ALFAGTV6.COM

SamW · Post by **SamW** » Mon Jun 20, 2005 3:13 am

Greg, you seem to be the expert on these things, how do the Bosch one's work? They have a power lead and the other goes to teh ecu, are they timed to come on after a little while, or do they shut off after the engine warms up? I know they have the bimetal strip to close the hole after the engine warms up, but not sure why the ecu would control it?

Hippo58 · Post by **Hippo58** » Mon Jun 20, 2005 3:35 am

Sam, have a look at Greg's website. It has everything written in detail about how the AVV works and how it can be diagnosed and tuned. I think the cable is there in order to help the valve warm up and not to control it. I don't think it goes to the ECU.

hmm... you are talking about the gtv6/75 AAVs right?? But you might as well relate to the newer AAVs since you have a motronic 3L installed.

SamW · Post by **SamW** » Mon Jun 20, 2005 4:35 am

The wiring diagram shows one wire going to the ecu, and I traced it on the harness, so I am just trying to figure out how to make it work with GoTech...

Greg Gordon · Post by **Greg Gordon** » Mon Jun 20, 2005 8:36 am

Sam, the ECU and AAV do not talk to each other. The ECU has no idea what position the AAV is in.

The wiring to the AAV simply provides current to heat it up. This helps it close at a rate that's compatible with the enigne's needs.

If you disconnect the wire the AAV will still work but it will close too slowly causing a high idle speed for a larger portion of the warm up period.

It's no secret that I don't like the Bosch AAV. It's too imprecise and it doesn't provide a great enough range of additional air flow for all the temps we get here in Texas 20F-120F. In other words it doesn't open enough on the coldest winter days, and it doesn't shut fully which robs a slight amount of horsepower.

To top all this off, it's very sensitive to oil and debris fouling it up. When this happens it quit's working well. Plus it's really expensive. Oh and I just learned that some of them are not air tight! A friend of mine just went through 3 of them trying to find one that was truely air tight (this was discovered as a supercharger boost leak).

I say dump the AAV and replace it with a manual valve. I have on all three of our V6s and I can say it's a great improvement. Not only in reliability but because it makes other problems easier to diagnose.

SamW · Post by **SamW** » Mon Jun 20, 2005 9:08 am

Greg,

thanks, I may try one of yours, but the AAV has a power wire and a wire to the ECU, should I assume the ECU wire is a ground, and simply ground it?

Greg Gordon · Post by **Greg Gordon** » Mon Jun 20, 2005 10:21 am

Sam,
I no longer sell manual valve but you should be able to match something up at your local part store. If not I can give you part numbers to look for.

Let me check on that wiring diagram and get back to you.

Greg Gordon · Post by **Greg Gordon** » Mon Jun 20, 2005 10:53 am

Ok, I just checked the wiring. It certainly looks like that's a ground. That whole side of the ECU is full of component grounds that tie into the main ecu grounds. If someone offers an alternative opinion I will go open up an ECU to verify it, but right now I don't see how it can be anything else.

SamW · Post by **SamW** » Mon Jun 20, 2005 10:57 am

Thanks Greg, I will attach it to a ground and see how it works, do you have a good idea of how the AFM triggers the Fuel pump, I could not follow this on the wiring diagram...

Greg Gordon · Post by **Greg Gordon** » Mon Jun 20, 2005 7:01 pm

It triggers the relay set which sends current to the pump. You can actually hear the relay set click when you move the flap.

SamW · Post by **SamW** » Tue Jun 21, 2005 3:45 am

Is that part of the combo relay, or is it somewhere else? DO you know where?

Reale · Post by **Reale** » Tue Jun 21, 2005 3:48 am

The AFM flapper triggers part of the combo relay.

DaveH · Post by **DaveH** » Tue Jun 21, 2005 4:13 am

Sam,

Check this 528i L-Jet schematic out: http://www.firstfives.org/faq/ljet/528i ... ematic.PDF

It's a bit clearer than the Alfa diagram you have. It shows the ECU providing a GND to the AAV.

Also, for the combo relay, it looks like the fuel pump is triggered by the ignition switch in the 'start' position (current to '86a'), then after that it is maintained by the AFM switch (flapper switch) once the key is returned to the 'run' position.

You can see 'Relay B' is turned on by the ig switch in 'run' position. This provides voltage to pin 39 on the AFM switch; the AFM switch is now providing voltage to the fuel pump relay coil. Pin 20 on the ECU is prob just feedback so that the ECU knows what's going on.

I just used up all of my coffee reserves...need to go and refill now.

SamW · Post by **SamW** » Tue Jun 21, 2005 4:57 am

OK Dave, So can you tell/show me how to wire the Aux wire from GT to keep the FP on?

I have the wiring harness lying in bits on my living room floor!

DaveH · Post by **DaveH** » Tue Jun 21, 2005 5:08 am

I think so. I need to look at the GT literature though.

Is this Aux wire pre-programmed to turn the FP on? If so, it looks like it needs to be wired to whatever 86b is on the Alfa combo unit. Pin 85 needs a ground from somewhere.

We need to do more research over a pint or 2.

SamW · Post by **SamW** » Tue Jun 21, 2005 6:14 am

Let's continue this under the GT forum...

AAV question

Relay