Fluctuating Idle

[gandrade1]

The red oval is the throttle body. 1997-1999 is non-egas. You can see the throttle cable in the picture.

I was trying to keep it simple if there is room to remove just the idle valve from throttle body. Have not tried to do it this way on a Boxster, but it can be done this way on a non-egas 996. To clean inside the throttle body itself you need to remove the large tube that comes from the air box.

Hi Tool Pants,

I opened my engine for the first time the past weekend with the intent to remove and clean the throttle body (TB). I have a 01 Boxster (egas) 40k miles. I gave up because the engine was very dirty in general and the components (tubes) don't look as flexible as I assumed they would be. I decided to give the engine a superficial clean and pursue the TB this week.

I was surprised how little space there is to access the parts and screws specially the ones in the lower portion of the TB. I am not sure whats the best sequence to get the TB out of there and in - hopefully :unsure: - again .

I have a couple of questions:

(1) What do I need to remove in order to have space to get the TB out of the car? Should I remove the air duct (large tube) in the end opposite to the intake ?

(2) Are there any other component I need to remove, tubes to disconnect.

I am very inexperienced working with engines and am a little skeptical on whether I can get this all back in....But want to give it a try. Any advice is greatly appreciated.

Thanks

Gus

[gandrade1]

Hi guys, I opened the engine again to take some pics and I tried to get the TB out once more.

In the picture below I loosened the hose clamp in blue, number 3 (the screw popped out and got lost in the open parking lot and I had to replace it with a generic, PepBoys clamp). Then I loosened the other hose clamp - number 2. After all this I could not move the tube a single inch from the TB, but the number 3 end came out easily. Should I just keep on pulling the end close to the TB or is there an easier way to do this? Can I cause any damage by pulling hard...

I also added a second picture just to show how dirty the Throttle is on the outside... I really need this cleaning.

Any help is appreciated.

[geoff]

Hi guys, I opened the engine again to take some pics and I tried to get the TB out once more.

In the picture below I loosened the hose clamp in blue, number 3 (the screw popped out and got lost in the open parking lot and I had to replace it with a generic, PepBoys clamp). Then I loosened the other hose clamp - number 2. After all this I could not move the tube a single inch from the TB, but the number 3 end came out easily. Should I just keep on pulling the end close to the TB or is there an easier way to do this? Can I cause any damage by pulling hard...

I also added a second picture just to show how dirty the Throttle is on the outside... I really need this cleaning.

Any help is appreciated.

I just cleaned the throttle body for the first time on my '01 2.7 this past weekend (yesterday - Sunday). Despite all the discussion on this in the past, I had trouble searching for the procedure for getting to the throttle body and removing it. Here's what I did:

Loosened the hose clamps on both ends of the plastic tube [1 in your first picture] running from just past the MAF / air filter box [3] to the throttle body [2]. As you noted, the end [3] that butts up to the MAF comes off pretty easily. The other end that joins the throttle body i[2] s a real pain to get off. I pulled, twisted and wiggled for about 30 minutes, and somehow just got the right combination of moves and it finally came off. My hands aren't that large, but my knuckles are pretty beat up. I found it's easiest to access from the driver's rear fender side. Don't worry about the trouble getting it off, because it's even harder to get back on!

I don't think it's possible to get the throttle body off without disconnecting the plastic tube at [2], but if there is, it would probably save half an hour or so. Same comment applies to reassembly.

I haven't read about anyone using a blow dryer to heat up the plastic tube at [2] to expand it to get it on and off easier. I was going to try that if all else failed after a few hours. Somehow, the plastic tube just came off after struggling for a while.

Once the black plastic tube is off, pull it out and set it aside. It was clean on the inside, but I wiped the outside down with several rounds of Simple Green, followed with water to get the Simple Green residue off. The throttle body comes off by unscrewing the 4 long bolts with a metric hex driver. The 2 long bolts on the driver's side have washers, and the 2 on the passenger side do not. Once you have the 4 bolts off, the throttle body is still connected with an electrical connector (e-Gas models), which simply unplugs. Pay attention to the orientation of everything. You'll notice on the throttle body there's an arrow that lines up with an arrow on the plastic air tube (visible in your second photo).

Cleaning the throttle body is the easy part. Just keep spraying throttle body cleaner and wiping the crud off. You can push the flap open to get all the way through - it's spring loaded so watch your fingers. I also tried wiping down the tubing on the back side of the throttle body, but it was pretty clean inside (at 51K miles).

The only hard part (as you would expect) is getting the plastic pipe [1] back onto the throttle body [2] after the throttle body is reattached. Expect another 30+ minutes of pushing, twisting, wiggling, swearing, etc. I lightly sprayed some silicon spray on a paper towel, then wiped it on the outside of the throttle body and inside of the plastic pipe. Hard to tell if it helped or not, but it didn't hurt. After everything is put back together, start you car and make sure everything runs and the throttle works before closing everything up.

When I was all done, I gently re-tightened all the hose clamps since several felt semi-loose

I don't think it matters how dirty the throttle body is on the outside for how your car runs! It's the inside that counts. But there's no reason not to clean up the outside when you have the throttle body out

[gandrade1]

Thank you so much geoff,

I guess your assessment is very close to mine - it is not a 30 minutes to 1hr job and would deserve some thought on to what the steps are to remove the TB and reassemble everything. And yes, cleaning the throttle is the easy part!

That being said, your steps sound pretty clear to me and simply explained so that someone with my modest skill set can pursue. Thank you very much....

I will give this thing another try, during the weekend and will let you know what I come out with. If you don't mind I will bother you for some help if I get stuck once more.

Thanks,

Gus

[geoff]

Thank you so much geoff,

I guess your assessment is very close to mine - it is not a 30 minutes to 1hr job and would deserve some thought on to what the steps are to remove the TB and reassemble everything. And yes, cleaning the throttle is the easy part!

That being said, your steps sound pretty clear to me and simply explained so that someone with my modest skill set can pursue. Thank you very much....

I will give this thing another try, during the weekend and will let you know what I come out with. If you don't mind I will bother you for some help if I get stuck once more.

Thanks,

Gus

No problem. I wish I could have come up with the magic sequence of twisting, wiggling and swearing that worked for getting the tube off and later back on the throttle body. If not for that challenge, the whole task is just a little more than a half hour job. If anyone has any tricks or tips, I'd love to hear for the next time. Maybe Loren or TP know some magic trick :P

[gandrade1]

Thank you so much geoff,

I guess your assessment is very close to mine - it is not a 30 minutes to 1hr job and would deserve some thought on to what the steps are to remove the TB and reassemble everything. And yes, cleaning the throttle is the easy part!

That being said, your steps sound pretty clear to me and simply explained so that someone with my modest skill set can pursue. Thank you very much....

I will give this thing another try, during the weekend and will let you know what I come out with. If you don't mind I will bother you for some help if I get stuck once more.

Thanks,

Gus

No problem. I wish I could have come up with the magic sequence of twisting, wiggling and swearing that worked for getting the tube off and later back on the throttle body. If not for that challenge, the whole task is just a little more than a half hour job. If anyone has any tricks or tips, I'd love to hear for the next time. Maybe Loren or TP know some magic trick :P

Guys, I gave it a another try today... the air duct just wont give away. I am getting frustrated. I think all the dirt accumulated around the throttle, just made the tube even stickier and it wont come out. I have been pulling pretty hard to the point where the intake moves slightly.

Is there an easier way to do this. Could it be that the cold made the tube even harder to remove? It was indeed a pretty cold day today around here in NJ.

Any ideas from the Boxster masterminds?

Thank you so much,

Gustavo

[Loren]

Last time I did this was at a work on cars day - so the engine was still warm.

I don't recall it being a big deal - I just wiggled it back and forth until it came off.

Maybe a warm (but not hot) engine would help?

[gandrade1]

Last time I did this was at a work on cars day - so the engine was still warm.

I don't recall it being a big deal - I just wiggled it back and forth until it came off.

Maybe a warm (but not hot) engine would help?

Thanks geoff and Loren,

I cleaned the TB yesterday. Well, I guess the warm engine helped a bit but it was a challenge, nevertheless. The air duct is tough to get out and, yes, even worse to get in. Took me, over one and half hour of squeezing, pushing and pulling to get it back in. :angry:

Well, all said and done I like the results, but I am sure I coul dimprove my technique a lot!

Thanks, guys

Gustavo

[fubar525]

Thank you so much geoff,

I guess your assessment is very close to mine - it is not a 30 minutes to 1hr job and would deserve some thought on to what the steps are to remove the TB and reassemble everything. And yes, cleaning the throttle is the easy part!

That being said, your steps sound pretty clear to me and simply explained so that someone with my modest skill set can pursue. Thank you very much....

I will give this thing another try, during the weekend and will let you know what I come out with. If you don't mind I will bother you for some help if I get stuck once more.

Thanks,

Gus

No problem. I wish I could have come up with the magic sequence of twisting, wiggling and swearing that worked for getting the tube off and later back on the throttle body. If not for that challenge, the whole task is just a little more than a half hour job. If anyone has any tricks or tips, I'd love to hear for the next time. Maybe Loren or TP know some magic trick :P

Guys, I gave it a another try today... the air duct just wont give away. I am getting frustrated. I think all the dirt accumulated around the throttle, just made the tube even stickier and it wont come out. I have been pulling pretty hard to the point where the intake moves slightly.

Is there an easier way to do this. Could it be that the cold made the tube even harder to remove? It was indeed a pretty cold day today around here in NJ.

Any ideas from the Boxster masterminds?

Thank you so much,

Gustavo

Not sure if you did this Gustavo, but if not, try taking the metal ring completely off the hose that goes around the TB. i just did this to my 2000 boxster this weekend due to an annoying CEL and bad idle. For me, just loosening the ring made the air duct very hard to pull off the TB, but once i removed the ring, the hose took 2 wiggles to get off and put back on. I didn't have to lube or heat anything. good luck my friend, and wish i could do more to help.

On another note, after cleaning my MAF and TB (which was pretty dirty), my car is still running like crap. air filter was clean, and the car ran great a couple months ago when i bought it. never drove it hard and my CEL codes are p1128, p1130, p0455, and p0450. gas cap is on tight and hisses when i unscrew it to fill up. crazy thing is after each time i fill up, the boxster doesn't want to start. it has to crank for a good 15 secs before starting and then it wants to die for about 20 secs after. it is a 2000 boxster 2.7 ltr. any help or ideas on diagnosing the problem(s) would be mostley appreciated. Thanks in advance -Ryan

[azzar0]

I just finished cleaning the throttle body. It wasn't easy, but I thought it would be a lot harder based on the reading I've done in the forums.

I pretty much followed instructions in this post - warm engine, completely removed the o-ring from the hose, and with a little effort it came right out. I had a harder time getting the throttle body out, especially the lower left (passenger side) screw. Once I removed the 4 screws I was able to lift the TB up high enough to spray and clean it. Putting it back together was actually a lot easier. The tube snapped right in, with a little aligning and wiggling. Again, screwing the lower left screw back in was the hardest part, but with some patience it can be done.

I decided to clean it because the car had a little bit of hesitation when switching gears (lower gears) at low RPM. I took it for a spin and it seems to behave better, but I'll have to drive it for a few days before I can make an educated conclusion. The idle is also more stable, although it still fluctuates a little when the engine is cold.

I have new spark plugs, I cleaned the MAF a few months ago (although it looks like it was recently changed by the previous owner). The coils on the spark plugs look good (a couple do have very small cracks, but I never got any misfire or error codes). Air filter is new. What else could contribute to the hesitation in changing low gears at low RPM?

Loren, you mentioned you add Techron every 3000 miles. I bought a 12 oz bottle and I want to add it to the fuel. I am less than half tank full. Should I add it now and immediately fill up or should I add it, drive a bit, and then fill up when the tank is almost empty?

Thanks!

:renntech:

azzar0.

[azzar0]

I took it for a spin and it seems to behave better, but I'll have to drive it for a few days before I can make an educated conclusion.

Definitely worth cleaning the throttle body! My car runs excellent now, the RPM is rock solid and there is no more hesitation in low gears / low RPM.

azzar0.

[tvacom]

So I just cleaned my throttle body on my 2001 boxster with 107k on it and I must be lucky because everything came off and went back on pretty easy in a little over an hour. It was dirty in there so I think that was the problem. Is there anything I need to do now that it is all back together or will the computer know automatically what to do?

Thanks

dave

Edited May 20, 2008 by tvacom

[robertd]

Very helpful thread. I'm surprised no one suggested disconnecting the battery before attempting the removal of the throttle body on a Boxster. Going for the bottom right bolt on mine the socket touched the positive terminal on the starter (less than 20mm away from the throttle body bolt) and welded my socket extension to the support bracket for the air intake tube with a shower of sparks. I'm just glad I was holding the socket handle ;-)

PHOTO LINK

(You can see the weld mark on the circular portion of the intake tube support bracket just below and to the left of the throttle body opening.)

This could be seriously hazardous if one did not fully remove the throttle body before cleaning (as suggested several times above) and this were to happen during reassembly. All that volatile carb cleaner sitting around the engine bay could get real scary real fast.

BTW, cleaning my throttle body seems to have cured a stalling problem I was having while the A/C was running. Thanks for the suggestion!

Edited May 23, 2008 by robertd

[Sputter]

This works like a charm to remove the 4 bolts holding the TB. It's just over 3" long.

As for getting the Tube from the box to the TB off, it helped having the car warm to remove it and I found having a third hand was a snap to pop that sucker back onto the TB.

Jim

[Kraftee]

I just bought and repaired a 99 for the wife. It had some minor right side damage and I do body repair. It sat in the shop for about 8 weeks while undergoing the repair, with the battery disconnected, and now has an idle issue ( may have been there prior to my obtaining it ) I have cleaned the throttle body already, without success. It wants to die at a stop, mostly when the A/C is on. Also noted that when your sitting still and depress the clutch, the idle becomes unstable, rocking between 600 and 800 for a few moments. I'm wondering if the ECM in this car has to "re-learn" the idle process, since the battery was disconnected for a long time. If so, does anyone know the proper process for this, or am I stuck going to the stealer ? Thanks !!

[Loren]

I just bought and repaired a 99 for the wife. It had some minor right side damage and I do body repair. It sat in the shop for about 8 weeks while undergoing the repair, with the battery disconnected, and now has an idle issue ( may have been there prior to my obtaining it ) I have cleaned the throttle body already, without success. It wants to die at a stop, mostly when the A/C is on. Also noted that when your sitting still and depress the clutch, the idle becomes unstable, rocking between 600 and 800 for a few moments. I'm wondering if the ECM in this car has to "re-learn" the idle process, since the battery was disconnected for a long time. If so, does anyone know the proper process for this, or am I stuck going to the stealer ? Thanks !!

Yes, if you disconnect the battery is does have to re-learn.

Just drive it as you normally would - it may take 5 miles or so to re-learn.

[1schoir]

This works like a charm to remove the 4 bolts holding the TB. It's just over 3" long.

As for getting the Tube from the box to the TB off, it helped having the car warm to remove it and I found having a third hand was a snap to pop that sucker back onto the TB.

Jim

Jim:

What brand of tool is that? Is it available on the internet?

Regards, Maurice.

[Sputter]

Maurice,

It's a Mastercraft set sold by Canadian Tire (up here north of the 49th :) ). I've never looked but I would think that you could find a similar set or even more of a complete set (a bigger range of bits) online. I would google "torx security bits". As a side note. I would avoid non-brand named stuff. Sloppy toleranced stuff can lead to rounded slots in the bolt head. Not fun considering how tight the work area is.

Jim

This works like a charm to remove the 4 bolts holding the TB. It's just over 3" long.

As for getting the Tube from the box to the TB off, it helped having the car warm to remove it and I found having a third hand was a snap to pop that sucker back onto the TB.

Jim

Jim:

What brand of tool is that? Is it available on the internet?

Regards, Maurice.

[Loren]

Harbor Freight -- $7.99

100 Piece Security Bit Set

[robertd]

I replaced my MAF and removed and cleaned my throttle body (following the directions in this thread). I disconnected the battery to reset the computer and everything seemed to be working like a charm- car ran better than it has since I bought it 18 months ago. A week later the idle and stalling problems are still gone (unless I turn on the A/C- another problem in another thread) but now the car feels down on power. It hesitates when cold and generally feels like I'm driving with the parking brake pulled up a click or two when warmed up. No new CELs as of yet. I'm thinking fuel filter. Any other thoughts? I'd rather order parts all at once to save on shipping costs ;-)

'99 2.5L US Boxster, 5-speed, 80K miles, questionable service history, AKA "Money Pit"

Edited May 29, 2008 by robertd

[1schoir]

Maurice,

It's a Mastercraft set sold by Canadian Tire (up here north of the 49th :) ). I've never looked but I would think that you could find a similar set or even more of a complete set (a bigger range of bits) online. I would google "torx security bits". As a side note. I would avoid non-brand named stuff. Sloppy toleranced stuff can lead to rounded slots in the bolt head. Not fun considering how tight the work area is.

Jim

Jim & Loren:

Thanks!

Regards, Maurice.

[Kraftee]

I just bought and repaired a 99 for the wife. It had some minor right side damage and I do body repair. It sat in the shop for about 8 weeks while undergoing the repair, with the battery disconnected, and now has an idle issue ( may have been there prior to my obtaining it ) I have cleaned the throttle body already, without success. It wants to die at a stop, mostly when the A/C is on. Also noted that when your sitting still and depress the clutch, the idle becomes unstable, rocking between 600 and 800 for a few moments. I'm wondering if the ECM in this car has to "re-learn" the idle process, since the battery was disconnected for a long time. If so, does anyone know the proper process for this, or am I stuck going to the stealer ? Thanks !!

Yes, if you disconnect the battery is does have to re-learn.

Just drive it as you normally would - it may take 5 miles or so to re-learn.

Loren,

Thanks for the reply. I cleaned the idle air valve and it helped tremendously. Car went for 2 days without a problem, rock solid, until this evening and started again. I noticed when I was cleaning everything, the plastic hose that connects the oil seperator to the throttle body had oil in it. It was wet enough to cover my finger, so I cleaned it as best I could. Is there a procedure to clean the seperator, or is it replace only ? Also, is it possible that the two problems are related, as in, a vacum problem not venting the crankcase ? Thanks for your advice !

[tvacom]

When I cleaned mine I worried about the same thing. But after driving it for a few minutes it was find and rock steady at like 650 rpm. I would double check to make sure everything is seated properly and no vacuum leak. There is a paper gasket in there that should be replaced when you put everything back together. Check that out could be a leak there. . .

[Loren]

I just bought and repaired a 99 for the wife. It had some minor right side damage and I do body repair. It sat in the shop for about 8 weeks while undergoing the repair, with the battery disconnected, and now has an idle issue ( may have been there prior to my obtaining it ) I have cleaned the throttle body already, without success. It wants to die at a stop, mostly when the A/C is on. Also noted that when your sitting still and depress the clutch, the idle becomes unstable, rocking between 600 and 800 for a few moments. I'm wondering if the ECM in this car has to "re-learn" the idle process, since the battery was disconnected for a long time. If so, does anyone know the proper process for this, or am I stuck going to the stealer ? Thanks !!

Yes, if you disconnect the battery is does have to re-learn.

Just drive it as you normally would - it may take 5 miles or so to re-learn.

Loren,

Thanks for the reply. I cleaned the idle air valve and it helped tremendously. Car went for 2 days without a problem, rock solid, until this evening and started again. I noticed when I was cleaning everything, the plastic hose that connects the oil seperator to the throttle body had oil in it. It was wet enough to cover my finger, so I cleaned it as best I could. Is there a procedure to clean the seperator, or is it replace only ? Also, is it possible that the two problems are related, as in, a vacum problem not venting the crankcase ? Thanks for your advice !

If there is oil in the throttle body then you likely have a bad AOS. This would also cause a vacuum leak (and corresponding fault code).

[Kraftee]

I just bought and repaired a 99 for the wife. It had some minor right side damage and I do body repair. It sat in the shop for about 8 weeks while undergoing the repair, with the battery disconnected, and now has an idle issue ( may have been there prior to my obtaining it ) I have cleaned the throttle body already, without success. It wants to die at a stop, mostly when the A/C is on. Also noted that when your sitting still and depress the clutch, the idle becomes unstable, rocking between 600 and 800 for a few moments. I'm wondering if the ECM in this car has to "re-learn" the idle process, since the battery was disconnected for a long time. If so, does anyone know the proper process for this, or am I stuck going to the stealer ? Thanks !!

Yes, if you disconnect the battery is does have to re-learn.

Just drive it as you normally would - it may take 5 miles or so to re-learn.

Loren,

Thanks for the reply. I cleaned the idle air valve and it helped tremendously. Car went for 2 days without a problem, rock solid, until this evening and started again. I noticed when I was cleaning everything, the plastic hose that connects the oil seperator to the throttle body had oil in it. It was wet enough to cover my finger, so I cleaned it as best I could. Is there a procedure to clean the seperator, or is it replace only ? Also, is it possible that the two problems are related, as in, a vacum problem not venting the crankcase ? Thanks for your advice !

If there is oil in the throttle body then you likely have a bad AOS. This would also cause a vacuum leak (and corresponding fault code).

Loren,

The codes I had were 1410 and 1411 ( Secondary Air ) I cleared them first thing, and they have not returned. Never had another code. Last night I went back in and found the oil ( minor amount ) had returned in the J pipe, the idle air valve was clean. I removed the pipe and cleaned it, took it for a drive and it idled good in all conditions. I will get an AOS and replace it next week. I was told that the oil fill pipe required inspection, as they were prone to crack and cause a leak in the system, is that information correct ? Also, is there anything else troublesome, that needs inspection/replaced while I'm in there that you are aware of ?

Thanks

Gary