Porsche 914 How to Rebuild the D-Jet Aux Air Regulator

Is your warm idle high? Auxiliary air valve kaput? Rebuilding it isn't difficult. Here's how I did mine. The AAR allows more air into the plenum when the engine is cold and, if working properly, closes off that extra air when the engine is warm. Many are stuck open and don't work anymore. Fixing them is pretty simple. This unit is used on D-Jet engines, but the principle is the same for the one used with L-Jet.

[@ideabrickworks9043]

Years ago, I restored a 1973 2.0 and made a tribute to the LE but did red with white trim and bumpers. My FI was gone when I got the car, so I went to a PMO dual Weber setup, which was awesome. I got into a racecar and my Dad bought it and only sold it when he moved into independent living. My focus was on getting a 911, or I would have kept it. Watching your series is bringing back good (and a few bad) memories…but I learned so much and became a better mechanic which really helped me in my racing 13 years. Keep up the good work, and I cannot wait for you to finish!

[@IanKarr]

thanks so much for watching! Please subscribe if you haven't already.

[@seanmabey1609]

These videos are gold

[@IanKarr]

Glad you like them, Sean!

[@Tmrfe0962]

Such a satisfying job! I will put this on my rainy day job list. As always your videos help those of us afflicted with the 914 spring, I mean coil…Lol….I mean bug….

[@IanKarr]

Thanks, TJ!

[@davedarling4316]

Nice video! Don't beat yourself up on the coil/spring thing--it's both. A bimetallic coil spring. When I did mine, I used a hammer and chisel (uhh, maybe a screwdriver used as a chisel, don't tell anyone!!) to pry open the lip of the can that folds over the top, instead of cutting the folded part of the lip off. I only folded a few spots back over again, as it looked like the metal might crack if I bent it too much. I also used RTV around the edge like you did. Mine wasn't nearly as bad as yours, I must say! I just pulled the guts out of the can, and used a slot-head screwdriver on the bottom of the shaft to twist the valve back and forth, which freed it up pretty well. I don't remember having to push the spring further in, but I might have had to. Removing the top hose fitting was a great way to show the actual workings of the valve! But I don't think it's necessary to do that if you are just repairing the valve, so skipping that makes the job even simpler. Great job as always!!

[@IanKarr]

Thanks, Dave! I took the top hose off in hopes that I could soak it from above to free up the mechanism. Otherwise, you're right...no need to remove. Also, I didn't cut off the lip...I grinded it. Actually also used my bench grinder to release the lip (though I didn't shoot that). Pretty much any method works, as long as you don't cut the ledge on the can.

[@stevekovacs6250]

Again, another informative video Ian! Thank you for all you do for our 914 brethren.

[@IanKarr]

Glad you enjoyed it

[@graemelliott3942]

Thank you Ian for the technical details and simplifying a seemingly difficult task!

[@IanKarr]

Glad it was helpful!

[@MrNipperthedog]

Bravo Ian !!!!

[@IanKarr]

Thanks Matthew!

[@euro9115]

I've refurbished a few of those over the years without complete disassembly. I soaked the ports in 'Berryman's Chem Dip' and applied 12 volts to the heater element off & on over a course of time and then rinsed with brake cleaner. Had to repeat the process on a couple of them, but eventually got those ones clean enough to work again. Nice to see exactly what's inside of one though ;)

[@IanKarr]

Cool. Great that you didn't need to go further. Mine was stuck hard.

[@jacobhunsinger7793]

I was afraid to take mine apart for fear I could never get is back together. Thanks for showing what is inside.

[@IanKarr]

Glad the video was helpful!

[@mikedx2706]

Great video, Ian. Thanks for posting it. I have to do this rebuild/cleaning of the AAR on my 1.7 Porsche 914. It’s never worked correctly since I bought the car.

[@IanKarr]

You can do it!

[@crtupper]

Precisely what I needed to see for mine. Looks like a project for the weekend! Thanks, Ian! BTW, I was out on LI last week, went to a nice LI VW Club show out in Riverhead!

[@IanKarr]

Cool!

[@MX-fo2nu]

Very good Job and Tip

[@IanKarr]

Thanks!

[@josephhaney3502]

Hi. Just wanted to let you know that your instructional video gave me the confidence to attack the refurbishment of my AAV because the Porsche shop couldn't get the idle to come down - the just blocked it off ! ? ! As I got to the refurbishment, it turned out the sleeve was moving without too much difficulty. I now believe I had too much paint between the AAV and the plenum attachment not allowing electrical operation ! ? Maybe, what I do know is the valve visibly works, and thank you for your excellent instructions. jh

[@IanKarr]

Awesome! Thanks for letting me know the video was helpful.

[@thevintagepassion]

Well done Ian

[@IanKarr]

thanks!

[@waxingchandler3895]

Another great video! Thanks!

[@IanKarr]

Thanks for watching!

[@danielebianchini7584]

Thank you so much! I hope it will work on my 914!

[@IanKarr]

let us know how you do!

[@danielebianchini7584]

@@IanKarr Sigh!!! In my AAR are broken both plastic isolator and electrical resistance.... I tried with hairdryer electrical resistance but no way....

[@Van-tastic]

I almost hate to see you buy a tripod because it’s become a sport to see what you can do one handed lol! But seriously, you need a flexi mount for your camera lol!

[@IanKarr]

Ha! I use both! Actually only a handful of shots in this are handheld. The one in the engine bay kinda needs to be. Especially when I’m shooting at 1am and no one is around to help :)

[@tonyhillyard1613]

Thank you Ian, that is very helpful. One question, what is this "RTV" you used. I have never heard of it. Is it some US based product?

[@IanKarr]

Thanksl Tony I just used permatex black RTV sealant. Pretty much any silicone sealant would work since it's just there to glue things together and keep it water tight.

[@starlightsims9229]

Great video leading me to check my AAR as a source of weird idle. My unit closes with 12V direct but not 100% closed. Should it be 100%? Shutter seems to move pretty easy back and forth when I probe it with a pick.

[@IanKarr]

Mine does close all the way. But you can compensate a bit with the idle screw

[@starlightsims9229]

Thanks. Not sure how to post pictures but in addition to carb cleaner, I turned the AAR upside down and immersed the top 1/2 in an ultrasonic cleaner and that really helped clean the gunk out.

[@stevenhardin996]

Ian, on the bench approx. 8 min close and 8 to return to open. Does that sound within normal range? Does this part this hot continuously when running? It is very hot. 12:05 12:05

[@IanKarr]

Hi Steven. 8 mins sounds long. Does the cylinder turn freely? Shouldn’t be super hot either…just warm

[@tnasburypl]

Ian!? Most awesome video ever I have seen about D-Jet analog electronic fuel injection auxiliary air idle control valves. Extremely rare and expensive when properly working. I PB soaked mine and smacked it several times with a plastic hammer to free it up after not driving for a couple of years. It does not help the bi metal spring pivots on exposed humidity ect from the air intake. The contention is that it needs to be cycled and never sat in moisture. Would like to share some other thoughts about the MPS and control unit as well. Perhaps share a telephone direct contact with you?

[@IanKarr]

Thanks, Tyler! I must admit that, when it comes to the mystical nature of the MPS and ECU, I generally leave that to the wizards. Happy to chat about it with you, though. You can find me as iankarr on 914world.

[@tnasburypl]

@@IanKarr Did you know that the 914 is the 1st electromagnetic fuel injection ever?

[@tnasburypl]

Why it is that your video is historically important.

[@r.arabian3056]

Ian, how did you get the top piece off. mine rotates freely but it looks like it is crimped too. Do you grind in there too?

[@IanKarr]

The top can be pried off with a little leverage. I put mine in a vise and just worked it a bit. But if your AAR rotates freely, don’t mess with it!

[@HugoR12005]

Thanks Ian, very usefull ! Whats that stuff you used to reseal the AAR?

[@IanKarr]

Just black RTV. The stuff that's resistant to oil and gas

[@jean-michel4665]

Hi is this piece used an all 914 ?

[@IanKarr]

Hi. It's for D-jet cars

[@dewder74]

According to a repair manual that I have, L-Jet equipped 914s also have a AAR, but I don’t know if it’s the same part.

[@davedarling4316]

@@dewder74 The early 74 1.8s used the same part (or possibly just looked the same?) but most of the 1.8s used a different part, one that looks a little like a witch's hat laying on its side. Disassembling would be fairly different, but it works on the same principles, with a bi-metallic spring moving a rotary valve (in that case, a disc rather than a tube) to allow or block air through the valve.