Which way to turn 3.2 air flow disk?
 

Want to lean the fuel out by adjusting the spring-disk in the air flow sensor. Am not sure what direction to turn it.

http://forums.pelicanparts.com/uploa...1714419537.jpg

this might helphttp://forums.pelicanparts.com/uploa...1714425123.jpg

What is the issue you are having?

What mods have you done to the engine?

Unless the answer to the above is something extreme, I'd have a hard time believing the spring needs to be changed.

There is also a bypass screw (Idle Mixture Screw) that will adjust mixture on the AFM. it has the most effect at low flow rates, but will have a slight effect throughout the full range.

Thank you Pro. It confirms previous input I got but was unsure of.


Issue is 11 mpg city after rebuild. Prior to rebuild I was getting 18. The 11 mpg result was had with driving the pedal in the same manner as when getting 18 so the test is "apples to apples." Engine starts on first crank, idles at 800 evenly, and pulls well. So everything is in order except for the fuel consumption.

Mods to 3.2 rebuild are 964 cams timed to 1.45 exactly on both sides, SSI exhausts, 2 in 1 out Dansk muffler.

There are new fly wheel sensors. New #3 cylinder temp sensor. New Bosch Ox sensor however I did solder-splice a few inches of wire into the stock length as the SSI exhaust bung is further back than the stock position (and I wanted to keep the cable/wires running through the stock tin hole. I was advised to check the area around the Ox sensor (thanks Pete) to ensure there was ample ambient air getting to it. There is.

ECU was "rebuilt" as part of engine rebuild but afterwards I discovered the ECU was swapped on me. If I can't find a solution that excludes the ECU, I'll be returning to that. There is a rotary fuel setting in a 3.2 ECU that is adjustable. I found this switch in the swapped unit set to the factory's 0 position. I turned it to #3 position. Specs for this rotary fuel switch are on Wong's website https://www.911chips.com/fuelsys.html Unfortunately I do not know what my prior ECU rotary fuel switch was set to.

Regarding the air flow adjustment, I was advised to first clean the air filter... Done. Found it only very slightly dirty and so consider this factor inconsequential. Then, rotate the disk inside the air flow 4 notches to increase the tension on the air flap. Direction of rotation for increasing tension is clock wise. Then drive the car. If it runs good, tighten the tension another 4 notches. When the car starts to run poorly, return to the prior setting. Then test the mpg. I tested the 4 notch adjustment and the car ran fine. Have gone another 4 notches now but have yet to drive the car. Get to that tomorrow.

When I first discovered the milage having dropped, I looked at the exhaust pipe and found the insides covered with black soot. I've cleaned the exhaust now and will be looking at it after adding some miles to the car.

What are you running for fuel pressure regulator and dampers? Are you still running stock fuel injectors or have they been swapped out?

Do you have access to a wide band O2 setup? It may be worth borrowing or purchasing one if you are going to be trying to adjust mixture.

Reg & damp are stock. Injectors are mine from before the rebuild, Lucas brand. I don't have a wide band but friend has an Ox meter that sticks into tail pipe. If adjusting the air flow disk---or whatever adjustment is made---gets the mpgs back in order, I can surely borrow his to fine tune.

Using solder on the Oxygen sensor wires is not advised since the sensor "breathes" outside air through the wires.
Normally the sensor will correct the average air/fuel ratio to keep it close to ideal.

Here's how the Ox sensor and wiring is set up. Can see a slight buldge in the black sheathing a few inches from where it starts... that is location of the splices. Discovering the mpg in the gutter, I was initially concerned about adding the 6" or so of wires and solder to this sensor as this might have affected resistance in the wires. Don't know if the signal from the OX sensor is resistance based and so that being pure speculation on my part. I have it on good authority that this wire addition & soldering business is not a problem.

http://forums.pelicanparts.com/uploa...1714495880.jpg

It's not the additional wire that's a problem, it's the solder.
This is why the Bosch universal sensors come with a crimp connector.
Search the web and you'll find many discussions like this...nobody recommends solder.
https://rennlist.com/forums/924-931-944-951-968-forum/645703-o2-splice-crimp-only-or-solder-too.html

Here's what I found when test driving 8 notch adjustment. (Am continuing to tighten tension of air flow spring-disk / air flap.)

Starts on first crank. Very slight roughness in idle compared to 4 notch adjustment. After op temp reached (210 df) drove engine to redline several times... consistently pulls all the way without a hint of stumble. One issue: stalled at red light when not warm. Wanted to stall at idle after warm up but touch on the pedal keeps engine running.

Plan...

Am going to adjust the idle rpm up slightly (900-1000) and run the 8 notch adjustment to see what comes of this. Post results when I have them. Until this puzzle is truly solved, doors open for ideas.
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That's NOT good! Now you have potentially another problem. Who's the "rebuilder".


Has very little effect on the engine's running. It's propose is for tweaking the emissions for some countries.

This is interesting info Brian. Thank you! Looked at Rennlist and info on Clark's Garage page. Clark's info is 944 related but I suspect an Ox sensor is the same in functionality across the board.

This is text posted on Rennlist. I do not recall what the Bosh wires looked like when I worked with them but know I soldered in copper wiring of the same gauge.

http://forums.pelicanparts.com/uploa...1714500308.jpg


Info from Clark's Garage...

http://forums.pelicanparts.com/uploa...1714500519.jpg

http://forums.pelicanparts.com/uploa...1714500519.jpg

Given this, and assuming the info is correct, handwriting's on the wall. Blurry at this stage but there. Will have to dive into more experimenting to find clarity.

Plan update...

Am going to run the 8 notch setting and adjust the idle... to see what mpg comes of this is given (since the set up is nearly in place.) After that, will return the air flow notch setting back to the original position. Will leave ECU adjustment to #3 fuel position as is. Cut the soldered Ox splice (that I put in) out and crimp the Bosch wires back together. That set up will have to pass between the engine bay seal and engine tin to make the connections (given SSI's placement of their bung.) If this direction solves the puzzle, will consider locating a proper hole in the tin for the shorter Ox cable. I don't recall the Bosch wires being of a config that allows air to travel along the wires to the sensor but then I've f'd up a few things here so am eating crow as it is. Next, will check engine performance and mpg with the splice out and crimps in. Later readjust idle if needed. Of course will post what is found. Brian, accolades pend. Ultimately I stick a portable OX meter in the exhaust to fine tune the AF ratio.
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The body of the O2 sensor is completely air tight and sealed (to prevent contamination, because they tend to be located where it's kind of nasty). Getting ambient air to the sensor body doesn't matter at all. Because sealed.

The O2 sensor requires a supply of ambient air in order to perform the chemical conversion.

The O2 sensor is designed to obtain this ambient air through the strands of the cable

Not only is this called out in all the Tech Docs since Bosch invented the thing, the universal installation kit provides screw-type connectors (Posi-Locks) to splice to the OE harness. And some (but not all) instructions specifically warn against soldering the cable or using heat-shrink.

eg, from Oxygen Sensors Trade Brochure (the bolded emphasis is Bosch's):

Dave... ECU was handled by Vertex. A Miami shop. Why the ECU went to them is a long story not worth getting into. Suffice it to say I'm not pleased with this ECU situation and will discuss it with parties when the time is right. On the rotary switch inside the ECU for fuel adjustment, agreed. Specs for the #3 position are a "correction" of - 3.9%. Peanuts but still something.
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Spuggy... thank you. Am truly getting Ox schooled as this thread progresses. ALL GOOD! Here's Bosch info...

http://forums.pelicanparts.com/uploa...1714503918.jpg

Bosch language about drawing air "through the wires" suggests the wires being air conductive. Or is this marketing? Were my plate not loaded already, this would be something to research.
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I believe if you get a working O2 sensor if will solve your overly rich mixture problem.

FWIW, I did punch another hole in the tin to allow the stock 02 sensor to work with my SSIs.

The ECU has been swapped. Who knows what fuel map is in there.

Have you opened it up and have a look see at the chip, they being labelled typically by the modder ?

Excellent point! Found this Pelican Parts post related to 911 3.2 "chip tuning";

http://forums.pelicanparts.com/porsche-911-technical-forum/683503-performance-tuning-myth.html

Am sensing that too. Have adjusted idle and will test run engine as it stands tomorrow, if for no other purpose than to see what comes of the standing config. Result notes on that tomorrow.

Did you gromet the hole? How / with what?


Good point P. I have opened the ECU and to my eyeballs, it's clean and everything looks in order. Am not an ECU expert so my view is entirely superficial. I did not look at any chip in particular. Nor did I see any notes or stickers on anything. I'll open it up again for this. Could you post a pic of or direct me to what / where I should be looking?

After test running the current config, and if the Ox correction is not a solution (as info suggests it will be)... and if no other possibilities arise and there's still an issue, ECU mapping would be next on the menu. I'd then be discussing the ECU "swap" with the responsible party. There's an ECU specialist in Lauderdale https://www.ecudoctors.com/pages/149-testing-service . I might pay them to test the unit.
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Oh, still pretending you're not Loren?

http://forums.pelicanparts.com/uploa...1714515384.jpg

The replacement sensor comes with a grommet
https://www.pelicanparts.com/search/?q=Oxygen+sensor

It's not special wire, it's just stranded and to a spec that'll support the required air flow.

The specs for the air requirement are detailed in the tech spec documents that Bosch provide. It's tiny, because the sensors don't require very much reference air.

But they do require some - or they don't work...

Automotive Applications

Here's a timing chart indicating what timing advance the "performance chips" do;

http://forums.pelicanparts.com/uploa...1714515371.jpg

As can be seen from the 20% engine load ignition advance over the stock value, all performance chips advance the timing.
One tuner advances as much as 25+ degrees over stock at some RPM. This is very problematic potentially causing engine detonation, damaging the engine.
The 911 3.2 lacks knock control which was added on the 964/993 engines plus twin plugs. Without knock control these excessive timing
conditions can lead to detonation when;
1. using low octane fuel (who knows what one really gets at the pump)
2. climbing a high mountain grade on a hot day

It's significant that many lack any real understanding of the above facts!

all this makes me wonder why do you even use oxy sensor??My 911 had it ,took it off the 1st week when i got it back in 1996..car runs a like champ...plus my gas consumption is excellent..you said your friend has the Co test machine, what is the co mix? When was the last time you adjust it?

Ivan

Look at the big chip on the board. It'll be either a 24 pin (early) or 28 pin (late) DIP. If there's no stickers on this chip and it doesn't have a little quartz window exposing the silicon die inside, then it's very, very, likely to be the factory chip.

Most aftermarket chips are EEPROMs (erased by applying UV light through the quartz window so they can be re-programmed - which is why you put the sticker over the window, even though it'd take a long time to erase them in sunlight). It's not impossible to get a PROM blown with a custom program - however, this is more expensive in small quantities (read: "you're not the factory") than just using an EEPROM, which can be erased/re-used over and over.

I'm not saying aftermarket PROMs for Motronics ECUs can't exist, just that I would bet money that there are very, very few - if any.

Address the O2 sensor first.

If it were me, and there was something wrong with the ECU, I'd buy a plug-in Motronic replacement that was programmable. IIRC, Rasant used to provide a kit that used MoTeC, and RaceBoy on this forum can supply VEMS stand-alone ECUs for 911s & 944s that plug into the factory Motronic harness.

Stand alone ECU options for a 3.2
VEMS Plug-n-Play - quick review


Either approach gives you an ECU you can tune in real time, with a laptop, and other features you'd expect from technology built this century. Like support for wideband O2 sensors, modern injectors etc etc.

Actually, that's not correct. Few if any 911 3.2 DME ECM memory chips were mask programmed, i.e. programmed when the memory chip was ordered by Bosch.
Most all the memory chips used by Bosch were EPROM, allowing Bosch the capability to update engine tweaks to the ECM requested by Porsche.

That's not correct, EPROMs are erased by UV and EEPROMs are a flash type memory.

Waste of time and money, and not good for a future 911 3.2 resale. Besides, most all 911 3.2 DME ECMs typically take less than 30 minutes to repair, if a problem occurs.

As already mentioned, look for these 24/28 pin flash memory chips ...

if there's a label on it and the manufacturer's still in business, they can be contacted for further details.
http://forums.pelicanparts.com/uploa...1714527739.jpg

https://forums.pelicanparts.com/porsche-911-used-parts-sale-wanted/1121894-carrera-3-2-aftermarket-dme-chips-28-24-pin.html#post11730846

Good luck !

They are EPROMs, i.e. one of these, either 16MB/32MB/64MB. The original Porsche ones, not Mickey Mouse "performance " chips, have just a printed number.

if you have this chip ..it is still factory.if you have an early Carrera it will be the short one..this one is for 87-89

Ivan
http://forums.pelicanparts.com/uploa...1714556100.jpg

You can check O2 sensor output while running, should be .3-.8V moving between those. Can give you a ballpark CO reading.Between meter ground to sensor wire.

Yesterday: Adjusted idle setting with warm engine. Jumped BC and turned idle screw 1 ¾ turns counter clock wise. Idle now at 1,000 rpm. (Shut down and left test drive for Wednesday.)

Today / Wednesday: Cold starts on first crank. Terrible idle right away. Bouncing. Then sometimes holding at 800… then 1,000… then 1,200. Almost stalls and catches itself a couple times… finally stalls. Restarts on first crank. Test drive… warmed engine to 210 dF. Pulls clean in first and second gear. Held steady throttle in 3rd gear heading to highway and after a second… bucking. Canceled highway. Heading home. Warmer engine gets, worse it runs.

Thought about pulling Ox sensor and having a look at the wires to see if they are stranded or solid. Doesn’t make sense to fiddle with this anymore. New heated sensor ordered.

Will return idle screw and air flow meter’s disk-spring to their original positions. Leaving ECU fuel adjustment on #3. Will open ECU to check chip status. After new Ox is in… test drive.

Will report on run of engine. Then check mpg.

Update - From the grapevine ;) word is this oxygen sensor inclusion is needless! Easy enough to disconnect it and see what happens.

Appreciate the input. Is now too much to respond to as I like to do. Know that I read it all.
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Be aware that a cyl that is not firing will cause MPG issues if you have the stock O2 sensor connected. Here's why:
A cyl not firing is a O2 pump, the O2 in the air fuel charge goes for the ride straight out the exhaust.
This extra O2 is then mixed with the exhaust from other 6 cyls.
Then the exhaust runs past the O2 sensor and the sensor sees all this extra O2 and thinks lean condition.
But in fact the other 5 cyls are not lean they are burning just fine.
What happens next is the O2 sensor sends this false lean condition to the DME.
Now the DME tries to fix the lean condition by riching the mixture to try and correct the false lean condition.
It's very common to see MPG drop by 20% when this occurs!

Are you certain all 6 cyls are correctly firing?
And do you have the stock O2 sensor plugged in?

You really need to get a WBO2 gauge to properly diagnose what the AFR is at idle, part throttle driving and WOT.

If cold start is hunting for idle up and down it means mixture is to rich. The reason it hunts is because rich mixture causes engine to want to rev up and as it revs up it then hits the fuel decel fuel cut limit that's set at around 1300RPM. When the idle hits 1300RPMs or so the DME instantly cuts fuel and now the idle speed drops like a rock. And the cycle repeats.

So why are you running rich?

To diagnose these issues you need to diagnose fully warm and you need a decent WBO2 gauge so we know the exact AFR.

Stop messing with the AFM spring tension, you are likely trying to tune the AFR around another critical issue.

Changing the spring tension is a very bad idea because it effects AFR a lot more at high air flow rates than it does at the low rates.

If anything, move the other adjustment so you move the carbon contact point further down, this will lean the entire air flow rates evenly.

I can help further if you PM me, it's hard to diagnose here on forum. I can help and if we fix the issue come back and report the fix.

Yes, please unplug the O2 sensor and leave it unplugged during all diagnoses, you only plug it back in once you fixed the core issue. And if you don't have a Cat converter you don't need the O2 sensor at all.

Sal... Appreciate all the info.

Bottom line here: all things point to the soldered extra wire I spliced into the Bosch Ox length of wires in order to extend them to reach the SSI bung. Discovery made (in thread) is those wires should NOT be soldered according to Bosch. Adjustments I made will be returned to the original settings. I'll disconnect the Ox and test drive the engine. If good performance, will check the milage. Ultimately I'll use a friends tail pipe meter to check the air fuel ratio.

You asked about the engine running on 6 or 5 cylinders. Rebuild was recently completed and aside from this milage issue and now the engine running poorly given my adjustments, there's no doubt all 6 are firing. That said, thanks for explanation in this regard.

Your offer to PM assist. Much appreciated / Thank you. I believe the situation's under "control" for the time being. We'll see if that bears out in a few days :)

Update

Today: Started engine with existing adjustments that proved faulty yesterday. Start on first crank. Erratic idle... Shut it down.

Returned Air flow disk to original position. Disconnected Ox sensor. Start on first crank. Even idle. Jumped BC and adjusted idle screw clockwise 1 3/4 turns (back to original position.) Remove jumper. Shut down. Start up on first crank (slightly warm engine.) Even idle at 800. Test drive... warm engine to 210 dF. Test pulls... to redline without hesitation every time. ...Making progress.

With faulty settings (from and tested yesterday,) engine would not tolerate being driven in high gears around 2,500 rpm without bucking. No bucking in high gears at that rpm level now after returning original settings and no Ox sensor.

Checking fuel milage next.

Input from you guys... priceless.
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Observing cold start will tell you a lot about the overall mixture as well as idle switch and ICV operation. At next cold start do as follows and observe behavior, a properly running 3.2 should behave as follows during cold start:

First, 84-85 cars idle at 800RPM while 86-89 at 880RPM
I assume if it's a 85 car it has the 85 stock chip.

- Engine dead cold
- Do not touch gas pedal during all testing
- Start engine
- Observe, does it hunt for idle at initial startup? If so it's likely running rich
- Does it sputter and cough? Lean condition
- At initial startup it should idle between 1100-1200RPMs
- Let it warm over next 3 minutes, do not touch gas pedal
- As it warms the idle speed must drop on its own to 800RPM assuming 85 DME
- After 3-5 min it should be idling at 800

If the cold start behaves as above your mixture is in the ballpark and we know your idle switch and ICV are controlling idle properly.

Report back on results for that testing.

Adjusting base idle speed with BC jumper and setting base mixture with 3mm allen key on AFM should only be done with fully warm engine.

You need a decent WBO2 gauge to set mixture and the WBO2 sensor must be installed in the exhaust Bung not the tailpipe. Sensors in tailpipe will read lean.

Fully warm engine at idle your target AFR is 13.8 to 14.4 AFR at idle. If you can get idle set correctly usually all other engine conditions fall into place.

A properly running 3.2L should hit these AFR targets, all testing to be done in open-loop mode with no stock O2 connected
idle - 13.8 to 14.4
PT 3000RPM steady state flat road in 4th gear - 14.4 to 14.8AFR
WOT - all WOT conditions MUST be below 13.0AFR the stock chip is tuned rich so likely in the 11.5 to 12.5 range. But you want to be in safe zone below 13.0

Enjoy

^^^ Thank you Sal. I did not set idle with a warm engine but idle did adjust to 800. Though not stone cold on the restart after adjustments, idle and performance was on target---stable idle and with the engine warmed up, a consistently clean pull through rpm/gears up to red line for multiple goes at it. This is good news but fuel consumption is where this journey started---mpg has yet to be checked.
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Opened ECU/DME and I didn't get to far. Appears to me there are soldered connections that don't enable the 2 boards to be easily separated to look "inside." Rather than screw something up messing with it, and given the engine running well, am leaving the chip question unanswered for the time being. If someone can tell me how to separate the boards, I'll go back in.

Pics of ECU/DME:

http://forums.pelicanparts.com/uploa...1714759584.JPG

http://forums.pelicanparts.com/uploa...1714759584.JPG

http://forums.pelicanparts.com/uploa...1714759584.JPG

http://forums.pelicanparts.com/uploa...1714759584.JPG

http://forums.pelicanparts.com/uploa...1714759584.JPG

http://forums.pelicanparts.com/uploa...1714759584.JPG

http://forums.pelicanparts.com/uploa...1714759181.JPG

Rotary fuel switch that was in position 0... Is now in position #3. This was the first adjustment done a number of days ago. No change was noticed. Supposedly this position results in 3.9% reduced fuel flow.

Moving the FQS from 0 to 3 does pull fuel out, about 3% leaner. But doing this is often a red flag that something else is off.

I did not ask, what altitude are you at? If Miami then sea level so no need to discuss.

DME boards can be separated, watch my video:
https://youtu.be/GAo01_454IY