Adjustable FPR and Exhaust Crank Evac
 

https://members.rennlist.com/porken/HuntleyFPR.jpg
Left: 85-86 damper $43, 5/16" hose barb x 1/8" female pipe sealed with 1/8" plug.
(In the lower photo the plug and damper are not attached.)
Right: Huntley 80-86 adjustable fuel pressure regulator. $165

I've only had a couple of hours of install and adjustment. I'm up to ~40 PSI (stock ~36) and the full throttle mixture is just about right (even at 130 :)).

*Update*
~thread~start~

https://members.rennlist.com/porken/...tCrankEvac.jpg
1/2" pipe, cut 45 degrees $1
Air injection valve $20

Stink is gone! All that's visible is water vapor.

excellent mods! any improvement in performance/running with the ajusted fpr?

Clever, but those mods are smog legal....not!

I also have the same regulator on my car, but I simply blocked off the return line from the original PS regulator and I return all fuel on one of the lines only.

hey porken,

will the rubber hose melt from exhaust heat?

It looks like the outlet is by the muffler, not by the headers.
So it should not be as hot back there...

Although I have heard that you get better suction if you
attach the outlet to the headers, and it burns off the
crankcase gasses more effectively. But in that case,
I think a more heat resistant hose would be needed...

drnick,

Strangely, it doesn't feel more powerful (but it is), it is the lack of drama that is remarkable. Just smooth power delivery from 0-130+.

I've had mixture problems, even before I did any 'work' on the car. I could not tune them out with the AFM bypass screw or anything else I tried. Especially if the oxygen sensor was plugged in. The idle was rough, and it would surge while cruising. I ended up grounding the O2 sensor ECU input (rich all the time) to make it run decently.

With the installation of the mixture meter I could see where it was going lean. With the oxygen sensor in the loop, the mixture would swing wildly, but too slowly, and it would buck when lean. At full throttle it would cut-out over 5700RPM.

It seems counter-intuitive, but the higher I adjusted the fuel pressure, the less time the oxygen sensor rich/lean swing would take. Now it's unnoticeable (as it should be) while driving.

At full throttle now the mixture is about 13:1 on my meter. I'm not sure yet if the cut-out is gone yet, that maybe ignition related anyway.

I'm going to increase the fuel pressure 1 or 2 more PSI to make the full throttle mixture at least 12:1.

...

I welded in the pilot tube after the muffler, where the exhaust temps are much, much, lower. (This was the only place I could fit it anyway.) Heater hose is what I've seen used on most installations. The one-way valve and hose don't get hot, even after a post freeway check.

The exhaust suction doesn't really pull much vacuum, it creates/needs airflow. I've noticed a reduction in oil expulsion from around the engine along with the lack of the steamy oil vapor stench.

John.. - the bastion (bastard?) of smog reduction... :)

I'll have you know, I have all the emissions equipment...safely stored in my garage.

So the dampers are just plugged regulators? No difference internally? A ball bearing inserted in the return hose would have been much simpler/cheaper for me.

I've stopped at 41PSI, which at sustained full throttle gives ~12.5:1 on the meter.

It took 10 CCW (from full rich) turns of the AFM bleed screw to settle the oxygen sensor down, but now it's real smooth. At idle the air/fuel ratio goes lean/rich slowly, with increasing speed the lights go back and forth faster and faster, kind of like a heart rate monitor.

It turns out my 5700+ stutter was an ignition problem. Fixed. Nice to be able to go over 6 grand again.

I'm ready for the dyno - for real this time!
:burnout:

OK I'm missing something here....

It appears that you ran a tube from your air pump to the exhaust. And this apparently decreases the stink?

Makes sense: add O2 to the exhaust so that chemical by-products of combustion can finish their reactions in the pipes. Am I right?

OK. Last night I made an asshole of myself [temporarily] by removing my plugged S4 cats and fitting an Ott X pipe. While I was down there, slithering over my garage floor like some sort of snake, I happened to notice the following. What is it? And where does the vacuum line that curves up attach to? I think this is an EGR. A copper line runs from this part on the passenger side manifold to the bottom of the spider...

Could this missing vacuum line figure in my Rough Running problems?

Normy!
'85 S2 5 Speed

PS: There must still be some adolescent hormones in me. I'm THOROUGHLY ENJOYING the sound of that Ott/Borla exhaust! I've learned to drive it- lowest rpm possible driving around keeps it almost quiet, but give them open throttle at 3k rpm for the nicest rasp you can imagine!

Forgot to add the picture...

N!

N!,

The tube goes from the oil filler cap down to the exhaust, where, by having welded a tube part-way into the exhaust pipe, a partial vacuum sucks out the steam and oil vapors from the engine.

Previously I just had just a K&N breather on the oil cap, and the stinky engine vapors would waft out when idling, now they get sucked out the back. It's basically the same as the factory PCV system, except that the oil and water vapors go directly into the exhaust, ie. they are not burned by the engine.

Oil-vapor reduces the effective octane, and steam is unburnable.

...

I know what you mean about the bad-ass exhaust thrill.

I can swap out the rear section of my 3" exhaust for a straight pipe, which rattles your ear drums at part throttle, but at 5 grand, it's luverly.

I confess. When I have the straight pipe in, I look for open-pipe Harley riders and drive up next to them in a low gear just to rattle their ears for once. ;)

https://members.rennlist.com/porken/HammerSystem.gif

I'm going for broke the next time at the dyno. I'm going to use the straight pipe for max power.

Oh Porken I know EXACTLY what you are talking about! A hooligan exhaust does nothing but encourage you to drive!

N!

'85 S2 5 Speed

Oh yes, mine appears to be smog legal too...

PorKen,
Excellent job on the mods!

I'm looking to install an ARRFPR myself (did it on my old 80), but my S2 doesn't have an O2 sensor.
Is there a good way to measure my AFR w/o an O2 sensor? ...or is my only option to install one for the sole purpose of measuring AFR?

Btw, how did you get you ignition not to cutout as it was doing (@5700rpm)? I have the same problem....

BC,
I like your suggestion of having the oil vapors released into the hot exhaust manifold.

I pulled the plugs to regap them. The plugs all have a perfect light brown dusting, ie. the mixture is dead on.

Jadz928,

Thanks!

You can check the plug color, but that doesn't tell the whole story, for example at full throttle.

Really, a mixture meter is invaluable, even if you are just trying to get the stock engine tuned. It makes it so easy to see what is happening at different times. If you get one, you'll kick yourself (like I did) for not installing one sooner.

I was being coy about the ignition problem because I want to put said problem back on eBay. :) (It was the Perma-Tune ignition box.)

If you put in a exhaust vent, make sure to put it after an oxygen sensor, otherwise the sensor will give false readings and might get fouled too.