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Rough idle/no power after 1500 rpms?

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Rough idle/no power after 1500 rpms?

  #1  
Old 11-21-2009, 07:58 PM
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Location: West Chester(Cincy), Ohio
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Default Rough idle/no power after 1500 rpms?

First off car in question is a 99.5 A4 1.8T quattro 5 speed. This afternoon i went to start my car it would not start(dead battery). Tried jumping it, still wouldn't start. Battery wouldn't hold a charge swapped it out at the store since it was under warranty. Now i have a battery to start the car turn the key, it turns over runs at idle, but very rough. As soon as i tap the gas it bogs down and sometimes stalls and sometimes it hits 1.5-2k rpm and than shoots back down to around 500rpms.

After reading around on here and a few other sites i went an loaned out a scanner to get the CEL codes. I pulled the p1545 Throttle Pos.Contr Malfunction and the P1338 Misfire. I knew about the misfire, as the ironic part of starting my car today was to take it into the garage to replace the plugs and other normal tune up stuff. From researching other posts i have come up with a lot of different speculations on what it could be. So far what i have done is cleaned MAF, cleaned TB, and checked for Vac. leaks. After doing those and restarting it, for one it idles better than before. But once you tap the gas it bogs down like before. Also after restarting i got the same two codes as well as P1544-
Throttle Actuation Potentiometer Signal too High, and P0123-
Throttle/Pedal Pos.Sensor A Circ High Input . I forgot to do the TBA, erased the codes, did the TBA, ran the codes again and it was back to the original 2.

I don't know if this will be a factor , but i do know the central locking module and ABS Module are shot, again those are two things i was going to fix once the car got to the garage. Going to send them to module masters to get rebuilt. Would like to get some input from you guys to see what i should do as my next step. Thanks for anything you can provide. If you need more info just ask.
 
  #2  
Old 11-21-2009, 08:48 PM
Andrew149's Avatar
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sounds like your not getting much gas.. maby vacum lines, coil packs?,
 
  #3  
Old 11-22-2009, 10:42 AM
bradtyler02's Avatar
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Just a shot in the dark from previous things I've read, but doesn't the car need some time to "readjust" after the battery has been dead for awhile?

I wouldn't bet my car on it, that's for sure, but someone should be able to explain it much better than me...
 
  #4  
Old 11-22-2009, 11:13 AM
Mike-2ptzero's Avatar
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Yes it does, when you clear the codes you also reset the fuel trim readings. This means the car needs to run and be driven a bit for the ecu to adjust those numbers again.

But he is getting a throttle code which could be the main issue.
 
  #5  
Old 11-23-2009, 11:43 AM
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I have checked for vac leaks, will be replacing plugs, filters etc.. later this week.

On another forums someone stated that I will most likely need a VAG com to adjust the TB settings. Think this is something i will have to do with the fuel trim ? Or if i let it run/drive it do you think it would adjust accordingly? I believe since I'm pulling a TB code it will have to be done with the VAG com which sucks because i don't have one as of yet.
 
  #6  
Old 11-23-2009, 12:21 PM
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There is nothing you can do with the vag that is going to help, the ecu self adjusts the fuel trim on its own and you cant adjust the TB with the vag. If the TB or TB sensor is bad it will have to be replaced.
 
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