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 Post subject: Re: 1978 242GT
PostPosted: Thu Jun 02, 2016 11:14 am 
Haha, I just built a W24 Octo-Turbo, now what?!
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Joined: Thu Dec 29, 2005 12:29 am
Posts: 1786
Location: Eating tofu and legumes in my hippie shack
Hah!

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 Post subject: Re: 1978 242GT
PostPosted: Tue Sep 26, 2017 12:54 pm 
First volvo in outer space
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Joined: Fri Dec 14, 2007 1:46 pm
Posts: 1593
Location: East L.A.
Well another year has passed so the slow pace continues. My apologies to Greg for making him "wait for it" as there was actually stuff happening last summer, just no real running/driving progress although there were cats confused...

Craig was looking for a car for the Great Beater Challenge https://greatbeaterchallenge.wordpress.com/ and offered to help get the GT running if he could enter it in the challenge, naturally I accepted. We knew the fuel system on a k-jet car wasn't going to be great after sitting for so many years, but it turned out to be even worse. The main fuel pump wasn't firing so I pulled it off and ran some mineral spirits through it and was able to turn it by hand, a good used FP relay and it turns but sounds noisy. Changed the fuel filter and turned our attention to the tank. The fuel tank was completely rusted inside, and the intank pump assembly crumbled in your hands when removed. The old style fuel tanks are not available anymore so Craig had to chop and modify the existing filler neck to work with the new style tank. A good used intank assembly with a new pump and an inline filter on the fuel return to catch any circulating crud from getting in the tank finished off the fuel side... kind of...

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The DS rear caliper was seized and the rear pads were thin so I replaced both calipers and pads. A roloc disc took the surface rust off the rotors which have lots of meat left and the system was flushed and bled after replacing the leaking master cylinder. We now have brakes although I "think" the pedal could be a bit higher/firmer so hoses may be in the future. The front brakes look good for operation and thickness, I still need to roloc the rust off of the front rotors.

Had a number of issues with lighting which ended up being the bulb integrity sensor which was replaced. A ground short on the PS tail light also got fixed so we now have functioning lights.

Under the hood was disgusting, so it got a major power clean before starting on anything. Pulled the plugs a number of days beforehand and soaked down the cylinders with fogging oil and PB Blaster with some engine rotation by hand every day or so, engine turns over easy so should be good to run. Craig was running plug #1 in and it was obvious the threads were stripped. He gave me that "Coburn" look but I am pleading innocent as I always run plugs by hand and felt nothing?? (FWIW the original plugs and wires were Motomaster brand so that's all I have to say) So the hole was tapped out and a Helicoil installed which killed that days attempt at starting the car. It should be noted that we were on a Roadkill like time frame near the end as we hadn't anticipated having this much work to do.

After letting the insert epoxy setup it was up to me to fire up the engine. Much cranking ensued with little indication the engine wanted to fire much less run. It should be noted we had confirmed spark and camshaft rotation previously so I pulled the plugs for an inspection and found the Helicoil stuck on plug #1. To add to the fun the front 2 plugs were wet, the rear 2 were bone dry. I cleaned up the Helicoil, reapplied the epoxy and drove it in to place and hoped for the best. Letting the epoxy dry I pulled the injectors and found them, as expected, covered in crud.

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Rigged up a length of hose so that I could fill it with carb cleaner and cleaned each injector using carb cleaner and compressed air, predictably the the 2 rear injectors took a few cycles before they were spraying properly. Re-installed the injectors with new seals, the old ones cracked like hard plastic when removed. Re-installed the plugs and and tried cranking with more or less the same results. The odd cough but no ignition. Pulled the plugs that were now all wet and the Helicoil stayed put so there was at least that for progress. By this time we were down to the day before with a non-runner plus some likely other issues to be dealt with before driving to Castlegar and back in a weekend. We admitted defeat and I went and had a long nap...

Fast forward to now and I dumped some seafoam in the gas tank, double checked all the connections wires etc. and tried starting one last time. It actually started and ran for a bit, but the amount of cranking required combined with no idle back firing etc. says there is still more to do in the fuel system. The FSM aka Air/Fuel control unit with Fuel distro. is now sitting on the bench (I am starting to get all of the k-jet hate now). The line pressure regulator didn't look too dirty, although it seems (guessing here as I've never had on in my hands before) to travel in and out a bit smoother since being cleaned. Otherwise all of the ports look reasonably clean and nothing really came out when sprayed with carb cleaner.

I have a seal kit and a k-jet pressure tester rig on the way as I have researched that nothing good happens with k-jet when the pressures are off. Also thinking it probably wouldn't hurt to pull the injectors again. Other than that should I separate the halves of the air/fuel unit?? Still haven't found the gasket that goes in between the 2 halves. Also the front rubber mount/isolator on the Air/fuel unit fell apart (the back 2 look OK). any ideas on how to replace that?? It looks like it was molded on to the body which seems dumb, I tried twisting on it thinking it's threaded on but it never moved.

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Jim

66 122S (Garage Queen)
89 244 (Hers)
90 745Ti (Mine)
89 744 (SOLD/Bought back for other daughter)
78 242GT (Project... LOL)
91 244 (Don't Ask!!)


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 Post subject: Re: 1978 242GT
PostPosted: Wed Sep 27, 2017 5:01 pm 
Haha, I just built a W24 Octo-Turbo, now what?!
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Joined: Wed Dec 21, 2005 8:40 pm
Posts: 3357
Location: Calgary, Ab
Hi, Jim

If you're planning on disassembling and rebuilding the fuel distributor, here are some links for you:

http://www.porsche928forums.com/downloa ... ebuild.pdf

http://salvox.com/index.php?cPath=12&si ... 3b6770e538

http://www.dssales.net/CIS.html

I've got some running issues with the Saab and its VW Golf fuel distributor, primarily due to a mix of components I think but also the fuel distributor seems to be flowing different rates out of each port. This could be from a dented dividing plate (I have no idea what that shim plate between the halves of the fuel distributor is called!) but this style of distributor also has individual cylinder trims that someone may or may not have messed with. I'm going to mess with them, once I get some time and some graduated cylinders. I've noticed that there's one cylinder that doesn't flow fuel until the plate gets lifted much higher than it takes to get two of the other cylinders to flow. Another cylinder is somewhere in between. I haven't measured the balance to see how they work at higher flows, but I have swapped injectors and lines and the problem stays with the same port on the fuel distributor.

I have a starting issue with the car too, and I'm trying to chase down the source of the leak. It could be a locked up fuel accumulator and it could be a leaking control pressure regulator (warm up regulator). The check valve at the fuel pump is new and I've replaced the o-ring on the line pressure regulator, so there shouldn't be an issue there. The test gauge I have needs some adapters to work everywhere in my car...

Were I working on your car, I'd start by mocking everything up on the bench, tubing and all. Working on a B21 sucks. Forgive the following if you already know it:

First check in my mind is the absolute pressure the pump will deliver, should be 150 psi or so. Deadhead it, and keep the gauge on there after you shut off the pump - it should hold that pressure almost indefinitely.

The next step is to check the line pressure regulator - do that by putting a gauge on the top center port of the fuel distributor, while disabling the control pressure regulator. It should be in the 75-85 PSI range - IMO the exact pressure isn't important. It should hold this pressure for at least 10 minutes after shutting off the pump - if it leaks down it's going through the line pressure regulator.

Then swap things around so you're testing from the same port, but with the control pressure regulator enabled. This is where the exact pressure comes in, and it's dependent on temperature. Less pressure means more fuel, more heat brings more pressure bringing less fuel. Again, pressure should remain for at least 10 minutes after the pumps are shut off, and if not it's leaking through the control pressure regulator.

If the system leaks down too quickly after the engine gets hot you get fuel boiling in the lines and a hard start. Occasionally the car will start & run great when cold but poorly when hot, sometimes it'll just start great when cold but run poorly after the starter (and cold start injector) are switched off.

Test your thermo-time switch - this triggers the cold start injector IF the engine is cold AND the starter hasn't been cranking for more than 10-15 seconds. The TTS is a bimetallic switch that is sensitive to both the heat of the coolant and the heat of the current draw to the cold start injector. Make sure both things are working. This can cause cold or hot start issues depending on what component has failed and in what state.

I have found that the fuel accumulator will often stick until the line pressure drops well below the line pressure regulator setting, and will then deliver a slug of fuel. A new one is probably not prone to this nonsense, and releases fuel smoothly. I'm betting that the one in my car is stuck fast, giving me at least part of my problem.

Be sure that your injectors are all spraying at least part of a fan. Streams & squirts are bad, and that's sometimes all you get at low flow (like in my questionable car). The injectors shouldn't crack open until enough pressure builds up, I'm not sure exactly what that is but it'll be below the cold control pressure (35 psi?). If they're spraying in a nice cone, you're golden. It's a good idea to have spares so you can mix & match.


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 Post subject: Re: 1978 242GT
PostPosted: Thu Sep 28, 2017 4:47 pm 
First volvo in outer space
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Joined: Fri Dec 14, 2007 1:46 pm
Posts: 1593
Location: East L.A.
Hey Matt, thanks for all of that. I've been reading everything I can find, watching youtube videos and am starting to go k-jet blind. I've seen a number of people doing the bench thing which probably makes the most sense, but is just that much more to try and put together that I suck at. That's probably the wrong way to look at it but I'm a little overwhelmed right now so testing on the car is my first option. I can see where working under that intake manifold is going to get old in a hurry, guess I'll see how it goes and work from there...

As far as rebuilding the fuel distributor, no I have no plans for that. Everything I have read on Tbrix (people I trust) say it is not a DIY job, and this car having such low miles I can't see it needing it??

I pulled the fuel distro off, but before I did I was holding the air control unit and turning it around looking at things and something fell out of the inside. (apologies for the terrible potato phone pic)

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Obviously the big plunger is the the flow control plunger which I removed, it was a bit sticky coming out but not too bad. So what is the other little plunger with the o-ring and how did it get inside the air side of the air/fuel unit? I can't find anything in the Greenbook that looks like it except for the pressure regulator valves which are inside the fuel distro so they can't get in to the air side much less fall out of the inside.

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Jim

66 122S (Garage Queen)
89 244 (Hers)
90 745Ti (Mine)
89 744 (SOLD/Bought back for other daughter)
78 242GT (Project... LOL)
91 244 (Don't Ask!!)


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 Post subject: Re: 1978 242GT
PostPosted: Fri Sep 29, 2017 12:37 pm 
First volvo in outer space
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Joined: Fri Dec 14, 2007 1:46 pm
Posts: 1593
Location: East L.A.
Ok, mystery solved on the plunger. It's the one on the end of the control pressure regulator, I never picked it up from the schematic pic in the greenbook. The pic below that I found online doesn't show it in real life either but it is what it is, it obviously fell out of the port in the head after I removed the regulator.

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Next question, the diagram indicates an o-ring inside on the plunger as well as the external one. How does the rod disconnect from the plunger to get the plunger out and replace the o-ring. Greenbook does not indicate it even exists, and this is the first diagram I have come across with it mentioned. FWIW I found the pic on a BMW forum so maybe someone marked it up incorrectly? I have cleaned out inside as best I could squirting carb cleaner in while stroking the plunger through it's travel, if there is an o-ring in there then I definitely want to replace it and clean a little more with the plunger removed.

_________________
Jim

66 122S (Garage Queen)
89 244 (Hers)
90 745Ti (Mine)
89 744 (SOLD/Bought back for other daughter)
78 242GT (Project... LOL)
91 244 (Don't Ask!!)


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