Problem after Cleaning Throttle Body and MAF

[Krueger]

Hello guys, I have a problem here. I cleaned my throttle body and mass air sensor. I now have a pretty rough idle. The car is jumping all over the place between 800-1200 RPM. I'm not sure what the problem is. I cleaned the throttle body and mass air sensor according to procedures I've researched on this website and a few others.

I used the appropriate cleaners (MAF cleaner on mass air sensor, throttle body cleaner on the TB), checked for vacuum leaks, made sure everything was assembled properly, followed the Throttle body adaption procedure according to RossTech, etc...

I did have an issues when I went to do the initial throttle body adaption with VAGCOM. I got an "ERROR" message in the adaption status box. And then two DTCs came up in the engine controller and ABS module:

1 Fault Found:
17967 - Throttle Body (J338)
P1559 - 008 - Fault in basic settings
1 Fault Found:
18256 - Please check DTC Memory of Engine Controller
P1848 - 35-00 -

I tried to do the alignment a second time and the same thing happened- Failure. The throttle body clicked as if it was trying to align and then I got the "ERROR" message again.

I did something different the third time. I started the engine, let it idle for a few minutes (idle was rough), turned it off, and then tried the adaption again. VAGCOM was showing "Adapt. status OK" in the status box so I ran the adaption. VAGCOM displayed "OK" after the program ran so I started up the car and again, it had a very rough idle.

I have no idea what is going on or why I got an adaption error the first two times I tried to do an alignment. Any ideas? I think I am going to disconnect the battery tonight and try to run an adaption in the morning.

[mbgt72]

VAG Maf's are very prone to dying after using "MAF Cleaner". Sounds like you just killed the MAF by soaking it with the cleaner.

[Krueger]

VAG Maf's are very prone to dying after using "MAF Cleaner". Sounds like you just killed the MAF by soaking it with the cleaner.

Thanks for the reply. Is there any way I can be sure? I get a consistent reading from the sensor when I monitor it with the vagcom. I took the car for a ride and it actually drives pretty well. The idle is just out of control.

[redls1bird]

Sounds like you could still have a vacuum leak, even though you checked. The mass air flow reading will be consistent, but you have "false air" or extra air not being measured by the MAF sensor. I would double and triple check your work, also, make sure the TB gasket is in good shape.

Side note people: Unless you have a problem sensors dont really need maintenance. They either work, or they dont.

[Krueger]

I did re-use the old throttle body gasket. I will start by replacing that. I have a feeling that may be the problem as it was not in the best of shape. As I said in my reply to the other gentlemen, I took the car for a ride after I did the work and it ran like a beast. The hesitation I was getting between 3500-4500 RPM was gone. That is the original reason I decided to clean the parts.

A vacuum leak does make sense. I did not suspect the TB gasket though. I only disconnected one vacuum line to remove/reinstall the TB, the large one which attaches and goes through the firewall. I reconnected that and checked all the other lines after I reinstalled the TB. That is why I was confident of my work. In any case, I'll order the gasket from a dealership and let you guys know how it turns out. If that doesn't work, I'll order and replace the mass air sensor.

[BC-S4/02]

So was it the TB gasket? What ended up happening? Reviewed several of these recently and seen a lot of issues with cleaning the MAF.

[Krueger]

So was it the TB gasket? What ended up happening? Reviewed several of these recently and seen a lot of issues with cleaning the MAF.

I did get the problem sorted out. I put a new gasket on, but that wasn't the problem. The rough idle + failure of the TB alignment process was caused by an issue with my throttle body and a bad mass air meter. It seems that when I removed the throttle blade for cleaning, it didn't re-install it exactly dead center. It was only off by a miniscule amount but it made all the difference. I played around with the screws on the throttle blade, put the car back together, started it up and it ran great. The result was a smooth idle at roughly 800rpm (where it is supposed to be).

As for the mass air meter, I do not think I killed it when I sprayed it with cleaner. I bought a new Bosch meter and logged some data with my vagcom. I also have logged data values post & prior the cleaning of my original meter. The values of the new meter compared to the old meter (post & prior) don't match up at all. I'm convinced my meter had been going bad for several months before I attempted to clean it.

The car runs great now, the hesitation I was getting is gone. Cleaning the throttle body and getting a new mass air meter solved my original problem.

[B6JoeS4]

I was gonna say the problem isn't the tb gasket. If removed mine a few times and it still seals fine.

[BC-S4/02]

Thanks for getting back on this and glad you sorted this out. Cleaning my TB momentarily.