924Board.org

[jacobroufa]

Drove it a bunch today and I was paying closer attention to the vacuum/boost gauge. I was seeing 7-8 in/hg at idle and no more than 3-4 psi on boost. Fuel filter and injector cleaning definitely helped a lot, but still not where I knew it could be. Well I should have been paying attention to that gauge more closely for the last couple weeks but I have a lot of little things nagging at me. Anyhow.

I remembered how much the vacuum lines made a difference in how the car ran when I did them back in 2020. I thought to myself "no way they could be rotted already", but figured it was a quick thing to check. Pulled off the line from the throttle body as it is easiest to get to. Sure enough. Dry, cracked, perished. Ugh.

Well, I was going to dig into the turn signal stalk, to see if I could get the twitchy high beam resolved, but I guess this problem stared me closer in the face. I remembered that I had enough line left from last time, sitting in sealed bags on the shelf. Changing all that out is more of a pain than I wish it were, but oh well.

17-18 in/hg at idle
7-8 psi on boost

Idles a lot more smoothly, and stable at a lower RPM. I don't smell fuel as aggressively, so has it leaned out the mixture as well because it doesn't have to compensate for all the leaks..? I'm happy, that was time well spent. And when I do it again, it'll be silicone lines.

Guess the electrical gremlins will wait until next time.
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1980 Porsche 931
1981 Porsche 924 Weissach

[Cedric]

Mixing two archaic measurements at the same time, my metric mind is bent Im glad it runs better, dont you have any wideband to put in for some measurments, that would take some guessing of the fuelling. And it should be possible to run euro boost safely. Some day i might buy a smoke tester for finding small leaks in intake and vac system, would make life easier

The dash lights leaves some to be desired for sure, especially with the green on black, I cant see anything when its dark outside, not optimal..

Mine feels very stable at 100mph/160km/h, or more, but its many parameters that affects that.
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1980 924 Turbo
www.instagram.com/garagecedric/

[jacobroufa]

Ahaha! Sorry. That is what my gauge reads.

I have a wideband sensor on the shelf, that will be another installation very soon as well! This sensor has its own gauge and readout, purely for measurement. How do I ensure it functions as the existing O2 sensor which I would remove? I know it can send data as well as display..

My plan is to buy Ciprian's EFI kit towards the end of summer and with that I will be able to hook up the wideband to that ECU, so it will be more effective.

For now though, what should I do? I will see what I can read into how it works, from the shop manual.. Maybe there is more outdated junk I can just remove.
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1980 Porsche 931
1981 Porsche 924 Weissach

[924RACR]

What brand do you have? It's usually possible to set up the output to mimic a stock style narrow band O2 sensor, which you could wire into the stock Lambda ECU while watching the gauge for function... and then wire to the MAXXECU later for the conversion, reconfiguring the gauge to send out the linear wideband output.

I use INNOVATE WBO2 sensors these days on my cars, and they actually have two analog outputs...
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[jacobroufa]

Yep it's an Innovate kit... PSB-1. Glad I got it a couple years ago knowing I'd eventually use it.. they have gone up $100 in two years!

Looking at the manual:

[924RACR]

Yeah, that's exactly the same as my MTX-L gauge setup...

Don't forget to cal the sensor as you install, before you screw it into the pipe!!
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[jacobroufa]

Well so this is fun. I drove it a bunch yesterday. Didn't look under the hood after I got back -- usually have done so this last month and change as I've gotten it back up and running -- and today popped the hood and found my coolant tank completely empty.

So I've had this little problem, after a drive the tank will lose 1-2cm of coolant, so I have had to keep it topped up. It's not leaking anywhere that I can tell. Seems to be overpressurizing and coming out the cap. Cap and bottle are both brand new.

Based on what I've read, this can be a sign of a head gasket failure, one failure mode where the coolant and oil do not mix.. I've just been keeping an eye on it, topping up as necessary. Car has not overheated, it's been in good temp ranges.

Well, I spoke with a couple board members Mike and Ciprian and they're saying probably I should just pull the head and take care of it. Definitely don't want it to get worse.

I was planning to pull the engine and reseal stuff, take care of oil leaks and such, over this winter. I had hoped to be able to drive the thing throughout the season. Now it seems my hand is forced.

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So new plan. Get the EFI kit a couple months early, pull engine and reseal now, and hope to get it done before summer's fully out.

I'm putting together a parts list (thanks to the PET) but I'm definitely wondering for anyone's input here on what I should take care of while I'm in there? I'll put a link to the spreadsheet when I've finished.

Some of the "while I'm in there" stuff that I'm thinking:
clutch, master/slave cylinders, engine mounts, battery terminals, ground straps and main battery/starter/alternator heavy gauge wires...

I may go so far as to set up a FMIC, as I have a turbo compressor housing from an Audi that I got from Eddie several years back. This was the housing that he used on his S1 before he upgraded, and let him clock it to face down and run an FMIC. I think I also have a billet compressor wheel stocked away somewhere; if so that might be a nice upgrade also.

I'm sort of tempted to contact Catellus Engineering who do G31 rebuilds, and see what it would cost to take care of my 1/2 synchro and maybe put an LSD in it. Thought being if I am going through this trouble and the engine will be out for a month or two while I work through it, I might as well go the extra mile..

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I dunno. My head is kind of reeling right now. I don't want to go too overboard, but my hand is being forced, so maybe now is the time..


Any advice, thoughts?
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1980 Porsche 931
1981 Porsche 924 Weissach