[Lawrence084]

I replace my DME Relay, (thanks for the advice)...and my car no longer is stalling...(so far, I replaced it 3 days ago), Up until today, my car has been running great, but after creeping in heavy traffic for 30 minutes, I can feel my car losing power, when I got thru it. I can still go 55+ MPH, but I can feel it taking more gas to do it.



Engine check is coming on periodically...I did the error code reading, by pressing the acellerator...and it is reading 1-1-3-2-1...(Knock Sensor 2)



My question is...Is there something I should try before tackling...changing the Knock sensors?

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[Greimann]

Try cleaning the contacts on the connector first.

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[sparky]

hmmm ... doesn't sound good. if the check suggested by Greimann doesn't stop the check engine light I would take it that code means the knock sensor is detecting continual or excession knocking, or detonation in at least one cylinder. The use of excess fuel would be the computer trying to stop the detonation by upping fuel to that cylinder, or cylinder pair, but whatever is wrong is so serious the computer simply can't add enough fuel. This aligns with your sense of power loss, which gets worse as engine gets hotter.



I would get a motor mechanic to do a compression test on all four cylinders. Sorry to say this, but I'd be prepared for bad news... but hopefully I'll be proven wrong!

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[earossi]

Before you go into panic made, it could be something as simple as a dirty knock sensor lead as suggested by Greimann. If that does not do it, I would replace the knock sensor(s), which I don't believe is major surgery (I've never done one, except on one of my other German cars). These devices don't sense vibration, but rather predetonation (knock) in your engine. To minimize the knock, they retard the engine timing, which does reduce output. The sensors are needed since Porsche has set these engines to put out the most power. You get the highest power by advancing the ingnition timing so that you are on the verge of knocking. These sensors keep your timing right on the verge of knocking.



Regards,



Ernie

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[Lawrence084]

To update this thread...A friend of mine told me to disconnet the battery cable for a few minutes to reset everything since I did replace my DME Fuel Relay, to make sure I was getting the correct error code. I disconneted my battery for an hour or so...then drove around for 5 minutes...Then did a check...The "Engine Check" light was off after reconnecting the battery...and gave me a code of 1-5....which translates to everything is OK. Still don't have the same power I had when I first replaced the Plugs, Distribitor Cap & Rotor week and half ago.



My Engine Oil Light is still on though...I have the oil level half way between the two lines on the dip stick.



After my 45 minutes drive home tonight from work..If the Engine Check light is still off, and the Engine Oil is still on, I am going to try putting in the better fitting spark plugs I bought and adding a little more oil, but keeping it under the maximum line on the dip stick...to see if there is a difference.



Thanks for your help and any advice...It is appreiated.

---------------------------------------------------------------------------------------------



That was a short lived sense of hope...



I went to move the car to a better parking spot and notice the engine check light came back on. My friend did find out if you hold the accellerator pedal for over 11 seconds it will clear your diagnostic trouble codes...which I did...and the Knock Sensor Code is still displaying.



Question someone may be can answer...I read on the internet...If you tap on the block with a screw driver handle, while the engine is running...if you engine reacts to the pinging against the block..then your knock sensors are working, and if they don't then they need replacing?...Is that true?

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[jaap]

If the DME detects a defective knock sensor will it then retard the timing as a fail safe mechanism, which would explain the loss of power, or will the DME not be able to detect knocking anymore? Although the CEL can give you trouble passing emission testing I still wish non us cars would have this feature, making it easier to diagnose engine problems. Would it be possible to somehow implement this on a non us car?



Jaap

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[flash]

lawrence - that is a quick test, though not particularly reliable



simple stuff first:



any smell of maple syrup? losing coolant at all?



pull the plugs and look at them - any black soot? wetness?



do a compression test - over 170 on all 4 at 8 rotations?

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[Lawrence084]

[quote name='flash' date='Feb 2 2006, 06:28 AM']lawrence - that is a quick test, though not particularly reliable



simple stuff first:



any smell of maple syrup?  losing coolant at all?



pull the plugs and look at them - any black soot?  wetness?



do a compression test - over 170 on all 4 at 8 rotations?

[right][post="15403"]<{POST_SNAPBACK}>[/post][/right][/quote]



No smells what-so-ever...



Coolant Level remain good, and only in heavy bumper to bumper traffic does the needle go higher than the 8:00 o'clock position.



Changed the plugs to Bosch last night the ones I replace look great and the ones I had previously replace two weeks ago...Those are the ones that been in the car for years...also look great...no oil, and they aren't white charcole looking, and they are black...but they look like what they are suppose to look like and had several people who know a little bit about cars...say they look good.



No smoke what-so-ever from the exhaust...



I definetly think it is a time issue...I can't find any signs of a worst case senerio.



The part that I find confusing is: After replacing the Plugs, Distributor Cap & Rotor, the car ran awesome for a few days then starting stalling, while going down the highway...With the advice of board...I changed the DME Fuel Relay...and the car ran awesome again for a few days...and then starting take more accelleration to maintain a certain speed. Don't get me wrong...I can still get up 80 mph....but a few days ago..I could have punch it...now..I have to medthodically get to that speed. I definetly lost response...The best way I can describe it..The engine sounds and feels like to running at a lot higher rpm that it actually is. At 60 mph in 5th gear it about 2500-2700 rpm but it feels and sounds like it 3500 rpm. When the car was running awesome, If I press the acelleration and inch at any speed, the car responded nicely...It definetly had pick up....now it is barely felt.



Question...I keep reading material on how to clean or change the Knock Sensors...and none of the material I have read has mention the fact...that they can be cleaned or removed simply without removing anything but the sensor themself. My hand reaches right down where they are...I might have to cut an wrench in half or make some contraption...but I see no need to remove intake...am I right? is it possible?

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[flash]

fuel filter is a possibility

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[Lawrence084]

After checking out the knock sensors...That the directions I am checking out next...Fuel Filter and O2 Sensor...



Thanks...it appreiated...

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[Greimann]

If you still have the knock sensor error code, then your timing is still retarded, or at least developmentaly challenged. Fix that and you should be OK. You are using premium gasoline right? Maybe top off with another brand.

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[earossi]

Let me throw a twist into this. Your car ran fine until you changed out plugs, wires, rotor, and distributor cap. In the process of doing that, is there a possibility that you may have altered the timing of the car? I would go back and pull the cap and rotor. Look for cracking or arcing in the new parts. Are the new cables firmly seated and installed correctly? Match up the old rotor and cap against the new hardware to assure that they are exact replacement parts. If for some reason you advanced the timing while working on the distributor, the engine would begin to ping. The knock sensors would sense that and retard the timing.



Just a SWAG on my part, but you should check the small things and never assume that the parts or work you did was without fault.



Sorry I can't be more helpful.

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[Lawrence084]

Yeah...I definetly think it a timing issue...whether the timing is off and the sensor are working, (not too sure if an error code means there is a knock or the knock sensor is no longer working) or the timing is correct and the sensors are not working, or both are bad.



I guess I will find out this weekend...First thing I'll do is check the timing...if that off...correct the timing...and see what results I get...then go from there.



Thanks...

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[Greimann]

The timing elements are fixed so there is really no chance to get that wrong, or even adjust it. Come to think of it, there is no timing mark on the crank so don't even bother breaking out the timing light.



Probably a bad sensor.

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[flash]

sensor is my guess too, though if the filter was clogged, and the cylinders ran dry for a second, and you had an extreme lean condition, i would think the sensors could trigger



i had a carburettor do this to me - ran fine for a few minutes, and then would leave me stranded - it was sucking crap up and clogging



p.s. - you can check the timing with the bosch hammer



couldn't you bring up TDC, make a mark on the lower pulley, and use a timing light?

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[Lawrence084]

[quote name='earossi' date='Feb 2 2006, 05:02 PM']Let me throw a twist into this.  Your car ran fine until you changed out plugs, wires, rotor, and distributor cap.  In the process of doing that, is there a possibility that you may have altered the timing of the car?  I would go back and pull the cap and rotor.  Look for cracking or arcing in the new parts.  Are the new cables firmly seated and installed correctly?  Match up the old rotor and cap against the new hardware to assure that they are exact replacement parts.  If for some reason you advanced the timing while working on the distributor, the engine would begin to ping.  The knock sensors would sense that and retard the timing. 



Just a SWAG on my part, but you should check the small things and never assume that the parts or work you did was without fault.



Sorry I can't be more helpful.

[right][post="15438"]<{POST_SNAPBACK}>[/post][/right][/quote]



Actually the car stalled while driving down the highway on a Thursday...The following Saturday...I replaced the Plugs, Distributor Cap & Rotor....Sunday - Tuesday...car ran perfect..On Wednesday..a little sluggish...Thursday...it stalled again going down the highway...On Saturday...I replaced the DME Fuel Relay...Sunday-Tuesday car ran perfect...On Wednesday...started to notice I was losing power in acelleration...Today...samething...Changed the plugs last night to Bosch...no difference...(well little difference...runs rougher at slow speed and better at high) but slighty..and still don't feel the response I got from the acellerator...on Sunday-Tuesday...



Today is Thursday...let hope I don't stall on a Thursday for three weeks in a row....



Thanks...and yeah..I starting to wonder when I replaced the distributor cap & rotor...did I throw off the timing a bit...and the sensor..are now trying to adjust to it...????? but check it out this weekend...

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[Lawrence084]

[quote name='Greimann' date='Feb 2 2006, 05:17 PM']The timing elements are fixed so there is really no chance to get that wrong, or even adjust it. Come to think of it, there is no timing mark on the crank so don't even bother breaking out the timing light.



Probably a bad sensor.

[right][post="15440"]<{POST_SNAPBACK}>[/post][/right][/quote]



Oh...OK...straight to the sensors then...



Thanks....

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[flash]

stalling takes me away from sensors - takes me back to fuel - sensors should make it run the same, regardless of plugs, etc, and should not result in stalling, but just an overall lack of power



i'd change the filter - those should be changed every 50k or 5 years anyway

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[SILVY968]

FLASH has a point. I changed my filter when I first got my 968 in an attempt to smooth out acceleration.

It was original, with so much dirt in it that it was surprising.

Quite a change!

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[sp4149]

From this thread I wonder if it is two problems at the same time.

The overall power problems sound like the Hall Sensor at the front by the Distributor may have become disconnected, the plug broke (like on my car), or the sensor has failed. Easy check disconnect the sensor and see if there is any difference in driveability. The black, not tan, plugs indicate a timing problem to me. Second, a weak fuel pump, will kick out and shut down the car for a period of time, especially after it has been running 30-60 minutes and there is a change in load. Out 944 did this for a couple of years, went to several Porsche shops, nothng cured it until in frustration I ordered a new pump. Problem gone. Spent a small fortune on injectors, plugs, etc... before then. Changing the fuel filter always helped, but after the first clogged filter the rest were always free flowing. Must have changed the filter 6-8 times before changing the pump.

Anyway two more things to check.

-sp4149

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