My CQ 20V is now running with a 078133471A fat MAF.
11-27-2006, 04:46 PM
#1
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My CQ 20V is now running with a 078133471A fat MAF.
I did the wiring exactly like I did on my 12V. I used a 3" silicone elbow, a Mance recovery sleeve (for the crankcase breather and ISV hookups) and another piece of 3" ID silicone hose to get from the throttle body to the MAF. I had to throw an Akimoto cone in front of the MAF since I couldn't make it fit with the stock airbox. I hate/don't trust oiled cotton filters, so I'm hoping to be able to integrate an OE Audi airbox of some sort when I get a chance (I now have spare B3, B4 and C4 airboxes here, hopefully one of them will be able to be shoehorned in).
I haven't yet set the new CO potentiometer exactly. I'll be borrowing a Fluke (all I have are cheap multimeters whose averaging I don't trust) and hooking it up where my A/F meter is connected now, adjusting the CO pot to get an average reading of 0.5 volts from the O2 sensor output. For now, I just fiddled with the pot until the engine ran smooth, but I doubt it's right on.
<a href="https://forums.audiworld.com/12v/msgs/28235.phtml" target="_top">Original 12V post with 4-pin to 3-pin wiring schematic.</a>
UPDATE: here's a pic:
<center><img src="http://pictureposter.audiworld.com/70334/cqmaf.jpg"></center>
I haven't yet set the new CO potentiometer exactly. I'll be borrowing a Fluke (all I have are cheap multimeters whose averaging I don't trust) and hooking it up where my A/F meter is connected now, adjusting the CO pot to get an average reading of 0.5 volts from the O2 sensor output. For now, I just fiddled with the pot until the engine ran smooth, but I doubt it's right on.
<a href="https://forums.audiworld.com/12v/msgs/28235.phtml" target="_top">Original 12V post with 4-pin to 3-pin wiring schematic.</a>
UPDATE: here's a pic:
<center><img src="http://pictureposter.audiworld.com/70334/cqmaf.jpg"></center>
11-27-2006, 05:54 PM
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Great to hear! I hope my questions had something to do with getting you motivated?
Let us know what you come up with for a final potentiometer setting? I was going to hook my setup up this weekend but ordered the wrong 4-pin male harness plug from 034efi. I'm guessing you had to cut the metal breather pipe that connects to the stock air boot?
For an idea of what the setup looks like...<ul><li><a href="https://forums.audiworld.com/9080/msgs/374511.phtml">My Setup</a></li></ul>
For an idea of what the setup looks like...<ul><li><a href="https://forums.audiworld.com/9080/msgs/374511.phtml">My Setup</a></li></ul>
11-28-2006, 08:57 PM
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I wanted to get it done to make sure I was answering all the questions correctly. :)
I've had alot of people asking about this since I first suggested that my 12V method would work on a 20V. I'll hopefully have more details/answers when I get some free time in a couple of weeks. Be sure to let us know how your install goes!
11-28-2006, 09:02 PM
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I haven't had much time to test it yet since work has interfered with my fun. :(
This particular MAF is as-yet unmodded, so it doesn't really flow much better than the one it replaced, but there does seem to be some power increase already, perhaps just from the intake boot flow improvements. The beauty of this mod, however, is that these later MAFs can be modifed/bored to great effect. I'll be doing that in a couple of weeks, hopefully. If it's anything like the improvement I saw on my 12V, the power increase is substantial, especially in the upper RPM range.
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11-28-2006, 09:28 PM
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Here are some details about CO potentiometer settings I posted under Zzak's thread at another forum:
You really need to set the CO potentiometer (this applies to either the old CO pot built into the MAF you are replacing, or the new CO pot you are installing here) according to an exhaust measurement, with the goal being a stoich mixture.
On 7As manufactured before March 1990 (an easy way to tell is if it has a Hitachi ISV), an average reading of 0.5 volts from the O2 sensor should do in a pinch - don't unhook the O2 sensor from the ECU, just tap into the signal wire like you would if you were installing a narrowband AF meter (this method still untested - I'll have my results with it soon). A wideband AF meter or an external exhaust sniffer (Sun EPA 105 or equivalent is recommended by Bentley) will do better.
If your 7A was manufactured after March 1990 (Bosch ISV), you should set it with VAG-COM - adjust the CO pot until you get a reading of 128 from measuring block 08.
See Bentley pages 24-180 (pre-March 1990 cars) or 24-390 through 24-395 (post-March 1990 cars) for more details on setting the CO pot. Some of the steps outlined there are not necessary, but it's good reading to understand what's happening here anyway.
You should really have a (narrowband at least, wideband is probably overkill) AF meter installed before attempting this mod. Become familiar with the patterns on it under all throttle positions and loads with the stock MAF. These patterns should not change after this mod - if they do, something is wrong.<ul><li><a href="http://www.motorgeek.com/phpBB2/viewtopic.php?p=153033&highlight=#153033">http ://www.motorgeek.com/phpBB2/viewtopic.php?p=153033&highlight=#153033</a</li></ul>
On 7As manufactured before March 1990 (an easy way to tell is if it has a Hitachi ISV), an average reading of 0.5 volts from the O2 sensor should do in a pinch - don't unhook the O2 sensor from the ECU, just tap into the signal wire like you would if you were installing a narrowband AF meter (this method still untested - I'll have my results with it soon). A wideband AF meter or an external exhaust sniffer (Sun EPA 105 or equivalent is recommended by Bentley) will do better.
If your 7A was manufactured after March 1990 (Bosch ISV), you should set it with VAG-COM - adjust the CO pot until you get a reading of 128 from measuring block 08.
See Bentley pages 24-180 (pre-March 1990 cars) or 24-390 through 24-395 (post-March 1990 cars) for more details on setting the CO pot. Some of the steps outlined there are not necessary, but it's good reading to understand what's happening here anyway.
You should really have a (narrowband at least, wideband is probably overkill) AF meter installed before attempting this mod. Become familiar with the patterns on it under all throttle positions and loads with the stock MAF. These patterns should not change after this mod - if they do, something is wrong.<ul><li><a href="http://www.motorgeek.com/phpBB2/viewtopic.php?p=153033&highlight=#153033">http ://www.motorgeek.com/phpBB2/viewtopic.php?p=153033&highlight=#153033</a</li></ul>