82 911SC Running Issues

[mike621]

Originally Posted by Dave Kost

Did you ever set the CO to spec?

Did you test the throttle switch?

Sorry I'm too lazy to re read the entire post.

Hi Dave,

CO is not to spec. Could not find a shop to do it, and don't want to drive this anywhere while it is exhibiting this random ignition cut & heating up in traffic. Looking around for info on the throttle switch. May dig into Bentley manual later to see if there is a testing procedure.

[Dave Kost]

Hi Mike.

You have two separate issues without taking into consideration the CO setting.

Overheating.- Check you trombone cooler in the front fender? Is it hot after the engine is warm? Lean running could cause the overheating too.

Intermittent shutting off. Most likely electrical. Again clean all connections, paying attention to the fuel pump relay and ground on the CDI box. I would send the CDI and ECU to Systems Consultating in La. for testing- if the stalling continues. Going over a bump could cause a loose connection.

Look at #20 & 21 in this thread about throttle switch (s) operation.

Cold start issue with my newly refreshed CIS

Hang in there.

PS- How about a picture

[pmax]

Originally Posted by timmy2

Plug for ROW vacuum time delay pod. Not used on US Lambda cars

Is there a mix of US and ROW components here ?

What's the history of the car and engine ?

[mike621]

Originally Posted by Dave Kost

Hi Mike.

You have two separate issues without taking into consideration the CO setting.

Overheating.- Check you trombone cooler in the front fender? Is it hot after the engine is warm? Lean running could cause the overheating too.

Intermittent shutting off. Most likely electrical. Again clean all connections, paying attention to the fuel pump relay and ground on the CDI box. I would send the CDI and ECU to Systems Consultating in La. for testing- if the stalling continues. Going over a bump could cause a loose connection.

Look at #20 & 21 in this thread about throttle switch (s) operation.

Cold start issue with my newly refreshed CIS

Hang in there.

PS- How about a picture

Running a bit hot in town, according to the gauge. Trombone reading about 210F which seems high. Running a tiny bit cooler with the condensor and a/c pump removed from the engine bay (belt was already off compressor).

I'm going to take a look at the electrical connections at the CDI, and the microswitch and report back.

Originally Posted by pmax

Is there a mix of US and ROW components here ?

What's the history of the car and engine ?

Hi Pmax. AFAIK original motor and components. Hard to say as I have only had the car since August. 250,000 miles on car.

[pmax]

What are the component numbers ?

"3. WUR model number: 0438140"

All WURs start with those, you need the 3 digits following which identifies the model in your engine.
Fuel distributor has the component numbers on a plaque 0438100xxx.
Post the model of the lambda controller under the passenger seat 0280800xxx.

Hopefully you have a matching system.

[ganun]

Sounds stupid but I saw an SC with the pop off valve installed backwards, at first glance I didn't notice but then it was like WHAT'S GOING ON!
Surely you've checked the airbox.

[mike621]

Originally Posted by pmax

What are the component numbers ?

"3. WUR model number: 0438140"

All WURs start with those, you need the 3 digits following which identifies the model in your engine.
Fuel distributor has the component numbers on a plaque 0438100xxx.
Post the model of the lambda controller under the passenger seat 0280800xxx.

Hopefully you have a matching system.

Does 086 on the WUR sound right? Pics attached

0438 100 077 on the fuel distributor.

I'll grab the ECU number in a bit.

[mike621]

[boyt911sc]

Originally Posted by mike621

Mike,

The FD is -077.

The number for the WUR is to the right of 086 or to the left of 980. You could see the numbers from your picture but hard to read.

Tony

[Dave Kost]

Originally Posted by mike621

Thanks to everyone on this forum and the CIS Dummies thread for the helpful information to help troublshoot my new-to-me SC. I'm posting a thread relating to my own vehicle hoping to get some perspective from experienced owners, as this is my first Porsche. I am pretty confident at DIY, have a decent set of tools, and a Bentley Manual.

The main symptoms I am attempting to solve for: 1) poor idle when cold, including intake backfire when I attempt throttle. Levels out eventually, but my other symptom presents itself once warmed up and driving. 2) Randomly loses power completely, and if I attempt to add throttle in response, will backfire out the exhaust and stall. Will start right back up and keep driving.

Here's my current data based on the CIS Dummies thread format, checked with CIS gauges:

1. Year of engine: 1982
2. US or RoW (Rest of World): US
3. WUR model number: 0438140
4. Ambient temperature at time of test (in degrees C): 19*
5. WUR Resistance (in Ohms): 9.5
6. System Pressure (in bars): 4.9
7. Cold Control Pressure (in bars): 2.1
8. Warm Control Pressure (in bars): 3.5
9. Time delta for Cold -> Warm Control Pressure (in minutes & seconds): 2 min
10. Residual Pressure @ 5 min (in bars): 1.4
11. Residual Pressure @ 15 min (in bars):1
12. Residual Pressure @ 30 min (in bars):0
13. Residual Pressure @ 60 min (in bars):0

My main concern among this data is the loss in residual pressure, though I am not sure my main conditions I am experiencing relate to this. Entirely possible I have multiple problems. I bought the car AS IS with issues.

There is a receipt from several years back stating the car was sitting and had the fuel filter done, mixture adjusted and pop-off valve added.

I've had the car two months and have done some work so that it will pass smog and complete the ownership transfer to me:

-Oil Service (Cooling Lines, Hoses, Feed Lines over cams)
-Valve Adjustment
-Ignition Service: Plugs, Wires, Cap, Rotor
-Vacuum lines Replaced off the throttle body, distributor
-Smoke Test (Airbox OK)
-New Catalytic Converter
-New Oxygen Sensor
-New Oxygen Sensor Relay
-New Ignition Switch
-Cleaned and replaced most fuses in the front fusebox
-R&I'd fan and replaced alternator ground
-Replaced Battery Terminals
-Set timing 5*, Z1, vac lines on (now seeing conflicting info to disconnect one or both vac lines, so some clarity here would be great!)

I am considering the following as next steps:
-Compression Check
-Fuel Injector check (will order new o rings and anything else necessary to reinstall)
-Swapping Fuel Filter (Last done in 2017)


I'd appreciate any advice or thoughts on where to turn my attention to next. I don't want to throw any unnecessary parts at it in lieu of solid troubleshooting.

Mike,
1 checked my Spec Book (Dempesy) It simply says 19-25 degrees BTDC at 6000 rpm with vacuum lines disconnected then let the idle ignition timing fall where it falls with vacuum lines connected. (I believe I plugged my retard vacuum line.)

So, check and see where your timing is at 5-6000 rpm?

Let us know.

[mike621]

Originally Posted by boyt911sc

Mike,

The FD is -077.

The number for the WUR is to the right of 086 or to the left of 980. You could see the numbers from your picture but hard to read.

Tony

Tony, I found a "481" on the WUR.

Originally Posted by Dave Kost

Mike,
1 checked my Spec Book (Dempesy) It simply says 19-25 degrees BTDC at 6000 rpm with vacuum lines disconnected then let the idle ignition timing fall where it falls with vacuum lines connected. (I believe I plugged my retard vacuum line.)

So, check and see where your timing is at 5-6000 rpm?

Let us know.

Dave, thanks for keeping me honest. I followed the Bentley spec, eventually, and timed to 6k with hoses plugged. Used an advance light. and it checked out.

Today, I :
-when pulled on throttle linkage slightly, i can hear an audible "click" from microswitch.
-Cleaned microswitch spade connectors
-checked the ecu connection and relay. (cleaned them before, theyre looking alright.)
-Cleaned both ends of the ground strap for the CDI box.
-Cleaned CDI Box connector (looked pretty good)
-Cleaned main harness connector at the engine bay fuse box
-Listened to my car idle nice and happy before its test drive

Took the car out for a test drive around town and on off the highway. Still running warm in traffic. Trombone still around 200. Hoses in the rear wheel arch test around 175-160 ea. Cut out on me on the highway while cruising again. Still seems like ignition is getting dropped.

[Dave Kost]

OK.

What coil are you running?
Get a voltage meter that plugs into the cigarette lighter plug to monitor running voltage. Maybe their is a correlation of the shut downs.

[Dave Kost]

With advance Vacuum line connected to ignition distributor total should be around 30*. Right? We are checking that the advance is working on the distributor. At 250K who knows.

Just thinking out loud from far away.

[mike621]

Originally Posted by Dave Kost

OK.

What coil are you running?
Get a voltage meter that plugs into the cigarette lighter plug to monitor running voltage. Maybe their is a correlation of the shut downs.

I was running a Bosch black coil. Bought and installed the MSD HV 8222 no major change.

Originally Posted by Dave Kost

With advance Vacuum line connected to ignition distributor total should be around 30*. Right? We are checking that the advance is working on the distributor. At 250K who knows.

Just thinking out loud from far away.

I think it was +21* btdc iirc. It advanced as anticipated, when I tested this.

Multiple failures at this mileage are no surprise - feel like Ive made progress though!

[mike621]

Quick clip of a startup after idling the car a few minutes.

[boyt911sc]

Mike,

“481” is not the WUR ID # (0-438-140-481). That is probably the serial number. Take a picture and post it. The numbers should read like 0 438 140 xyz. XYZ would be the last digits.

Tony

[mike621]

Originally Posted by boyt911sc

Mike,

“481” is not the WUR ID # (0-438-140-481). That is probably the serial number. Take a picture and post it. The numbers should read like 0 438 140 xyz. XYZ would be the last digits.

Tony

Thanks for clarifying Tony! I had to get the brass brush out to clean up the number.

EDIT: Also mentioning I pulled the vac line off for the photo!

Reads 090. Also including the number from my ECU, requested earlier

[boyt911sc]

Mike,

If you want to find out the culprit of your cold idle problem, take a short video after sitting over night. Show how the engine does its warm up cycle for the first 3 mins. Attach the pressure gauge and monitor the control pressures versus time. Based from the information in post #1, the engine will experience a cold erratic idle specially at this time of the year when it is colder.

Once the engine has warmed up, everything would be normal. And that’s what your video showed up. Thanks.

Tony

[mike621]

Originally Posted by boyt911sc

Mike,

If you want to find out the culprit of your cold idle problem, take a short video after sitting over night. Show how the engine does its warm up cycle for the first 3 mins. Attach the pressure gauge and monitor the control pressures versus time. Based from the information in post #1, the engine will experience a cold erratic idle specially at this time of the year when it is colder.

Once the engine has warmed up, everything would be normal. And that’s what your video showed up. Thanks.

Tony

The following clip shows this morning's start and warm up. Idle settles down around 7mins.

This represents an improvement versus when the FV wasn't working. No more backfires into the intake. Its also 50-70* in SF pretty consistently.

[boyt911sc]

Mike,

The video of the warm up is of no value because you were helping the engine by pressing the gas pedal. What I like to see and watch is how the cold engine performs during its warm up stage.

Repeat the test and put the car in neutral and hand brake on. Open the driver side window and reach for the ignition switch. Do not get inside the car. Start the motor and video the start up. I like to see the cold engine RPM for the initial 3 mins. unassisted. Meaning you stay out of the car and let the engine run unassisted.

If you install a CIS pressure gauge during the test, you will have an idea how the cold control pressure transition to warm control pressure in a couple of mins. or less. If your engine will not idle without further assistance, you got a big problem. Thanks.

Tony