When Well Enough Can't Be Left Alone; Backdate, EFI/ITB, AC, and more!

[Showdown]

So guess who's back at work, not doing work... (where's the "this guy" emoji?)

Taking Jonny's sage advice I pulled the ITBs for bench testing. All of my new gaskets look perfect and I'm 100% confident I have no leaks there.

I rigged up my shop vac with a fitting to go into the bottom of each ITB. Very fancy and advanced stuff. Word to the wise- skip the regular electrical tape and go for the thicker insulated stuff; it saves tons of time.

I tested each ITB with my synchrometer. I tried to upload photos but Pelican is borked.

Suffice it to say I the results were eye opening.

-On each of the ITB banks the outer two ITBs read 0 on the synchrometer.

Hooray!

-On each of the TB banks the inner ITB was reading about 2 on the synchrometer.

WTF!!


I started working on the center ITBs and no amount of adjusting made a difference. So I took the ITB apart and cleaned the entire thing thinking that maybe there were some contaminants holding the butterfly open... With it squeaky clean I reassembled it and it made no difference.

Each of the center ITB's is leaking like a disaffected government employee.

I tested each center ITB independent of the others and they still leaked. I used my smoke machine to try an isolate the leak and it's coming from the butterfly shaft on either side of the ITB.


I have come to the following conclusion:
The design of the RHD ITBs makes the center ITB inherently leaky and as such a poor candidate for delivering a MAP signal. Now, I don't know anything about anything but that's the only conclusion I can think of. Please enlighten me.


I also did a lot more reading about ITBs and MAP and the overwhelming consensus from users and tuners is to just avoid it all together and just use Alpha-N. Some folks can get it to work but it seems incredibly unreliable, very finicky and just flawed. So that's what I'll be doing.


This brings me to the question of the manifold and what to do with the manifold and the hoses...

I was thinking of two options:

1.) Run the brake booster directly off the #3 ITB which is not leaking. My brake booster hose has a check valve so that should be fine and cap or plug the other hose ports on the ITBs

2.) Run all the hoses to the manifold but install check valves on each one and then run the brake booster as it currently is. This might also give me the option of running a hybrid system with Alpha-N for throttle below a certain point... maybe 30% (??) and then switching to MAP.

[Mr Beau]

Is there's a known good recipe (MS + ITB + vacuum manifold + MAP sensor + base map) then it seems reasonable to expect the car to be able to idle and drive.

Whacky ITB calibration wouldn't help. Stock cams? If so, seems like getting a decent MAP signal shouldn't be too troublesome. Appropriate filtering would be needed, and as trond said, you can't run AE off MAP.

Biggest reason to not go down the Alpha-N route right now would be if there's a good baseline map that uses the MAP sensor. Alpha-N fueling tables can be tricky to get dialed in whereas MAP vs RPM vs VE tables are "logical" and something functional shouldn't be that hard to build from scratch.

I also don't think the timing has been synced. The ECU needs to have the timing 'locked' at say 10*, and then a timing light needs to be pointed at the crank pulley to confirm it matches what the ECU is commanding. You then (most likely) adjust an offset in the ECU to get them to match.
"I set the timing, or started to; I have the rotor pointed at the #1 notch with the crank at Z1. It was off a bit; hopefully this little adjustment will make a big difference."

[Showdown]

Yeah, I need to synch the timing but I need a running car to do that and I don't have that right now because the vacuum leak is so large that the ECU is dumping fuel as if it were WOT and fouling my plugs faster than the car can start. It's a feedback loop...

I mean, can I just eliminate the center ITBs from the vacuum manifold if they're the source of a massive vacuum leak and just run the car off the other 4?

Check valves on the center ITB hoses?

[Jonny042]

Originally Posted by Showdown

So guess who's back at work, not doing work... (where's the "this guy" emoji?)

Taking Jonny's sage advice I pulled the ITBs for bench testing. All of my new gaskets look perfect and I'm 100% confident I have no leaks there.

I rigged up my shop vac with a fitting to go into the bottom of each ITB. Very fancy and advanced stuff. Word to the wise- skip the regular electrical tape and go for the thicker insulated stuff; it saves tons of time.

I tested each ITB with my synchrometer. I tried to upload photos but Pelican is borked.

Suffice it to say I the results were eye opening.

-On each of the ITB banks the outer two ITBs read 0 on the synchrometer.

Hooray!

-On each of the TB banks the inner ITB was reading about 2 on the synchrometer.

WTF!!


I started working on the center ITBs and no amount of adjusting made a difference. So I took the ITB apart and cleaned the entire thing thinking that maybe there were some contaminants holding the butterfly open... With it squeaky clean I reassembled it and it made no difference.

Each of the center ITB's is leaking like a disaffected government employee.

I tested each center ITB independent of the others and they still leaked. I used my smoke machine to try an isolate the leak and it's coming from the butterfly shaft on either side of the ITB.


I have come to the following conclusion:
The design of the RHD ITBs makes the center ITB inherently leaky and as such a poor candidate for delivering a MAP signal. Now, I don't know anything about anything but that's the only conclusion I can think of. Please enlighten me.


I also did a lot more reading about ITBs and MAP and the overwhelming consensus from users and tuners is to just avoid it all together and just use Alpha-N. Some folks can get it to work but it seems incredibly unreliable, very finicky and just flawed. So that's what I'll be doing.


This brings me to the question of the manifold and what to do with the manifold and the hoses...

I was thinking of two options:

1.) Run the brake booster directly off the #3 ITB which is not leaking. My brake booster hose has a check valve so that should be fine and cap or plug the other hose ports on the ITBs

2.) Run all the hoses to the manifold but install check valves on each one and then run the brake booster as it currently is. This might also give me the option of running a hybrid system with Alpha-N for throttle below a certain point... maybe 30% (??) and then switching to MAP.

I think you're expecting too much from the RHD's (EDIT - THIS IS NOT A CRITICISM OF THE ITB's, nothing wrong!!) - if you've got a reading of 2.0 on the center, maybe increase that to 2.2, and open up the outter ones to match. I'm not familiar with these throttles but assume they have bypass screws for idle air?? Think about this - if they were all zero the engine would just die. You just need to find a nice balanced idle where all the cylinders ingest the same amount of air (since they are all getting the same amount of fuel).

Just think how much more tidy and simpler things will be without that vacuum manifold.....

[chrisbalich]

Julian,

If all of your ITBs are synced to zero flow, the car won't run at idle.
IIRC, my ITBs at ~900rpm were around 4.75. (I forget the units)

[chrisbalich]

Originally Posted by Jonny042

...
Just think how much more tidy and simpler things will be without that vacuum manifold.....

Can confirm that this is how I ran my car for some time. So much tidier in the engine bay, no vac leaks, no MAP except for baro. Not a terrible way to go.

[Jonny042]

Originally Posted by Showdown

Yeah, I need to synch the timing but I need a running car to do that and I don't have that right now because the vacuum leak is so large that the ECU is dumping fuel as if it were WOT and fouling my plugs faster than the car can start. It's a feedback loop...

I mean, can I just eliminate the center ITBs from the vacuum manifold if they're the source of a massive vacuum leak and just run the car off the other 4?

Check valves on the center ITB hoses?

Once you get them balanced, the car is running, and you can tweak them, they will all be pulling the same amount of vacuum, more or less. The middle ones aren't leaking so much as the throttles are effectively open more than the other 4. You need to even that out. The car will run a lot better.

It doesn't matter what you do, MAP or Alpha-N, you are going to be tweaking the tables to get it to run right. Don't expect a base map to get you any closer than you've gotten - there are just too many variables.

[Mr Beau]

36% TPS, 3000 RPM, 93 kPa shouldn't result in off-the-scale rich AFR of 10:1 if the baseline map is close and everything else is working properly.

In other words, 93 kPa is a reasonable MAP reading for 36% TPS at 3000 RPM. So why isn't the fueling correct?

If a complete log is shared then maybe something obviously wrong will be identified.

[Mr Beau]

Originally Posted by Showdown

Yeah, I need to synch the timing but I need a running car to do that and I don't have that right now because the vacuum leak is so large that the ECU is dumping fuel as if it were WOT and fouling my plugs faster than the car can start. It's a feedback loop...

The log doesn't show that. Seems to show 12ish AFR at IDLE, and <10 at part throttle. O2 can be incorrect though if there's misfires and/or leaks, but these would make it show leaner than actual.

Timing can probably verified while cranking. Won't be perfect but would be a much closer ballpark.

O2 correct needs to be turned off. It looks to be oscillating at idle. Is it turned off?

Get the TB's balanced as much as reasonably possible, switch to alpha N and start tweaking the fuel map to get a stable idle. Lock the ignition timing. Turn off O2 correction. Monitor AE to ensure it's not being triggered. Point a IR thermometer at the exhaust tubes to balance the airflow.

[al lkosmal]

Based on my experience....Typically, the airflow measurement will be 5 to 7 kg/h while idling at 1000 rpm or so....and still have a good MAP signal. However, if there are no major vacuum leaks found and the MAP signal, at idle, is above 70 or so, your not going to get much signal resolution between fully closed (butterflies cracked open slightly) and fully open pedal /butterfly travel.....and then it is time to head into Alpha-N mode.

regards,
al

[rwest]

So I think I figured out how to smoke the ITBs. I used the rubber cone that came with my machine and put it in the trumpet and then used a vacuum hose clamp to squeeze the vacuum line. I got no leaks on #4- my tester is an OTC and it has a ball indicator that gives a visual indicator on the machine as well as looking for smoke traces. #1 has a smoke plum coming out of the idle screw and I think had an open intake valve as the indicator still showed high.

[al lkosmal]

Originally Posted by rwest

So I think I figured out how to smoke the ITBs. I used the rubber cone that came with my machine and put it in the trumpet and then used a vacuum hose clamp to squeeze the vacuum line. I got no leaks on #4- my tester is an OTC and it has a ball indicator that gives a visual indicator on the machine as well as looking for smoke traces. #1 has a smoke plum coming out of the idle screw and I think had an open intake valve as the indicator still showed high.

Rutager,
Last log of yours, i reviewed, your MAP signal was very good....like 50 or so at idle with the TPS at 0....what makes you think you gave a significant vacuum leak? None of the ITBs are likely to be completely airtight.......but your system almost appears to be as good as they get.......based on such a good MAP signal.

regards,
al

[rwest]

Originally Posted by al lkosmal

Rutager,
Last log of yours, i reviewed, your MAP signal was very good....like 50 or so at idle with the TPS at 0....what makes you think you gave a significant vacuum leak? None of the ITBs are likely to be completely airtight.......but your system almost appears to be as good as they get.......based on such a good MAP signal.

regards,
al

Hi Al,

Just a matter of making sure everything was in good kit so I know that I’m not trying to tune a mechanical fault out of the system. Remember, I have an IAC, so my MAP is only coming off of 2&5, so could still have had leaks on the other 4.

Didn’t take long and now I know.

I loaded your last tune, thanks, but Mother Nature and the MN salt trucks stopped my on road testing. I will do some up and down the driveway cold running and idle tests.

The one and maybe only good thing about winter is that you can tune cold starts multiple times a day!

Merry Christmas Al, I appreciate all the good after sales support and will send you another datalog soon.

Rutager

[Mr Beau]

Get it running at 2000 RPM and any leaks won't be a factor. It'll let you get the ignition timing set, check warmup enrichment settings and get it running smoothly.

[al lkosmal]

Merry Christmas Rutager....we'll continue in the new year...and/or when the big thaw comes.
I expect that with your ITBs airflow balanced..I.E. all cracked open slightly and airflow measured and adjusted to match, within reason,.... and having the very good MAP readings, you are ready to rock and roll.....

regards,
al

[Showdown]

Day 8

Well, if it wasn’t clear thus far, the last flurry of posts should make it crystal: I really haven’t the slightest clue as to what I’m doing. Ok, to be fair to me, I kind of know what I’m doing but lots of the subtle nuances of working on a 43 year old German car and EFI/ITB conversions are just foreign to me. Let’s remember, one year ago I had only ever changed a flat tire.

Before we’re wise, we’re not…

I’m trying to learn as fast as I can and luckily there are a whole bunch of folks (you!) who have been ridiculously patient and helpful thus far. I feel like if we (hopefully) meet one day I’ll slinging bottles of champagne from the trunk of the 911.

Anyhow, back to the car.

I decided to take a break from the back of the car while I’m waiting on some packages and turn my focus to the front of the car. The easy part… ha!

Remember when I said I cut the long hood extension off the short hood. Well, I did. I had originally welded a new hood extension to the short hood and began working those billion MIG welds. Well, I decided I wasn’t satisfied with it so I cut it off and started anew, this time with TIG.

I should have done this from the get-go but I was young and dumb back then.

It’s a this point in the story that our hero (me) either makes a critical error that seals his fate as dragon amuse bouche, or threads the needle, succeeds and wins the heart of the fair maiden… Now, being a Chicagoan, a Cubs and Bears fan too boot, I’m all too familiar with snatching DEFEAT from the jaws of VICTORY. Luckily this time fate was on my side and I was able to successfully weld the new panel to the short hood. It ain’t prefect but it’s completely workable and I’m totally ok with that. Some fiberglass filler and it’ll be fine.


The photo doesn't do it justice... this is smooth and really quite nice!

More importantly, I felt confident to tackle the light boxes now.

The light boxes I bought looked really great in raw metal. Then I primed them with weld-thru and frankly, they’re just a substrate for the filler that will be necessary to create the actual shape. This is not to say they’re worthless- I couldn’t have made these myself without a full metal shop which I don’t have so they’re fine. It’s just that the bends are rough, there are dents and tool marks all which will have to be glazed over. I’m not really surprised or complaining as I figured they’d need ancillary work, I just want other DIYers to know that these parts are really just “body shop ready.”

I’ve procured a small fortune worth of Evercoat products, and a mountain of sanding blocks and boards to assist in making the welded panels look acceptable. I’m actually looking forward to this part as it’s more my wheelhouse and I have much more confidence in my ability to work with filler over metal.

A wise man once said “don’t quote me boy, I ain’t said ***** yet”

We’ll see how I feel about filler once I’m covered in it

While TIG was a great choice for the hood extension it was not for the light boxes. I started out with TIG but the light boxes were so thin, maybe 26 or 28 gauge steel that all I was doing was burning through them or making a righteous mess- I can TIG but super thin sheet metal is still really difficult for me. Luckily the compound curves of the light boxes reduced the distortion to almost nothing so MIG was fine.


This was without a doubt the most scary thing I've done- an angle grinder to otherwise fine fenders!


We have welds!

I then began dressing down the welds, first with a Dremel and cut off disc and then with various angle grinders and pneumatic sanders…. You aren’t working hard until you kill a Harbor Freight angle grinder. To be fair, this $10 tool lasted a decade. A DECADE!


RIP Harbor Freight angle grinder, you served valiantly

So with the hood now long and the light boxes in, the heavy body work is all done and I feel pretty good about it.


All ground down and baby butt smooth


Oh yes..


OH YES!

[ToySnakePMC]

I’m enjoying your build thread - it seems like you’re having fun and possess the right attitude! Front end is looking really nice. Congrats!!

[chrisbalich]

Snatching defeat from the jaws of victory!
This is so Chicago sports it hurts my soul.

Looking great, Julian!
Keep chugging along. 2022 looms ever nearer.

[Jonny042]

That's looking great!!!

[Showdown]

Day 9

I hope everyone has had the holiday they wanted and is ready for 2022!

This weekend saw the first snow storm in Chicago which means not only is it raining snow, screams from sledding children and heart attacks from snow shovelers, it's also raining salt and that means the roads are shot until the spring rains. Or more likely late winter rains, thank you global warming.

So that means that there's no real rush to get the engine work finished because I can't take the car out to tune it or even drive it so much of that will be on the back burner.

I was able to get another full day working on the car without having to wake up at the crack of dawn which felt great.

I filled in and welded up the mirror and antenna holes as well as the rocker trim holes. This car had enough holes to fill the Albert Hall! The mirror mounting area was pretty mangled and I tried to flatten it out but it’s going to need some filler for sure. I haven’t yet decided on which mirrors I’m using (leaning toward partially painted bullet mirrors.)


Goodbye flag mirror!


Though my father was and I am by extension, Swiss, I'm happy to see these holes gone!



Porsche really just drilled and screwed rockers into the body...geez!


Oh, hey, you know what showed up... BUMPERS!!

If you’ve been obsessively perusing the Parts-For-Sale section of Pelican (wait, I’m not the only one, right?!) you many have noticed I listed a whole bunch of bumpers. I was able to order very nice fiberglass bumpers from Anna and Siegfried Thom in Germany and when they arrived I was both elated at how beautiful they looked and devastated because they didn’t fit my car. There was a bit of miscommunication and I ended up with parts for a non-narrow body car.

So, I went looking for the right bumpers and landed on Rennspeed. I used a Rennspeed IROC rear bumper for my first go-round of deleting the IBs last winter and It was a perfect fit and the finish was surprisingly good so I figured why reinvent the wheel and try another vendor. Also, the price was right and given that even the most expensive glass pieces still require work I'm ok with any imperfections.

With a new R-style bumper in hand I started with the lovely process of figuring out how to mount it. This bumper has some bizarre fiberglass flanges for mounting but they certainly don’t fit my car so I cut those interlopers off! I fabricated two aluminum brackets with rivnuts and slotted holes (kinda hard to see but they’re there) so that I can mount the bumper to the front bulkhead. This will make removal easy as the bolts will be accessible from the trunk.


Rivnuts, you're my best friend.


In order to find the location of the holes I threaded some bolts into the rivnuts and dabbed some white grease on their heads. When the bumper is fitted and in position the grease leaves marks and all I have to do is drill the holes.


Lipstick works too, if that's your jam...no judging.



A very scientific method



The bolts allow a bit of adjustment and are rock solid when tightened.


The bumper will also be secured to the bottom of the fender light boxes I just welded in. I would love to add an outrigger support from the hole in the light bucket to the fender but that would interfere with the carrera oil cooler and AC condenser (damn, I still need to start that project!). That said, with just the brackets, the bumper is solid, in place and not going anywhere.

With the bumper fitted I temporarily placed the front rubber seal in place to see how everything aligned…. Pretty damn good, in fact, the measurements are identical across the bumper, so…perfect! I'm elated with this result as just a few weeks ago getting to this point seemed like a huge mountain to climb.


That's damn pretty, if I do say so myself.


I still have a bit of body work to do; filling up the spot welds from where the rear reflector mounting panel was, finishing off the hood by welding an inner panel on the underside for structural rigidity and folding over the lip, and finishing up an aluminum filler panel for the front of the car where the longhood latch panel would be. But for now I feel really good about where I’m at.