[sp4149]

Went on a 25 mile drive Saturday. On the way back the Cab had no power or acceleration. The car was not missing but would only slowly accelerate to speed and couldn't hold the speed on freeway grades. I limped home and parked the car.



There was no smoke; the car was running a little warm, around 9 o'clock on the water temp; the engine was running smooth, just wouldn't easily accelerate. The Cab is a Tip and the few times I tried to downshift, there was an increase in engine RPM but no accompanying increase in speed. The car was close to empty, I stopped and filled the tank, no change in performance.



Recently I changed the front Hall Sensor (bad connector) and the damper for the Tip. The NGK plugs have about a thousand miles. When the Hall Sensor was disconnected the car was sluggish, but not this bad. Was running great until Saturday, took it to work last week.



Thoughts? Comments?

Have Autothority chip, could it have gone bad?

Partial Post: Please Login or Register to read the full post.

[PorscheDude]

Check your vacuum lines for leaks?

Partial Post: Please Login or Register to read the full post.

[flash]

blink test

Partial Post: Please Login or Register to read the full post.

[sp4149]

[quote name='flash' post='51933' date='May 5 2008, 02:01 PM']blink test[/quote]

Blink test results,



one long, one short, five short, then repeat. Since there are no 3 number codes, I assume the long indicates the start of the code and that the actual result is 1-5 or no fault.



Vacuum lines appear to be intact and attached, no cracks or breaks seen and no loose connectors. Looked only at top of engine. Are there vacuum lines to the Tip in the back?



-sp4149

Partial Post: Please Login or Register to read the full post.

[PorscheDude]

Check the rubber elbow between the MAF and the throttle body for tears.

Partial Post: Please Login or Register to read the full post.

[flash]

ruh roh



i am hoping it's not what i am beginning to think - any hints of maple syrup smell?

Partial Post: Please Login or Register to read the full post.

[PorscheDude]

Pan Cakes?

Partial Post: Please Login or Register to read the full post.

[sp4149]

[quote name='flash' post='51958' date='May 6 2008, 07:23 AM']ruh roh



i am hoping it's not what i am beginning to think - any hints of maple syrup smell?[/quote]



No smells that I have noticed.

Partial Post: Please Login or Register to read the full post.

[flash]

a weeping head gasket can cause the problems you describe



any signs of coolant loss?



have you pulled the plugs to check them for wetness?



this could be a control problem for sure, but i would check the simple things first

Partial Post: Please Login or Register to read the full post.

[sp4149]

[quote name='flash' post='51974' date='May 6 2008, 11:03 AM']a weeping head gasket can cause the problems you describe



any signs of coolant loss?



have you pulled the plugs to check them for wetness?



this could be a control problem for sure, but i would check the simple things first[/quote]



When I blew the head gasket a couple of years ago it was running much better than now.



No coolant loss, and coolant in reservoir is clean.



I'll check the plugs later.



When the hall sensor connector broke, the car was sluggish. This is much worse.



There is very little throttle response, could it be a bad throttle position switch? No vacuum advance due to a vacuum leak, or is the vacuum not used by the DME to accelerate. In a 1986 Pontiac I had a similar situation that was due to a plugged catalytic converter. This is an aftermarket Cat that was on the car when I got it. I have been worried about meeting CAL emissions as this car doesn't smog test as well as those with the stock Cat.



-sp4149

Partial Post: Please Login or Register to read the full post.

[flash]

there are different kinds of head gasket leaks - weepy ones between jackets can do this - it can do it without oil mixing in the coolant



could very easily be one of the controls, just trying to eliminate the "easy to find" ones first



then look at the new components



loose plugs will do this too - given that these are new - i'd check them first



hall sensor is suspect too



keep in mind this was a sudden problem - that generally means failed component - cats don't generally do that



could be MAF - could be clogged FPR - could be a lot of things - one by one, start with the easy ones

Partial Post: Please Login or Register to read the full post.

[Cloud9...68]

The throttle position sensor is easy to check. You just need an analog voltmeter, and a helper. This is a copy of the procedure somebody posted some time ago:



The 968, like most all cars uses a true throttle position sensor. A variable resistor that can read out to the ECU the exact position the throttle is in. There are 2 ways to test it. Connected, and disconnected.



First the connected way: turn the ignition on, but don't start the car. you'll have to have some type of voltmeter probes that can make connections without unplugging the connector. Usually you pull the boot off the back of the connector, and push the probes in there. If i'm reading the wiring diagram correctly, you should find 5V on pin 2 (the blue/green wire) pin 1 should be ground (the yellow/brown wire) and pin3 is the output (the white/green wire). To test, you should hook the voltmeter between pin 1 and 3. as you slowly open the throttle, the voltage should go from about 0.4V to 5V with no abrupt jumps, either up or down. Abrupt jumps are a sure sign of a bad TPS. An old, analog voltmeter is MUCH, MUCH better at seeing intermittent jumps than a digital one, but who the heck has one of those.



To test the disconnected way: uplung the TPS, and hook a ohmmeter between pins 1 and 3. slowly move the throttle open and you should see a smoothly changing resistance value. I don't know what the range should be, but again, smooth changes are the important point here.



The disconnected way should be a little easier, but the connected way is more accurate.



I used the connected way, and found it to work very well. I found it to be much easier to have someone slowly depress the throttle to the floor while holding the voltmenter leads in place against the TPS connectors, vs. trying to do both things myself. It's free, so definitely rule stuff like this out before going on to more complicated and costly steps. Good luck.

Partial Post: Please Login or Register to read the full post.

[sp4149]

Today it's reborn. Shop installed a German-made OEM replacement catalytic converter, much bigger and heavier than the aftermarket one (made in ??) that was on the car. Local Porsche parts service recommended this Cat over the Porsche one saying the major difference was price. Shop owner said he ran the car up to 125 to make sure the exhaust was free flowing and the car was still pulling when he let up. Feels good not to be passed by golf carts on the sidewalk anymore.



Old Cat put on by PO had failed big time, chunks were in the muffler. After we bought the car we were told by a local shop, it had an aftermarket Cat, but it passed emissions and things were good back then. Last year it barely passed smog on the dyno test; I had started to expect the Cat was just about gone and would need to be replaced before next year's smog test. Now that's one less worry and a lot more power. After replacing the Tip damper and the catalytic converter, I now hear noises that I didn't hear before. A low speed whine, Alternator bearings or AC compressor? It's a Porsche, there are always something ready to be replaced.



-sp4149

Partial Post: Please Login or Register to read the full post.

[xrad]

congrats!



whine up front or in the rear?

Partial Post: Please Login or Register to read the full post.

[sp4149]

[quote name='xrad' post='52546' date='May 14 2008, 01:44 PM']congrats!



whine up front or in the rear?[/quote]



Up Front, and RPM not road speed dependent. Of course with the Cab and road noise, you can't hear the whine above 25 mph.



-sp4149

Partial Post: Please Login or Register to read the full post.