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View Full Version : alternator help 1.8t



itln650r
12-28-2008, 06:51 PM
ok so its not an audi, its a 2003 gti with a 1.8t. i was refered here by a good friend with an s4, he said id get an answer quick and thats what i need. so its an automatic gti, i put a system in not knowing its only a 90 amp alternator. granted its only a 250watt system with one 12. the problems only surfaced a month after it was put in. the install isnt the problem i did it myslef and have complete confidence in it. anyways on to the issue. after driving for a while (an hour or so constant highway) with the system blaring, then comming to city streets, coming off a light the car would bog, shift itself into nuetral. with my foot trying to take off normally it revs up when it hits neutral and pops back into drive by itself at about 3k. (not a rice neutral drop, this was purely accidental) after that it didnt have another issue for about 6 months. just recently it did it again so i took the fuse out of the power wire to try to eliminate a variable. now the battery is going dead every time the car shuts off. now i tested the battery with a meter and got 10.4 volts. i know this is bad but i cant tell if the battery is bad yet. i tested voltage with the car running and it was at 13.8, too low for a good alternator, also tested for ac voltage at the battery and got 5v and spikes to 100+ v ac. thats no good. SO now another question, i know by now the alternator needs to be replaced and i was wondering if the a4 1.8 alternator is the same as the gti one. and if so does anyone have an extra one?? (btw this is in b5 a4 because my roomate has one and thats about my knowlage's end in audis other than an s4) any info is appreciated. thanks

Seerlah
12-28-2008, 07:02 PM
You will need to replace the alternator with whatever the unit that is currently on your car has. I will go on assumption that if you have the same engine as ours, then you can do a direct swap (logically speaking). Meaning that if you have an AEB, ATW, or AWM engine code (when it comes to the B5 A4). You can upgrade to a 120 amp with no issues, but you must also get the brand with what is currently on your vehicle. If you currently have a Valeo unit, then you must replace with a Valeo. If you currently have a Bosch unit, then you must replace with a Bosch. If you don't, you will have fitment issues. And go with a 120 amp alternator.

If your battery has 10.4v with the car off and 13.8v with the car running, then your alternator may be on it's way out. With the electronics on your car off, you should be ~14.5v. So to answer your initial question, I would only trust a direct swap if you have the same engine code. Otherwise, another will have to chimme in to grant a better explanation. Is there an Audi that you share the same engine code with; what is your engine code?

itln650r
12-28-2008, 07:16 PM
engine code is awp. its still the 20 valve 1.8 i dont know how similar the bracketry is. im not sure what alternator it is but if i had to guess id say bosch. i guess im going to get one from advanced, although i just now realized they didnt ask me what year or engine code it was. i dont have much faith in those parts stores but the dealer wants 384 for it.....im thinkin hell no.

Seerlah
12-28-2008, 07:38 PM
I just learned that the AWP is from the Audi TT. Another thing I just learned is that you only use a Bosch unit, so no concern. You should be able to do a direct swap with the Audi TT, as you guys have the same engine. You should post in that section and inquire.

And as for the price of the alternator, you can always find one cheaper.
http://www.mjmautohaus.com/catalog/product_info.php?cPath=2_6_17_45_115_3906&info=Bosch_AL0726X_Alternator_120_Amp_OEM_Rebuilt&products_id=938

Good luck [up]

itln650r
12-28-2008, 07:49 PM
sweet, thank you very much

Affinitive
12-28-2008, 08:05 PM
I kinda just glanced through through this thread, so forgive me if I missed something.
Couple of things.
Your battery sounds like a poblem if it's only maintaining 10.4 Volts with the engine off and no loads on it. Sounds abotu right fo the age of the car if it's the original battery. Do yourself a favor and spend the extra couple of bucks to buy an OE battery at the dealer. Interstate batteries are good and all but still no comparison when it comes to OE quality of batteries used in european cars. If it has to be aftermarket, then interstate would be the only acceptable option....if need be.
Long story short, a good battery should be holding at 12.3 - 12.6 volts
Go get a battery

As for the alternator, there is a 120amp option available fo your specific application. The price the dealer quoted you is also pretty good. In this case the dealer is probably buying the unit fom the same place I would as you can see in the sceen shots included further down. I went ahead and took of my price column but you can still see the retail price range. As you can see, good quality stuff costs money. No sense in buying a cheap 60 dollar pile of junk just to end up replacing it again 3 months later..........
You'll also notice the appropiate pat numbers and such including the bosch numbers in case you have the bosch system. As the othe person noted you have to go with the VALEO if it's got the VALEO system and vise versa if it's bosch. If you do have the bosch system, then most any pats store should be able toget one of those but I would expect the price to be a whole lot less as they would just have to buy from the same place as me and they do need to have some sort of maergin to work with.............

Something else to consider. A little trick I've done, so to say, for a number of my customers with "systems" in their cars. You can turn up the idle speed a little using the adaptation function when using a vag com. In your case, the car may be new enough to where you need to have a wrokshop code set in the vagcom in order to change or set adaptation values....we'll deal with that if it turns out to be the case........
Even if you install the 120 amp alternato, I would still ecommend that you crank up the idle speed just a little as it will tremendously ease the load on the alternator at idle speed when using the system.
Using vagcom, connect to the engine contol module and go into adaptations. Pull up channel one and you should see a number of "128" being displayed. That number can be adjusted fom 124 - 132 to increase or decrease the idle speed slightly. keep in mind that if you go to the maximum, you have to be more maticulous about maintenance and possible clean the throttle periodicly to keep idle adaptations faults fom settign once in a while. Basicly means keep good maintenance habits for the engine oil and spark plugs..............we'll get into more specifics if need be............

Anywho, I'll add them pics into the next post............give me a couple of minutes.......

Good luck

C

Affinitive
12-28-2008, 08:09 PM
Here's them pics

http://www.audizine.com/gallery/data/500/medium/GTI_Alternator1.JPG

http://www.audizine.com/gallery/data/500/medium/GTI_Altternato2.JPG

http://www.audizine.com/gallery/data/500/medium/GTI_Alternato3.JPG

Affinitive
12-28-2008, 08:11 PM
Whoops, that didn't work too good

Hang on, I'll ty that again..........

Affinitive
12-28-2008, 08:15 PM
OK. How about this one......Sorry about that.

Uploading images is entirely too complicated and teedious......



http://www.audizine.com/gallery/data/500/GTI_Alternator1.JPG

http://www.audizine.com/gallery/data/500/GTI_Altternato2.JPG

http://www.audizine.com/gallery/data/500/GTI_Alternato3.JPG

itln650r
12-28-2008, 08:20 PM
"Using vagcom, connect to the engine contol module and go into adaptations. Pull up channel one and you should see a number of "128" being displayed. That number can be adjusted fom 124 - 132 to increase or decrease the idle speed slightly."

i do have vag-com, but im not too familure with using it, but do you know how many rpms one digit controls? or if you know what number is about 800 or 900 rpms. its my girlfriends car and i keep on the up keep pretty well. i just need a little more insight on the 124-132 deal. i have vcds release 805. i dont know if i need an access code to get to this point, seems i need access codes for everything in this system.

Affinitive
12-28-2008, 08:26 PM
I just learned that the AWP is from the Audi TT. Another thing I just learned is that you only use a Bosch unit, so no concern. You should be able to do a direct swap with the Audi TT, as you guys have the same engine. You should post in that section and inquire.

And as for the price of the alternator, you can always find one cheaper.
http://www.mjmautohaus.com/catalog/product_info.php?cPath=2_6_17_45_115_3906&info=Bosch_AL0726X_Alternator_120_Amp_OEM_Rebuilt&products_id=938

Good luck [up]


Too bad that alternator doesn't have the pulley on it. One would also need a special tool to swap the pulley to the new unit.........if using the 120 amp unit

http://www.audizine.com/gallery/data/500/GTI_Alt_4.JPG

Affinitive
12-28-2008, 08:32 PM
"Using vagcom, connect to the engine contol module and go into adaptations. Pull up channel one and you should see a number of "128" being displayed. That number can be adjusted fom 124 - 132 to increase or decrease the idle speed slightly."

i do have vag-com, but im not too familure with using it, but do you know how many rpms one digit controls? or if you know what number is about 800 or 900 rpms. its my girlfriends car and i keep on the up keep pretty well. i just need a little more insight on the 124-132 deal. i have vcds release 805. i dont know if i need an access code to get to this point, seems i need access codes for everything in this system.

Each single digit corresponds to 10 rpm's. 10 rpm's at the crank would tanslate to far more on the alterrnator due to the difference in size of the pulleys. Keeping the alternator spinning faster means the voltage regulator would not have to go to "full feild" which in turn burns out the voltage regulator over extended periods. 9999 out of 10,000 alternator failurres are because of bad regulators...........

Get the battery and alternator deal figured out and we'll get into the specifics of changing idle speed..............

C

itln650r
12-28-2008, 08:52 PM
thats the route im going. ill have them both on wed. possibly put them in, if not theyll be in by thursday. do you know of any relearn processes on the gti??

Affinitive
12-28-2008, 08:58 PM
Just do the throttle adaptation and 5 - 10 minutes of normal driving and you will be fine.
You said the car has an automatic. Being an 03, I believe it will have that japanese built transmission which I believe does not require a "kickdown" adaptation. regardless though, it would "learn" it on it's own if it did.

A4Rob
08-17-2010, 08:35 AM
Too bad that alternator doesn't have the pulley on it. One would also need a special tool to swap the pulley to the new unit.........if using the 120 amp unit

http://www.audizine.com/gallery/data/500/GTI_Alt_4.JPG

Very true. I tried to run my 90amp pulley on the 120amp alternator. It WILL make the belt fall off over time.