Awful Acceleration, Air Injection Pump, MAF, Misfires

[Magiko]

For some months, I'd warned my fiance that trouble was around the corner with some less-than-smooth shifting in her 1999 New Beetle 2.0L. I was considering replacing the transmission fluid after finding this article: http://www.newbeetle.org/forums/showthread.php?t=1036

She has some new problems, however, and I'm a newbie to all engines, so I'm doing a LOT of googling here.

After a cold start, it acts as if it does not want to give gas to the engine. For about 10 minutes (we're in the cold months still), if I rev the engine past 2000 RPM or so, it cuts off the gas and the engine RPMs drop very low. If I try to drive the car, I can only get only about 5-10MPH. If I punch the gas, it punishes me and I'm back to very low RPM and no accelleration. When the car heats up a little, we get much, but not all, of the acceleration back -- I can get to 40MPH, which is enough to get me a miles to work (that's right, I'm driving it, she traded me cars). I just put a higher octane (91) gas in, and it is so far doing a little better after the 10 minute warm-up.

I took it to Auto Zone to have the codes read. 10 codes. The first 6 relate to misfires on all cylinders, along with:

P0422 - Main Catalyst, Bank1 Below Threshold
P1128 - Long Term Fuel Trim mult.,Bank1 System too Lean
P1421 - Sec.Air Inj.Valve Circ Short to Ground
P0411 - Sec.Air Inj.Sys. Incorrect Flow Detected

I inspected the Secondary Air Injection Pump and have found the rivets popping out (literally).

A few minutes ago I found an article about how I can possibly repair this $350 part:

http://www.motor.com/magazine/pdfs/092007_04.pdf

The article explains that it could have cracked open with a little water and freezing. I have no idea if my home repair will make any difference.

My question to the forum is: Does anyone think this could cause the bad acceleration problem?

One of the other codes (P1128) is for the Mass Airflow Sensor. Google says this part can be cleaned. I do not know much about this part.

Code P0422, as far as I can tell, is pointing to the catalytic converter, which I'm led to believe is probably not the culprit in the acceleration.

Input? Thanks

[Magiko]

This evening I pulled the Air Injection Pump. It came off pretty easy - 3 nuts, 2 hoses and an electrical connection. The electrical connection seems easy to break, but I used several flathead screwdrivers and managed to get it off with minimal damage. The 3rd nut is also a little tricky to get to, but with enough extenders it's not bad.

When the pump came off, I noticed a little moisture (in the "outlet" side). For all I know, this has been sucking up water from the air (it hasn't been rainy here lately).

The loose rivets came right out with some needlenose pliers. I peeked inside to see what magic might be in there, thinking I would put anything back in that might need putting back in (per the article) - I found nothing to tuck back in, and I finally decided to put the screws in (#8 machine screws with nuts), and put it all back in the car.

Overall change? None yet - I'll have the codes read again soon. A buddy of mine suggested the car might be in a "limp mode" where the computer is keeping the car's RPMs low on purpose.

[D2Beetle]

"Limp mode" is usually transmission related.

There are three parts to the Secondary Air system...

1) Pump
2) Exhaust Manifold Valve
3) Solenoid Valve

There is a vacuum hose that goes from the Solenoid Valve to the Manifold Valve; make sure it is not leaking.

If the flow goes from the exhaust manifold to the pump, which is the wrong way, condensation will occur in the pump and the pump will fail. If it has been doing this for a while the pump may not be repairable at this point.

Check junkyards for another pump, it would be cheaper.

[Magiko]

Hey D2 - Thanks for your input. I've seen some of your other posts about this same topic. Took your advice and I bought another pump (salvage $100).

It sounds a little different, and it seems to drive a lot better (made it to 70MPH and came back home). It still can't go more than 2-5MPH while cold, and I'm still hunting.

Also, I'm still seeing moisture on the output of the pump, so I'm looking for the vacuum leak. Which means I'm looking for the solenoid valve and vacuum tubes - I can't find any photo, but I do find this digram:

http://www.vagcat.com/epc/cat/vw/BE/...06/49/2495360/

It looks like 15 is the solenoid, and 16, 17 are the vacuum tubes I'm looking for.

Am I going to be able to do this from the top of the engine? Moreover, am I going to be able to do this without removing many large pieces? (Not afraid, I just don't know).

[Magiko]

This evening I replaced the two vacuum hoses. Not as hard as I feared - I could do it from the top. With the help of the diagram I posted earlier, I followed the outlet air tube to find the combi valve (which isn't in the most convenient spot) - from there, I couldn't really see the vacuum tubes without removing parts.

I rem'd the top of the air box, the tube that connects it to the manifold, and the bracket holding the solenoid. The solenoid was located right behind the airbox.

The vacuum tubes were pretty awful, but I'm not entirely convinced they had a leak -- at any rate, the act of removing them proved they needed replacing (2 of the ends snapped off). I replaced it with $4 worth of tubing from Auto Zone.

Still no change in operation - and I'm next considering either the solenoid or the combi valve (or both), and I'm not sure if the MAF is bad or not. Solenoid and MAF seem very easy to replace -- the combi valve was still pretty hidden.

So, I'm really not sure what my next step is.

In other news, I decided to open up the pump I replaced - just to see what I could see.

It is obvious it was ruined. Some part that would normally go around the outer edge of some metal disks was shredded to bits, and there was still quite a bit of water in the pump.

[D2Beetle]

I'm not registered user at vaqcat, so I could not view your pic.

If you determine that the combi-valve needs replacing, I currently do not know of a way to get it off unless the cylinder head comes off.

[Magiko]

Sufficiently afraid about replacing the combi valve, I haven't done much of anything to the car.

However, I'm no longer in limp mode for 10 minutes at cold start - I hadn't done anything since the changes above (new pump and vacuum hoses).I believe I reached the number of starts required to clear the computer. Is it 30?

Auto Zone wouldn't reset the computer for me, and I (for whatever reason) didn't unhook the battery to reset it -- btw, warning for others reading this in the future - unhooking the battery could render the stereo inoperable as they have an anti-theft "feature" - I happened to have made this mistake a few years ago, gave up with fixing it and simply replaced it (my gf wanted a cd player anyway).

I believe the pump is not turning on. Reading around, I have learned that the pump's fuse is usually blown when the pump fills up with water and reports the ground problem. I've spent some time looking for the pump's fuse & relay, but I can't find them. I do find several fuses on top of the battery in a plastic compartment, and they look just fine (and I don't see any relays there, just terminals).

[larue708]

Hey Magico I've had some trouble in the past with mine not wantting to accelerate in a similar fashion. If yours starts acting up again you can find out if it is an issue with the mass airflow sensor by unplugging it and running the car. My problem was that the mass air flow sensor was sending incorrect information to the ECU and it was causing my car to try to slow itself down. If you unplug the MAF sensor it will go into a factory preset "limp mode" that will allow acceleration but will give you less than optimal gas mileage. But you will know that teh MAF is the problem and can replace it for relatively not very much money.