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Discussion Starter · #1 · (Edited)
I could REALLY use some advice, but be forewarned, this post is pretty long! Please try to stick it out? :) I bolded the main questions and the important part of the background if you want to skip to the heart of the matter.

This is my 2001 Beetle that I've owned for its whole life. It has about 83,000 miles on it.

I don't know much about cars, but have recently been trying to learn more so I can stop mechanics from talking me into unnecessary or overpriced repairs. I have done a LOT of internet research on the SAI system though, so I think I have that part down (although I can't seem to locate the solenoid?).


My whole story starts with me hearing a whistling sound after starting my car from cold in the morning. Some research on the internet lead me to the secondary air injection pump. I found that the intake hose had a small crack in it, and from what I've read water could have gotten in through that and caused the pump to start going bad. I did NOT have a CEL at this point.

I contacted my mechanic only to find the part was over $500. I found it at ECS Tuning for much cheaper and the mechanic said the labor was $89. However, the part looked pretty easy to connect, so after much deliberation I decided I was going to order the part online and do the replacement myself (myself ended up being me and a friend).

Unfortunately, during the replacement, my friend snapped the output hose in half. We taped it back together with electrical tape. In addition, we couldn't get the end of that hose to go all the way back in the new pump. At the time we were not aware, but later my mechanic informed me, that this is a high pressure area and not only did the hose have to be connected all the way, but the electrical tape fix was not cutting it. My CEL came on with code P0411 incorrect flow.

I had the mechanic order me a new hose and install it (I had him do it because we could not get the other end of the hose off the combi valve for the life of us - still not sure if that labor was worth $35 but oh well). He cleared the code and I thought everything would be good. Unfortunately the light came back on after just a couple drives in the car. I haven't read the code yet, but I'm guessing it'll be good old P0411 again.


Now that you have the back story, here are my questions.

I'm concerned that the new pump might be bad, since before I replaced it I did not have a CEL. The pump DOES turn on. When I detach the output hose from the pump while the pump is running, no air is being blown out from the pump. Is this bad? Should it definitely be blowing air out when disconnected from the combi valve??

The pump, after installation and loose hose fittings, originally ran very loudly and rough sounding. After the fixed hose, it sounds like it used to (before the whistle) again, no rough noise. This leads me to believe that the pump is working, otherwise the output hose being attached versus not attached wouldn't change the sound. Is this logic incorrect? Does the vacuum applied to open the combi valve actually suck air through the pump and cause the flow to happen?

I've read about testing if the combi valve is broken by blowing in to the intake hose while the pump is off and seeing if you can. I have done this with the new output hose and I CAN blow into it. It's not like blowing into a hose that's not attached to anything, but it's not like blowing into something completely shut and sealed off from allowing air flow through. Is that bad? Would an always open combi cause P0411? From what I've read, it being always open could just lead to the pump going bad from backflow exhaust gathering up moisture in the pump, but if it's always open then I should be getting air flow through the system... right?

If I remove the intake hose from the air box while the pump is on (and output hose is attached), and put my hand up to the hose, I can feel air being sucked into the hose. That seemed good to me, but that paired with no output from the pump seems odd, and leads me to believe that the output hose actually helps pull air from the pump. The word "pump" however, makes me think that previous thought is dumb, if the $500 pump requires vacuum to suck air out of it, what good is it? :p

I've visually inspected the vacuum hose going to the combi and it looks completely intact. Is there another vacuum hose I should be looking at? I don't see any others coming from that area.

What I've described above is pretty much the extent of my testing abilities, as far as I know. I've read about testing vacuum at the combi, but I don't know how to do that (do I just take the vacuum hose off the combi and put my finger up to it?). Will it go right back on again and still be airtight, even after my inexperienced hands have fiddled with it? I've also read about applying vacuum to the combi to see if it opens, and I definitely don't have anything to do that.


Is the information I've provided enough to take some guesses about what's wrong? Of course, being Sunday, my mechanic is closed, so until Monday morning rolls around there's not much I can do except ask for guesses from you guys! Thanks for reading all the way to the end, and thanks in advance if you reply!
 

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I could REALLY use some advice, but be forewarned, this post is pretty long! Please try to stick it out? :) I bolded the main questions and the important part of the background if you want to skip to the heart of the matter.

This is my 2001 Beetle that I've owned for its whole life. It has about 83,000 miles on it.

I don't know much about cars, but have recently been trying to learn more so I can stop mechanics from talking me into unnecessary or overpriced repairs. I have done a LOT of internet research on the SAI system though, so I think I have that part down (although I can't seem to locate the solenoid?)...
Pics 023, 024 and 025 in this thread post shows you the vacuum solenoid for a 2000 1.8 APH. The vacuum hose (024-9) from the combination valve (right side of pic 23 out of view), runs from the valve to solenoid connection 025-9 (left side of pic 23 out of view).


Now that you have the back story, here are my questions.

I'm concerned that the new pump might be bad, since before I replaced it I did not have a CEL. The pump DOES turn on. When I detach the output hose from the pump while the pump is running, no air is being blown out from the pump. Is this bad? Should it definitely be blowing air out when disconnected from the combi valve?? ...
Pumps do two things, suck something in, and pump something out; if it is not doing this, then their is problem.


The pump, after installation and
loose hose fittings, originally ran very loudly and rough sounding. After the fixed hose, it sounds like it used to (before the whistle) again, no rough noise. This leads me to believe that the pump is working, otherwise the output hose being attached versus not attached wouldn't change the sound. Is this logic incorrect? Does the vacuum applied to open the combi valve actually suck air through the pump and cause the flow to happen?
It is my understanding that the pump is force feeding fresh air into the system during initial startup. The combination valve opens (via vacuum) allowing the pump to pump air into the system.


I've read about testing if the combi valve is broken by blowing in to the intake hose while the pump is off and seeing if you can. I have done this with the new output hose and I CAN blow into it. It's not like blowing into a hose that's not attached to anything, but it's not like blowing into something completely shut and sealed off from allowing air flow through. Is that bad? Would an always open combi cause P0411?
If air flow is detected going backwards, then yes it would.


From what I've read, it being always open could just lead to the pump going bad from backflow exhaust gathering up moisture in the pump, but if it's always open then I should be getting air flow through the system... right?
Regardless of air flow, if the system detects an incorrect air flow an error code will be noted.


If I remove the intake hose from the air box while the pump is on (and output hose is attached), and put my hand up to the hose, I can feel air being sucked into the hose. That seemed good to me, but that paired with no output from the pump seems odd, and leads me to believe that the output hose actually helps pull air from the pump. The word "pump" however, makes me think that previous thought is dumb, if the $500 pump requires vacuum to suck air out of it, what good is it? :p
There would be no need for a pump then would it.


I've visually inspected the vacuum hose going to the combi and it looks completely intact. Is there another vacuum hose I should be looking at? I don't see any others coming from that area.
There is only one vacuum hose.


What I've described above is pretty much the extent of my testing abilities, as far as I know. I've read about testing vacuum at the combi, but I don't know how to do that (do I just take the vacuum hose off the combi and put my finger up to it?).
Yes.


Will it go right back on again and still be airtight, even after my inexperienced hands have fiddled with it? ...
Just replace the hose.
 

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Discussion Starter · #3 ·
So I should absolutely, without a doubt, be feeling air being blown out of the output side of the pump. Correct?

Is there any other reason I wouldn't be feeling this output air aside from a bad pump?

I'm guessing that's the only possible cause of that symptom, since the intake hose is just pulling in fresh air and could be removed and replaced with a filter instead without any negative effect to the system, from what I understand.
 

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Discussion Starter · #4 ·
When I contacted the supplier about the fact that no air was coming out of the pump, he agreed to immediately ship out a new one. Hopefully this one will work completely!
 

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Am new at the vw motors My question is those the airpump starts every start? because it been super cold here in Michigan last two days, i started the NB and i didnt hear the pump and the motor started to shake and turn off i turn it back on and gave it a little gas to keep it at 1500RPM for 1 min then i let it idel it was fine it was 5 degrees this moring, any idea let me know (no cel came on)
 

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Discussion Starter · #7 ·
Am new at the vw motors My question is those the airpump starts every start? because it been super cold here in Michigan last two days, i started the NB and i didnt hear the pump and the motor started to shake and turn off i turn it back on and gave it a little gas to keep it at 1500RPM for 1 min then i let it idel it was fine it was 5 degrees this moring, any idea let me know (no cel came on)
The pump turns on when your coolant is between 59 degrees F and something like 199... not sure on that upper number, but the lower one is the key. When it's really cold outside and your car has been parked outside, the pump won't come on right away when you start because it's outside the temperature range. From my experience with my pump, which started to whistle loudly, it comes on a couple minutes into the drive instead of right at start when it's really cold out, and then maybe again a bit later. And when it does come on at start, it goes off after a minute and comes back on a few minutes into the drive for like thirty seconds and turns back off again. I noticed mine sporadically coming on in the middle of drives even if I'd been driving for over ten minutes... don't know if that's normal functionality.

Sometimes in the cold my NB turns off right after turning on, and I have to try again and I give it a bit of gas to keep it going. I don't have to give it gas for that long though, just a couple seconds to make sure the start sticks. It's been around 15-20 at it's coldest here, I don't know if ten degrees makes a difference in that.

It doesn't sound to me like you have any problem...
 

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Discussion Starter · #8 ·
Does anyone know how I can go about testing to make sure my new secondary air pump works before putting it in the car? Does my mechanic probably have the capability to hook it up to power outside of the vehicle to make sure it functions correctly? Would that be something I should expect him to charge me for if I'm in there for other maintenance, or if he can do it would it be a pretty quick check? Is it safe to power up the pump when it's not attached to the car (would it shake too much to hold by hand while it's on)? I doubt there's a way I can test it myself but I might as well ask that too while I'm at it, I don't have any special tools for electronic stuff...
 

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it's essentially a fan. You can just hook up power to it. When mine went bad all it did was whine like a jet engine. Picked up one from the local junkyard ran power to it. It should blow steady and relatively quiet.
 

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Discussion Starter · #10 ·
I had my mechanic do it. I can't really just hook up power to it, I have no way to plug it in, that was the problem, and I don't have any special cables that I could have used to try to jerry-rig something. But my mechanic had the exact right connector for it and he had it turned on in just a minute or so. It worked, and I installed it last night. Hopefully this is the end of my secondary air injection issues for a while, but it's still early, I'll have my eye out for the CEL on the next few drives, probably give it a week before I conclude the CEL is going to stay off this time.
 

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Discussion Starter · #11 ·
Let us know if the replacement works.
It seems to me that the replacement was a success. Out of curiosity, I compared the pump I originally pulled from the car (the one that was being really loud) to the defective one. I noticed something different about the power connectors.

Original pump:


Defective replacement:


Is that piece of purple plastic in there necessary? Could that be why the defective one wasn't doing the trick? If so, is it possible to get the plastic out of the old one and put it in the defective one to make it work?
 

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Discussion Starter · #12 ·
Bumping this in case anyone knows if that purple part missing could keep the air pump from pumping out air but still powering on?
 

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P0411 Secondary Air Injection Incorrect Flow

Trying to debug my daughter's 2003 1.8l turbo secondary air injection system and ran across this thread. Hoping to maybe get some helpful input from persons with more knowledge.

Background. CEL came on - P0411 code - Secondary Air Injection Incorrect Flow. Cleared code - same code came back a few days later. So we've got a reoccurring issue in the Secondary Air Injection system.

First I checked the vacuum line between combi-valve and the vacuum solenoid. No cracks or leaks. Appears to be in good shape.

Next, I took the output hose off the secondary air pump that goes to the combi-valve. I did not feel any air being blown out by the pump. What I don't know is if this pump is supposed to blow at all times or if it turns on off at various times. So it could be a bad air pump.

Next, I tried to blow through the output line into the combi-valve. Could not blow any air through at all.

Then, I took the vacuum line off the vacuum solenoid and hooked a hand vacuum pump to the vacuum line connected to the combi-valve. The vacuum line held a vacuum. However, I still could not blow any air through output hose into the combi-valve.

This indicates to me that either the combi-valve isn't working or else the little hand vacuum pump can't pull a strong enough vacuum to actuate the valve. So, it could be a bad combi-valve.

Does anyone have any idea what vacuum pressure it take to open the combi-valve?

Both the secondary air pump and combi-valve are expensive parts. So, I really would like to definitively nail down the culprit before I buy anything.

Any input into figuring this thing out will be appreciated.
:confused:
 

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Discussion Starter · #14 ·
The pump does not always run, it comes on after a cold start, and stays on for ~1 min, maybe less. So, to test whether the pump is outputting air when it's on, test it right after you turn the car on in the morning, or after it's been off long enough to cool down completely.

I wish I could help you more with your combi valve questions, I could have back when I was dealing with my issue, because I'd done a ton of research about it. I know I've read the answers to the questions you asked (except for the amount of vacuum required) on the internet here somewhere, so they're out there if you can find them. Good luck!
 

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Secondary Air Pump Test

Does anyone know if the secondary air pump is powered by 12 volts DC?

Or in other words, if I rig up some wires and connect it directly to the battery and it does not run, does this confirm that I have a bad air pump?:confused:
 

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Make sure

you check the hoses! They become very brittle due to heat generated in the engine compartment. I was able to put off the replacement of one with strategic duct tape. The one from the pump to the airbox developed a crack at the base of one of the rings (only way I noticed was a great deal of air passing through).

If you need a new pump I have one (NIB) Pierburg.
 

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Took off secondary air injection pump, which I never observed blowing on the engine, even at "cold" start-up. The removal of this thing is a pain. You have to unbolt the housing removing three (size 6) Allen bolts. Then you have to manipulate the housing and pump so that you can unbolt the pump from the housing by removing the the three 10mm nuts from the rubber connecting mounts. Also had to remove the bracket holding the hoses to the pump and to release the hoses from some hose clamps to get enough room to wiggle the two parts out. I expect the re-installation will be a similar PitA.

Part of my testing problem is that it has been relatively warm here in NC and I read something on the original pump manufacturer's web site that it was designed to come on when coolant temps are below 70 degrees F. Also, I figured there is possibility of bad relay or bad coolant temp sensor. Jerry built a direct connection to the battery - no blow. Have ordered an aftermarket blower from autowarehouse.com for around $160. If no other posts from me in this thread in the next week or so, diagnosis is correct and problem was fixed.
 
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