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squirreljuice
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Discussion Starter · #1 ·
Ok so my MAF went bad. Car ran lean for a bit. Replaced MAF. Car smelled so rich I thought someone was just pouring gas out my tailpipe, and then it leveled off and went to normal. Idle is ridiculously quiet now too (I have a 3 inch exhaust and I can't hear it idle anymore). But anyway, this morning on my way to work, the car would not build past 10 psi and acceleration under half throttle was super jerky, like when you run an MBC (which I'm not anymore) and then I got thrown into hard limp mode and it won't build past 1 psi. Anyone got any troubleshooting ideas for me to try?
 

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Have you scanned the car for trouble codes; please post any and all trouble codes here (if you have VCDS; please post the whole scan). Have a scanner with live data? What are the trim levels? A common failure; is the diverter valve and the n75 valve; here is a thread, where I discussed my situation and my repair, resolving of the issue:

http://newbeetle.org/forums/1-8-liter-turbo/61285-710n-diverter-valve.html

http://newbeetle.org/forums/1-8-lit...ock-motor-apr-aftermarket-vs-stock-bosch.html

Here are some links on MAF troubleshooting and trim levels:

http://www.ross-tech.net/vag-com/advertising/DiagnosingA_MAF_TechTip.pdf

http://wiki.ross-tech.com/wiki/index.php/Fuel_Trim_Info
 

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squirreljuice
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391 Posts
Discussion Starter · #3 ·
I haven't seen any codes yet, I will scan when I get home from work. I know it's not the diverter or N75 because they both got replaced 6 months ago when I was trouble shooting other things. I don't have any fancy scanner though, just the $50 amazon one specifically for Audi/vw. I'll post anything that comes up on that when I get home.
 

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squirreljuice
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391 Posts
Discussion Starter · #4 ·
The only code stored in my ECU is P1166: long term fuel trim additive air bank 1: range 2: system too rich. I drove with the window down this time and I could hear the turbo spooling like it was under regular operating conditions. My vacuum level has almost fallen in half, so I am going to start looking for boost leaks.
 

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here is a good thread; with some ideas about to check for with that code:

VWVortex.com - Repeated Fuel Trim errors after MAF replaced

Also from another website:

P1166 Volkswagen
P1166 Volkswagen - Bank 1 Long Term Fuel Trim Range 2 Rich Upper Limits Exceeded
PDF
0 P1166 Volkswagen Comments | Add Comment
Possible causes
- High fuel pressure-Blocked return system or failed pressure regulator
- Faulty fuel injector
- EVAP purge solenoid stuck open
- Cylinder misfire- Correct other codes first
Help with Possible causes What does this mean?
Possible symptoms
- Engine Light ON (or Service Engine Soon Warning Light)

Read more: P1166 Volkswagen Bank 1 Long Term Fuel Trim Range 2 Rich Upper Limits Exceeded OBDII Engine Light Trouble Code | Engine-Codes.com

and vwvortex:

17574/P1166 - Long Term Fuel Trim Additive Air; Bank 1; Range 2: System too Rich

> Check fuel pressure regulator and holding pressure
> Check injectors
> Check fuel pump
> Check intake system for leaks
> Check exhaust system for leaks
> Check exhaust gas recirculation system
> Check activated charcoal filter system for leaks
> Check Lambda probe and Lambda regulation


What scanner are you using; looks to be non vw type; can it read live data?
 

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squirreljuice
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391 Posts
Discussion Starter · #6 ·
Read the links you sent. One of them mentioned the MAF being the wrong one, and since that is the only thing I changed, I grabbed my old one and voila! I get 10-11 psi. This MAF is still bad, though, so I guess I now need to find the correct MAF for my car, and I am not ordering it from Rock Auto. They can't seem to find the correct one, because the one I have now is #3 from them. The first two were the wrong size housing, and now I guess the third one has the wrong sensor.

I am tuned, though, and should be getting almost 15 psi. Don't ask me what tune it is, because I don't know. My ECU fried last summer, and I was short on cash and needed my car asap so I bought a cheap one on ebay that claimed to be tuned. Which it was. I was running 15 psi until this all went down. So either I still have a leak, or the car just runs different when the MAF is bad. I don't know yet.

Stealership aside, could someone point me to where I could get a MAF for not too much and be 100% sure its the correct one for my car?
 

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Yeah, stop buying junk; go with a OEM genuine Bosch maf, you can look up the correct parts for your car here:

http://www.boschautoparts.com/vehiclepartfinder/pages/vehiclepartfinder.aspx (look under: "air management sensors")

Once you get the correct Bosch part number; you can get it from many places online like Amazon or your local auto parts , stores like Pep Boys, Autozone, O'Reillys, or Carquest or Napa. Online is usually cheaper but call around in your area to see when is available.

Meanwhile; you might try cleaning your old maf and see if that makes any idfference, until you get your new one. I use CRC Maf cleaner with excellent results:

05110 – Mass Air Flow Sensor Cleaner, 11 Wt Oz (check your local Walmart; last night I saw a maf and throttle body cleaner double pack; for a great price).

http://crcindustries.com/ei/product_detail.aspx?id=05110
 

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I'm not a dude.
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You might want to check your local VW dealer.. I just found out mine now sells OEM remans for ~$150. Guess they weren't selling enough brand new ones haha. Mine doesn't even carry brand new ones anymore.
 
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