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

I decided that after working really hard today I would take off an hour or so early to tinker with the car- the nice thing is that it lives at my work... that's also a dangerous thing because really, I should be working...



Last night I pulled the wideband and soaked it in gasoline. It was filthy and looked like a fouled plug so I figured, why not. I also cleaned the plugs which were fouled of course.



Today I did the following:



-Checked my timing and found that it was correct and as spot on as I could ask for. there's a bit of variation in the idle (>100RPMs at max) but for now I'm totally happy with that. After emailing with Al and understanding how his setups work everything made sense. He uses both the dizzy and MegaSquirt to control timing where as I understand it's usually one or the other.



-Checked all the linkages and made sure everything was tight. Good lord these ITBs are sensitive. I felt like I could blow on them and change the idle.



-Launched TunerStudio and confirmed all the sensors were calibrated and that all the settings were as they should be. Always nice to known that you're doing it right.



And then I fired it up.



It took a little while to find the sweet spot between idle, balancing the intakes and AFR but eventually I got the idle to average 1100, the intakes pretty closely balanced and the AFR sitting at 13.58 and the MAP at 63. I only have one wideband on the 1-2-3 bank and I suspect that at some point I'll probably run another to the 4-5-6 bank (I should have done that in the first place but I was young and stupid then) also, Chicago has winter every 4 months so projects are welcome.



After a few mins I decided to take it out and see how it ran.



1st and 2nd are bogged down a bit and running rich, but that's fine- I haven't touched the fuel map and Al's starting maps are Saudi rich to be safe. 3rd is a hoot and honestly doesn't feel like the same car I bought. I was kind of shocked at how quickly the power came on when I hit 3500 RPM and how quickly I got up to 60mph. Fourth was just as fast and it felt like a bottomless pit of power. Of course with the 2.7 and the CIS P&C it's pretty limited to about 4500 and lots left on the table but mark me impressed. The car also felt like it was running smoother as it got warmer. Suffice it to say, that even wit a raw and choppy tune this no CIS.



So now I'll keep my fingers crossed that tomorrow I can repeat the easy start up, and short drive. If so, then I'll start diving into the tune.



If anyone is curious the log is here: https://www.dropbox.com/s/3z46a1u6dhsnu3b/2022-06-28_15.56.37.mlg?dl=0



There are two manual marks, the first just to see if it worked and the second when I start driving. Everything before that is tinkering with the ITBs and letting the car get warm.



I know there are plenty of valleys ahead but I'll take the W today.

https://uploads.tapatalk-cdn.com/202...fe2468821f.jpg

Yes please. And before these images get buried with pages on pages of tuning jargon... and I do I agree it is of critical importance for the car to run well.
You nailed it; the result is a fine execution if I dare say so myself! Now back to your regularly scheduled programming SmileWavy

Julian,
Do you have a hand-throttle? Or does your TPS need re-calibrated? I'm reading that TunerStudio screen to show TPS of 1.3% at idle?

You can also re-scale 'engine load' and 'MAP' gauges to give you a more accurate picture...with the needle. I do realize the digital readout at the bottom tells you exactly. But once you start street-tuning, it'll be nice to glance at the gauge and know approximately where the needle is pointing.

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

No hand throttle- the linkage is sticky. Sometimes it snaps back to 0, sometimes not… when I’m driving and using the pedal it generally returns to 0 but when I’m fussing in the engine bay it’s finicky. I added a pretty strong helper spring to return it but even still it doesn’t always reset to 0.

I should probably replace the bushings or get a heavier helper spring.

Good to know about the gauges- I had no idea.

You're making great progress!!!

It's not a terrible idea to calibrate the TPS to a 1% value (or even less) at no-throttle. Just in case things go out of adjustment to the point where the actual throttle position goes into negative (but the gauge doesn't show it).

So for instance, if your throttle moves a small amount before the TPS starts to show a value above zero it could cause issues, more so if you are running TPS based load.

Of course this might steal a bit of range from the top end of your throttle but generally the last 5% doesn't make much difference.

ITB linkages can be fussy. It's easy to give into the temptation to add more return spring to the system but be aware it can cause driveability issues - ITB's have such incredible response off idle (which is the reason they are tougher to tune) that if there's a massive amount of stiction in the system you'll have a tough time easing into the throttle.

This approach to timing control would be referred to as "overlay" timing. Again the CDI+ manual explains this fully. There's nothing wrong with that right now your system is completely relying on the mechanical distributor to control the timing, as you're "overlay" timing contribution to total is 0.

Even if you do start to add (or subtract) a bit of timing to the curve the distributor is providing, you'll only know exactly what your timing is doing at idle and at max RPM and have no idea where you're at in between. And you're relying on a 45 year old mechanism of unknown condition to provide timing.

It's a lot of control to give up just for saving yourself the trouble of locking out the advance.

The GOOD part of the approach is that it gives you one less thing to worry about at this point, and you can spend this year fiddling with fuel (and enjoying the car!) without wondering about timing.

Keep up the great work!!

^^Everything that Jonny said.

Building off his comments on ITB return spring pressure...

If you overdo it with the return spring tension/pressure, you can actually affect the sync. You'll have one (or two) TBs that are being pulled hard closed when the rest aren't.

Makes sense when I actually think about it- thanks for saying it aloud.

I think at some point when the engine needs a rebuild (55k on it now) I'll move to COP and do another round of improvements; P&C etc... But for now, as Jonny said- I'm sure I'll be plenty busy with fuel.

Regarding adjusting the TPS at idle, absolutely required to have it correctly fall back to 0% (or whatever you want to be considered fully closed- I use .4%) idle well and to cut fuel during decel. Makes all the difference because if you have configured idle to be active when TPS is < .X% or decel to be active when < x% and the value is higher than that value it won't utilize all the idle maps correctly.
Keep posting about your experience though. A lot of us find this way more interesting than doing our actual day jobs!

Day XX

Where to start…

Wow, it feels like just yesterday that I was dutifully updating this thread weekly and keeping a meticulous log of the life and evolution of this car, and then I kind of fell off the face of the earth...

In late June kind of out of the blue, on the heels of our 11th wedding anniversary, my wife told me that she no longer wanted to be my wife. Sometimes you're the nail, and other times you're the hammer. And sometimes you're the 2x4 at the mercy of a novice with a rapid-fire nail gun... It’s been overwhelmingly difficult and sucked away a lot of my energy for well, everything; work, the car, getting out of bed….

But we have to evolve or we cease to exist and the next chapter will be nothing if not interesting; 42 years old, two kids under 10 and single once again. Wait, wasn’t there an ad about Porsches getting you laid…? Advertising is true, right? Right! RIGHT?!

Anyhow…

One of the reasons I chose to work with Al and X-Faktory, aside from the cool (and affordable) EFI kit he offers, was the promise of having a real live human on the other end of my questions; an expert to help me through the myriad of problems I was sure to face.

After gathering some data logs and sending them to Al he responded with a new VE and AFR table to correct the initially safely rich tune that I was running along with detailed screenshots with arrows and notations explaining what was going on and why. A solution and an education!

I loaded the new tables and fired the engine right up. Low and behold, it was running really quite well. It found idle fairly quickly even though it was cold and settled in.

My newfound marital state has resulted in a lot of free time lately… I’ve been taking lots of drives; 6 hours on Saturday, 5 the next Sunday, 8 the Sunday after that. All the while trying to tune this damn car to run well and perform as it should.

I’ve become amazingly adept at adjusting the ITBs and have achieved a magical state of perfect balance and beautiful idle. I’m very proud of that as I’ve spent countless hours on the side of random roads, sweating into the engine while adjusting the linkages.

I’ve been making progress but am acutely aware of my own limitations having only been at this for a month or so. I have some tuners who are interested in taking a crack at the car and I’m about ready to hand it over. Partially, I want it done well but I also want to see what they do; to watch a master at work will be worth the cost and provide a lesson that I wouldn’t otherwise have access to.

In addition to tuning and logging miles I purchased an M&K active exhaust. Unfortunately it just didn’t fit my car. I don’t understand why or how as it was designed for an SC and my 1977 has the same bumper mounting brackets as an SC. But for some reason they prevent the muffler for fitting…grrr.

To hell with it. I cut apart the muffler and started making modifications. It needed to be 2” shorter on each end. My bandsaw made quick work of that and now I know what the inside of an M&K muffler looks like!

http://forums.pelicanparts.com/uploa...1659964112.jpg

http://forums.pelicanparts.com/uploa...1659964112.jpg

While I was recklessly cutting my new muffler apart, I cut the vacuum pots off and replaced them with electric gates; I want to be able to decide when and where I’m going to be an obnoxious *******! With it wired up to a toggle switch on the dash I can now go from civilized to hooligan.

http://forums.pelicanparts.com/uploa...1659964202.jpg

http://forums.pelicanparts.com/uploa...1659964202.jpg

http://forums.pelicanparts.com/uploa...1659964202.jpg

http://forums.pelicanparts.com/uploa...1659964202.jpg

Honestly, at first it was a bit of a disappointment. At idle and anything lower than 3000RPMs it kind of sounds the same, just louder and a tad raspier: M&K mufflers aren't known for being quiet, even the Street versions are significantly louder than a Dansk. Now, above 4000, it’s a lot of fun and the car sounds like an early 70s rallye beast, particularly when abruptly letting off a hard throttle and in-gear decel…OMG, I can’t get enough of that!!!

I can’t wait until the engine (55k miles currently) needs a rebuild and I get to put non CIS P&C to use. I can only imagine what an RS spec 2.7 feels and sounds like.

So, for all intents and purposes, my work here, for this phase of the project is done. I missed my June target by about a month but did so much more than I originally planned so I’m ok with that. There are more projects for winter; interior, suspension, buying another one and doing it again ;)

It’s still got a long way to go to being done (will it ever though) but so far, it’s been totally worth it. Totally.

And thank freaking god, because I’m going to have a lot of free time to work on the car in the near future. I know it’s cliché but this car is now high octane therapy.

While out tooling around last weekend I stumbled on a few car shows; in my village of Lincolnwood it was almost all American muscle but they let me sneak in and everyone wanted to know about the car, and up in Winnetka at a massive European car show where my little car seemed to pull people in like flies to... well, you know.

For now, it's driving, tuning, getting ready for Checked It Out and hopefully some road trips this fall to keep my sanity and flog this car like it was designed for.

I do have something else to say; something that I’ve been rumination on throughout this project but I’m going to let that simmer for a few more weeks… I need to spend some time with the car before I put those thoughts to paper.

Julian,
I was going to text you yesterday, but figured you were busy with the car or kids or both.

Glad the car is coming along.
Sorry to hear about the Mrs. That's nightmare fuel for me.

Looking forward to seeing your car and shaking your hand in a few weeks.

I wish there was something I could say, other than sorry, about your troubles at home. Unfortunately many/most/all of us have been there, but you'll get through it all and be better for it in time.

And, yes, great therapy for sure. Nice to have you back. We need more pics of the car in the wild!

No Bueno about the life changes. But, as others have said, This will pass and the future is good.

At least the car is relatively cheap therapy.

Thanks for pics of the muffler. I notice that the perf tube goes all the way through the center. To me, this explains why there is so much drone due to direct center mixing of pressure waves.

Glad to hear the car is running better. drop me an email. I have some tuning stuff that will help you.

Inspiring read! Thanks for commenting in my thread and leading me here. Although I won't be tackling the same projects, I learned a lot reading through this.

How am I just now seeing this, this is one of my favorite threads.

I'm sorry to hear about the wife, I'd be a wreck if mine wanted to leave, but, like they say, this to shall pass.

Thanks for the kind words everyone- no doubt it’s a pretty lousy moment but yes, it will pass eventually.

And I suppose on the bright side, my 26 year old assistant has assured me that if and when I’m ready, she’ll assist me in conducting an anthropological experiment with her pier group to see how effective a vintage 911 is at getting a 42 year old divorce laid.

So I got that goin’ for me. [emoji1787]

Anyhow, not much to report- still trying to find time to gather data and tweak the VE map. Jamie gave me some incredibly helpful times and techniques that have changed how I approach the process and made huge leaps.

In anticipation of Check22 I’ve been doing a bit of final styling to the car. Probably not forever, and probably not the last but it’s fun to play around.

If we recall post 1, my father introduced me to Porsche and though he came awfully close, in the end he opted for a sailplane instead of a 911

All along this project, I’ve had that in the back of my mind. This is of course my car but in part it’s his too.

To that end, a nod to propeller spinners:

https://uploads.tapatalk-cdn.com/202...2d41c5b653.jpg

And his tail number as my “license plate”. It’s hand painted on vinyl in hopes that it’ll rock chip and wear with use.

https://uploads.tapatalk-cdn.com/202...e6d8dc956e.jpg

I also replaced my missing headlight, finally.

I actually LOL'd when I read this.

Car looks great. I really like the spiral on the mirror.
While I have plenty to do in the interim, I'm very excited to see this car in 10 days.

If you're looking to attract the youth market, the backdate may hurt you a bit. Watching parked 911s in the paddock at vintage races, the teen/20 somethings will routinely walk by a '73 Carrera RS to oogle an impact bumper car. Longhoods appear to pull in the "mature" crowd lol. However, yours has gold bits which may act like a fishing lure, similar to the banjo minnow (it triggers a genetic response!).

Please publish your study!

Julian,
Greetings. Sorry to hear about the divorce....that must be very difficult to be dealing with.
But, as others have said.....digging in to the projects can help you to keep your head screwed on straight.
I' am glad to hear that the last round of tuning mods worked well ....and that you have Jamie helping too! Jamie and i have compared notes, helped to debug EFI installs etc, for a while now. He is who i go to, when i get stuck. You are in very good hands.
I am really liking your 911.....great vision, executed very well.......
It is also great to work with someone who has the hands-on, DIY, mindset and skillset and open to learning a new trick or two...like tuning EFI/M'squirt systems.

regards,
al

PS: Good luck with the project.....and getting laid

http://forums.pelicanparts.com/uploa...1660911598.jpg

CIO is next Saturday!
Super excited to see this car in person.