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Discussion Starter · #1 ·
Hello fellow club B5er's'

I'm having a tough time to get my car running nicely. It is not holding an idle and it stumbles.

I tested and replaced the ICM and put in new plugs as they were black and sooty.

My OBDII reader throws code P0103 and P0121;

P0103 Mass or Volume Air Flow Circuit High Input

P0121 Throttle Position Sensor/Switch A Circuit Range/Performance Problem

Any suggestions in course of action to remedy my poor running car.

Thanks,

Malcolm

P.S. If you do not have input to help remedy the situation, please hijack a different thread! Thanks!
 

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If your plugs are sooty, you've got oil leaking into the cylinders. That needs to get fixed. Hopefully it's just a valve cover gasket leak, and not a cylinder head gasket leak or blown rings.

Take your MAF off and spray it with electronics cleaner inside and out.

Is the wiring harness plugged into the throttle? If it's not, that would be where the TPS error is coming from.
 

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Discussion Starter · #3 ·
If your plugs are sooty, you've got oil leaking into the cylinders. That needs to get fixed. Hopefully it's just a valve cover gasket leak, and not a cylinder head gasket leak or blown rings.

I just had the valve cover gasket replaced, so I believe that I am fine there. I think the sooty plugs are from the incomplete combustion.

"Take your MAF off and spray it with electronics cleaner inside and out."

Next I will be cleaning the MAF.

"Is the wiring harness plugged into the throttle? If it's not, that would be where the TPS error is coming from."

I'll check that...

Thanks,

Malcolm
 

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check connections

if you just had your gasket replaced then i would check all connections from that work being done. did it run ok when it came back from the gasket service?
 

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Discussion Starter · #5 ·
if you just had your gasket replaced then i would check all connections from that work being done. did it run ok when it came back from the gasket service?
The valve cover gasket was replaced two oil changes ago, and had been running fine up tl this recent bout of car problems....

Thanks,

malcolm
 

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Discussion Starter · #6 ·
Supplemental info update...

I just ran out to check electrical connections to throttle body and they appear fine. The idle is still lumpy and the power comes on from dead to rev as combustion seems to be incomplete down low. There is alot of soot exiting the tail pipe.

Hope this helps with diagnosis...

Malcolm
 

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Well, it's not oil. A leaking valve cover gasket won't leak oil into the combustion chamber (unless it's leaking around the plugs and the plugs aren't torqued properly).

Soot is too much gas or not enough ignition.
It is highly unlikely that the fuel system is supplying too much gas all on its own. And you don't have misfire codes, so it's not likely ignition.
More likely that the MAF is bad. If it's reading too high, then the ECU is going to pour more fuel into the combustion chamber, making you run rich.
A "rebuilt" MAF is only about $100 dealer cost. It's a new sensor with a re-used housing. Same part number with an "X" at the end.

If you can get hold of a VAG-COM, fuel trim (block 032) info would be useful.
 

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Well, it's not oil. A leaking valve cover gasket won't leak oil into the combustion chamber (unless it's leaking around the plugs and the plugs aren't torqued properly).

Soot is too much gas or not enough ignition.
It is highly unlikely that the fuel system is supplying too much gas all on its own. And you don't have misfire codes, so it's not likely ignition.
More likely that the MAF is bad. If it's reading too high, then the ECU is going to pour more fuel into the combustion chamber, making you run rich.
A "rebuilt" MAF is only about $100 dealer cost. It's a new sensor with a re-used housing. Same part number with an "X" at the end.

If you can get hold of a VAG-COM, fuel trim (block 032) info would be useful.
Your description of leaky plugs is exactly what I had on my AEB when I first got it, hence why I mentioned it. Plugs come loose over time.
 

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Discussion Starter · #9 ·
Hello everyone,

I just cleaned the MAF Sensor with electronics cleaner and the situation is better, but still not perfect.

As I just put in fresh plugs, I am certain that they are torqued.

Do you think a new MAF Sensor is the solution? How can I test it before buying a new one?

TIA

Malcolm
 
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