Yes, I wouldn't have done it that way. The good news / saving grace, is that this is in a 914, and is pretty much the only car I have that can do burn-outs. I.E. it has a lot of horsepower to spare for the car that it's in. Still, every HP is sacred!

-Wayne

Probably easiest and an elegant way is to take a piece of mandrel bent aluminum tubing and fab an aluminum adapter between the AFM and intake boot to a minimum angle to straighten the air path, maybe ending up with a 30-40° elbow, and replace the air filter adapter with one from MSDS, internally ported as below to maximize the velocity stack from the filter to the meter. This is what most of Porsche club racing on the west coast is running after extensive testing I did years ago:

http://forums.pelicanparts.com/uploa...1589573219.jpg

That AFM trace is trashed. Reposition so the wiper is actually on the resistor trace.

On the filter adapter, 3D print one...

I just got off the phone with Mike at Autobahn in San Diego, and he's going to be sending me a really nice Air Flow Meter from a 964 ($350, Phone 619-444-3229). They have sold about 76 of these, and have about 60 in stock. Seems like the best approach, as the rebuilt ones are suspect, from what my research says.

As for my old one, I took two more photos. Steve W. - I do agree with you that this looks odd, as the trace is "worn" off of the plate on the right-hand side. I can think of no reasonable explanation for this, as the unit is currently "homed" in the proper position. Looks like perhaps someone mucked with this in the past, and then someone then went and "fixed" it and centered it back again.

Here are two photos showing what I'm talking about:

http://forums.pelicanparts.com/uploa...1589577064.jpg
http://forums.pelicanparts.com/uploa...1589577064.jpg

closer up:
http://forums.pelicanparts.com/uploa...1589577241.jpg
http://forums.pelicanparts.com/uploa...1589577241.jpg
http://forums.pelicanparts.com/uploa...1589577241.jpg

Heading out to the garage to start on my list for today:

http://forums.pelicanparts.com/uploa...1589577241.jpg

-Wayne

wow - this thread moves fast:

- The noise you see is ignition-interference most. Don't worry about it
- I don't think the track is your current problem, the scope verifies that. I might turn into an issue later
- The spring tension might be way off because someone was clearly in there before and that could be most of your problem
- BTW, Sal here on the board has largely disassembled and modified the machine code for the 3.2 and really developed a new chip rather than just changing the fuel and ign maps like all other "tuners" here. He is a real expert on this matter when it comes to the Motronic software.



Ingo

I had a conversation this morning with my contact over at one of Pelican's main suppliers, SSF. He confirmed what I thought was true:

- Porsche does have a supply of these available (about $900 at Pelican).

- These are BOSCH remanufactured units (you can tell from the sticker on the side).

- Just because it says BOSCH remanufactured on the side doesn't mean it's been remade or redone by Hans or Franz in Bavaria. From what I've been told, BOSCH contracts nearly 100% of their rebuilt parts to outside contractors, many of them here in the states. So, what you might be getting would be a Programa or Brett or who the heck knows US-based company that rebuilt this and BOSCH then stuck a sticker on it, and then sold it to Porsche, who then stuck it inside a Porsche box. Unfortunately, this is how it has been for many years, I would suspect that it's similar with this particular unit:

https://www.pelicanparts.com/More_Info/930606123X.htm?pn=930-606-123-X-OEM&utm_source=googleppc&utm_term=930606123X&utm_c ampaign=Shopping+Feed&gclid=Cj0KCQjw-_j1BRDkARIsAJcfmTHAPLHWNgI4aHF1X_-P4p59WL6WFuQf_phdpv_1od00cae3LFBao5QaAtJ-EALw_wcB

https://cdn1.pelicanparts.com/catalog/images/SuperStock/930-606-123-X-OEM.jpg

-Wayne

I agree. The scope (4 times) has said that the track is not a problem, so I think I'm going to use some very strong tape and just tape up the cover for now.

As for the spring tension, that may be off too, although I really don't see any evidence of the spring holder being moved. Like in this shot from a video, you can see a mark where the years of the spring holder being in place has deformed and marked the plastic slightly. I don't see any of that in this AFM.

-Wayne

http://forums.pelicanparts.com/uploa...1589579393.JPG

Looks like you've... traced the problem to it's source.

http://forums.pelicanparts.com/uploa...1589584938.jpg

I'll show myself out.

OK, but since the source of the poor running engine has not been determined yet, to conclude that the spring setting is correct, is naive.
Furthermore, with the engine running, the wiper arm has not been slowly moved, without changing the spring tension wheel,
in either direction to determine if there exists a fuel mixture problem causing the poor running condition. If little or no change occurs,
then one can basically eliminate a fuel problem the result of; a marginal fuel pressure, a bad temp sensor, poor injectors, an intake air leak,
or an incorrect setting of the AFM spring tension.

It's that simple! Obviously easier and less costly than using the continual shotgun approach of buying and replacing unnecessary parts, right?

Bingo. "Dave" is correct on this, it's premature to say the problem is with the air flow meter. The meter resistance strip is definitely worn, so it's a worthwhile endevour to get a replacement one that hopefully is in better condition. Everything that I've replaced has been visibly worn or tested to be defective (with the exception of the coil, which was just a guess - coils are tough to test). I'm uploading the latest video right now.

-Wayne

Friday update:

- Installed the cylinder head temp sensor
- Reinstalled the narrow-band oxygen sensor
- Buttoned up and reinstalled the air flow meter
- Installed the new wide-open-throttle switch, and repaired harness. Tested with “wide open throttle tester” (a big, long poster tube that presses down the gas pedal).
- Warmed up the engine and adjusted the idle screw and then the mixture, then the idle again, and the mixture again.

Result: NO CHANGE.

Video:

0:00 - Engine bay - engine running poorly when warm (o2 sensor unplugged)
0:14 - Tailpipe – you can hear it missing
0:26 - AFR on exhaust shows spot-on 14.7 (where it should be)
0:37 - Back to tailpipe
0:56 - Tach -> about 800 or so rpm
1:06 - Rev car to about 2000-3000 or so, revs fine – can’t hear it on the video but I believe it’s still missing. Certainly sounds good on the video.
1:39 - Rev car again to 2000-3000 or so, mixture shows 14.3-14.4
2:12 - o2 sensor – plug it in (put phone down to do that)
2:35 - Back to AFR monitor – the engine starts to run lean (15-16 AFR)
3:00 - Rev engine with camera on AFR meter – 15.0 / 14.9 etc. engine at 3000+ rpm, which is leaner than before the o2 sensor was plugged in
3:32 - Back to idle -> goes lean

<iframe width="560" height="315" src="https://www.youtube.com/embed/NPSuuZUxp2E" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

My thoughts:

- Just to recap, I have replaced only the stuff that was worn out, looking worn out, or tested faulty:
- Spark plugs, wires, cap, rotor, (coil, although I put the old black one back in)
- Cylinder head temp sensor (tested faulty)
- Wide-open-throttle switch (I broke this removing it to test)
- Took injectors out to have them cleaned and tested (they were dripping according to the report we got back)
- Cleaned the fuel injection harness connectors which seemed to fix the higher resistance of some of the injector plug harnesses
- Replaced O2 sensor (original was 12+ years old)

- The car has run consistently poorly this whole time – this is not an intermittent problem. It’s very, very consistent. It seems to warm up and run fine and then after about two minutes, it runs poorly.

- As mentioned in the early pages of this thread, the car runs poorly at idle, missing (after warming up), with the O2 sensor unplugged. AFM out the tailpipe shows 14.7, but the car is missing.

- If the sensor is then plugged in, the car starts to run lean. We checked the sensor (multiple sensors), and the O2 sensor is indicating that the car is running rich on cylinders 1-2-3 which presumably makes the Motronic system try to lean it out (we’re seeing it go from 14.7 to lean when the O2 sensor is plugged in). PROBLEM: the tailpipe shows 14.7, yet 1-2-3 show rich. This has been a consistent problem during our testing. The presumption is that 1-2-3 are rich, and 4-5-6 are leaner, which is causing the O2 sensor in the tailpipe to read normal. I currently do not have a quiet way of individually testing left / right on the car (I might take it to the shop where we can take off the muffler and test each bank individually).

- Plugging in the O2 sensor makes the Motronic system lean out the engine (it thinks the car is running rich when it doesn’t appear to be).

- This does not appear to be an ignition issue. I've checked the ignition system numerous times with no signs of problems, and an ignition issue would not give this weird left/right lean/right issue?

Again, car seems to much, much better well when stone cold. See stone cold video:

<iframe width="560" height="315" src="https://www.youtube.com/embed/4eGqyUTsGZA" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

As I’ve mentioned before, I do not think that the air fuel meter is the issue, as the mixture appears to be correct at the tailpipe, but the engine is running terribly. The evidence seems to point to 1-2-3 running rich, and 4-5-6 running lean. Again, I won’t be able to tell unless I head to the shop, remove the muffler (again), and individually test the left and right banks of the engine.

QUESTION: If my supposition is correct (lean on one side, rich on the other), what is a plausible explanation of what could be causing that to happen?

Steve W lent me a fuel rail, injectors, fuel pressure regulator and damper yesterday – I will probably just swap all of these out over the weekend and see what happens. I’m not sure if I will go to the shop and test left/right before or after I do this (probably before).

Thoughts?

-Wayne

Okay, just went for a bike ride and thought about this a bit. If the supposition is true, that one side is running lean and one side is running rich, then what indeed would cause that to happen?

- Problem with the wire harness? I checked out the wire harness and cleaned the contacts and both sides seem to be okay now. Since pin 14 and 15 are joined together in the ECU, the only way this could be a problem is if there were a problem in each individual side harness. After cleaning the contacts on the harness, the resistance seems to have evened out. Steve W. lent me a harness for the injectors, I could try swapping it out (would take about five min). Maybe tomorrow.

- Clog in the fuel lines somewhere? More than one person has suggested this. Higher pressure on one side of the engine than the other. The fuel pressure gauge seems to indicate 2 bar of pressure, which is accurate, but there's only one pressure port on one side. If there is something causing a pressure drop (like perhaps a bad fuel damper), then that could be causing the issue.

- Problem with injectors on one side? I swapped around the injectors and the problem seems to stay the same. Plus I had all of the injectors tested and cleaned. Plus I individually looked at them yesterday for leakage and fuel flow and they all seemed similar. No obvious issues.

- Air blockage somehow to one side of the engine? This is an interesting thought. So, if there were a paper towel or rag stuffed in the engine / intake manifold, it would cause an unequal distribution of air throughout the manifold. I could take off the manifold and look inside. It also might show me the air route to each cylinder and see if any thing is blocking either the air or the fuel spraying into each cylinder.

- Also worth thinking about out loud is the almost 180 degree bend behind the air flow meter. Could this be somehow interfering with the routing of air into each cylinder? I doubt it, because it still has to make it past the throttle plate / bypass. A test for this would be to try to run the engine with the boots off, and the airflow meter disconnected from the air supply. You'd have to prop open the air flow meter and hold it at a certain amount, but then you could measure the mixture on the right bank and then also out of the tailpipe and see if that discrepancy between the two gets any closer. Note: I'm not sure this test would work very well and I don't think this is the problem.

- Air blockage somehow in the exhaust on one side? If there were something stuffed inside the exhaust causing a blockage or something then that would cause air to circulate around the pipe with the blockage and would feed more air to the other pipes. A blockage in the exhaust might show up if I take off the muffler and measure the mixture on each side - I could measure the volume of air coming out of each bank and see if there is any discrepancy left-to-right. I'm not sure how each this would be to do either.

I'll have to think how any of these potential issues fits in with the observations observed so far. Most curious is the "running on three cylinders" and then plugging in all six injectors causes the car to run increasingly poorly. That is a big clue that seems to perhaps point to fuel pressure / damper issues.

Hmmm....

-Wayne

You're not reading/understanding the posts! That was explained in post 194;

Having six injectors or three injectors connected is significant! Closely check the injector pulse widths with your scope.

When listening to your videos, it's not easy to detect a miss. Time to take the vehicle to a knowledgeable Porsche shop,
e.g. Aase Motors presently has three 914s with 3.2 motors.

Yes, yes, yes. "Dave", I do understand your posts. I am well versed in problem solving skills. I graduated from MIT a semester early undergrad with Tau Beta Pi honors, and also from MIT grad school a semester early with a master's in manufacturing. They taught us the "proper" way to test systems and analyze results - nearly all of which I have perhaps completely flubbed here. That was indeed about 25 years ago and perhaps I'm rusty on my skills. Probably been spending too much time behind a computer at Pelican, and for the past two years probably spending too much time with my family. Agreed - I do not see the volume of cars that a local shop like Aase sees - daily experience does often tremendously outweigh "practical" or "institutional" knowledge. These guys "on the ground" know their ^%$# and there is indeed absolutely no replacement for the experience that a shop like them would have.

BUT (and this is a big BUT), this car is my first car - the first car I ever bought. The first car I ever owned on my own, my 30+ year old 914 which I cut the trunk floor out, the car I drove 700 miles to Phoenix to go see my girlfriend, the car I swapped in the 914-6 powerplant - the car that I have spent more time on than I spent working on any of the books. This tiny 914 is my personal Ahab. I let the car out of my control when I had someone install the 3.2 motor and I've never been quite happy with that decision/result. When it was stolen I went out at night at 2AM for weeks at a time looking for it (found it). So, for me, it's a personal mission, a vandetta per se, to see this through and to "take it over" myself, no matter how hard the mission and how difficult it may be to solve. Indeed, this is what our Pelican customers strive for with their own cars - that "feeling", that sense of accomplishment, that "win" and sense of ownership that is difficult to explain. Sure, anyone can take a car to a shop and pay someone "else" do it. But isn't that like sending off your wife to be serviced by some other… , well, you can fill in the blanks...

There's the technical side of this business - the nuts and bolts, and the volts and the resistors. And then there's the passion, the smell of burnt air-cooled motor oil, the challenge and the reward of figuring it out, of restoring something to new (or better than new!). When one looks at it from a 100% practical sense, it doesn't add up - it doesn't make sense. Why spend so much precious time and money messing around with a bucket of bolts? But when passion and pursuit is figured in, that human element is what makes this special - it's what I did for 20+ years (before the stress started to take chunk out of my stomach lining – just recovering now).

So, I appreciate your input, your knowledge, and your “witty” sarcasm – I have a thick skin and I am not easily bothered. But, I am also stuck at home with my three teenagers, and I don’t have very much else to do but wrench on this car and struggle to figure out what the heck is going on with it. Maybe someday in the near future I will give up and ship it to Kenny/Ray/Grant @ Autowerkstatt or Aase, or someone else. But for now, I really want to fix it myself – I think I owe it to the car at this point for letting it out of my control (multiple times) in the past.

I really do appreciate everyone’s help and assistance here on the boards.

😊

-Wayne

P.S. This post was written after at least a ½ bottle of wine…

Here's another question - the 964 has only a pressure regulator and no "fuel damper" in the fuel system. Why is this?

-Wayne

From the Service Information Technik for the new 964 platform.....

“The use of sequential fuel injection means that the fuel pressure damper is no longer required on the 911 Carrera.”

Indeed, that makes sense, since all of the injectors are not firing at once in sequential injection...

-Wayne

Can the position of the o2 sensor in the custom exhaust system have anything to do with it ? Contamination by condensate so for down the line (if I remember the picture well) ?


Sent from my iPad using Tapatalk

Wayne, you never mentioned whether you tried the suggested test of moving the barn door while the engine is idling. This will quickly tell you if a different mixture makes things better.

+1 on this

I'd be keen to see the results of this too as a number of people have previously mentioned. Remove the intake pipe from the AFM so you can access the door inside the AFM and run the motor without the filter for a few minutes. Using a screwdriver or a pencil push the swinging door inside the AFM in a touch and see if that smooths out the running. Also try pulling it back a touch with a small pick and see what difference that makes. In this way you will be able to gauge if the spring tension is incorrectly calibrated.

My 3.2 AFM had been tampered with and altering the spring tension just two teeth made a huge difference to idle and general running and fuel mixtures are now perfect from idle to redline.

Pushing the door in will richen it up and pulling it back will lean it out. If one way helps you then have some clues on whether to tighten or loosen the clock spring inside the AFM.

Once you get the spring tension right you can then adjust the idle mixture with the hex screw on the body of the AFM to get the mixture correct at idle. If the spring tension is right the hex screw should only be one or two turns out from fully in.

I did this yesterday and took a video of it but the video wasn’t that good. I’ll recreate today. Bottom line, the mixture does get richer but the car does not run any better.

Wayne

Wayne - that’s a strange result. I’m trying to consolidate the statements that changing the mixture doesn’t appear to help and your other finding that can be paraphrased as “different VE of bank 1 and bank 2”

I don’t quite understand how this is possible unless there is something severely different in how much air, fuel, or spark goes to the left vs. the right side.

You mentioned 90 degree intake flow (next to impossible, since at idle there isn’t much air flow to begin with), partially plugged intake or exhaust (maybe but unless you’d have a cat on each side not very likely)

How about this: someone swapped out a broken cam with one with a different grind.

Indeed, very true. This car has me starting to cast doubt upon the measuring tools that I'm using, and/or starting to think that there may be something unusually wrong with the engine. Either that, or I've completely overlooked something obvious. But in 11 pages on this thread, I think something obvious would have been pointed out to me by now. I mean, it is still possible that the wire harness is slightly messed up and not driving enough current to either the injectors or the ignition. My gut feeling though is that particular problem would get worse as the engine revs higher (it doesn't appear to get worse).

From Wikipedia:

Volumetric efficiency (VE) in internal combustion engine engineering is defined as the ratio of the mass density of the air-fuel mixture drawn into the cylinder at atmospheric pressure (during the intake stroke) to the mass density of the same volume of air in the intake manifold.

It's certainly hinting like there's something potentially off left-to-right. Today I'm going to take the muffler off (again), and replace the bolts with a "quick release" system (studs and c-clamps), and drive it off to a parking lot (away from my neighbors) to measure the mixture out of the left bank and the right bank. I'll also redo my video from yesterday where I was poking the AFM flap with a wooden stick.

The most likely thing I can think of would be some type of fuel pressure drop through the fuel rails caused by a bad pressure regulator or bad pressure damper. My colleague who works at SSF mentioned that he was working with someone who had a 1988 BMW 5-Series that had similar issues. They replaced nearly everything, and then when they replaced the fuel damper, all of the issues went away. Since I have Steve W.'s spare fuel rails, injectors, regulator and damper, the logical thing would be to start taking a closer look at that. Or, I can just wait until Monday when the replacement 964 air fuel meter comes and try that first.

I think I'll measure left / right fuel mixture using the LM-1 and see how that works first.

-Wayne

Wayne,

As my Dad would have said, "Keep your chin up, lad!"

John

I would be easier to just weld another bung on the other header, and you can always retest in the future much easier, or even run two LM-1s. I can loan you one of mine if you want. The thread is 18x1.5, same as a spark plug. That's what we've done in the past and doesn't take that long. Make sure it's after the collector so all three primaries are sampled.

I agree that would be the best solution. But, I don't know how to weld (bought a brand new Miller unit like a decade ago, and "learn to weld" has been on my to-do list ever since), and these are stainless steel which I hear is much more difficult. In non-Covid times, I would have just driven the car to the local muffler shop and had them weld it on. But it's not that easy these days.

I found a good parking lot to take the car to. Hopefully I won't drop the hot muffler on any important body part.

-Wayne

Wayne,

I had similar symptoms on my '86 Carrera, which got progressively worse. Until the engine would not turn over. Car was running very rich, especially the cylinders on the left side( drivers). I am still in the process of replacing the regulator and damper(waiting for my parts). Found fuel in the vacuum hose that connects to the damper. Maybe you have a small hole in the diaphragm (regulator/damper) and for some reason, the driver side cylinders are getting more fuel from the intake than the right side ones(fuel from vacuum lines into intake manifold).

I must have a larger hole in one of the diaphragms, since car was smoking and fouling plugs.

also, the intake manifold was cold to the touch(very cold< even condensation ).especially on the left side. most likely from the fuel leaking into the intake manifold.

Cool deal, it's good to hear that my theory is on the left/right side imbalance is not completely crazy. I had not thought about perhaps measuring the temperatures of the left and right manifolds. Although I'm skeptical, having more data is usually not a bad thing...

-Wayne

Chip Foose once said “I can’t weld but I can grind!!”

So I took the car to a local medical plaza where I could run it without headers and will only puss off people that aren’t my neighbors. :)

I’ll post the videos soon, but the results are what I expected 1-2-3 is running okay and 4-5-6 is running leaner. So there is that disconnect between left and right.

Now the trick is to figure out if that is caused by a mechanical issue or a fuel injection issue. The compression check came back fine and I ordered a new leak down tester to replace the one that broke - it should be here tomorrow. So I will check that - compression and leak down.

Just sitting here leaning against a concrete wall waiting for the car to cool down to bolt up the muffler.

Wayne

http://forums.pelicanparts.com/uploa...1589669502.jpg

Cams?

Videos showing the mismatches side-to-side. I think this test here confirms what Steve W. originally predicted / figured out about 5-6 pages ago, that the air-fuel mixture coming out of the muffler was reading lean while 1-2-3 was reading richer, leading to the thought that 4-5-6 was running leaner than 1-2-3.

Video #1 - Cylinders 4-5-6 (left side) - idle, running quite lean. The car goes super lean and then stumbles and then recorrects. Not sure how important this clue is.

<iframe width="560" height="315" src="https://www.youtube.com/embed/IfMs3ltFR9g" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

Video #2 - Cylinders 1-2-3 (right side) - idle, running close to 14.7. This is what we've seen when the O2 sensor was plugged into the 1-2-3 side header previously. Since I tuned the airflow meter mixture to be 14.7 when the LM-1 wide-band O2 sensor was plugged into the 1-2-3 header, this makes sense.

<iframe width="560" height="315" src="https://www.youtube.com/embed/1RdKOmj0bHI" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

Video #3 - Cylinders 1-2-3 (right side) - idle and about 1500-2000 rpm. The air-fuel mixture on this side is very good / close. You can hear the car sputter and miss though as this is revving.

<iframe width="560" height="315" src="https://www.youtube.com/embed/kDHpUdShcRk" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

Video #4 - Cylinders 4-5-6 (left side) - idle and about 1500-2000 rpm. Same thing as when at idle - runs much leaner than the 1-2-3 side.

<iframe width="560" height="315" src="https://www.youtube.com/embed/Qa4GlDssAvM" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

-Wayne
-Wayne

So in summary left side sucks at idle (lean) and all else is well?

Left side runs lean in 1500+ as well...

Although this looks bad, it's getting me closer to figuring out the cause:

- Fuel (blockage in the lines?)
- Air? (blockage in the runners?)
- Mechanical / timing / compression (I'm not sure how likely that is1)

I think ignition is pretty much excluded as a potential culprit, as even a missing / dead cylinder wouldn't necessarily cause the mixture to change - the O2 sensor doesn't detect unburned hydrocarbons (HC).

-Wayne

Hm, not easy to see in the videos. Too me it looked like only one of the idle video showed 18+ while the rest was inline around 14.

- Have you had the intake off to check the gaskets?
- Any chance one of the injector o-rings got damaged during install?

Your warm running issue is not likely the CHTs given your numbers above. Once fully warm if the CHT reads below 200ohms then cold start enrichment is no longer used. You said that after 10 minutes you read 155ohms, it's not the CHTs.

Unplug the O2 sensor, get engine fully warm, what's the AFR at? You need to know if you are lean or rich. A properly setup 3.2L should be at 13.8 to 14.4AFR fully warm with O2 disconnected. This engine does not like to run lean at idle, if it's lean it will result in lean mis-fires and drive the WBO2 nuts! You need to set base mixture at around 14.0AFR and leave the O2 sensor unplugged.

Other thing I noticed is the extra 90deg rubber elbow going to the AFM, this has me concerned. Can you remove that elbow and put the AFM onto only the first elbow, put it as if it were in a normal 911 configuration. Not sure why that extra elbow was added? I've helped on a few 914 conversions and none have that crazy intake setup.

RHS vs LHS mixtures not the same usually means bad injectors, swap injectors between RHS to LHS, does the issue move to the other bank? Just swap 1,2,3 with 4,5,6 and test bank mixtures again.

Those are good suggestions, so to double-check, I ran another smoke test this evening (4th one). I also pulled the injectors out of their mounting holes just to confirm with my eyes that smoke was in the chamber (it was). No leaks appeared there. I also presume the intake gaskets would be fine too if there was no smoke leakage there either...

-Wayne

Thanks, that's a good suggestion - I did remove it tonight. Injectors are all rebuilt and I've been swapping them around a bit. Steve W. lent me some used one that are old, but may still give good clues as to what is going on. I swapped out the fuel damper tonight with the one that Steve W. lent me - I'll have to test it in the morning to see if there is any difference. Changed the 2-year old fuel filter too while I was in there.

Static pressure with just the pump running (hotwired from the DME plug) is about 40 psi on my gauge, which may be high. I have a brand new regulator I may swap in since this seems slightly out of spec.

-Wayne

Okay, I installed the pressure damper loaned to me by Steve W., and I removed the 2nd boot on the intake - no change. The car behaves exactly the same. I'm going to recap all that has been done so that perhaps it might be come obvious what the issue is. I also might get some ideas too.

Summary: The car (seems) to run well (slightly erratic idle) when started cold (I have numerous videos of it starting cold). Then after about two minutes is just starts to miss and flub. Revving the engine will work, but the car will miss when revved. When driving, power feels down, and when there's the miss, there's a matching dull thud clunk coming from the engine. My gut is that it is not a mechanical engine issue, otherwise it would run poorly on code start up - I cannot really think of a mechanical mechanism that would cause the engine to run fine for 2 min and then just take a dump like this is.

I'll spend some time on a recap post today, it will help clear my mind too.

-Wayne (seriously bummed)

Actually this is incorrect. A missing cylinder will cause that cylinder to act essentially as a straight air pump, pumping all that O2 that came in from the intake out to the exhaust. That extra oxygen is detected by the O2 sensor which causes it to sense that car is running lean. You can see missing on a wideband as spikes that go lean (> 18-19:1). Excessively rich mixtures (> 9:1) can also fool a wideband into displaying a very lean mixture because the excessively rich mixture fouls the spark plugs causing missing. Usually in such instances, that can be detected by excessive hydrocarbons that you can smell and if at a standstill, burns your eyes and nostrils.