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  #1  
Old 11-23-2005, 10:48 AM
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Join Date: Jul 2004
Location: NC
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Can AMM fail without CEL?

Haven't had codes read but no CEL has come on. I made a post about car running rough and using gas. It's still doing that some days better than others, but now anytime I get on the gas hard causing a trans kickdown, motor surges and lulls, surges and lulls, rhythmically. NO high-end power but all seems normal in city and even moderately-hard driving, just not when higher-RPM pwoer is called for. Tach does not jump/recede, doesn't seem to be a trans issue/slip. Definitely stumbling when power is needed. Also, motor bogs pretty noticeably now after a gear change if I step on the gas.

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  #2  
Old 11-23-2005, 12:23 PM
3 MB's and counting!
 
Join Date: Apr 2001
Location: Toronto, Canada
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Mine just failed recently and I had the same symptoms for quite awhile...a big loss in power and the car stuttering..forget about kickdown..it didnt know what to do...then finally 3 months later the check engine light came on and it gave the MAS code.

Your MAS is cooked for sure.
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  #3  
Old 11-23-2005, 12:25 PM
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Cool!

Well, not cool, but I've had one fail in 2 of my former VWs and it caused similar issues. I'll feel more confident buying one now - thanks for the reply.
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  #4  
Old 11-23-2005, 02:14 PM
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Join Date: Dec 2000
Location: St. Albert, Alberta, Canada
Posts: 3,492
My AMM failed without throwing a CEL, but the fuel trim adaptation codes were close to the threshold for throwing a light, so I'm sure it was coming. Loss of power and stumbling at 4000rpm and above is a classic AMM failure symptom. However, before I threw a part at it, we read the adaptations and installed a "known good" AMM and only after confirming the problem did I buy one and install it. Change your engine air filter while you're at it. Keeping your engine air filter fresh will greatly extend the life of your AMM. I got 160,000kms out of my original one by keepign the filter fresh and regularly cleaning the air box.
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  #5  
Old 11-23-2005, 10:24 PM
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Thanks. I'm gonna get one from Phil within the next week. My hunch was AMM, really classic symptoms as you described. AFAIK it's original anyway, 104k. I do change the filter every 10k and vaccuum it at 5k, including the airbox. But I didn't own it for the first 61k.

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