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

[Mustangkev]

Option 3 get my vote.

[Daver22]

Julian

Figure I will weigh in since you asked for opinions. We met briefly the morning of CheckedItout a few weeks ago. I had the red 87 Targa across the street from you.

Interestingly I like option #2 as well. I like the lower nap(?) and wonder could you use it on the diagonal?


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[Showdown]

Well today didn't go as planned.

You know when you're about to waltz into the end zone and then the keeper stops the puck from going into the hoop and scoring a run? Felt like one of those days. Surely the sum of the poop I've been consistently stepping in as of late has colored this day a bit but I was really looking forward to success.

I dropped the car off at the dyno and walked through an industrial wasteland for a mile and a half to a Starbucks where I camped out for the next 4 hours. Luckily I got some work done and found the end of the internet; it's an old Geocities site with one animated gif.

The long and short is that after 4 hours of working on the car it was not running in a state that would have made a full pull safe and the tuner really didn't want to hand be a milk crate with pieces of my engine in it...

There was a bit of stumble/misfire in the idle that amplified under load through the RMP range but really presented at around 2200-3500. It could be felt at WOT as well, but it was less noticeable. I thought this was a fuel map issue because I don't know anything about Porsches, cars, or EFI.

Me and the tuner, a very accomplished fellow with 20 years under his belt had a long talk and brainstorming session with the rest of the shop about the problem and here's what we've come up with.

ITBs
The shop all agreed that the ITBs were marvelously balanced (I'll take that compliment thank you very much) They were all very impressed and measured a variance of no more than 1/32" max.

Fuel table
The fuel table I had created was damn near there. Again, they were very impressed that I had gotten that far without any experience or equipment. Kudos to Jamie for the guidance; you earned some fans today.
They worked on the fuel table a bit more and it made a difference in overall driving but the stumbling was still there.

Timing
He tried everything with timing to see if that had any effect. Remember, my timing still controlled by the analog dizzy: +/- 2 degrees @ TDC. He used Megasquirt to add across the board (starting at 1 degree and working up to 15) to see if that altered the stumble/misfire. No dice. He concluded that it wasn't a timing issue as he could affect no change by altering the timing. Further, before the EFI/ITB conversion the car ran great and nothing about the dizzy changed; it didn't even move. He did recommend that I advance the entire table 2 degrees once I get the misfire sorted as that would give better performance while still being safe and streetable.

So, with that said, and knowing that the only thing that changed between a great running car and this not great running car was the fuel injection system and air delivery method and the ITBs are fine- it must be a fuel delivery issue.

The consensus was that it was my injectors (at least one of them) were closing incorrectly when trying to minimize fuel delivery. The pulse width was too short and the injectors just couldn't operate so they were closing- at least one of them. The recommendation was to lower the fuel pressure to 30 down from 40 to see if easing the pressure on the injectors would stop that closing; apparently sometimes the pressure on the injector can cause it "clam up" so-to-speak. After that, if it didn't work testing the injectors or replacing them was the next recommendation in addition to pulling the plugs and doing the same.

We didn't play with pulse width as he felt that it was unnecessary to start adding variables before we had everything running perfectly and that it could just create noice that would mask the real problem.

They felt confident that addressing the injectors would yield results and told me to look into Fuel Injector Clinic and Injector Dynamics. I did and do not want to look again. Those are expensive AF!

So now I have to decide what to do: pull the injectors and sed them out for testing and cleaning at $25 a pop and a few weeks, missing the best part of the season around here, or just replace them.

I'm leaning to replacement as I'm not here to mess around anymore; I want to drive this mofo and if I can get injectors for a reasonable amount, fine.

The question is with what?

The injectors I have are Bosch 30#:

Coil Resistance: Approx.12 Ohms
High Impedance Static Flow Rate: 30 lb/hr = 315cc/min @ 43.5PSI ( 300kPa )
Gain: 0.12ms/MG
Offset: 0.055ms
Turn on time @ 14VDC: 1.14ms
Turn off time: 0.85ms @ 300KPa
Amperage: 1.0 Amps
Pressure: Min 30PSIG/ Max 100PSIG
Length: 3" (74mm)
Diameter: 16mm
O-Ring Diameter: 14.5mm
OEM Part Nmber: M-9593-BB302 0280150945 0280155759 M9593BB302 4.6L 5.4L LSX L98 L99 LS2 LS3 LS9

And the plugs are NGK 7131 BPR6ES

So, advice?

[timmy2]

These ones worked well enough for me for 10
Years in my Bitz EFI conversion.
So well, that I bought new ones for my PMO ITBs.
https://www.summitracing.com/dom/parts/acc-150630

[chrisbalich]

Joe Smallwood has had good experience with those Accel injectors as well. Heaven knows Summit ships fast and ground gets to us in 1-2 days max.

I'm presently running Bosch 315cc from fiveomotorsport.
They sent me a full latency chart, printout of the flow test results, and a set of 6 matched (new) injectors. $80ea plus the ride.
Overnight cost me, but they shipped it promptly and the gent I spoke with on the phone was super helpful.

Then, you've got your current injectors to send out for cleaning/testing at your leisure.

[pampadori]

I don't have much to contribute here other than I just realized that I'm running the original injectors that came with my Triumph ITBs when i purchased them on eBay ($125 per bank with injectors and rails). They must be 24 years old now considering the T595 donor bikes were a 1998 models.

[mikesarge]

How new are your plugs?

I’d pull em out and check the gap, check for small cracks, and put em back in if they’re good- that’s free!

Otherwise, tested/confirmed good injectors sounds like a good idea- eliminates a variable completely that way.

What do your data logs show during the stumbles? Probably a lot of things happening at once, so likely difficult for me (a know-nothing) to decipher much from, but others may have insights.

[Showdown]

Plugs are new as of Feb or March but they've had to be cleaned at least once as a result of fouling during initial startup and tuning. They're so cheap that I just ordered a new set; one of the benefits to running a single plug, 87 octane, mild cam engine, I guess.

I have new injectors en route from Joe Smallwood (the ones Dennis recommended and Al confirmed were great) so I'll just change them out.

I also have a stethoscope coming so I can check the injectors. At all of $4 I think it's money well spent.

I'm also going to take a look at TunerStudio's injector testing protocol and see if that can shine some light.

I'm keeping my fingers crossed that it's the injectors or plugs as these are easy solutions that don't really cost that much money. An electrical or ECU problem would be not good.

I have a road trip coming up on 10/7 so this mother better be humming like an a cappella choir by then.

One of the nice things that came out of yesterday was that the tuner was really impressed with how much I actually knew about EFI and this car (I know, I was shocked too). He offered that when I do get the issue resolved he'd let me bring the car back to the dyno and allow me to run the car while he was monitoring. He felt that I could handle it on my own with a little guidance and supervision.

In other news; leather ordered, fabric ordered, new sewing machine needles ordered. Can't wait to get started!

[chrisbalich]

Excellent.

Don't forget a soapstone for marking your fabric & leather.

[mikesarge]

That's great! stoked to see progress coming up

[Marwil]

This is curious that you are dealing with the misfire/stumble. I've tried everything to resolve my similar issue with an MS2. Followed jpNovak's advice in various threads, replaced injectors, readjusted dead times, replace injector harnesses (old ones were crusty), etc. I am currently starting with mechanical verifications - leak down, valve adjustment, cam timing adjustments then will on to the fuel regulation circuit, etc. I feel like it's a feeling issue. At times if almost feels like a very quick, sharp fuel cut. You can feel it an hear it but not see it in the logs - unless it is in the bank without the O2 sensor. Mine is worse hot and I am wondering if it is injector driver circuit problem in the ECU. The ECU warms up and a trasistor goes funky at temp. Completely mystified.

What are you running for exhaust - could it be resonance that is causing the stumbles.

Mark

[Showdown]

I have an m&k 2-in 2-out street muffler with electrically operated bypass valves.

I had a similar muffler on the car before the efi/itb conversion, and the car ran very well.

Jamie took a look at a log file of mine and offered some suggestions on how to address the injector issue that should benefit the car in all respects, and specifically eliminate the issue with dead time.

He also identified a problem with the ITBs that I thought I had squared away. Apparently one bank is opening before the other, either, they’re not balanced once the throttle opens, or there’s some corruption in the linkage.

So, that means it’s back to rebalancing the ITB‘s and effectively starting all over.

I’m really feeling not positive about this whole project right now.


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[chrisbalich]

Originally Posted by Showdown

...I’m really feeling not positive about this whole project right now...

I've been feeling the same way about my jalopy lately.
From past experience, I prescribed myself a drive. In this instance, it was just to take the car to work.
I feel much better having driven it, even with its warts.

[al lkosmal]

Julian,
A few posts up, you mentioned that the dyno shop/tuner commented on how well you had the ITBs balanced. How did your tuner, at the dyno, verify the ITB balance?

"Me and the tuner, a very accomplished fellow with 20 years under his belt had a long talk and brainstorming session with the rest of the shop about the problem and here's what we've come up with.
The shop all agreed that the ITBs were marvelously balanced (I'll take that compliment thank you very much) They were all very impressed and measured a variance of no more than 1/32" max.

[Showdown]

Good question Al, I wasn't at the shop when he was working at first (he called me back later) so I can't say for sure. For all I know htey were giving me some sugar to make the medicine go down...?

I've measured the ITB's at idle with they synchrometer and have them as close as I can get (~1/32") but Jamie believes that there's an imbalance as the throttle opens; one of the linkages is longer than the other or bent causing a different travel rate...

[al lkosmal]

I'll email you a linkage setup doc (although you may already have it) and you review/compare with your current setup ....and, if you will take pix of your linkage setup, especially at the drop links...I can review and forward to Rama at RHD. I'll touch base with Jamie, as well.

[Showdown]

Every once in a while, the universe has to take a break from kicking you if only to tie its shoes…

Avid readers of this thread (both of you will be keenly aware that the past few months have been rough for me. Last week was no different with more bad news. My grandmother entered hospice care and though at 92 years old we’re not surprised, we’re still reeling. Yes, everyone dies and 92 is a helluva run, but it’s still hard…Hell, it should be hard.

In the context of everything, the issues I’ve been having with the car are trivial, at best. Yet, that couldn’t be farther from reality, at least my acute momentary reality. The car has been a safe harbor as everything else slowly crumbles… the work and the progress, have given me something to focus on, something that I can affect change on and something that I can control. An anchor, mooring or compass.

A few weeks ago at CheckedItOut everything felt pretty magical and the high was palpable. Since then I’ve been to a few local car shows and that high is still potent.

Yet, all along there have been nagging issues with the car that I just haven’t been able to sort out myself. And these issues have started tainting the experience of the car. In short- I started to feel not so good about it and began passing up opportunities to drive it. My limitations were being revealed and into those wounds; salt.

Maybe, apropos of all that, today the universe’s laces came undone and I was tossed a bone. My marrowy morsel came in the flavor of Jamie Novak who was in Chicago for work, only a few miles from my studio.

Throughout my EFI tuning Jamie has been a constant commenter and emailer with tips, advice and the generosity to take a look at my tune logs to help me figure out what the heck I was doing. Well, today was no different. Fresh off a long day of work Jamie drove over to my shop and proceeded to school me in EFI/ITB, MegaSquirt, TunerStudio and Porsche. For over 3 hours we drive and tuned and tinkered and tuned and drove and tuned and so on.

It was bonkers to see how Jamie could just feel, hear and see issues that I couldn’t. More so, that he could affect positive change on them was mind blowing. And the speed with which he worked was downright awe inspiring. I know at this point the post feels hagiographic, and it should, damnit!

I was dealing with some misfires and stumbles during acceleration. Jamie went to work identifying the issue and narrowing it down to ignition. The long story short is that my rotor cap is on its last leg, my rotor is limping along and my Dizzy is in dire need of service. We landed on a two-tiered plan: replace the rotor with a resistor-less version, replace the cap, clean out the dizzy asap and finish tuning the car this fall and enjoy driving it. In winter, pull the dizzy, lock it out and move the timing to the MegaSquirt as the CIS timing is severely limiting the car, even with CIS P&C. Jamie suggested against a COP solution but mentioned a sweet optical timing setup he's been running that may be of interest if I feel the need to embark on another project

None of these issues arose because of the EFI/ITB conversion, they were just magnified. Whereas with CIS they were present but masked and not a real issue, with ITB’s they are screaming. The magic of CIS is that once it's setup properly it just works- it has a great tolerance for imperfection and largely manages just fine. This is not to say that it shouldn't/couldn't be tuned to optimal performance, but I'd guess that lots of CIS cars have issues that the CIS is just making due with.

The feeling of not only identifying the culprit but it being something that I can solve quickly and get back to enjoying the car feels like everything all at once. A win that I'll gladly take.

It’s kind of crazy that Ian read my post about the dyno day being a wash and mentioned it to Jamie during a phone conversation who reached out to me to offer help via email and then just flat out came to my studio and car. All along this project I kind of thought that the car was important and what was giving me the drive to wake a 4am, cut up my hands and push myself beyond the confines of comfort. But it clearly was just part of the story.

In Panorama, the Porsche magazine the oft repeated catch phrase is “it’s not the cars, it’s the people” I’m loathe to admit it, but they’re right.

Damn, they’re right.

[chrisbalich]

JPN is in a class by himself.
Glad you two got your stumble sorted.

Sometimes, you have to pile up little victories just to get by.
But then after that pile grows, you find maybe it wasn't as bad as you thought/felt afterall.

[Hulley]

Glad you got it worked out, that has to be a huge load off in itself and yes, there are some great people in this community. I lost my grand parents a couple years ago at 88 and 86, we were very close. When I'm struggling, or having a bad day, I go for a ride or just sit in the garage with a beer and some music and let it go, it's definitely my escape.

[jpnovak]

Some say his blood runs with pure molten magnesium and he drinks beer through an MFI pump.

Julian, It was great to meet you. Glad I could lend a hand. Great diversion from a stressful work trip. It is not often that I find a few extra hours when traveling. But I will certainly have to look to build more into my schedule. It truly is about the people in the group. So much more fun to be there in person rather that sending electrons (key strokes) back and forth.

This almost feels like I am being introduced as something more than just a guy wanting to get another old 911 running to its full potential. I appreciate the compliments and am happy to help where and when I can.

You have really done a great job on the car and you are so close to finalizing those last few details. There are so many personal touches that really stand out on the car when you see it in person.

I am certainly looking forward to the next installment when you have new ignition parts.