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Fuel Injection Problem - air leak

3717 Views 11 Replies 4 Participants Last post by  lasajef
I was having mysterious engine problems. Some days the car would drive fine, most days you could barely drive the thing. If I pressed the gas pedal more then 1/4 way down it would lose all power and then buck like crazy. I followed the LJet manual on Gregs site and had done pretty much everything, short of pulling the injectors. One time when the engine was idleing really rough i poped the hood and started squeezing the vacum hoses with my fingers and blipping the throttle to see if i could feel anything. I noticed that when i pinched the hose going from the Auxilary air device to the manifold things seemed to get better. I pulled the AAV and put my finger over the one end and blew in the other and sure enough it was coming out the seal. I didn't have a picture of my own so i'm borrowing the one from Gregs site. The seal on the opposite side of where the screw driver is pointing. I've just blocked off the 2 hoses while i fix the AAV but now the car is driving fantastic.


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Bob, good job finding that leak. It's becoming almost common for aux air devices to leak. It's even worse under boost! in fact it's hopeless under boost. I really suggest going to a manual valve or if you don't want to do that get a new one for any pre 1990 Z car.

Hi Greg,
I didn't see the manual aux air device listed on your site. How much for one?.
I Jb Welded the seam and now i've discovered that it also leaks around those little round tabs that can be seen above and below the screw driver.
Hey Greg,
It looks like the pre-90's Z AAV has one port on the bottom, where as the 90 to 96 AAV has the ports with the same orientation as the Alfas.
Hmm, well I assumed all the pre 1990 units are the same, I guess they are not. Look at at one from a 280ZX, that should work. Some of the early 300ZXs (1984-1989) have a compatible unit but probably not all of them.

I don't sell the manual aux air valves any more. You can make one yourself. Get a "Factory Air" brand valve from AutoZone, part number 74627. Now the catch is they stock two different valves under that part number. You need the plastic one, which is the one shown in the parts book. You may have to go to two or three AutoZones to get the right valve. Hook it up with hoses just like the original valve and use a cheap choke cable to operate it.

Greg Gordon,
Mine is working (for now), but doesn't close 100%, so hot starts not as good as cold starts. You could replace the AAV with a a manual "choke" valve with wire back to cabin, but I've decided to try a solenoid valve from air suspensions.
eBay Motors: Brss 1/2" Solenoid Train Air Ride Valve Horn Suspension (item 270180646920 end time Nov-02-07 15:33:05 PDT)
I'm gonna wire it to a switch on the console, so it will still be manually operated.
thats a pretty cool solution, i'm guessing it only has 2 states, fully open and fully closed.
The solenoid idea will work, however if it has only two positions, on and off, you will have a very high cold idle when it's cool outside. You really need a device that can open a variable amount in order to duplicate the stock function.
Oh, I dunno - perhaps the stock one does kinda "kick-down" because of the slow closing. It's going to have to wait a bit while I perform a couple of more urgent fixes - But that's what I'm going to try. Full open AAV or full open valve, same difference. Set cold idle speed accordingly yes?
Sort of, if it's fully open, it doesn't matter if it's an AAV or a solenoid valve. However the stock AAV doesn't snap open or closed, it slowly opens and closes. Plus the amount it opens is related to temperature. For example, it may be fully open at 32F, and fully closed at 100F, but at 65F it's in between.
Yeah, time will tell - I'll report back when I have this mod installed.
Here's a source for a new $53 valve for a VW that works on Alfa's. J. C. Whitney supplies Python Injector valves at a reducd price.


That ZX492186Y unit at Whitney should work. I'm not sure about the
connector, but I believe that they are the same.

All the best,

Jason Groom
Vice President Sales & Marketing
Python Injection, Inc.
Venom Performance
Phone: 800-959-2865 Ext. 12
Fax: 714-828-0964
Cell: 714-334-1692

E-mail: [email protected]
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