1990 Porsche 911 C2, A Story

Everyone knows that one of the maddening things about owning a 911 is that parts can be quite expensive. Case in point, the blowers talked about above. The flip side to this coin, is that when you look around your 911 pretty much every part you see is available. You can go junkyard scrounging for little plastic bits and weird trim pieces, but you don't have to. Somebody somewhere wants to sell you every part of your car, and it's not always expensive!
Here are some little rubber caps.

They go over the door switches that turn to dome light on and off. The switches look very sad all naked.

Now they look happy.

I can honestly think of no more unnecessary part than these little switch condoms. You only see them when you open the door and who's really looking at the door jamb when you do that? Doesn't matter, it was something on the car that could be made better for only $3.25 each, which when I think about it is probably an insane amount of money for a tiny rubber switch hat. No matter, Pelican is a friend to married men everywhere and doesn't put prices on the invoices that they put in the boxes of parts that have been coming weekly.
Tomorrow marks the one month anniversary of the car making it back to Texas. Since that first time I presented the car to my wife, we've managed to drive it almost 1100 miles. We're having a good time.

mazdeuce said: we've managed to drive it almost 1100 miles. We're having a good time.

Keep it up. 911s like to be driven.

Drove the kids to school, drove my wife to get fabric for a quilt, and then changed the oil. I've changed oil in cars about 1000 times in my life, it's not a huge deal. It's just oil. I read all of the things online about huge catch pans and the deluge of oil and chalked most of them up to guys that had spent most of their lives paying for an oil change and then deciding to become "car guys" and change the oil on their mid life crisis 911.
I was wrong.
There is nothing that could prepare me for the waterfall of oil that comes out when you remove the oil tank plug. It's like a fire hose of oil. It's like those old time movies where the hero spends his last dime to drill an oil well and just when things look the darkest he hits a gusher, except pointing down instead of up. It was both frightening and amazing.
The oil is changed. It looked fine. I'm sending a sample into Blackstone to hear what they have to say about it. I filled it with 9.5 quarts of Brad Penn. All is well.

I took my oldest daughter to the MotoGP race this weekend and had a ball. We didn't take the Porsche because we rightly feared having to sit in traffic with marginal AC. This left the car home for my wife to drive around the kids with, which she did. The problem is that she had the car cut out under deceleration and stall. She pulled over and it started right up, but she's not happy and has said that she's not comfortable driving the car with me out of town now. I'm going to need to track this down.

mazdeuce wrote: ...she's not happy and has said that she's not comfortable driving the car with me out of town now. I'm going to need to track this down.

Uh, yeah. If momma ain't happy, ain't nobody happy. Gluck, man.

does it have a lightweight flywheel or has the rubber center clutch been replaced? When you take out mass from the flywheel this stall can happen. Aftermarket chip that advances timing below idle bins is the solution (better and cheaper than the clutch replacement parts.

You will want the Steve Wong Chip (911chips.com).

I don't think the flywheel has been mucked with. I suspect that something is making the computer shut itself off temporarily. From what I'm reading, the computer on the early 964's is sensitive to electrical stuff misbehaving and it's response to inputs it can't handle is to sort of reboot. If this is what is happening then it's probably somewhere between the coils and the plugs. I've ordered the plugs that let me plug the car into my laptop and run the scan tool software that is available for these cars. I'm not sure that I'll find my answer there but it seems reasonable to at least be able to ask the car if it knows what the problem is. Then I'll start testing coils and what not.
My wife drove the car to work today and is in love with it again, so that's good. It buys me time anyway.

Car stalled twice today. Once at a light and it restarted. Then about 3 miles down the road it died at 55. I pulled over and yanked the DME and tapped it and replaced it and it started right back up. The DME was quite hot. Much hotter than any of the other relays in the car. I'm going to put the other known good relay in and see if it gets hot as well. If it does, then I need to figure out why there is so much current going through it.

mazdeuce wrote: Car stalled twice today. Once at a light and it restarted. Then about 3 miles down the road it died at 55. I pulled over and yanked the DME and tapped it and replaced it and it started right back up. The DME was quite hot. Much hotter than any of the other relays in the car. I'm going to put the other known good relay in and see if it gets hot as well. If it does, then I need to figure out why there is so much current going through it.

bad/loose ground?

Could be a bad ground. I went through all of them on the front of the car earlier but I need to search and find more and check them. Is there a list of all the grounds and their locations? Another option is the fuel pump fuse. Of all the fuses in the fuse box, it's the loosest. In fact it pretty much wants to fall out if you touch it. It's borderline floppy. The only way to get at the pins that grab the fuses is to completely disassemble the fuse box. This involves taking out every fuse and relay and popping six relay holders out and then undoing about 30 clips while trying to break as few as possible. Interestingly enough, evidence on the fuse box indicates that I'm not the first person to have opened this.
Take pictures!
Never have I been so happy that I took a picture before a project. I had to take out all of the fuses and relays and put them back in the right spots again. Without a picture it would have been a pain, with a picture it was easy. I got the box down to this point, spent two seconds tightening up the fuse location, and put it back together.

The car starts and runs so I must have done it right. The hope is that the loose fuel pump fuse, which is on the DME circuit, was somehow making the DME mad and it was getting hot and that was the cause of my stalling. I'll drive it around and give the relay a feel and then see what's up. I decided to leave the same DME relay in the car so that I minimize variables. At least I have an excuse to take the car for a drive tonight. That's nice.
GPS, did you ever change the fuel filter when the car was in your posession? A bit of reading turns up the theory that a struggling fuel pump could cause a higher current draw as well. Potentially a clogging filter or a failing pump though the car shows no other symptoms of that.

mazdeuce wrote: GPS, did you ever change the fuel filter when the car was in your posession? A bit of reading turns up the theory that a struggling fuel pump could cause a higher current draw as well. Potentially a clogging filter or a failing pump though the car shows no other symptoms of that.

It was new at ~80k miles.

Jogging my memory - the fuel tank was out recently to attempt to repair the noisy fan with lube - hence the disturbed fuse box too.

Underneath the car in front is a panel that covers the fuel pump (just at the front of the panel that covers the shifter...). It is possible but not probable that one of the hoses was twisted or kinked during re-assembly or the vent hose that comes up behind the tank is pinched. I wouldn't count on it as I was careful not to... but it's an easy thing to check and correct .

I'll check those things, thanks.

There's lots of pretty cool things that Porsche did when building the 911 that you really don't see in more mundane cars. One of these is twin distributors.

The car has six cylinders, two plugs per cylinder, 12 plug wires, two distributors, and two coils. It's a bit daunting and I'm quite frankly terrified of it. It does provide one pretty cool diagnostic tool though, namely the ability to disable half of the system to check the other half. One of the potential sources of my stalling is electrical interference with the computer, and one of the likely sources of that is a failing coil. All you need to do to check if either coil is firing right is unplug the other one. This effectively kills half of the ignition system, but the car will idle and run just fine as long as the active half is working well. Then you plug that side back in and check the second side. Pretty nifty.
Checking the system this way yielded nothing. Both ignition systems seem to be working fine. I did pull the ground for the coils and clean it while I was deep in that part of the car, and maybe that's helped. Certainly the car has been idling well the last four days and hasn't stalled. Maybe that ground was flaky? All I can really do is drive it and see. In other news, it's leaking a bit of oil, I think from around the plug in engine case. I might have to tighten that up a bit. Also, summer is getting closer and I have to use the AC more. Even though it sounds like you fired up a chainsaw in the cabin when you turn the blower on, it's blowing nice and cold. I also discovered, quite by accident that the way to get the air to blow the hardest is to set both of the little air control levers all the way to the left. If I had read the manual, I'd know that the bottom lever controls how much air comes out toward my feet, and the top one controls how much comes out toward the windshield. I though that the top one controlled how much came out of the dash vents like every other car that I've ever been in. Silly me.
Anyway, the car has been running great and the AC blows loud and cold for now. Pretty much perfect.

Last week this little guy arrived in the mail.
They claim, and forums agree that these chips tend to make the cars behave better. It seems that in 1990 the whole world was trying to figure out how to meet CARB numbers. Porsche figured out how to do it with programing and because they didn't know which cars were California cars and which were going to other states, all of the US cars received a tune that chopped about 20hp off and made them a bit moodier at idle than cars in the rest of the world. The chip I bought is supposed to be even better than the Euro tune in 1990. We shall see. The computer lives under the drivers seat. In typical Porsche fashion it's dark and tools barely fit and the job is easier the smaller your hands are.
Once out we have this musty crusty box. Note to Porsche and every auto manufacturer in the world: The floor is a terrible place for computers, especially on cars with sunroofs. Idiots.
Once out you flip the box over and bend a few tabs to get at the guts. Interestingly enough, I am not the first person to pry this box open. Perhaps not even the second. The car continues to reveal it's shady history.

Once the box is apart you simply pop out one circuit board. Simply. Right. Instructions state that you should pry, but not too hard because if you do it too hard then you'll break the idiotically expensive circuit board. What is too hard? My assumption is that if it's not coming apart then I should pry harder, but if it breaks then I went too far. This was not fun.

I did get it apart, and the chip was pried out of the board on the left and the new chip was put in. The chip I found looked stock-ish. Who really knows what it was or what has been in the car over the years. The verdict? Much better. The car idles better both when hot and cold. The revs don't dip when you push in the clutch. It doesn't threaten to stall at all really. Does it have 20 more hp? Probably not, but the power delivery is much smoother. Before there was a significant power gain at about 4500 rpm's. It felt like the car came on cam or something. That's gone. Seamless delivery all the way up to redline. The chip wasn't cheap, $450, but the car is better. It just keeps getting better. What a fantastic car. I took it out today around a nice set of local curves away from any houses. I don't know what sort of surveying problem led to the two 90 degree corners right after each other, but they're great. Because of trees, the first one is pretty blind, but the one right after that has a good view 80 or so yards down the road so you can exit with a bit of enthusiasm. I came around with the rear of the car moving sideways under power in a very controlled fashion with a truck just coming into view. As I came past them I received two very enthusiastic thumbs up though the windshield. Felt good man.

Sounds like a great upgrade. $450 isn't exactly cheap, but it sounds like it was worth it.

Also, this continuous barrage of Porsche goodness is really making me consider selling the Baja and getting a 911 or 951. Once the Spitfire is finished (i.e. I have a backup vehicle), that may well come to fruition.

I have just finally gotten around to reading this thread. It sounds like a good car and you're making great progress.

One thought popped into my head way back when I read about the time your wife couldn't get the car to start. Porsche builds a safety into the ignition that prevents you from engaging the starter with the engine running. If you turn the key and the car doesn't start, you must turn the key all the way back before it will crank again. If she was having a hard time turning the tiny key, she may have been coming up against this.

Keep cleaning those grounds. They're everywhere.

I'm still not sure what happened with that one. It started, she backed it up about 5 feet and it stalled and wouldn't restart. By the time she came inside she had been cranking on it for a bit. I went out and tried and it wouldn't fire. I tried swearing and that didn't help. I let it sit for 10 minutes and it reluctantly started. It has never repeated. The car really is getting better the more we drive it. I've refreshed something like 13 grounds and I keep finding more.
Your Dirty 911 thread is the one that started me down this path. Thank you.

That's good to hear! That was kind of my goal with that thread. I wanted people to know that they don't have to be so afraid of these cars.

I'm not really familiar with 964s, but you'll probably find a fairly large, corroded ground wire under one or both of the front seats, too. If you do, they will be important ones.

In the fuse box, is that a built in fuse tester?

mazdeuce wrote:

That 23 year old fuse box looks brand new compared to an SC or Carrera box!

Awesome Porsche!

I do automotive electrical repair on the side. Your Porsche is outstandingly clean, however I’m troubled with the corrosion on all the tin plated parts. I have seen this before on vehicles that were stored in tents or metal storage sheds.

Anyway, the fuses may look ok, but if the tin plating gets slightly oxidized, random things will happen. It may be helpful to replace all the fuses with brand new ones.

Also, I use DeoxIT on all electrical connections. It cleans and lubricates the connectors and keeps oxidation from reforming. You can get a small aerosol can of DeoxIT at radio shack or order a bigger can off the internet. DeoxIT is industrial strength stuff, It is way better than any contact cleaner available off the shelf.

Kenny_McCormic wrote: In the fuse box, is that a built in fuse tester?

Of course! We're all civilized here aren't we?

In reply to fujioko:

Thanks for all of that advice. There is certainly a degree of corrosion in a lot of unsavory places. One of the things I'd did that I can't remember if I wrote about was to take every fuse and relay out and put dielectric grease on them and reinstall them. I replaced a few that were incorrect as well. More than a few of them were well and truly stuck and would not come out with a standard fuse puller. I had to use pliers. Interestingly, the only connection I've found in the car that was greased was the million pin plug that connects the computer under the seat. I'm quite sure that electrical gremlins will continue to be the largest source of frustration with the car. I'll pick up a can of DetoxIT and have at it. Thanks again.

mazdeuce wrote: Pelican is a friend to married men everywhere and doesn't put prices on the invoices that they put in the boxes of parts that have been coming weekly.

I'm always trying to watch for the mailman whenever I know something is on it's way, gotta snag those big ticket items before she comes home with a box in her hand asking "what's this?" with the ever present follow up question "and how much was that??"