"RallyWrench" (rndlitebmw)
05/03/2019 at 15:10 • Filed to: Porsche, Porsche 911, Project Car, Parsh
22
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"RallyWrench" (rndlitebmw)
05/03/2019 at 15:10 • Filed to: Porsche, Porsche 911, Project Car, Parsh | 22
| 28 |
( repost for daytime crowd )
I figured it was time for an update post on the SC, since I didn’t get into any details of the work I’ve been doing in the “intro” story. I’ve been a busy boy because cheap 911's inevitably have a mountain of needs. Mainly I’ve been working towards solving some rich running issues and setting a maintenance baseline, as well as getting the car ready for the drive to Luftgekuhlt in LA. That last bit is important, as I’ve thus far only done local driving in it, without the sustained higher speeds and temps that Southern California roads can bring. So, without further ado, this is what I’ve been up to.
First up was an oil service, spark plugs and valve adjustment. A few exhaust valves were slightly tight, but not nearly as bad as I feared given the mileage. As we did the top end of the engine about 60,000 miles ago, this indicates it’s doing fine. I also cleaned the PCV breather trap. Basically just a metal pipe with some steel wool in it, the trap was almost completely blocked with sludge. The previous owner of the car did much of his own service work, so the oil had not been changed since some time well before he passed away. I sent that sample off to Blackstone Labs and await their report, and I’m looking forward to seeing how the next sample compares. This car has run Castrol 20w50 its whole life, so that’s what I put in it with a splash of Lucas Zinc additive to make up for the reduced ZDDP content in the modern formulation of GTX. Going forward I may switch to Kendall GT-1 20w50. During the valve adjustment, I found a stash of acorns atop the oil cooler on the right side of the engine, so I’m glad to clean that out. Makes me wonder what else is hiding under the engine’s top cover though, I’ll have to drop the engine for that sometime down the road.
Cylinders 4-6 exhaust valve adjustment
Breather trap was full of congealed dinosaur
Next up, the rich running issue, which turns out to have been much more involved than I expected. The car had always run a little rich, but suddenly became much worse and started misfiring on tip-in due to badly fouled plugs. It was also mostly unresponsive to mixture adjustments. This would not only fail to pass smog, but would destroy the catalytic converter and wash down the rings in short order. This is the famed Bosch CIS/K-Jetronic system (OOooh voodoo, witchcraft, dark magic and sorcery wooOOooo!), specifically early K-Lambda as it has an oxygen sensor and frequency valve for mixture adaption. First I checked that the injectors were holding pressure (they’re completely mechanical and have a specific opening pressure) and that their spray patterns were good. Next I checked the control pressure and found it out high and out of spec, i.e. it was not being regulated down from system pressure correctly. This meant it was time to remove and disassemble the Warmup Regulator (also known as a Control Pressure Regulator), which is basically a heated bimetallic spring acting on a diaphragm to regulate the system’s basic fuel pressure. The oxygen sensor/frequency valve combo then adapts around load. When I got it apart I found corrosion everywhere, so it went in the ultrasonic bath. Fortunately, the heating coil around the bimetallic spring met the resistance spec. I also disassembled the diaphragm plate and cleaned the fine screens to the input and output ports with brake parts cleaner until I got clean streams through both, which was the real problem.
Warmup Regulator blown apart. Yech.
Ultrasonic bath worked great
After cleaning, going back together.
Ready for install
With this done and the warmup regulator back in the car, the control pressure settled down to spec nicely after warmup, running about 52psi (system/supply pressure is around 78psi). Still, it ran too rich, so I looked elsewhere, which is where the fun begins. First, I found the cold start injector miswired and the airflow plate lift sensor disconnected and plugged into some kind of a jumper harness. After correcting these issues, I moved on to the Fuel Distributor (also known as the metering head), which I like to call the fuel spider, shown below with a Volkswagen factory service bulletin.
Suggested maintenance technique. A friend at a standalone EFI company laminated this for me over 10 years ago because I like CIS. Came in handy here.
I looked through the records and realized that about 8 years ago I had diagnosed the car as having a bad fuel distributor because, surprise! It ran too rich. I really should have remembered this, but I are dumb sometimes and have worked on and written up a lot of cars since then. The owner didn’t have us fix it at the time, and either did it himself or had someone do it for him. This also explains the wiring issues mentioned above. It must have worked for awhile because the car passed smog in the years since, but the issue came home to roost for me. I removed it from the car for inspection and found its plunger and bore badly scored, worse than any I’ve seen, and better yet, it was glued together.
This is supposed to be coated in very resilient black paint. First red flag...
Below, the plunger. These surfaces need to be perfect . Obviously, they were not. This plunger moves up and down via the airflow sensor plate through a sealed bore in the fuel distributor, changing the pressure relationship between upper and lower chambers of the fuel distributor depending on height. On this updraft-style system, the higher the plunger, the more fuel goes to the upper chamber and thus out to the injectors, which are constantly fed (hence C-I-S, Continuous Injection System).
Fack
Faaaack
Turns out, whomever “rebuilt” the unit seems to have done nothing more than strip it and put it back together with RTV or similar. This, as you may guess, is a big no-no. Bosch’s service information is very, very serious about this stuff and basically says DO NOT FUCK WITH THESE EVER. I had really wanted to take it apart myself to see how bad it was, but as it was so thoroughly glued together I didn’t want to risk damaging the unit because they’re very finely calibrated, not exactly easy to find, and are very expensive when you do. I decided to order a really nice rebuild kit from !!!error: Indecipherable SUB-paragraph formatting!!! , $125 with a laser cut stainless diaphragm and Viton seals, and sent the unit off to the good folks at !!!error: Indecipherable SUB-paragraph formatting!!! in Tracy, CA for a rebuild, who we’ve used for years at the shop. A little more than a week and $400 later, I had it back:
Worth every penny. After installation, the car settled into running much better after warmup, so I tuned it on the 5-gas with my multimeter watching duty cycle on the frequency valve, and it came right into spec, running great. I was elated. With that, I was off to smog, where it passed nicely.
Needs an Oppo sticker
I have not been that relieved about something in a long time. The great injection battle consumed several of my limited weekend days, including Easter afternoon after playing bunny and hiding eggs for the kids in the morning. It was a bit of a tight timeline, because I bought my ticket for Luftgekuhlt 6, and damnit, I want to drive this car down there so I needed the tags up to date by May 11. I’m still sorting out some uneven running during warmup ( I think the Warmup Regulator may have been adjusted around the bad fuel distributor, but there’s no way to know visually and it’s also something not normally messed with), but after the first minute or so it runs perfect. With smog done, I moved on to sorting some smaller issues. The first of those was the steering column bearing:
The bearing itself is fine, but they have a plastic sleeve in the center which crumbles, allowing the steering wheel to wobble around about 1" in any direction. Replacing the bearing requires removal of the steering column, which is a pain in the ass, but the aftermarket has come to the rescue with an easily installed metal repair sleeve that presses in place of the plastic one. The helm is so much better now! Next I’ll need to rebuild the shifter or save up my pennies for a Wevo unit, the 915's gates are a little squiffy so it’s hard to get first sometimes. In other news, wheels & wings...
Fat Fuchs fit fine
STUFF
Check that stuff out. I scored a set of 7 & 8" polished Fuchs off of a client’s old 944 that he’s parting out to turn into a race car, for the low low price FREE.95! Actually, I have of to take the engine and driveline out of another parts 944 for him, but still... big, fat, dished and delicious Fuchs, an inch wider than mine, for no dollars! I’ve test fitted the rears to make sure that 245's don’t rub (they don’t), and I need to find new rubber because the perfect-looking Dunlops are in fact well past the expiration date. This is a slight bummer because 245/50R15 tires don’t exist in anything other than full race gumballs so I’ll have to drop to 40 series out back. This won’t look as cool, but the BFG G-Force Rivals I want are a well regarded tire nonetheless. I also scored a Craigslist hoard of parts (see back of truck above), including a fat rear swaybar, spare rear muffler to experiment with, Turbo whaletail and fiberglass IROC tail for a few hundred bucks. I plan to clean up and resell the wings to make up for the cost of the lot and put some coin back in the car fund, though I have an idea for a bike rack for the rough Turbo tail...
Dissecting whales
Lots more to do on the ever-growing list on this car, but that’s all for now. Luft6 here we come, fingers crossed.
MM54
> RallyWrench
05/02/2019 at 21:17 |
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Very nice work, glad it’s running well for you. K-jet is a fascinating system that I hope to avoid for the foreseeable
future.
Nibby
> RallyWrench
05/02/2019 at 21:21 |
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firstly this is dope
second keep it up and it shows you’re putting lots of love into this project
third i saw this on the way home... well, a similar 911 with the NY plate “MIAMIBLU”
functionoverfashion
> RallyWrench
05/02/2019 at 21:45 |
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I love reading about this car, and it also makes me feel like a total slacker for what I haven’t done on my truck that I’ve now had for over 3 years. The wiper motor is sitting on my work bench, along with the materials for the most basic of maintenance items, an oil change, and I don’t know when I’ll get around to either. I’m having a shop do the brake conversion next week because if I try to do it, it will happen approximately never.
Anyway, I love your car and I’m happy to read about it anytime. Nice work, enjoy that car - as I’m sure you will. Cheers
Cash Rewards
> RallyWrench
05/02/2019 at 21:51 |
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This is amazing!
Tapas
> RallyWrench
05/02/2019 at 22:04 |
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Glad to see your Porsche is running well.
In some cultures, congealed dinosaur is a delicacy :D
Full of the sound of the Gran Fury, signifying nothing.
> RallyWrench
05/02/2019 at 22:31 |
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Nice write-up - thanks for sharing.
Maybe it’s just from the period in which I grew up, but two of my favorite things are those cool old California plates and K-Jetronic. That system always served me well in most of my water-cooled VWs (Vanagon being the exception since it had something fancier) and my first BMW, an E21 320i. Even when things got weird, like when a backfire blew an injector out of the head, it was easy enough to get going again and never really have me any issues.
And if my 968 pissed out all of its coolant, could I take it to Luftgekuhlt?
superdave847
> RallyWrench
05/02/2019 at 23:13 |
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I came here for the brown wagons, but stayed for the air cooled Porsche maintenance. Great post! I’m following!
shop-teacher
> RallyWrench
05/03/2019 at 00:18 |
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Excellent progress!
arl
> RallyWrench
05/03/2019 at 07:09 |
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That’s an awesome write-up. You lost me once you got to the eletro-difribulatory-K-Jeto -thingy, but it’s great to see people keeping these on the road.
LimitedTimeOnly @ opposite-lock.com
> RallyWrench
05/03/2019 at 08:58 |
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Terrific write-up. I wish I had the opportunity to obtain one of these as you did, and the knowledge to work on it as you do. Please continue to share.
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RallyWrench
> functionoverfashion
05/03/2019 at 12:20 |
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As your truck is one of my very favorite Oppo machines, you’re forgiven for any slacking. Also it’s an old truck, being a little broken is totally normal. Thanks for the complements, I’m looking forward to piling on some miles now. Post some progress on that truck when you can!
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RallyWrench
> Full of the sound of the Gran Fury, signifying nothing.
05/03/2019 at 12:33 |
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I love the plates too, and K-Jet has just always called to me. I’ve owned a bunch of VAG products with it and kind of cut my teeth on the system when starting out as a tech, it always fascinated me. One big appeal is that as long as it has fuel pressure it’s practically guaranteed to get you home, even if something goes wrong. This car is a good example. Even with the screwed up wiring and bad fuel dizzy, the thing still started and ran.
You have a 968?!? I love those things!!! Underappreciated and rare. Funny you mention losing the coolant for Luft , a coworker just bought a terrible, salvaged 996 C4S to hoon around in and just this morning we joked about draining the coolant and rigging a fan to troll Luft .
On a sadder note, I just saw the post about your friend- I’m so, so sorry for what she and you have been through, and I hope she is comfortable and at peace . My beloved grandma was in the same state the last time I saw her after falling ill suddenly. I’m not a religious man, but I have to believe she knew I was there, holding her hand, as I know your friend felt your presence . All the best.
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RallyWrench
> MM54
05/03/2019 at 12:35 |
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Thank you! I really like CIS, it s elegant simplicity is the draw for me. I like tinkering with it, the system bridges the gap between EFI and fully mechanical injection well, and when sorted out is dead reliable.
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RallyWrench
> Nibby
05/03/2019 at 12:38 |
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Cheers, thanks! I’m just stoked to have the opportunity to be this car’s caretaker, and working on 911s is a genuine joy to me.
As much as I love aircooled cars, I have to admit the 991 looks awfully good, and Miami blue is such a good color. Not one I’d choose for my own car, but I’m sure glad others do because it looks bitchin’.
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RallyWrench
> arl
05/03/2019 at 12:41 |
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Thanks, it’s a slight source of pride that I can work on this system, but I was just lucky to cut my teeth on it under some Bosch master techs when starting out so it was pretty well ingrained. D efinitely not everyone’s cup of tea, but I like it and love working on these cars because there aren’t many I still like after two decades doing it.
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RallyWrench
> LimitedTimeOnly @ opposite-lock.com
05/03/2019 at 12:50 |
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Much appreciated, I feel really fortunate to have the opportunity at all. It’s better when shared, thanks.
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RallyWrench
> superdave847
05/03/2019 at 12:51 |
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The brown wagons are the only reason I’m here ;) Thanks! Hopefully I can put some miles on and do some trip reports, as well as continued maintenance .
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Full of the sound of the Gran Fury, signifying nothing.
> RallyWrench
05/03/2019 at 13:06 |
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Had a 968, years ago when I worked at a talent agency in Beverly Hills. Stupid money back then, and I spent more than I made on silly purchases that I shouldn’t have made . I now live in the Midwest and work in public transport, paratransit operations specifically, and drive a Mazda minivan, albeit a sporty one with a 6MT. I’m much happier these days and don’t drink to excess or, umm, partake like I used to back in the high-stress days. I still miss that Porsche and would like to have another, although I suspect that my fun car purchase will instead be a Miata. I was seriously pro-German car back then and wouldn’t consider anything else, but age has a way of mellowing you out and changing your perspective. Potentially fatal diseases do that as well, but I prefer the slower method.
If you don’t already have a copy, seek out and purchase a copy of the Bosch Automotive Handbook. I haven’t bought one in years, but I still hang onto my 3rd and 5th additions. Fascinating detail and endlessly useful, especially when working on older cars. Lots of detail on, well, everything, but especially good when it comes to their fuel injection systems, of course. They also have Technical Instruction books on specific systems, and I probably still have my K-Jet one in a box somewhere, probably with the Vanagon and mk 1 Golf Bentley manuals, because I still want to own t hose cars again someday now that I have something reliable as a DD.
Thanks for the kind words regarding my friend. I, too, am not religious, but at this point I just want her suffering to end so she can move on to whatever's next, whatever that may be.
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RallyWrench
> shop-teacher
05/03/2019 at 13:08 |
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Thanks, I’m pretty stoked. So much left to do, but the injection was a big hurdle. Now to save some money for other needs.
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RallyWrench
> Cash Rewards
05/03/2019 at 13:08 |
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Thanks! Happy to have the chance to do it at all.
RamblinRover Luxury-Yacht
> RallyWrench
05/03/2019 at 15:18 |
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We’ve got a W124 4MATIC with KE-Jetronic, and I can confirm after a series of running issues and nunfuckery that it is kind of pants.
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RallyWrench
> RamblinRover Luxury-Yacht
05/03/2019 at 15:33 |
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KE is a bigger pain in the ass than any other version, in my experience . At least at this age. They’re all easier to bork than get right, but KE has j ust enough electronic control to make the car undriveable and unfixable on the side of the road if it has a problem, whereas K-Lambda like mine and simple old K are about as simple as can be. But a couple of Bosch Master techs beat it into me at a young age. These older systems can be fucked beyond belief and still get you home.
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RamblinRover Luxury-Yacht
> RallyWrench
05/03/2019 at 15:40 |
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In our case, it has involved semi-random running with off mixture, arbitrary “AH! FATHER! I DIE” in traffic, and some other issues. I think part of it might have had to do with a vacuum leak, and something else with the flapper-doohickey, but don’t quote me on that as I was not the diagnosis guy. I think it’s still not right, but *better*.
Then again, the Digifant I had to mess with on a
Wasserboxer
not too long ago was pretty derpy.
BvdV - The Dutch Engineer
> RallyWrench
05/03/2019 at 16:16 |
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Great write-up! I even learned some things about K-Jet from reading it :p
I love seeing a car like this being done on the (relatively) cheap, between all of the high dollar 911 builds the internet seems to prefer.
Have fun at Luft6!
CaptDale - is secretly British
> RallyWrench
05/03/2019 at 18:09 |
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I still want that IROC tail... for pornografic future endeavors XD
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RallyWrench
> CaptDale - is secretly British
05/03/2019 at 18:37 |
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For you buddy, we make good price. :)
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CaptDale - is secretly British
> RallyWrench
05/03/2019 at 19:18 |
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Need a babysitter ?
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functionoverfashion
> RallyWrench
05/04/2019 at 20:13 |
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Ah, thanks. If we were closer, i.e. not in completely opposite corners of the country, I’d say let’s swap cars for a day sometime. But umm yeah.
Anyway, maybe you’ll inspire me to write up my windshield wiper motor replacement, which is an ongoing saga in my head that seems totally boring. But maybe what’s boring is when you go to the parts store and they just have the parts you need, in stock. And no modification is required just to fit up a replacement part!
Well anyway, rev that thing up for me and have fun. Cheers. I’ll write about mine again soon and I’ll... drive it through the woods or something.