A burst/cracked/broken 993/964 fan housing rubber heater duct

 

A known failure item is easy to replace with hand tools. No biggie. Mine blew out at 70K miles or so making it a not too often repair. There are two part numbers, one for Varioram engines 1996-1998 (993 993,106.403.00) one for the earlier non-Varioram engine, pre-1996 (964.106.403.02). The one pictured above is the Varioram installed version. When replacing, it is very important to remove any rubber fragments from it bursting from the engine bay and behind/below it on top of the cylinder fins so nothing gets ingested into the fan, melts or burns on the cylinders, or interferes with the belts or their pulleys.

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Preparing for Passing an Emissions Tail Pipe Test with a 993:

I regularly read postings like this by folks who were able to clear a failed tailpipe inspection on their 993 by doing this:

" Took my '95 993 (148k miles) [an OBD-I car] for typical California smog test. Never had a failure. Except this time! High HC values [of 47 Parts Per Million - (PPM) Max. allowed 35PPM]."

Added a bottle of Swepco 503 fuel adder, filled the tank, and drove the snot out of the 993 over the weekend (240 miles, up and down the coast. High rev's and aggressive (but safe!) driving). Came back, re-tested, and blew all the numbers out of the water [well within allotted maximums]! Passed with flying colors" "Bottom line, car needed a proper "Italian tune-up". I've been driving the car frequently, but going to Chick fil A with my kids does not cut it. Car needed a serious work-out. Lesson learned."

If you live in a state where tailpipe emissions testing is done here is what preparation is needed to pass the test without drama.

• Checking for the readiness of the emission reporting system to conduct an emissions test:

• For 1995 and earlier OBD-I cars if you have a Check Engine Light (CEL) illuminated do what is needed to clear the code, discussed below. A good inexpensive choice is to run the OBD Codes with a generic handheld Autel AL519 reader. For these early cars, it is usually something very simple like the replacement of the one oxygen sensor, an inexpensive part if purchased in BOSCH branded box from a general auto parts store and is easily replaced in your driveway. The how-to is on this page. The OBD code(s) given, in most cases, makes it specific as to what is needed to be done. Once the cause of the CEL is addressed clear the codes with the reader or by disconnecting the car battery if the CEL persists.

• For ALL OBD-II cars, 1996 forward, These cars have something called Readiness Testing which is a series of EPA-mandated specific timed tests the engine management does during specific running conditions and at cold start. Whenever the battery on the car is disconnected all the readiness codes, sometimes referred to as flags,  are reset to "NOT READY" as the system cycles through redoing tests. 
   
  The issue is that unless specific driving conditions are met one or more of the tests remain incomplete and when the car goes in for emission inspection & testing it will fail the emission inspection. Also upon being reset any change in the engine's running condition that has resulted in it not functioning properly will report as a "FAIL" from the system on the related test. Seems simple enough except for the typical car owner it can take weeks or months for the car to have completed all the necessary driving cycles to set all the readiness code statuses to a "PASS" condition. Compounding this is disconnecting the battery is a common procedure during many routine service and repair activities.

Here is how to go about managing the readiness tests:

• First of all, when using an On-Board Diagnostic reader the ignition on the 993 must be on and the Immobilizer inactive on so-equipped cars for the reader to access the MOTRONIC ECU and retrieve the readiness codes. No need for the engine to be running to see the diagnostic information. 
• Run the OBD Codes if a CEL light is present or not using an OBD code reader such as an Autel AL519. check the individual readiness code states and for any "FAIL" statuses, the car will need to have any "FAIL" statuses addressed, the codes reset (cleared) via the reader's reset function or disconnecting the car battery, then run through the OBD-II Test Drive to set all the readiness code statuses from "NOT READY" to "PASS". 
• More on On-Board Diagnostics (OBD) and the readiness code status can be found here. 
• Actions Taken nine times out of ten to remedy a "FAIL" on 1996 forward OBD-II cars there is a problem with the Secondary Air Injection (SAI) System with a few ways to address it here.  Specifically, the air system's check valve is regularly the culprit and can be replaced.

• Change the oil

• If your caps and rotors on your distributors are more than three years old consider changing them this is especially important if you are encountering an occasional  OBD Code "Cylinder Misfire" with a CEL illuminated from time to time that, self-extinguishes.

• Drive the car until it is good and hot just before going in for emissions testing. A half-hour of spirited driving brings the temperature gauge up to its normal operating range. The definition of spirited driving is to run through the gears so in several instances the engine is run near or to redline during acceleration.

• Do not turn the engine off, with the hot engine drive directly to the inspection center to have your car's emissions tested. Do not turn off the engine at any point before the inspection while waiting in the inspection queue for your turn. Turning off and restarting the engine may introduce enough unspent fuel into the exhaust system to trigger a fail on the tailpipe emissions test.

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The 993 OBD-II Readiness Tests' Drive Cycle made easy!

Read this entire document including the notes & comments at the bottom before attempting this procedure.

In order to successfully pass a State Emission Inspection in many states a series of tests conducted by the Motronic Ignition Computer (ECU) internal to a 993 must be completed and result in a PASS status for all the tests. The results of these tests are referred to as the Readiness States. They can be in a PASS, FAIL or NOT-READY state. The tests are made while the car is driven and each driving sequence for testing purposes is referred to as a Drive Cycle. The below procedure is designed to set all the Readiness States once any repairs are made and/or a reset event such as a battery disconnect or a reset using an On-Board Diagnostic Code (OBDC) reader has taken place.

This procedure is based on the published Porsche OBD-II Test drive document. It is intended to make the process simpler to complete successfully on a DIY basis.

Why success at the processes' completion seems somewhat variable for some:

The official Porsche document used to specify running conditions for the Readiness Tests specifies engine speed under specific engine loads for certain tests. This DIY procedure uses engine speed in combination with road speed & gearing as a proxy for engine load. This can result in a little bit of a hit or miss on meeting test conditions required on a single test drive cycle. This is most likely, for some, why completing the test drive and getting across the board PASS results takes more than one drive cycle to complete. 1996 and some early manufactured 1997 OBD-II cars require that all tests to be completed in a single engine running event contributing to the perception of offering additional difficulty completeing the Readiness test sequence.

This document includes consolidated information gleaned from personal experience, several public domain sources including Porsche enthusiast technical forums and Porsche published documents. The procedure described below is used successfully to set the Readiness statuses for many 993 owners, but this is not guaranteed for the above reasons. 

Here are the five systems it will test and report results on:

Autel AL 519 Readiness Screen 

     - Three-Way Catalytic Converter Efficiency
     - Fuel Tank Ventilation
     - Secondary Air Injection
     - Oxygen Sensors
     - Oxygen Sensor Heating

During the drive cycle, it helps to have a generic OBD-II reader such as the inexpensive Autel AL519 to see what progress you have made by reading out test statuses as "NOT READY", "PASS" or "FAIL" as you complete the process**. Not all generic OBD readers can see the readiness test status information.

**For MY 1996 and some early MY 1997 cars the ECU will only report to the reader statuses once all the tests are complete in a single drive cycle. For later MY 1997 forward cars each readiness status will report to the reader progressivly as each test is passed or fails.

The Drive Cycle:

1) Start the engine from dead cold, let idle for approx. 2 min, 10 secs. 

(Tests Secondary Air Injection (SAI)) 

2) Accelerate to 20-30 MPH, in the 1600 to 2800 rpm range, (2nd or 3d Gear*), maintaining a steady speed for approx 3 min, 15 secs.  

(Tests Adaption Ranges II, Oxygen Sensor efficiency & Ageing-Heating)

3)  Accelerate to 40-60 MPH, do not exceed 60 mph in the 1600 to 2800 rpm range, (5th or 6th Gear*), maintaining a steady speed for approx 15 mins. 

(Tests Oxygen Sensor efficiency)

4) Continue at 40-60 MPH, do not exceed 60 mph in the 1600 to 2100 rpm range, (5th or 6th Gear*), maintaining a steady speed for approx 1 min. 

(Tests Oxygen Sensor Period Length)

5)  Decelerate and come to a stop and idle in neutral for 5 mins. for the six-speed cars and in Drive for Tiptronic cars

(Tests Adaption range I & Tank Venting)

6) Check the statuses with an OBD reader to see if all have moved to a "PASS" status. If so your car is ready for state emission testing.

* These RPM values are for a G64/20 & 21 Transmission USA & ROW markets respectively. I have been unable to verify which of the two gears is preferable, only that the specified RPM can be achieved by the stock transmission in either gear. For step 4 6th gear provides a broader RPM range within the specified MPH range.

Notes:

 For the 1996 and some early 1997 Model Year cars:

• An initial cold start followed by two complete Drive Cycles without an engine shutdown between is required at a minimum to complete all the tests.
• After the second drive cycle, do not shut the engine off, use an OBDC reader to check to see if all the statuses have moved from NOT READY to PASS and/or FAIL. If not repeat the Drive Cycle without turning the engine off.
• If you see a "FAIL" result for one or more of the tests once the drive cycle(s) is complete, address the failed condition, reset the codes to NOT READY with your reader, and try again. 
• If all the drive cycle tests are not completed before the engine is shut down, all the completed cycle status flags for that trip will revert to NOT READY. Early OBD-II 993s set monitors based on tests conducted in a single continuous engine running event including one or more Drive Cycles.
• These cars do not report out to the OBDC Reader individual Readiness statuses as individual test requirements are met, just all the results once all the test requirements have been completed after a series of Drive Cycles.
• There may need to be an extended, overnight cool-down period and then a new drive cycle sequence attempt conducted from an initial dead-cold engine if the Secondary Air Injection (SAI) test has not been completed at the beginning of the initial drive cycle in the sequence. This can arise when one clears the codes, causing a readiness reset via an OBDC Reader or a battery disconnect where the drive sequence is begun with a previously run engine that is not dead-cold.

For late 1997 and 1998 Model Year cars:

• As each element of the test moves to a "PASS" or "FAIL" state, it will not revert to "NOT READY" until a reset event such as a reset using the OBDC Reader or the disconnection of the battery. 
• If you see a "FAIL" result discontinue the Drive Cycle, address the failed condition, reset the codes, and try again. The reason is that there is no point in going any further as a system reset will be required and the test run will need to be repeated anyway to clear the "FAIL" and some tests may only run sequentially if a previous test related to it has moved to "PASS"
• Once the drive cycle is completed and one or more of the statuses is "NOT READY" and none have moved to "FAIL" do not reset the statuses with your code reader, just run through all the drive cycle steps again to pick up the additional "PASS" statuses needed.
• One can leave the Altel reader attached during the drive and check as each individual status flips to "PASS" or "FAIL" if one likes.
• The statuses are set individually over time as the vehicle is driven unrelated to the number of trips with engine shut-downs between.
• There may need to be an extended, overnight cool-down period and then a second drive cycle conducted if the Secondary Air Injection (SAI) status has not moved to "PASS" at the initial cold start at the beginning of the drive cycle. This can arise when one clears the codes, causing a readiness reset via an OBDC Reader or a battery disconnect where the drive sequence is begun with a previously run engine that is not dead-cold.

General Notes, All Model Years.

• The best result in getting all the statuses to change to a "PASS" is by being easy on the throttle with light accelerations when required. 
• One source from the Pelican Parts discussion board in 2009, stated backing up with the car before or during testing or using cruise control will cause a problem with running the drive cycle. I have not been able to verify this. But by prepositioning your car the night before so no backing up is required in the morning the engine will be dead cold to test the SAI system and eliminates the need to put the car in reverse before the test run. 
• After using this document any feedback to improve its clarity, accuracy, functionality, or reliability is greatly appreciated and can be added in the reply section below or by emailing me at Andrew.hess@differentlight.biz
• For reference here is the original factory OBD-II Drive cycle document.

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The mysterious rubber part found on the floor of the Frunk

Frunk firewall gasket end piece part number 993 504 521 00 illustration 801-65 in the PET catalog. There are two of them and they fill the gap between the ends of the firewall gasket strip and the sidewalls of the frunk. 

I suspect their purpose is to stop battery and fuel fumes that may be in the frunk from working their way into the cabin. Many are lost and fall below into the abyss when the plastic cover in the frunk at the base of the windshield is removed. They can be glued to the seal or glued in places against the body with a little 3M weatherstrip adhesive to keep them in place.

#end #cap #strip #gasket #identify #rubber #wedge #firewall #seal #rubber