Wideband data for 3.2 getting 10 mpg city - what do you think?

[Discseven]

Right rear.




Coating has blistered look.




Adjustment hole is present. It’s in face of hubs—-I was looking for it on the side.




Soft lines are in good form all around. Forgot to check right side wheel bearings.

Testing parking brake over the next day or so. If good, will fill fuel tank and start city mpg test anew. Recheck rotor temps too. RR should fall in line now.

Swapping #4 & 6 injectors tomorrow morning.
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[Mr Beau]

Cruising AFR is probably more relevant to fuel economy than idle.
If the plugs all look the same and are not super sooty then it's unlikely fuel injector(s).
That leaves ignition misfire, which should be felt as lack of power. Or lack of advance (not applicable with DME?).
Cam timing could be off from bank to bank...
A quick dyno might be useful. You could also send out all the injectors for a flow characterization if that's still a doubt.

[scarceller]

A properly running 3.2L with no O2 sensor (in open-loop) should see these AFRs:
- Idle 13.8 to 14.4
- 3000RPM in 4th gear steady state on level road 14.4 to 14.8AFR
- WOT needs to be below 13.0 at all times, stock chip may be in the 11s

All AFR testing done on fully warm engine.

[Discseven]

Originally Posted by Mr Beau

Cruising AFR is probably more relevant to fuel economy than idle.
If the plugs all look the same and are not super sooty then it's unlikely fuel injector(s).
That leaves ignition misfire, which should be felt as lack of power. Or lack of advance (not applicable with DME?).
Cam timing could be off from bank to bank...
A quick dyno might be useful. You could also send out all the injectors for a flow characterization if that's still a doubt.

Matt... Ignition components, fuel injector harness, ECU/DME has all be checked. 964 cams are set to a precise matching overlap of 1.45. Injectors have been flow tested by Idaho Bill.

You'll see where status is below.
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[Discseven]

#6 and #4 injectors are now swapped. Have also reinstalled O2 sensors from Innovate. (Bylund sensors are removed.) Prior and new cylinder balance for 4-5-6…



Cylinder balance prior to swap.




Cylinder balance after swap.

…Not what I expected.


Note for file… Injector that was in #4 cylinder is a recent replacement for one of the original Bosch 158 injectors that failed a few years back. Back then I replaced the 5 Bosch with Lucas (from Five O) given the cost of even a used 158 at the time. The Lucas do have 18 mpg city to their credit as they were installed and operating prior to the rebuild. For testing purposes during this 10 mpg puzzle solving, the Lucas were removed and the 5 original Bosch 158s (that were good and in storage) were tested together with the replacement just acquired. ALL injectors proved in good form and were installed. Is Idaho Bill who tested these injectors. His report is posted earlier in this thread.



The newly acquired injector at right has the Bosch part number molded into the neck as do the originals at left. Dimensions match but the discharge ends are clearly different. Whether this matters or not is questionable. According to Bill’s report, the flow of all the installed Bosch injectors match.

Sal highlighted the fact that 3.2 manifolds have an off-center throttle body, result of this being a slight + bias of air flow to 1-2-3. Makes sense then for 1-2-3 to naturally run slightly leaner than 4-5-6. Is that bias seen here…


After swap of #4 and #6
Warm idle
Mixture screw 5 turns out:




If the imbalance is a delta of airflow to 1-2-3, and, possibly caused by the throttle body’s offset position, a way (not “the” way) to correct for it is to adjust fuel flow to either side of the engine. Perhaps the engine and we have already been witness to this “correction.” That being with the “combo” injector config—Bosch in 1-2-3 and Lucas in 4-5-6…



Bosch-Lucas injector combo - old test (Before swap of 4 and 6)
Warm idle
Mixture screw 5 turns out:




Looking at this, it would seem the Lucas injectors flow slightly less than the Bosch. Sufficiently less to apparently compensate for whatever is going on… throttle body offset? On the subject of air, worth saying the rebuild provided the engine new intake spacers, new intake gaskets top and bottom, and new intake nuts that are confirmed tight. Ignition components, injection harness, and ECU have been checked. There was a loose vacuum hose at the boster’s Y but that’s now tight with the oil cap confirming no vacuum leaks. All this stuff and testing doesn’t “100% guarantee” anything but does slant probability towards something else… throttle body offset bias perhaps.

When Lucas injectors return from Idaho Bill, am returning Lucas to 4-5-6 and leaving Bosch in 1-2-3. Do some testing afterwards. That’s the plan concerning the “imbalance” between sides.


10 mpg puzzle

Been working parking brake now (after rebuilding both sides,) driving, and shooting new rotor temps multiple times yesterday. Below, in next post, are three samples taken from the many that all say the same thing.

I mentioned not using the parking brake much… Thinking it through, I “move” the parking brake more frequently than I realized. This is to clean the center console tray. To vacuum. Recently to do wiring. Car sitting idle for 18 months while the engine was being rebuilt, and this being in the humid conditions this car exists in… not good. Put all this together and dragging parking brakes makes sense. The odd twist to this is my having checked the car’s free roll on a few occasions during this 10 mpg puzzle solving. Had I caught anything along the way… red flag. No flags. It must be the drag came and went. Backing up does release the p-brake and of course backing up happens quite often.

What new rotor temps say is not taken as proof the dragging p-brakes were the cause for 10 mpg city. Am taking what’s seen as a preliminary indicator of something positive. Tank has been filled at Westar (to keep that brand of fuel in the tank for now.) City mpg test in progress.
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[Discseven]

[Discseven]

Based on Sal bringing up throttle bias towards 1-2-3, been digging into that. Found Gliding Serpent's 3.2 intake flow test. Credit to him for the pic and CFM data. Glider’s thread: https://forums.pelicanparts.com/porsche-911-technical-forum/862450-3-2-intake-plenum-flow-testing-interesting-results.html



CFM air flow:
#1 261
#2 251
#3 252
#4 245.5
#5 248
#6 238

Figures above charted...



Assuming this data is correct and it’s a standard for 3.2 manifolds, the O2 imbalance side-to-side seen in my engine (with 1-2-3 leaner than 4-5-6 and with either all Lucas or all Bosch injectors)… puzzle is coming together bit by bit.

If returning to the combo of Bosch inj in 1-2-3 and Lucas in 4-5-6 does not even things out as it did previously, a tuneable air bypass comes to mind. Combo of injectors may not do what is desired given Idaho Bill having serviced the Lucas injectors before I could stop him.
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[Discseven]

Induced air leak into intake manifold...
Is to see if 4-5-6 side (blue trace) went any leaner... and how much 1-2-3 side would be affected.

Warm idle
idle mixture screw out 5 turns
All Bosch injectors



Loosened then retightened right hand clamp on rubber collar that joins the intake manifolds. Idle drops and becomes very slightly rough. When tightened, idle returns to where it was. Doing this a few times, I found O2 very sensitive to nearly any turn of the clamping screw after the seal is compromised. Chart is with quick turn of the clamp-screw and between 1/4 and 1/2 a turn.

Waiting on Lucas injectors from Idaho Bill.
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[Mr Beau]

Your idle AFR imbalance does not explain 10 mpg. I think you're barking up the wrong tree. What do the numbers look like when cruising down the highway at steady state?

[Discseven]

Originally Posted by Mr Beau

Your idle AFR imbalance does not explain 10 mpg. I think you're barking up the wrong tree. What do the numbers look like when cruising down the highway at steady state?

Matt... 10 mpg city and imbalanced O2 side-to-side are being treated as two separate challenges. 10 mpg puzzle may have been solved with rebuilding the parking brakes as was just done. City mpg test is in progress.

Highway cruise with either all-Lucas or all-Bosch injectors is imbalanced. 1-2-3 is lean compared to 4-5-6. I did not test highway cruise with the Bosch-Lucas combo but believe a near balance would exist. Bosch injectors: 0280150158 (original to this 3.2) and Lucas: 24lb. low impedance from Five-O.




This is WOT to redline in 1st, 2nd, 3rd with the Bosch-Lucas combo installed. There's a hint of cruise in this.


Re the O2 imbalance, it's possible this being due to the offset of the throttle body and the resulting bias of + air flow to the 1-2-3 side. Look at Glider's 3.2 manifold flow data that I posted earlier... Assuming the shop that did this for Glider got it right, it suggests an inherent imbalance in 3.2 intake manifold design. Surly Porsche engineers tested intake flow and if what Glider posted is indeed accurate, I assume Porsche concluded the 3.2 intake's imbalance being acceptable.

I may be splitting hairs over the O2 imbalance in hand but since I got O2 very close to being in balance side-to-side at one point---with the Bosch-Lucas injector combo---makes sense to set that combo up again and see what happens. Am waiting on Lucas injectors to get back to me in order to reinstall them in 4-5-6. Because the Lucas have been "serviced" by Idaho Bill after the combo config was tested (and near balance was achieved,) there's no telling what O2 will be seen now when this combo is run again.

Leaking air into the manifolds yesterday was revealing. Even a small adjustment to what air was allowed in was instantly realized in combustion/exhaust. I have a new found appreciation for what our AFMs accomplish when an engine's fuel trim is on target.

[Mr Beau]

Looks to be about 3% difference (as measured) between the banks. Lots of tolerance stacks there, so some of it could be real and some could be just normal noise.

Intakes are a dynamic system. If you get idle balanced, it doesn't mean that they will be balanced at other RPM/flow conditions. If you measure AFR by cylinder, you'll see some cylinders that are richer than average at some points, and leaner than average at others.

Here's a good video showing effects of AFR on power/torque: https://www.youtube.com/watch?v=yjvPmG123nI

The goal is to get two squigely lines to overlay each other? Or is there also another metric?

[Discseven]

Originally Posted by Mr Beau

Looks to be about 3% difference (as measured) between the banks. Lots of tolerance stacks there, so some of it could be real and some could be just normal noise.

Intakes are a dynamic system. If you get idle balanced, it doesn't mean that they will be balanced at other RPM/flow conditions. If you measure AFR by cylinder, you'll see some cylinders that are richer than average at some points, and leaner than average at others.

Here's a good video showing effects of AFR on power/torque: https://www.youtube.com/watch?v=yjvPmG123nI

The goal is to get two squigely lines to overlay each other? Or is there also another metric?

Thanks for vidlink Matt. What you mention raises the question as to how Glider's test guys performed their flow analysis on his 3.2 intake manifold. Will PM him. I did see another vid with O2 sensors in each of a V8's down pipes. O2 did change cylinder-to-cylinder as rpm changed.
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[Discseven]

Bosch 0128150158 compared to Lucas D1540BA…








Bosch-Lucas combo are reinstalled…

Combo Retest
Warm idle
Bosch in 1-2-3 | green
Lucas in 4-5-6 | blue
Mixture screw out 5 turns - until balance is achieved, leaving mixture at 5 turns




Given 1-2-3 side of intake manifold being + air flow compared to 4-5-6 (per Glider’s testing,) why 1-2-3 side now running richer than 4-5-6 side is another mystery.




Bill's Report. Lucas are now—as installed—flow matched to Bosch at 260 cc/min. Injector from #6 is unlike others.


Previous Bosch-Lucas combo O2 result. More I mess with things now, more I appreciate what had occurred here:



Was tempted to leave combo config as it was at the time and walk away… couldn't. Lucas injectors are different now because I sent them to Bill to test them. Didn’t want him to service them but that got lost in translation.

Going to swap injectors side-to-side. Before doing so and with the engine cold (just started it)…

Cylinder balance test
COLD idle
Bosch in 1-2-3 | green
Lucas in 4-5-6 | blue




Injectors are now swapped side-to-side…

After the swap test
Slightly warm idle (impatient to see outcome)
Lucas now in 1-2-3 | green
Bosch now in 4-5-6 | blue




Lucas lean delta from 1.0 lambda and Bosch richness from same has increased after swap.
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[Discseven]

1-2-3 side has progressively soured over the last few days. Sensation = going backwards! (Wideband business has been a whipping post of sorts. No complaint. Is clearly a necessary evil to embrace.) Questioned/tested sensing gear. Ignition. Fuel. Culprit = one or more of the Lucas injectors in 1-2-3.

During this fault-hunt, found Innovate extension cable---serving 1-2-3---to have gotten scorched. Cable was run ahead of the engine from left to right. Exact position is uncertain. Should have stuck camera back there to check. Insides of cable are now just barely exposed. Tested cable as it is. Not at fault here. New 8’ extension is installed. Revised run avoids whatever the hot-spot was. New passage is now completely along outside perimeter of engine bay connecting with sensor cable on 1-2-3 side in the engine bay. Sensor is notably from Innovate---sensor cable lengths vary depending on sensor's source. This new run with 8’ length leaves just enough in-cabin cable so extension cable’s junction (that connects to the controller) sits between the squabs. My cable passage from cabin-to-engine-bay is at bay's forward, passenger-side corner. 10' extension cable would be preferable. Innovate's next extension longer is 18'. My Innovate system is portable for the time being. Have yet to decide if making it permanent has appeal.

Removed Lucas from 1-2-3 and Installed Bosch 158s in their place…

All Bosch injectors installed
2 new & calibrated 4.9 sensors
New 1-2-3 extension cable
Warm idle
1-2-3 = green
4-5-6 = blue
Idle mixture screw 5 turns out




"Leave it alone now you idiot!" would come from someone I know. NP. Lewis & Clark syndrome... Must see what happens with existing Bosch 260cc injectors in 1-2-3 and to-be-installed 255cc injectors in 4-5-6. Trust is in specs & reports in this exploration---and we know those are always spot on.

...255s in transit.

...City mpg still in progress.
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[scarceller]

The average flow per runner for 1-3 side is 255 and the 4-6 side is 244 that's a difference of 4.5% favoring air flow to the 1-3 side.

If 4.5% more air flows to the 1-3 side that means that side should read 4.5% leaner than the 4-6 side. The math is usually correct.

The last pic you posted with all six same 158 injectors looks like the green 1-3 side is at about 0.98lambda while the 4-6 side 0.94 lambda. So, 1-3 side is leaner than the 4-6 side by about 0.98/0.94=4.3% that matches the runner flow difference. At this point you are done, side to side is withing 5% on AFR, I've known for a long time that the air flow favors the 1-3 side, it's simply the manifold design.

I know the flow data you found from Gliding S. is correct I helped on that build with him his car was tuned by me when he installed my MAF setup. The owner John D. is meticulous!

Keep in mind those flow numbers are done at extremely high flow rates above 200cfm but in reality at 7000RPM a 3.4L will only draw in about 60CFM at most, no where near those 250CFM numbers! The intake plenum is not a restriction in these engines. How the runners behave on a flow bench is NOT how they behave in car, but the flow bench data is still telling about the overall design of the plenum.

Originally Posted by Discseven

Based on Sal bringing up throttle bias towards 1-2-3, been digging into that. Found Gliding Serpent's 3.2 intake flow test. Credit to him for the pic and CFM data. Glider’s thread: https://forums.pelicanparts.com/porsche-911-technical-forum/862450-3-2-intake-plenum-flow-testing-interesting-results.html



CFM air flow:
#1 261
#2 251
#3 252
#4 245.5
#5 248
#6 238

Figures above charted...



Assuming this data is correct and it’s a standard for 3.2 manifolds, the O2 imbalance side-to-side seen in my engine (with 1-2-3 leaner than 4-5-6 and with either all Lucas or all Bosch injectors)… puzzle is coming together bit by bit.

If returning to the combo of Bosch inj in 1-2-3 and Lucas in 4-5-6 does not even things out as it did previously, a tuneable air bypass comes to mind. Combo of injectors may not do what is desired given Idaho Bill having serviced the Lucas injectors before I could stop him.
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[Discseven]

Originally Posted by scarceller

The average flow per runner for 1-3 side is 255 and the 4-6 side is 244 that's a difference of 4.5% favoring air flow to the 1-3 side.

If 4.5% more air flows to the 1-3 side that means that side should read 4.5% leaner than the 4-6 side. The math is usually correct.

The last pic you posted with all six same 158 injectors looks like the green 1-3 side is at about 0.98lambda while the 4-6 side 0.94 lambda. So, 1-3 side is leaner than the 4-6 side by about 0.98/0.94=4.3% that matches the runner flow difference. At this point you are done, side to side is withing 5% on AFR, I've known for a long time that the air flow favors the 1-3 side, it's simply the manifold design.

I know the flow data you found from Gliding S. is correct I helped on that build with him his car was tuned by me when he installed my MAF setup. The owner John D. is meticulous!

Keep in mind those flow numbers are done at extremely high flow rates above 200cfm but in reality at 7000RPM a 3.4L will only draw in about 60CFM at most, no where near those 250CFM numbers! The intake plenum is not a restriction in these engines. How the runners behave on a flow bench is NOT how they behave in car, but the flow bench data is still telling about the overall design of the plenum.

Sal... I think you're saying there's balance indicated by the all-Bosch delta between sides due to the delta of air flow side-to-side. If that's indeed a correct translation, there's an elusive logic to this for me. I see it then I don't. Am more inclined---as a gnat that I am amidst an air-fuel giant---to see this as an imbalance between sides. Respectfully

To speculate... if it's possible to get AFR so both 1-2-3 and 4-5-6 are at 0.95 lambda at warm idle, would seem both sides then have optimal O2 symmetry. Or, would that O2 symmetry with the bias of intake air flow to 1-2-3, and let's suppose a reduction of fuel to 4-5-6 to create the O2 symmetry, would this have the 1-2-3 side running with a slight bias of power?

PS - my iphone is out of order for another day or so.
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[scarceller]

I'm slightly confused now, are you saying you sometimes have both sides at 0.95lambda with fully warm engine at idle?

The most important test is part throttle steady state load, 4th gear 3000RPMs what's the lambda in each bank? Can you please do that test when you have time? Idle conditions can be very finicky to get perfect mixture because flow rates and injector time are both very low.

[Joesmallwood]

Originally Posted by scarceller

I'm slightly confused now, are you saying you sometimes have both sides at 0.95lambda with fully warm engine at idle?

The most important test is part throttle steady state load, 4th gear 3000RPMs what's the lambda in each bank? Can you please do that test when you have time? Idle conditions can be very finicky to get perfect mixture because flow rates and injector time are both very low.

Is light load/partial throttle balance more important than high load? I would think that it's more important to be balanced under mid/high load (accelerating) than it would to be balanced at idle or cruise.

I'm also confused by Porsche would design in an imbalance in their manifold. I find this perplexing. It's true, the distances from the common plenum to the the intake may be different, but I can only assume that balancing the overall vacuum/flow to each cylinder was considered in Porsche's simulation, calculations, and testing. I could be wrong as it's only an assumption.

[Discseven]

Must be flow data is relative to the manifold being tested. I say this because while cc flow is mentioned, nothing is said about what vacuum force is being applied. Obviously that vacuum must be the same for a single manifold. But could be different from one manifold to the next. And different shop to shop---unless there is an applied standard. Posted vid as some ref to how this is done---I had no idea.


Loosing sleep over the math on hand, calculations on paper are called for. Am going at this slightly different than Sal. And this is to play with numbers---am not seeking Nobel calculus prize here. And certainly not competing with Sal. Curiosity that's got hold of me is the air flow delta side-to-side in my 3.2 intake. Without Gliding Serpent's ("Glider's") air flow figures, I'd not be at this---TY Glider. Never mind how his numbers were arrived at, or what the reality of air flow is in a working engine, or the potential infinite variables involved, am plugging numbers in to see what comes of it...

Question being, can we do the math and sort out what injector flow rate is wanted for one side of an engine when we already know the air flow rate, AFR/Lambda, and flow for injectors already in an engine? This assumes there's an imbalance in O2 side-to-side and the goal is to improve O2 balance. Not saying this is necessary to do or not... doing it to see if it can be done. Empirical stuff.

Added each side's cfm per Glider's data:

1-2-3 = 764
4-5-6 = 731.5

Total up both sides:

764 + 731.5 = 1495.5

Calculate each sides percentage of 100%:

100 x 764 = 76400
76400 / 1495.5 = 51.08659

Side 1-2-3 = 51.08659 %

100 x 731.5 = 73150
73150 / 1495.5 = 48.91340

Side 4-5-6 = 48.91340 %


Calculate 4-5-6 side’s cc fuel flow based on existing 24 lb. 260cc Bosch 158 injectors:

48.91340 (Side 4-5-6) x 260cc (side 1-2-3 cc) = 12717.48579 / 51.08659 (side 1-2-3 %) = 248.9398

Target injector cc flow for 4-5-6 = 248.9398

24 lb. 255 cc injectors should arrive later today. (Ordered these injectors a few days ago based on "dirty" Lucas test results.) Will install them tomorrow morning and run a log. IF... and that's a big "IF", all the numbers applied work, the result would be an AFR/Lambda which brings 4-5-6 O2 closer to the 1-2-3 side than the last log with all Bosch injectors installed. But 4-5-6 O2 will not go above 1-2-3. So 4-5-6 will still be slightly richer than 1-2-3. A speculative prediction. Am fully prepared to eat crow.
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[917_Langheck]

Originally Posted by Joesmallwood

Is light load/partial throttle balance more important than high load? I would think that it's more important to be balanced under mid/high load (accelerating) than it would to be balanced at idle or cruise.

I'm also confused by Porsche would design in an imbalance in their manifold. I find this perplexing. It's true, the distances from the common plenum to the the intake may be different, but I can only assume that balancing the overall vacuum/flow to each cylinder was considered in Porsche's simulation, calculations, and testing. I could be wrong as it's only an assumption.

It's all just nonsense. 60 CFM nominal max is 24% of theoretical max of the plenum, so hardly impinged by any noncentral alignment of the throttle body.