VAF Tuning

[link5186]

Hey guys, here's the deal. I've been doing a bunch of reading about the hesitation and wierd idle issues that have been plaguing some members as I have noticed the same issue with mine. I knew the ignition timing was off on mine. I finally got around to re-checking my valve timing, installing a timing cover (woot!) and dialing in the ignition timing dead on the mark. The problem got worse! Not only that, the exhaust manifold got really good and toasty. Everything else has been checked. Plugs good, wires new, cap and rotor good, valve timing good (double checked #1 tdc through spark plug hole), injectors good, fuel pressure good, fuel filter new, iac good, vacuum lines good, O2 sensor new (denso), Coolant temp sensor good, and so on.

So on a hunch I figured I'd pull the VAF cover and see what I come up with. What I found was marks on the spring wheel that seem to indicate that the adjustment has slid (probably due to a hard hit on a chunk of "patched" asphault). I did a little bit of playing around with the spring wheel just to see what results some minor adjusting would do, and was rather pleased with the results. I should have left it after the first adjustment, considering how easy it was to break traction and the smoothness of my idle, but this was for science! I just had to play more. After some trial and error adjusting I finally gave up and threw on a spare VAF. Seems sluggish with the spare, but leaps and bounds better than the other before adjusting. Without any method to gauge my air-fuel mix I don't care to run it regularly like this.

That brings me to my question: has anybody tried making adjustments to their VAF and what kind of experience did you have with it?

[M3NTAL]

http://www.youtube.com/user/aintnobitchms?feature=mhum#p/a/u/0/cyRxVTh8jXQ

[Pu241]

Took me a while to find it, but I remembered this thread hope its of some uae.

http://www.fordfestiva.com/forums/showthread.php?t=8591

[link5186]

Thanks guys! Looks like I slid about 6 teeth to the rich end of things. Explains my drop in mileage too. Maybe he's just begging for boost!

Sent from the bathroom via crapatalk

[sc72]

Pu241, have you personally made this adjustment and what were the results.

[Pu241]

No, I have not.
Probably safe to go a few clicks without issue, but I was waiting to get a AF gage and maybe an exhaust temp gage.
This way I can monitor the changes and hopefully avoid burning a valve.
Now that I think of it this is the perfect way to get all the benefit purported by HHO crap without the snake oil hardware cluttering up the engine compartment.
Just have to be careful as the alloys of both the pistons an valve have limits, and if you exceed the margin built into the engine you will reduce longevity.
This then leads to contemplate the use of some of the ceramic coatings for the pistons and valves, or maybe use sodium filled valves if we can find any that could be modded to use in a B3 or a B6 for that matter. Much interesting stuff might be learned with a little work.

[sc72]

The AF guage, isn't that a fancy vacumn gauge, The E.G.T can be found at any speed parts wharehouse. Sodium filled valve stems, they can be ordered to the right length from Manly valve systems. So for the E.G.T. were in the head pipe would you put it, before or after the o2 sensor.

[91mcnasty]

I'm gonna give this a try and see if it helps with my studded problem, I'll report back tommorow!

[link5186]

So here's an update from me. I got off work and decided to fiddle around with that VAF some more. I was wrong on my last post in that it actually slid lean. Did a rough-in adjustment through a combination of throttle snapping and sniffing at the exhaust (WOOHOO!). There's a bit of a sweet spot where I don't get a stutter when I snap the throttle open. I choose a spot on the slightly richer end of that range just to be on the safe side. Test ran into town and then to my folks appartment. So far so good. I'm idling great and pulling pretty smooth through all the gears. Great response between 3k and 4k rpms. I'll be pulling the plugs later tonight just to get a general idea of how it's going and I may do some more tweaking from there. This is the stuff that makes me wish I had a wideband.

How's it going over there mcnasty? I know you had your idle speed screw bottomed, so I'd start with backing it out a bit. If you don't get any change out of it I do have an extra VAF (yup I keep 3) you can swap in to make sure you aren't shorted partway through. Another thought, double check to make sure the dashpot isn't frozen up and keeping your throttle part way open. Also, before making any adjustment I'd recommend marking the spring wheel just so you know where you started.

[91mcnasty]

I had an extra as well so I swapped them out then cut the cover off and went four clicks to the right. My car smelled badly of gas and didn't respond very well so I set it back to factory, then went two more clicks left. Response seems great and it pulls good, I still can't figure out why it idles so high. It's idling around 1350, even when warm. It's getting really annoying!!!!

[sc72]

Have you taken the IAC off and cleaned it, it helped my car.

[91mcnasty]

Yup about three times!!

[Zanzer]

So I'm guessing from these replies the turning the wheel to the right (clockwise) makes it richer and going to the left (counterclockwise) leans it down?

I have an extra VAF that I took the cover off of because the silicon was coming loose. I was going to reseal it with black RTV but now I'm thinking it would be the perfect test piece for trying this