OK, I have been tinkering with the new-to-me AFM on my 1911cc engine all weekend. I have adjusted the spring about 20 teeth CCW to get to this point.

I have been using an A/F sensor and gauge. can someone tell me, or direct me to a chart/table of what A/F I should be shooting for on my daily driver.

The last adjustment of the CO screw has left me here:

I have always had a strange idle situation, so lets ignore that for now. any normal adjustments to reduce the idle at normal operating temp eventually stall the car. A problem for another post.

the idle is high.... at 1200 the A/F is a smooth 12.2.

I found a long hill and drove up it at about 3800 rpm and the A/F was 12.5.

thoughts?

Got this from one of Chris Foley's posts

in A:F ratio, you want to see:

13.5-12.9 on the gauge while accelerating or climbing,

12.8-12.5 at WOT,

and 16-17 while cruising, going downhill or decelerating.

Right now I am in those ranges with FI. A little richer on WOT as I can get to 11.5 at times. But seems to run well in these ranges.

Great. I get to drive to work tomorrow (no rain). So I will do some documenting. Thanks.

My experience ( before and after the top end rebuild and new TB) is 12-13 idling in the am; constant cruising speed 14-15.5; up hills it richens a bit.
I used the innovative as the AFR for 3 years; just removed it though.

Agree with the ranges in Jim's posts for varying load conditions.

Getting idle and AFR can be a challenge. As the engine warms up, things expand, adjustments can change, seals seal better. In tuning the ITB's on my car, I find that it liked around 12:5 or less at idle. If you open the throttles slowly, the afr would take a dive just as the throttle plates opened, and came back to a more expected level just after that. Listen to your engine, give it what it wants. The guidelines are just that- expected guidelines. Let the motor tell you what it wants to run best, and do that.

Peak power is made around 13.5:1, idle is usually smooth at that level as well. You can run leaner at cruise for fuel economy especially if you have load sensing for timing advance (vacuum advance or programmable system). You can get as lean as 15s if you can advance timing enough, but be sure your system will retard and richen as soon as you put a load on it or detonation and eventual damage will occur.

I don't like to see much higher than 13:1 in an iron cylinder engine, my nickies engine I can easily run 14:1 no problem.
I can really see the performance degrade as the temps go up in a iron cylinder engine if you run much over 13:1, the nickies equipped engines doesn't suffer from this issue.

Deceleration it doesn't matter...no load.
I have a fuel cut below a certain TPS setting so on decel my meter goes off the scale.
Fuel cut stops popping and/or backfiring on decel on wild cam engines.

plays with cars I'll have to say you are wrong, those number might be fine on a watercooled car, but aircooled always needs to be a bit on the rich side.
Trying for those numbers on an aircooled and you will hole a piston.

Big issue on a performance, wild cam, ITB Type 4 is your vacuum signal will be total shit. This gives the MAP sensor a horrid signal that peeps chase forever, often blaming the FI system.
I run TPS/O2 only program on my T4 2600cc engine, zero issues, runs on par with a modern FI car.

Aircooled engines may need to run slightly more rich than the water coolers

When in doubt, do the spark plug color test.

I still do this time to time as a control, but a proper working O2 wideband meter will be spot on.

I tune both FI and carbs with a wideband, they're so cheap now anyone who tunes their own engine should have one.

Doing final tune on my Zeniths,dropping idles down a touch as well as mains,I always run a little fat on the jets with any aircooled engine.
I don't really trust plug colour to much with the modern fuel.
Mark what is the best performing/value AFR kit to use?,would like to install one,the 911 engine is a hungry beast on carbs would like to get that the best I can.

Help me out with WOT. I played with that a little at lunch today.

How do you test that? I was running in third gear about 45 mph. I floored the pedal. The car picked up speed and the gauge dropped to 10-ish and the car accelerated.

I only held the pedal down for about 15 seconds. Was not sure I was doing it right.

How and how long?

You want one with the biggest LED numbers, a tiny dial or numbers are hard to read on the fly.

I'm not sure what's best now, my O2 WB is a WMS that I bought 10+ years ago and has been solid as a rock. They stopped making them because they couldn't compete against the cheap china made units, it cost $500 back then. It's small but has 1.25 tall LED numbers.

I've heard good things about the PLX and if you're a techie they have a bluetooth for your phone or tab. Like my WMS it has datalogging, but with the bluetooth option you can do this right on your phone.
But there's also a real cheap one on evilbay for $135

Beware of the $80 Inovate "deal" on evil bay, it doesn't have the lambda sensor... the most expensive part.

I think it would be a cool gauge to have. Would it be better to have it as part of the car or a tool in your toolbox?

Thanks have somewhere to go now,

Yes I do this all the time BUT for some odd reason the lambda doesn't like to be removed and reinstalled many times. After it has been in several cars they tend to fail. They also seize in place, but using an anti seize paste they often don't ground properly.
Believe me at $80-$100 a pop I'm damn careful removing and installing them, but they still fail.
Leave it alone and they will last 100K+ miles. If it's dedicated to the one car leave it installed on the car.
Aftermarket FI you have to have a O2 sensor for the computer.

It's a great tool to have, especially if you're going to start messing with the AFM. I picked up an Innovate, from eBay, almost 4 years ago. Works fine. My car runs well, but cold start up requires a foot on the throttle for 30-60 seconds, depending on temp.

Hope to get it on a lift within a month for a good valve adjustment and some push rod tube seal replacement...

That's theoretically ideal. But if you want to drive your car in the real world, you need to forget about theoretical. Or at least pay more attention to what the engine is telling you. No dyno-graph in the history of cars had peak power at 13.5:1. Ever.

I've heard reading spark plugs was more accurate on older fuels. Supposedly new fuels don't indicate as well on the spark plug. I don't have any real world experience to share in this department though. I look at them, I 'read' them, but I don't trust it much.

You want to hold WOT and see how things respond. So it's one of those annoying answers -- hold it long enough to learn what you need to know. 15s should tell you all you need to know though. You want to see AFR go rich as soon as you hit the gas and stay rich while at WOT. You want something in the neighborhood of 12:1. 15-16 at cruise will give you great fuel economy, but may be a little lean in my experience.

Reading spark plugs became outdated with unleaded fuels. Mark, you never really lived with leaded fuel so...

Not totally and it also helps when looking for mechanical issues. You are still looking for a greyish or brown tan colour and oil fouling and too lean still looks the same.
I use the plug check when I suspect the sensor may be failing.

Way too lean or rich I don't need a meter to tell me that the engine is running like shit, but it sure makes life easier.

But on top of the WB meter you should have a head temp gauge, if you do try to lean the engine for cruise you will see your head temps climb like crazy when you go too far.

Yesterday, travelling the same route I always travel, I noticed that my CHT was slightly higher than it had been. Higher that is, when I was on the interstate, about 70 mph, going up a long hill. The normal reading was slightly below 350. I was slightly above 350. so maybe 15 - 20 *F higher.

The AFR was reading 12.5-ish. So I would be concerned if I needed to set the AFR at 15-16 while cruising at 70mph.

350 degrees is not normal, atleast I hope not. Remove the thermostat cable and repeat the test.

The good thing about a CHT gauge is you know your CHT. The bad thing? You know your CHT.

These engines are highly dependent on fan speed. I found 5th gear with good stock EFI to be almost unusable!

3000 rpm rule, for proper cooling never drive below 3000rpm.
Don't lug those engines boys!

Well this car has run between 325 and 375 since 2013.

The VDO CHT gauge has 350 at 12 o'clock. Each tick is 50 degrees. So around town I am just above 300 and pulling long hills on the interstate I get just over 350, not quite to 400.

Somewhere on 914world is a nice write up by Jake. He explains a lot about CHT. From what I remember this car pretty much follows the temps in his explanation. I will see if I can find it.

By the time I get to the 2nd stop sign in my neighborhood the T-stat flaps are (or should be) wide open. If I disconnect them, they will be wide open for that first cold 1/4 mile. Disconnecting would have no effect on interstate driving 10 miles from home, everything is nice and hot by then.

A quick video of the car in the garage. I posted this one on my AFM thread for you Tim. Notice at 11 seconds.... CHT is 325-ish.


https://www.youtube.com/watch?v=BMspGlzl6Lo

I remember hearing that several years ago when I asked a question about shift points on a daily driver. I believe it was Cap'n Krusty that said to shift closer to 4000 and cruise or drive at 3000 +.

70 mph cruising on the interstate in 5th gear, my RPMs are 3200 or 3400, something like that. and CHT is 350 to 360. If I go faster CHT moves up a bit. And as I mentioned above AFR was 12.5 (that was Monday). Still in the adjustment phase with AFR.

not exactly what I was looking for, but it will do:

Click to view attachment

When I set up my L jet that had been horribly messed up, after warming up the car I jumped on the freeway and ran at 3000rpm. WOT was running way to rich as was AF ratio at 3k. I would shoot down an offramp, tighten the spring and jump back on the freeway. When I finally got it to run at 15.8 at 3k the WOT was right where it should be. Popped the lid back on the AFM and the only problem I have had since is that when really cold I need to crack the throttle just a bit to start. The motor is old and a bit low on compression but cruises like a dream.

When you say WOT was "where it should be", do you mean per Chris's statement (12.8 -12.5?)?

And when you say "run at 15.8 at 3k" are you cruising, downhill or decal-ing, also as Chris suggests?


one of Chris Foley's posts

in A:F ratio, you want to see:

13.5-12.9 on the gauge while accelerating or climbing,
12.8-12.5 at WOT,
and 16-17 while cruising, going downhill or decelerating.


I need to read up on all the adjustments, cause when I move the spring every level moves.

I have not moved the spring this week, but I did back out the CO screw. It is about centered (4.5 turns from the btm) now, with the @20 teeth CCW of the spring(last Saturday) I get:

12.5 at @1K idle,
12.5 at 3200 cruise at 70mph
10.5 at WOT.... after about 15 seconds the needle heads back up a bit.

Question for all.... How can Cruising and Decelling be the same? I have a steep hill in my hood. I coast down (leave the car in 3rd, foot off the gas) and the AF goes to 18.

You are running WAY to rich. At full throttle only guys with turbos or huge motors need below a 12 or 13, I don't remember which. There are a ton of post out there, and specs from Porsche. Cruising flat land the mixture should be at what is called Stoic which is short for stoichiometry which is used to figure out what is the best combination of compounds to get the max use out of everything involved. Cruising downhill you should go above 15.8, completely letting off throttle there should be almost no fuel and you will see very high numbers.
Look up factory specs and set to that at 3000rpm cruising flat land. Stoic for gasoline is 15.8
NO vacuum leaks anywhere
leak test all 5 injectors
check cold start valve for proper function.
check the ohms on the cht sensor. I have different units with different ohm readings and they greatly affect the stoic.
check the sensor and switch for WOT
crank case vent system can be checked if above measure don't help
checking flow rates of each injector if nothing above is helping.
compression more than 20lbs from the highest to lowest cylinder can cause problems
I knew nothing and read every article I could find an all the factory specs etc.
good luck

If your air flow meter has been mucked with already it can be very hard to get set correctly.
I had a 78 VW Bus 2.0L L-jet that the AFM had been messed with.

There is an adjustment for the wiper arm relative to air flow flapper that affects the fuel mixture as well as the spring tension adjustment.
I had to play around quite awhile to get the 2 adjustments working together and get proper fuel mixture at different loads.
It has been too many years to remember my methodology.

I believe I ended up loosening the spring so I would get more flap movement for the same air flow but then moved the wiper to lean it out some to avoid excessively rich mixtures.
Of course what I had to do to mine would have been relative to what the PO had done to it before I got it.

I eventually ended up with a good running bus that ran lean enough to pass smog and get good mileage without cooking the motor.

I was using a 12 volt portable 4 gas exhaust analyzer hooked up everywhere I went for some time.

Good Luck
Jim

Ummm, I dont know what kind of gas you run but usually its 14.7

Yep you are correct. It has been a while. So it was 14.7 that I was going for. Thanks for catching that

If you are running at stoich AFR on an aircooled you're cooking your heads.
Buy a decent head temp gauge and see for yourself.

Decel AFR is useless info, stop obsessing on it, it doesn't matter because there is no load on the engine. AFR has no bearing on mechanical braking load.
As I said my FI system cuts all fuel at TPS zero on decel (except for idle between 800-1200rpm*) that's no fuel you can't get much leaner than that.

AFR is important under load, WOT, hills, cruise, etc.
WOT 12.5, nickies you can be just over 13:1
Cruise 13 to 13.5 max I aim for just over 13:1, nickies you can run up to 14:1
Hills basicly the same as WOT, maybe a hair more.


* IIRC I'd have to check my program to see the range and my car is in storage, but 800-1200 is close enough.

On WOT are you documenting at bottom value? I tend to dip to 11, then rise back to 13. I can say that this is the 1st time I ever ran the car at WOT. Kinda fun but it is acellerating so fast i get skeerd.

I ran the CO screw out 1 more rotation last night. That got me from cruising at 12.5 to 12.8.

That screw is about 4.5 turns out now.

Clark, are you referring to the screw on the AFM itself? Thats the only one I know of and is only an air bypass for idle. I found my car idled like crap if it was too rich, opening the screw helped.

Mark, i get the nickies can deal with a leaner mixture, but what about your head temps, where are they running?

IIRC, I'm at 13.2 or so at cruise. The engine seems to like that. Idle im just over 14.

Have you seen the Itinerant Air page? Kinda gives the overall impression that the engine will dictate what it wants, then you have to fine tune from there.


Of course, there shall be no vacuum leaks...

Yeah, IIRC it is to adjust the CO. But I don't have a CO meter. SOme youtube vids on it too.

Yes it is a bypass within the AFM like on the TB for idle. But this is unmeasured air that is going to increase the AF # as you open it. I believe it is the fine tune portion of the mix.

I really need to open the itinerant how-to document again and read it. I am finally to a point where adjustments and tinkering with the AFM can be measured with my borrowed AFR. And they are moving the needle.

That is where the AWESOME smoke machine comes in.

I still see some wisps of smoke, but very little. I think I will smoke it a bit in the morning and see if I can knock the remainder out.

The dip stick was one. I added an o-ring but have not re-smoked since that addition.

The hose to the fuel reg was one, but I had some slack in the hose, so I cut it off a bit.

I seemed to see some coming from under the distributor. Is that possible?

These are very lite amounts of smoke, very tuff to tell for sure.

Is there some sort of limp home mode if something with the O2 circuit craps out?

Can you run 2 O2's for redundancy?

If you have smoke coming out from the dizzy, you will need to replace the shafts' O ring.

well damn. That is what I thought might be the issue. If the smoke is coming from there. That damn WASHER is gonna cause problems, and then I have to set the timing again. Who sells them? Guess I better check the parts catalog for a part #.

Tim, You are always telling me bad news. It is usually right.

EDIT>>> I found them. AA has them for $1. it is always a nickel holding up a dollar on this car.

And AA just closed 9 minutes ago.

AA is now closed, so now your thinking RTV?

You should also check for vacuum leaks at the valve covers while your waiting.

My system it runs, just take it easy on the go pedal. only thing that can really go wrong is fuse wiring or more likely the sensor.

Just a FYI, PLX has their O2 WB meters on sale $160 for the gauge type or $190 for the bluetooth.
Bluetooth has no gauge, you use your phone, tab, ipad, etc., but you can also install a gauge for extra coin.

http://www.plxdevices.com/PLX-Wideband-O2-...auges-s/125.htm

So with bluetooth you can buy a sensor for each car then use the same "display" phone or tablet? Cool idea. I tried a bluetooth OBD2 set up. But it only works with Samsung stuff not apple.

RTV on the ditzy hole? Great idea.

Under the car? Very nice. Gotta remember to look. Charcoal is lit now.

It says "Smartphone connection - Compatible with Apple and Android"
On the con side so far it only works with their WB and vac/boost gauges.