Auxiliary Air Regulator

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914NNP

Auxiliary Air Regulator

Post by 914NNP » Mon May 26, 2003 11:36 am

Hey.
I remember having read a post which described the process for rebuilding an Auxiliary Air Regulator. I think Mr. Greenwood was a major contributor. I've searched this site and the Pelican 914 site but I can't seem to find it. Can anyone point me to it?
If Mr. Anders is out there, I'd like to suggest that this information would be quite complimentary to what he already has on his web site, a site that I know most of us consider to be the definitive location for 914 information.
Thanks.

DaveCa

Re:Auxillary Air Regulator

Post by DaveCa » Mon May 26, 2003 7:53 pm

:D
I have been developing a idle speed regulator that uses a solenoid air control valve. The circuit has a micro-controller with inputs that connect to the coil for RPM measurements, temperature sensor, and throttle position switch. It can be easily setup, with a Palm computer or PC with a serial port. I have been testing on a type3 engine at the moment. I it should work for any fuel injected engine.

Features:

Fast Idle settings for warmup and AC, or other loads
Battery Voltage Monitor
O2 sensor monitoring
Temperature monitoring
Auxillary Switch Monitoring
Serial Setup and Monitoring Connection
2"x3" circuit board with screw terminal connections
Modern relable air control valve with 2 ports

If there is interest in this please let me know. I expect the initial price to be about $100 including control valve.

Also in the works is, an EFI/Ignition system specially designed for 4-cylinder air cooled applications.

Dave

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raygreenwood
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Post by raygreenwood » Tue May 27, 2003 1:52 am

Just a question, why would you need an idle air controller on a type 3 with D-jet? It never had any variable idle problems, unless there were vacume leaks or huge variances in fuel mixture. Also, how are you going to keep the introduction of an outside air source...that is not planned for or known about by the D-jet ECU, from causing the MPS to enrich at inoportune times? The auxiliary air regulator, is not really similar to the later model multiposition idle air controllers of Digifant and later injection. Those are activated by the ECU in response to sensor input...usually temperature....to add air into the mix, when the necessary response is either below the "encremntality" of the metering system...wether its flap or hotwire....or is needed to re-establish a new baseline idle mixture when the ambient changes a noticable amount. In basic D and L jet, the AAR is only used...or needed, during warmup phase when extra air is needed because fuel is condensing on the cylinder walls...and also because the cold sensors have upped the enrichment level Just .wondering...Ray

Guest

Post by Guest » Tue May 27, 2003 8:16 am

Ray,

You are correct that the type3 in correct operating order keeps running at idle reasonably well. The idle air controller leaks justs the sufficient quantity in the same manner as the original auxillary air to maintain the suggested idle speed. It can be done with time and temperature in a fashion identical to the original.

It has been my experience that most auxillary valves need to be dissasembled and cleaned otherwise they are often stuck. This control system is for those who desire an alternative for an obsolete part.

The built in diagnostics and the ability to configure the system makes it an excellent engine tuning tool. The parameters, O2, temperature, RPM, battery voltage, tps location aid in checking for proper operation.

Idle control will be integrated into the EFI system also under development. The air bypassing the throttle increases the manifold pressure suggesting a richer mixture. A modern EFI system has the ability to correct the mixture even at idle.

I have experience with D-Jet EFI on a 2.0L 914. The engine runs quite well and meets clean air tests. I feel the idle control could be improved.
When cold it is slightly rich, when medium warm it is lean and hunts slightly, when warmed up it runs correctly and meets local clean air specs.

I am on a quest to make a EFI system make aircooled engines run the best they can all the time. I have just started working on this full time.

I have been working on VW's since 1977 and the EFI system part time since early 1997.

Dave

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raygreenwood
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Post by raygreenwood » Tue May 27, 2003 8:41 am

Yep, the original auxiliary air reg definately needed cleaning ocassionally. I have not found them ever to leak though, when adjusted properly. The reason most of the D-jet models have the stepped slot is to run a little better in the 8 minute or so medium warm up phase. Most of what you are finding in that phase with D-jet is from the CHT and not the AAR. On my last engine, with a bit of tuning, I was able to remove the AAR. Not recommended on every engine though. I do know that the AAR on other types of injection are designed to sometimes have an air bleed built in. Thats why I tell people to be careful when swapping in non-stock AAR. Some are very specifically tuned for the engines they came with. Many watercooled engines have a bleed in the AAR.
A lot of the midrange warm-up difficulty is from the CHT, as I mentioned. Ballasting will help (variable potentiometer). The rest is a combination of adjustments to main load stack sensitivity on the MPS and installing a temperature sensitive cut-out for the manifold temp sensor. Most can get away with simply unplugging that one. It has problems...like the CHT, with banking heat. Most of the warm-up phase issues can be tuned out though, with little defference to the AAR. One problem with tuning the MPS for higher performance andleaner running, is that it becomes overly sesitive to any vacume leak not induced by the throttle plate. Glad to meet someone else who likes to play. Ray

DaveCa

Auxillary Air

Post by DaveCa » Tue May 27, 2003 9:03 am

Ray,

I am impressed with your ability to tinker and modify D-Jet system. You have skills that few have.

I hope to bring the adjustability of EFI systems to the masses with a EFI controller with a simple Palm interface. My work will aided by the +36 years of technology progression since the first D-jet was introduced in 1967. The sensors and computation methods are much improved today.

I am starting to be off topic and should relocate this to the EFI forum.

Dave

914NNP
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The original question

Post by 914NNP » Tue May 27, 2003 10:20 am

So raygreenwood... did you post a fairly complete description of how to rebuild the AAR and if so where might I find it?
Thanks.

Guest

Post by Guest » Tue May 27, 2003 10:44 am

Plug the AAR valve into 12V and if it gets warm the little heating unit is fine. Usually the valve is just rusty and you can free it up by squirting some PB Blaster (not WD40) into the ports. Let is sit and then hook it up to 12v to check that it closes after a few minutes.
Geoff

914NNP
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PB blaster

Post by 914NNP » Tue May 27, 2003 11:20 am

Thanks Geoff.
I've not used PB Blaster before. Is that something I can get at B&B or Schuck's?

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vwduud
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Re:Auxillary Air Regulator

Post by vwduud » Tue May 27, 2003 12:18 pm

DaveCa wrote::D

If there is interest in this please let me know. I expect the initial price to be about $100 including control valve.

Dave
Dave, I have been contemplating a similar idea, to control idle speed, but just haven't had the time to do the R&D. I am definitely interested in having better idle control. Would you please e-mail me, so I can contact you? vwduud@yahoo.com. How close are you to having a releasable version of this? - Jim

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raygreenwood
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Post by raygreenwood » Tue May 27, 2003 5:28 pm

I seem to remember that the description may have been back around January of this year. There were several other persons comments about various ways to re-do the heater coil itself. It was a good thread if I remember right. I have also contemplated simply removing the bottom cup, install a nice bracket and an 0-ring for the valve shaft and either using a solenoid with a simple thermo time switch to close the valve...or simply using a cable. With D-jet...in general....having encremental closing of the valve is not really important. Even in the mid ranges, the idle only changes a hair. This was also part of my earlier point. When the D-jet is properly adjusted...there should be no change in the rpm from open to close. This is not really just like a choke. It is....as the name implies, an auxiliary air source. It should supply, when the fuel mixture and MPS are adjusted properly, just enough air to keep the engine idleing at the correct level. It is designed to bleed air into the mixture...mainly because the system sensors are stone cold, the fuel mixture is heavily rich, and the idle circuit passage itself is generally not enough to maintain NORMAL idle. If your engine idles at 900.....it should stay that way from open to close on the AAR...if all else is correct. By the way, this is the nice thing about the type 3 AAR. You can pull it out of the block, and re-set it with the set screw and scale, so it operates properly with your engine. The type 4 AAR has thesame adjustment, but it is factory sealed by the electrical cover on the bottom. Ray

pbanders
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Post by pbanders » Thu Jun 05, 2003 6:04 pm

The purpose of the AAR is to provide additional air past the throttle plate to elevate the idle when the motor is cold and must ovecome additional friction while warming up. When everything is working correctly, for a "cold" motor (sitting overnight), right after starting, the idle will be at about 1800 rpm. As the AAR heats up, both through engine heat radiating up from the case, and from the internal heater (13 ohms, powered by +12V source from the relay plate), the bi-metallic coil rotates an internal port, shaped so as to provide smooth transition down to normal idle levels (about 950 to 1000 rpm).

AAR's often fail from internal crud that jams the rotating port, blocking it either open or closed. Spraying solvent into the port and sitting overnight can often clear this type of problem. The other main failure mode is the heater coil either failing open or short. Short is easy to detect, it blows the 25 A fuse until you figure out there's a problem. Open is a bit more tricky, as the AAR will eventually shut just by engine heat alone. If your car has a high idle for longer than 5 to 10 minutes after starting, check the coil resistance and see if it's open.

Rebuilding an AAR is done by prying back the lip that retains the top plate, opening the unit, and cleaning and repairing the coil if needed. The 13 ohms of resistance that the heater provides can be replaced by small (but properly-rated) power resistors, enough to total to 13 ohms.

Brad Anders

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