Check engine light and fault code questions: I think I botched my plenum install

So I installed the plenum a few weeks back (full write up to come shortly), and all was well for about 150 miles. I then let the car sit for 1 1/2 weeks as I recovered from ACL reconstruction surgery. Today I get in the car to drive to work and I have a CEL. Code reader indicates the following codes: P0401 and P1411, which after a bit of research I now know indicates some sort of fault with my secondary air injection system. I know my pump is running, so I assume the culprit is one of the valves beneath the alternator, and plan to start checking them shortly per some nice instructions over at Renntech. However, before I do so, I thought I'd ask if anyone thinks that it may be worthwhile looking for any leaks in the vicinity of the plenum/throttlebody, since I had to kind of muscle the old plenum out and the new one in, and I wouldn't be surprised if I knocked something askew in the process. I just thought it was kind of coincidental that the code tripped after I installed the plenum, and would thus like any advice concerning things I could check before I take off the alternator and start trouble shooting the numerous valves associated with that system. Thanks!

You mean P0410 and P1411? right? If so, start by looking for a hose you accidentally pulled off or knocked loose. Then have a look at the fuse and relay - you say you can hear the air pump at start up? If you find anything loose then correct it and reset the codes and see if they come back.

Hi Scott, I hope you are recovering well from your surgery. I would check the two small hoses on the bottoms of the collars (black rubber) on either side of the plenum...they were very easy to knock loose. Good Luck. Scott, feel free to call me [phone removed]...you should be able to feel them without removing anything.

thanks for the input guys. Loren, you are right, the code was p0410. I do hear the pump operating in the morning, so I'm pretty sure that is not the culprit. I also checked for obviously loose hoses, and there don't appear to be any. Mark, you've got my curiousity piquied, because I just studied the plenum area, and I can't seem to identify the two small hoses you refer to. My curiousity is piqued because I don't ever recall encountering them. Although my dad helped with this and did most of the grunt work (I was not very mobile at the time as a result of my bum knee). Could you describe the appearance and location of these hoses? What is their diameter and location in relation to large rubber hoses that attach to the plenum sides? Thanks so much for the advice. Scott.

Those two small hoses come off the bottom of those rubber collars on each side of the plenum. If you jam the plenum on there too far on either side, you can end up crimping or breaking off those little hoses. They sit on the bottom of each rubber collar and are only about 1/8th inch wide....they're black so it's easy to overlook them. If you can get your hand under there, feel under the rubber collars on each side slightly towards the upside of the back of the rubber collar....I almost broke one but saw it before I started muscling the plenum back on. You could have pushed the plenum too far to one side when trying to get it back on and either broke or crimped that hose, or you may have rotated the collar too much and crimped the hose. I'm not sure what that hose does, but since it's hollow, it's taking some sort of pressure to a sensor. Chuck

Scott, here are some pictures that I took when I did my plenum install. If you look at the collar on the right side in one of the pictures you will see the small hose coming off the bottom of the collar. I would not have know there was one on the left side if Chuck hadn't told me when he was doing his install. Mine are probably not in the stock position because I didn't have any point of reference when I rebuilt my car. I'm sure it is not a coincidence that you are having this problem after the plenum install. It would have been very easy to cause a vacume leak during the install....those hoses are the most likely culprit...next, I would check the seal on the collars (to the plenum and manifold). Good luck. The hose on the right collar is probably pointed toward the back of the engine on your car.

Wow guys, thanks for the input. I have no recollection of messing with or even seeing those hoses, so there is a good chance one or both got knocked loose if they are not on that snuggly. I will hobble over and check when I get home tonight. You guys are awesome. By the way, I've been driving pretty conservatively as of late due to my knee surgery, but once I feel comfortable again I'll do some high speed runs and give a full review on plenum. Initial reaction is definately positive, but I'll reserve final judgment 'till I can really exercise the engine. Talk to you guys soon. Scott.

Mark: The orientation on those hoses when I did my plenum was they came directly off the bottom or canted slightly to the rear and the hoses traversed to the back, not to the front as your picture shows. I don't know if it makes any difference which way they traverse, but if they go towards the back they seem to be out of the way and less likely to get snagged. Chuck

Well, I took everything out today to check the alignmnet/fitment of those dang little hoses. The driver's side hose was almost out of the boot, but still hanging on a bit. It is very possible that this was creating a vacuum leak as the little hose as a stop that is suppossed to snug up to the nipple on the collar where the hose enters. I snugged it up, cleared the codes by removing the battery cable, and so far, after 30 miles, no codes. We'll see what happens in the next few days! Thanks for you help guys!

Scott, I hope that cured your problem. Do you notice an improvement in your acceleration from 5,000 to 7,000 rpm? Let me know if your Gtech shows an improvement in your 0-60 time. I had both ACLs reconstructed back in the dark ages when I was in college (early 80s). I have run and worked out all my adult life...my knees have never given me any problems. As active as you are, you should have a great recovery. I'm recovering from spinal fusion surgery a couple months ago. It's no fun not being able to do the activities that you are used to doing, especially during the summer. I hope you are back wakeboarding soon.

Thanks for the encouraging words Mark. You are right, its no fun (for me or my family), when I can't do the things I typically enjoy doing. It's good to hear your knees are fine today. When you had your ACL repaired, you probably used your own petalla tendon to repair your acl. I opted to use cadever tissue, which according to my surgeon (team surgeon for our pro-hockey team), is much less traumatic to the knee (because I am not donating my own tissue), and the recovery time is quicker. We shall see. Back on target, I did a few g-tech runs immediately before the plenum install. The temp was 101, and my three times varied between 6.15 to 6.42. After the install I did one run, and even though it was 111 degrees, I managed to pull a 6.01, for an improvement of about .14. I bet I can knock even more time off if I do a run in temperatures closer to 100, which I will try to do shortly, after the re-install has time to adjust again. (for those who don't think ambient air temp makes a difference, my alltime best g-tech 0-60 time was 5.41 in 33 degrees). I'm also curious because since reinstalling, the car feels even more eager, which may indicate that I truly did have a vacuum leak following my first attempt to install the plenum. As far as power is concerned, its really hard for me to tell if the car is more powerful post-plenum, at lower rpms. At high rpms, the car does in fact feel quicker. I will also say that at least subjectively, the throttle response seems better at all times, and the tranny seems to shift quicker, which is a good thing for us folks with a tiptronic.

Scott, it's always a pleasure talking to you. Back in the dark ages they reattached your own ACL (if it didn't dissolve) Mine tore off clean on both knees. Cadavers are a wonderful thing. I now have three sections of cadaver bone where three of my discs used to reside. I'm thankful to whoever gave their all so I could walk upright. You are right about the recovery time being hard on the family. That is an impressive improvement with the Gtech. Temperature is obviously a significant factor. Weight probably makes a difference also. I don't carry a spare or passengers when I do my runs. It sounds like you are happy with the new part (which is all that really matters). Take care, Mark

Likewise Mark. If you are every in Arizona, you better let me know so we can meet. I hope your recovery from back surgery is going well. I'm only 8 days out from my surgery, so it is still slow going. When the doc went in he found a fair amount of damage to the miniscus and mcl, so there was a lot going on in my knee following my unsuccessful attempt at a Kobe Bryant cross over a few weeks ago (it was not pretty!). At least I can drive now, albeit with my seat back pretty far! With regard to the plenum, I can say I am very happy with it, even happier since I re-installed. With regard to your question about high-rpm improvement, to be honest, it is hard for me to notice improvements at the very high end of the rmp range becasue I don't go there at that often. The car just feels so good around 4-5, that I rarely find myself feeling like I need to go much higher. This cracks me up, becuase with my two prior boxsters, I absolutely lived in the upper range of the rpm band because the car did not feel fast unless you were above 5k (especially my 2.5 liter 1998, but even the 01 S to a certain extent). To me even a 99 tipronic is lighting fast coming from boxsters. I'm excited to try a g-tech run under similar conditions to my pre-plenum runs. I'll let you know. Cheers! By the way, on the freeway today I jostled a bit with a freindly subaru WRX that appeared, by the size of the exhaust pipe and the "centerforce" clutch and flywheel decals, to be fairly agressively modded. I know those are quick cars that will take me off the line everytime, but he could not hang from 80 on, and he knew it as he passed and gave me a huge thumbs up. These things are truly built for the high speed stuff (that is one fun aspect of the tiptronic tranny...when you are cruising in 5th at about 75, slam the pedals, and the tranny grabs 3rd and rockets you to well...too fast for street driving!

Scott, I bet you are really glad you have a tiptronic about now. You and I both appreciate the tiptronic for the same reason. It's great fun to punch it at freeway speed and have it shift down to the lowest gear possible and put you right in the sweet spot. I'm afraid the computer is better at shifting then I'll ever be. Next time I'm in Arizona, I'll be sure to call....please do the same if you are out my way. You are probably learning the same thing that I am about growing older. You can do most of the same things, they just hurt more afterwards.

Scott: Mark loaned me his GTek...and I haven't been able to replicate his 4.7 0-60 times...best I can get is a 5.4....but I have a clutch that's going to need replacing and I haven't been doing very aggressive launches just to try to catch Mark's specs. I was actually quite surprised that he got that sort of GTek times out of a tiptronic. If I didn't know Mark personally, I'd have a tendency to say he was BS'ing me. Glad you seemed to have fixed the problem you were having with the CEL's. This forum is great for this sort of thing. Chuck

Chuck, I wouldn't feel bad about the 5.4. My best friend has a 2003 M3 cab six-speed with a few bolt on mods, which by published accounts is a sub-5 second car, and the best he has been able to pull is a 5.4 with my gtech. He has chalked this (in his mind) poor performance up to his bad driving technique and the fact that it was about 100 when he tried. I bet if you were to try again in cooler temps when you clutch is perfect, you would be much quicker.