Contracted 914 fever— is this the car to cure it?, What do you think of this ‘73 914 2.0 on Bat— pass or play? Options

[trylon]

New to the forum and the car. Was pointed to it by an aficionado on The Samba— I have a ‘59 Karmann Ghia. https://www.thesamba.com/vw/forum/viewtopic.php?t=723793

He suggested that the people on this forum were the brain trust for all things 914 and that I should vet one here that has caught my eye on BAT:

https://bringatrailer.com/listing/1973-porsche-914-113/

Any insight would be appreciated!

[trylon]

I actually rewound a seatbelt after that. Worked just as well as when I let the magic winds out. Ended up buying new ones before track day last July. Good investment. Not that expensive, and much safer.

You are a better man than I am, Gunga Din.

[trylon]

Can you believe I am still working on the horn!?

If you recall, the horn button was disconnected with its innards haphazardly arranged and the horns themselves in need of point filing. Removed bumper, removed horns after testing, drilled out rivets, filed points, bolted back together, tested, re-installed.

When the bare wire of the horn button is grounded, horns sound. Yay, electricity stills works.

So on to putting the horn button back in correct order. After much trial and error and upside and backwards imagining I think I figured out the order of the parts and what is supposed to take place.

As I wish I had found this information instead of having to generate it, here is how I think it is supposed to go (but what do I know haha):


Porsche logo on horn button face points up in direction of blue arrow


[edit] Insulating material washers (not shown in previous picture) to isolate the contact plate from horn button.


Contact plate oriented with blue circled terminal as shown


Non-conductive washers next to electrically isolate contact plate


Connecting spring next


M4 nylon washers next to maintain contact plate isolation from screws


Metal washers next to keep heads of screws from digging into nylon washers


Screws next making sure to center all items


Rubber cup last

[trylon]

So my next question:

Is the grounding wire long enough to travel along with the turns of the wheel from lock to lock?
[Have since determined that the wire travels with the steering wheel!]

[emerygt350]

Looks like my wire, plus electrical tape.

[emerygt350]

Dbpost

[trylon]

Looks like my wire, plus electrical tape.

Thanks for the confirmation.
Sorry for the double post.

[trylon]

Video shot last fall of the Porsche taking a spin around Lake Waramug in Connecticut.

https://youtu.be/JLcAUhXo5BI?si=Z_2IJaglTS9kUDP5

[trylon]

Pulled the AAR:



Discovered an unplugged sensor:



What’s up with that?

[emerygt350]

Doh! That's important. Plenum temp I believe. And it looks like your thermostat bellows is shot as well.

[trylon]

Doh! That's important. Plenum temp I believe. And it looks like your thermostat bellows is shot as well.

So the plot thickens…

As you know I am at the apprentice level with 914s (well, at best probably any car for that matter haha). When I pulled the AAR I noticed that I could blow through it, interestingly one side seemed easier to blow through than the other. Given this, I am wondering if my original assessment of the rough starting cause might not be correct.

If you recall, the car cold starts as though it needs to pull the choke out. As there is none, my understanding is that in a 914 the AAR creates a vacuum leak (an automatic bit of throttle pedal down if you will) that will bring up the revs when cold.

The fact that the revs are too low at cold start led me to believe that the AAR was stuck shut and not causing the vacuum leak needed. But the fact that it is not shut and lets air through seems to point to some other reason for the rough cold start.

I also now see that the AAR is not like the thermostat bellows in that it does not use engine heat directly to close but instead is electrically heated when some switch is closed when a sensor determines the engine is warm enough.

So, now I wonder if the sensor that is unplugged is the sensor that determines this engine heat. If so, that would make the AAR inoperable and always open.

This is all so convoluted that I wonder if someone misunderstood the functioning of the AAR and unplugged the sensor and did other adjustments to get the engine to run— because it does seem to run well after it warms up. I just wonder at what cost!

So the AAR has been soaking in Blaster and I am going to empty it out and put 12Vs on it to see if it ever closes and doesn’t permit air through it. If it seems to work, I will put it back on and for grins reattach the sensor.

I think I am going to have to screw up how the engine runs before I correctly get it to run well!

[trylon]

Hooked up the AAR to 12V and let it warm to about 90 degrees. It must have closed as I could no longer blow through it! So we know that is working now ( or always was doh).

Will put it back on tomorrow and plug in the sensor. Let’s see how it starts and runs then…

[emerygt350]

The AAR circuit is pretty dumb. It's just a heater and it just heats. Always. Once the engine gets hot enough the AAR tends to just stay open or open quickly once started. That AAR being open would cause what you are looking at. I have not delved into that plenum charge temp sensor but it is just another way for the engine to modify the richness. So depending on whether open means hot or open means cold would drive whether you were too lean at start or rich enough but then rich as you warmed up. Some sensors have bigger impacts than others. I suspect this one is middle to small impact on richness. There are nice diagrams out there and explanations. Here is what PBanders has to say: (from https://members.rennlist.com/pbanders/DJetP...Vacuum%20Leaks)

Air intake temperature sensor:

Function: Senses intake air temperature and sends signal to the ECU to provide mixture compensation.
Normal Value(s): 300 ohms @ 68 deg. F, about 100 ohms @ 122 deg. F.
Failure Modes
Open: Makes the mixture somewhat richer. Check with an ohmmeter.
Shorted: Makes the mixture somewhat leaner. Check with an ohmmeter.
Notes: The output of this sensor is used by the ECU to adjust the mixture for the intake air temperature. This is a secondary adjustment and has a small effect on the mixture. The sensor corrects for the decrease in air density with increasing temperature by leaning out the mixture. Disconnecting this sensor has the effect of richening the mixture, a common mechanic's trick.
More: This sensor and the cylinder head temperature sensor are negative-temperature-coefficient (NTC) thermistors. Here's a URL on thermistors and how they work:
http://www.rtie.com/ntc/ntcappln.htm

Here's a URL that describes the manufacturing process:

http://www.ussensor.com/manufacturing.html

Below is a URL to a reference that has two charts showing the resistance vs. temperature relationship for the intake air sensor and the engine temperature sensors used in D-Jetronic. The engine sensor data looks OK (about 2.5K at 68 deg. F), but could be from any sensor. Bosch used the same air temperature sensor on all D-Jetronic cars, regardless of model, so the data should be accurate for the 914's sensor:

http://www.icbm.org/erkson/ttt/engine/fuel...tion/d-jet.html

The charts are about half way down the page.

[emerygt350]

"a common mechanic's trick." I may have to try that trick some time.

Looks like the PO was fighting a lean condition.

[trylon]

"a common mechanic's trick." I may have to try that trick some time.

Looks like the PO was fighting a lean condition.

Wow! This is great stuff! Thanks for taking the time to find and post it.

Yes, it seems that if the AAR were stuck open, the mixture would be lean indeed and pulling the plug on the air intake temperature sensor might have well been the cheap trick to enrich the mixture. Further, that enriched mixture might be causing the cold start!

So my hope is, now that the AAR is working, I can simply reconnect the air intake temperature sensor and, voila, no cold start, perfect mixture!

Ha ha, we shall see…

[emerygt350]

Hope springs eternal. 914 owners tend to be 'better tomorrow ' folk.

[trylon]

Ok, put it the AAR back in and reconnected the temp sensor.

Car hasn’t been started for months.

Turned the key, waited for fuel pump, a few short grinds, and up it came— immediately went to ~900 on the tach. No if ands or buts. After a bit it started to see-saw then settled back 900 after about a half a dozen fluctuations. Let it run for about a minute and revs were steady at 900.

Turned it off, waited about a minute, and restarted. Man, it has never started so strongly and willingly! Pegged 900 and stayed there.

Just went and tried again. Quick start up, see-saw about 30 seconds settling down to much lower revs ~200 (the first short line on the speedometer).

Stepped on it and released to see how it recovered— not well, almost stalling on one try, but always coming back to ~200.

Idle too low now, so let’s see what happens when I set it higher… hmm, interesting catch-22, how do you set the idle with the air cleaner on? Seems if you remove it, the idle will be different when you replace it.

[trylon]

And while we are poking around…

Slid under for the first time only to find this:



Any guesses as to what precisely is leaking?
Remember, this has been on a lift all winter.

[emerygt350]

If it is the cv gaskets, super easy and cheap. Engine looks dry so I don't think it's motor oil.

[emerygt350]

Your idle cold should be around 1600 as it warms. Cold start it will struggle a little but should be around 900-1100, as the car warms the idle will rise to 1600ish, then drop slowly as the AAR closes.

How long did you run it?

[Shivers]

And while we are poking around…

Slid under for the first time only to find this:



Any guesses as to what precisely is leaking?
Remember, this has been on a lift all winter.

Put some of that lubricant on your finger, rub it around and smell it. Gear oil has a gamey smell. At least you will know what is leaking