a reminder of how efficient fuel filters really are.
This is why it is so important to clean your fuel system at least every now and again. I began the reassembly and resealing process. First new o-rings for the caps and the injectors themselves. the seal on the cap is the first line of defense against vacuum leakage whilst the outer seal is a total seal from the outside dirt from getting into the intake runners.
This is a closeup of the fuel injector sans cap to give a little insight on how it functions.
For those who are new to the wonderful world of K-Jetronic Fuel Injection here’s a crash course. The fuel pump stays on constantly supplying a continuous pressure into the fuel metering assembly. When the throttle opens up, the vacuum present in the manifold lowers the pressure of the intake tract and lifts up a plate attached to an arm on the metering device. this arm is attached to, basically, a needle valve that allows pressure to increase into the fuel lines allowing the injectors to inject fuel into the engine. The injectors act as pressure check valves so when the pressure reaches a certain point, it overcomes the spring inside and moves the pintle outwards to release the fuel. The injector pulses several times a second as the pressure oscillates between high and low causing them to “sing” allowing one to hear them working. The caps that go on the business end of the injectors actually create the desired spray pattern.
Before I installed and resealed the caps, I had to remove the old main seals and replace those. Simple task, pop the clip off and shove the seal off.
Then the cap is next.
I used a dental pick to remove the old seal.
New seals. The large skinny seal is actually for the composite air guide which seats into a boss in the head before screwing in the brass injector holder. I’ll be using the fat one for the injector body and the small one for the cap.
Keep your parts in order!
New seal on, install the clip. this is a very important step for without the clip, the pressure in the injector while its firing is enough that over time the injector will actually shoot out of its seat.
This is a tricky bit. I used a common adjustable clamp used in woodworking to square the injector with the cap before squeezing it together. MAKE SURE ITS SQUARE. if not you can cause irreparable damage to the cap forcing you to buy a new injector.
And here is the set of refreshed injectors ready to go into the car! Before installing them, I tapped the screw end on a block of brass I had lying around, so as not to damage the seat, to remove any loose debris in the injector.
Using a quite expensive tester from the internet, I verified the spray patters and made sure the flow was within specification to reuse all 5 injectors. Luckily they were still in spec, so back in the head they went. Reassembly went surprisingly well and I didn’t get hardly any pictures of it.
Timing was done and the plumbing was all that was left. Afterwards I had to deal with installing the fuel metering device below.
That bit I mentioned earlier about the lines and the plate make sense now don’t they? After another few days of puttering around I was left with this.
The intake tract on any turbo car is crazy. Piping everywhere! I had to install the rubber boot on the fuel meter into a pipe that went to a hose attached to the turbo that went to another elbow into a pipe that went to another joint to the intercooler to a joint with a pipe to the boot on the throttle body. Those silver lines are the fuel injector supply lines, one each for the injectors plus the cold start and also to another block with wires coming off of it on the side of the engine. I topped off the fluids, primed the fuel system, and she fired right up. Set the distributor timing and drove it 5 miles home. The next day I went to start it and the starter failed. At this point I know it runs and runs well but I am so done with this project that it is now up for sale to anyone willing to finish it. Offers?