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Throttle cable to throttle body advice needed ASAP


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Is there a doctor in the house for a 1999 Carrera Cab 6Spd ? Yesterday I cleaned my throttle body and IAC valve (no biggie), replaced all the parts and my throttle cable seems extremely tight at the level of the accelerator pedal yet the butterfly on the throttle body is closed (just a hair opening but I would think that that's okay) When I start it up the engine revs at full throttle. What the freak am I doing wrong ? Do I need to give the cable more play by adjusting a nut or something ? Any help is deeply appreciated as I have not had my ride on the road for @ 4 days and I need to know if the cleaning has resulted in a better idle/acceleration.

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Undo the cable from the TB and check for smooth motion of the cable.  Might have someone push on the accelerator while you observe the motion of the cable.  I had this happen to me once and found that the cable was not "snapped" into the little black plastic guide on the TB.  Fixed by undoing the cable from the TB and pulling on the cable so that the outer cable sheath snapped into the plastic guide.  You can't see behind there to make sure it is seated all the way.  But that is what it was for me.

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Hey DB Joe, thanks for the advice on this. When I was trying like nobody's business to unclip the cable so that I could back it out of the square hole on the TB housing, I took a pair of pliers to the cable trying to back it out. I hope I didn't let my frustration get the best of me. Like I said before, when I get in the car with the engine not running, It's almost as though I can feel the tension on the cable when I press on the gas pedal. It is not smooth at all and almost feels as though it could snap. This is the same thing you experienced ? Can you be more specific on the outer cable sheath being snapped into the plastic guide? Are you saying the plastic  outer sheath needs to be placed over the end of the black plastic piece that protrudes out of the back of the square hole ? I'm trying not to make this more complicated than it needs to be. I have a very short piece of what appears to be outer sheathing attached to the back of the black plastic piece that is not actually attached to the rest of the sheathing. Is there a chance I inadvertently cut this piece?

 

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Yes, pretty much what I experienced.  And yes, the outer sheath of the cable actually snaps into the black plastic guide as you discovered when you took it apart. The outer sheath snaps into the black plastic piece that protrudes out the back of the square hole.   It took no more than a pretty good tug by hand on the internal cable to get the sheath seated back into the plastic guide.  It actually did "snap" into place. That removed all the tension on the whole cable and then the TB butterfly valve operates correctly.  Do not use pliers on the internal cable or outer sheath as you may damage it. This is sort of like a fulcrum point for the internal cable and outer sheath.  When it is not snapped in, the cable just doesn't work properly.

Edited by DBJoe996
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DB Joe, I have some photos of throttle body I would like you to check out and. I'm more visual than conceptual. When I would push the plastic outer sheathing back into the engine bay, this metallic piece with the cable running through it would appear only to disappear as I would pull the plastic sheathing towards me. Can you tell if I accidently cut the plastic cable piece. The cable sheathing and that piece you see with the nut on it seem to be of the same diameter. Are you saying that I need to take the throttle cable out like I did the first time in order to get it snapped back into place? How can I know if the cable sheathing actually separated. I don't want to have to call a tow truck if this is something elementary that I just am having a problem understanding.

TB1.jpg

TB2.jpg

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Sorry for the delay.  It really looks like you have either cut something apart or pulled apart the outer cable sheath from where it seats in the black plastic grommet.  That unit is all one piece.  If you look at part number 5 in the attached diagram, then click on part number, it will bring up a picture of the one piece accelerator cable that includes the black plastic grommet as one whole unit.  I'm trying to find a better picture but I have not found one yet.  The way you are supposed to undo the cable is to insert a flat blade screwdriver under the black plastic grommet on the TB.  If you look closely you will see it has a tab on it that needs to be compressed to release the whole grommet from the TB as one piece.  The reason I mention this is you may be able to release the grommet from the TB and repair the cable connection to the grommet with some epoxy.  But I would not rely on that as a long term fix.

Diagram: http://www.autoatlanta.com/porsche-parts/hardparts.php?dir=996-99-05&section=702-10

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Thanks for the response, DBJoe. I had suspected that I may have severed the sheath and I think you have confirmed this. The price of the part is reasonable and I hope that the job isn't too labor intensive. I'm going to call now and get an estimate. When you mention about the McGiver method of using the epoxy, do you mean placing the epoxy on the edge of the outer sheath and let dry and hope it holds until I can make it to my local indy 2 miles away ? I'm definitely purchasing the new throttle cable but I'm wondering if the epoxy would hold long enough to get me to the indy (maybe place a smaller metal band where the two pices join) Whaddaya think ?     Thanks again

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Yes, that is what I was thinking - small dab of epoxy on the outer sheath and then slide it firmly back into the grommet.  You might do several test fits to make sure it seats completely in the grommet.  Was also thinking that if the "nut" prevents the cable sheath from sliding all the way in, cut it off with a dremel and epoxy, then use a worm clamp to provide compression.

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Again, DBJoe thanks for the advice. Advice well given and advice well taken. I've got one more question for you though. In order to maximize the chance of it "holding together. wouldn't I first need to cut off the piece of outer sheath that's still attached to the grommet and then use the epoxy and slide the remaining outer sheath aft of the grommet into the grommet ? I'm convinced that the piece in behind the grommet in the photos is a piece of outer sheath that separated and is still attached to the grommet y'know? After you answer this question, I'm done. I just wanted to know this for "knowledge sake".

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I see what you are saying.  My take on that, a piece of the outer sheath is still attached to the grommet, is (1) I would try to get it to slide back in the piece still attached to the grommet; (2) if you can't get it back in, cut off the compression nut and see if it will slide back in, then use some epoxy and a worm clamp; (3) if it does not slide back into the sheath with the compression nut cut off, then I would try to slice or cut the outer sheath remaining in the grommet lengthwise just a little bit and see if the exposed metal part of  the cable will slide back in the grommet.  The deal is not changing the effective length of the cable assembly and outer sheath.  If you remove the piece of outer sheath still remaining in the grommet, I'm afraid even with a liberal dose of epoxy, it won't hold

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Hey DBJoe, I just wanted to give a quick shout out to ya to say thanks for the advice. I took to heart what you said about shortening the length of the cable sheath and it having a negative impact on the part's overall function with the grommet serving as the fulcrum of the whole assembly so to speak. I get that. With all the strength I could muster without hurting myself and further damaging the cable/sheath, I was able to get most of the bulbous part of the cable through the compression nut and then formed another "compression point" with a worm clamp as you advised. I didn't even need the epoxy. I had a little scare when after  replacing the cable through the square, replacing the throttle body and  air box, I still felt tension as I pressed on the gas pedal. After a few pumps, I could feel something moving back into its neutral state and all was well. The idle air control valve and throttle body cleaning worked out very well. It still idles a bit low (640 RPMs to around 680) with occasional blips toward 700 RPMs. It has idled on the "south side" of 700 RPMs since I purchased it. Will I need to purchase a new IAC valve in the future ? Yeah but until I get a fault and no crazy stalls, I'm good. Determination/confidence are key with these DIY's y'know ? Chock it up to getting experience/confidence for future fixes. Thanks again, DB Joe. I appreciate the help.

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You are very welcome.  Glad to hear you got it sorted out!  The ICV is a tricky bit of business, particularly to clean it out.  I use a 9V battery to cycle the valve back and forth while soaking it in carb cleaner.   Mostly, a sticky ICV will cause the idle RPM to wander, or float about a particular RPM range.  Could be that now you just need to take it for a nice easy drive to get the DME adaptation back.  If the idle doesn't correct itself, then you are correct, a new ICV would at least eliminate one problem with low idle.

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Okay, DBJoe. I'm a glutton for punishment when it comes to learning how to solve issues with my ride. The 9 Volt battery cycling the door of the ICV back and forth. How does one accomplish this ? Rig some small gauge wires to the terminal of a 9V battery. One wire lead goes to one of the 3 pins on the ICV and the other goes to which other pin on the ICV ? I'm assuming that one of the pins on the ICV serves as a ground perhaps ? How long should it soak and how likely is it to actually solve my issue of a relatively low idle ? You've done this before so were you still being plagued by occasional "blips" or was the idle steady as a rock afterwards ?

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Steady as a rock after cleaning.  I was subject to occasional blips, more like hiccups.  I pulled the ICV, filled the inner chamber with carb cleaner and let it sit overnight.  Then I rigged up a 9V battery with some small wires and alligator clips, and then just touched the pins on the ICV until I figured out which connection cycled the valve open.  Pretty simple to do really.  I will say this, I had done some cleaning in the past but didn't cycle the valve open with a 9V battery.  I thought I had it cleaned out, but then not really.  Same idle problems came right back.  I noticed the rotating valve inside the chamber kind of "snapped" back and forth and would stick open.  Not good. The interior chamber and the rotating valve I thought was always black.  Turns out that is not the case!  The rotating valve inside the chamber is silver when clean.  So I cycled the valve, gently scrubbed the interior and valve with Q-tips (lots of Q-tips) soaked in carb cleaner paying close attention to the edge and underside of the valve, got it all shiny again, sprayed it with a light spray of WD-40 and then the rotating interior valve worked smoothly.  I don't know if that will completely solve low idle RPM but it sure made the engine idle smoothly once again. 

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Good evening DBJoe. Driving around to day (City driving) and a CEL comes on. I take it to Autozone for a read out the codes and they come up as P1128 and P1130. I already know what that entails after I checked out my Bentley's Manual. For some time, I had suspected that the Posret Cat O2 sensors needed replacing. Don't ask me why though. I had replaced the Pre Cat O2 sensors @ 2 months after taking possession of the car, replaced the Fuel line Vent Valve, The SAI check valve and air change over valve (this was the last thing done on the car before I decided to clean both the TB and ICV. Ya think I may have inadvertently created a vacuum leak when I started placing things back with this last DIY ? I have 1 post CAT O2 sensor and waiting to purchase another at a good deal (Bosch  13723) So far my suspicions on failing parts have been pretty "spot on" and I hoe this is the case. I doused the MAF with MAF sensor cleaner, placed in a new Hengst air filter and made sure that I was tightening everything to ensure a good seal on the intake. I want make intelligent decisions going forward towards clearing the cel and not just throwing parts at the issue like one may be prone to do out of frustration and/or impatience. Oh and I don't own a scanner (that's on the Christmas list) Where would you start ?

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p1128 corresponds to: "Long Term Fuel Trim B1 System Too Lean" which means that the car thinks it's running leaner than it should be.
p1130 corresponds to: "Air/Fuel Sensor Circuit Range/Performance (Bank 1 Sensor 1)" which basically means the same as the p1128.

Bank 1 is cylinders 1-3, left side of engine when looking into the engine bay

– Incorrect signal from MAF sensor
– Intake air system leaking (there are sprays made that you spray on the outside of the air intake and listen for an RPM change to give you a hint)
– Fuel pressure too low
– Volume supply of fuel pump too low
– Fuel injectors fouled (Techron)
– Exhaust system leaking (Cover the exhaust pipes partially when the car is in the air and the motor running and listen)

1) Make sure you installed the MAF sensor in the correct way (towards air flow) and that the electrical connector is snapped in tight and correctly

2) Put some Techron in your fuel, clear codes and see if they come back

3) Clean MAF sensor again if they come back

4) Clear codes and repeat

5) Most people solve this P1128/P1130 problem with a new Bosch MAF sensor.  I cleaned mine several times, then just simply replaced it with new.  That solved my problem.  Could be your O2 sensors, but I would start with the MAF sensor.

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I would like to give you a recent chronology of events on my ride. I was getting the infamous P1411 and P0410 codes for a good while (emissions codes). I went on ahead and had an indy replace both the Check valve and Air Change over Valve which is just behind the SAI pump. Pick the car up and noticed that there was no CEL illuminated. Cool, I'm thinking that this CEL problem is history. No sooner than getting down the rode about 300 ft and lo and behold the CEL illuminates. I just thought maybe the Indy never reset it and it's popping up as a stored fault code. Now I did take notice that the car was doing something different like the acceleration wasn't smooth but on the good side I could hear a different sound when the SAI check valve would close which I never heard when I still had the previous one in the car (It was toast and full of loose rusted bits which fell into my hand when the Indy turned it upside down into the palm of my hand). Anywho, took the car to Autozone and get a P0112 or P0102 . What ???. So now I'm thinking a new MAF. Next day I start cleaning the MAF as a money saver and notice that the Indy had left the connector off the MAF. Okay, cool. I reconnect it and CEL still lit so I disconnect negative battery cable, reconnect and no CEL. No CEL lit until after I start the whole TB and ICV cleaning (current code P1128 and P1130). I should mention also that the air filter that I just replaced was very dirty I'm almost embarrassed to say but I had cleaned the MAF before putting the airbox and all back while doing this recent TB and ICV cleaning. Do you think I should still go through the steps you outline above or can I eliminate a few ?

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I was simply suggesting a course of action for narrowing down the problem to the MAF sensor.  Sometimes it is something simple (as you found - disconnected connector plug) and then it could be your MAF sensor needs replacement.  The MAF sensor is delicate.  Short of having Durametric to see real time values while the engine is running, the best course of action is a process of elimination.  You can get an inexpensive OBDII reader from the auto parts store for <$50 to clear codes.  I have one, plus Durametric, that I use on several of my vehicles and it has proven invaluable.  Or you could just jump to step 4 and replace the MAF sensor.  The sensor is critical to engine performance and emissions.  As I said, in the end I replaced mine with new and that worked after several attempts at cleaning it failed to solve the problem.

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With that being said, I think the path before me is clear. DB Joe, you have been a well of information and I really do appreciate all the information you have given me in obtaining a better understanding of the systematic approach that one needs to consider in "thinking through" the issues which every 996 owner will inevitably face. Thanks again.

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