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Discussion Starter · #1 ·
Heres the story. The car is a b5 99 manual 1.8T with 195K Km, chipped with APR, K&N cone filter and the 710N DV. I have noticed in the past couple of weeks that the car doesnt accelarate the way it used to. In the past 2 month i have changed the timing belt, fuel filter and the spark plugs. Also my catalytic converter broke about a month ago and my mechanic was able to weld it back with no problem. I Cant seem to figure out what is wrong with the car. It feels super slow. My sisters freakin 92 accord is faster than mine. anyways i changed the vaccum lines also so i doubt there's any leak. somebody from passat world recommended i go try a b5 at the dealer and see how it feels compare to mine. So i finally found one yesterday and Omg whata huge difference. Stock b5 ran better than my chipped B5. My luck i received the boost gauge that i ordered yesterday and installed it this morning. With the chip i get about 18-21 in vac when in neutral. The maximum boost that i got was barely 9lb. so i figured maybe the chip is faulty and i put back my oem ecu. Got the same vac numbers but the max boost was like 6lbs. so now im lost completely and dont know what to look at anymore. Could my cat be blocked or something? how much of a difference will it make? I need advice guys.
 

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Discussion Starter · #7 ·
I also forgot to mention that the mechanic checked for codes and nothing came up. He didnt use a vagcom dont know if it makes a lotta difference, i have no check engines or anything anyways.
 

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With no codes, full vacuum (18-21 inHg), and moderate boost (9 lbs), this one's going to be difficult.

Possibilties that immediately come to mind:
Bad N75
Bad Wastegate
Clogged CAT (maybe during the break and repair some of the substrate broke loose, or some debris got in).

The first thing I'd do is eliminate the turbo/wastegate as a source of the problem. Do this at your own risk, but disconnect the vac line leading from your N75 to the wastegate. This will eliminate ECU/N75 control of boost, and you will be full boost all the time, so go easy with the right foot. If you get high boost out of this test, then your wastegate and turbo are OK. If you still have low boost with the wastegate line disconnected, then it's the wastegate, the turbo, or a really badly clogged exhaust.

Again, the stuff above is in the absence of codes. Access to a VAG-COM is priceless - it's more than just error codes. Fuel trims, for example, can tell us a lot.
 

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Discussion Starter · #9 ·
Thanks Rusty, I took an appointement for tomorrow to go and see if its the turbo or maybe the exhaust. Ill let you know as soon as i know something. Btw how much boost will i get with the wastegate line disconnected?
 

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Enough to go BOOM.
 

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Enough to go BOOM.
Yes, enough to go BOOM. :lol:

That's why you have to be very careful. Since you are chipped, it's not nearly such an issue. But your boost will be directly controlled with your right foot. It will be entirely up to your right foot what the boost gauge says. Keep your right foot connected to the boost gauge, so that the boost gauge does not read more than what your chip is designed to give you.
 

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Discussion Starter · #12 ·
OK so i went to the garage today and again another dissapointing day. We disconnected the pressure hose from the n75 to the wastegate and i took the car for a drive. The most boost i got was 7-8 lbs not even the 9 i got 2 days ago with the chip.(Im running the oem ecu right now) So once again im stuck. My guy is gonna try to remove the cat on monday and see if its really clugged up. Will a clugged cat make sucha big difference anyways? Do you guys think my turbo might be done? I mean it still boosts up to 7-8lbs.
 

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Discussion Starter · #13 ·
Guys i need ideas for tomorrow, the car is going back to the garage and i would like to know what else i need to check. BTW the car has a little hesitation now around 2200rpm and it sometimes the rpm drops low to 600-700. anyways let me know guys.
 

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Discussion Starter · #15 ·
I dont remember exactly but i think around 3000-4000 i reached full boost. Also the car pretty much dies out and it begs me to shift around 5500rpm in every gear. the other car i test drove the other reached 7000 with no problem. Im not planning on redlining my car but i feel like i have a freaking cutoff or something. i thought it was the spark plugs till i changed them and didnt notice any difference.
 

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If your turbo only gets 7-8 lbs with the boost line disconnected, then you have a bad wastegate or turbo.

I doubt the CAT is clogged enough to cause this, but I suppose it could happen.

I think you're going to have to trust your mechanic.
 

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If your turbo only gets 7-8 lbs with the boost line disconnected, then you have a bad wastegate or turbo.

I doubt the CAT is clogged enough to cause this, but I suppose it could happen.

I think you're going to have to trust your mechanic.
Rusty, couldn't his extra boost be pushing its way out through the diverter valve? If the vacuum hose to the diverter valve is busted, then the only thing controlling when it opens would be the spring, and I believe the OEM diverter is rated for 8lbs.

Also, if his alignment is toed-out really far, isn't it entirely possible that he wouldn't notice any handling problems but he'd still be scrubbing his horsepower into the pavement?
 

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Discussion Starter · #18 · (Edited)
the thing is i have the 710N and i doubt that it is leaking. Anyways for the HP problem that i have he still didnt get a chance to check the wastegate actuator and see if it moves easily. if its not then We're gonna change the cat. Hate to spend 500$ just on a freaking cat converter.
 

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Same problem

I have a '98 1.8t, 5sp with 217k miles and have the exact same problems as you describe. I am chipped (.08bar) and also have 710N. I have a cel code (P0422 Main catalyst efficiency below threshold (bank 1) ).

My car is operating at about 50% right now. The engine still runs and revs smoothly but I have no power, it takes a while for me to get up to highway speeds. I can't even redline it in first gear. Very frustrating. I do believe it is the catalytic converter, in my case anyway. I have never replaced the PCV system and I believe it is the primary cause of the clogged cat. I'm looking at options now, maybe an excuse to replace the entire exhaust. Keep us informed, please. Good Luck
 

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Same Problem

Getting the P0422 code, and poor acceleration. Also getting a P1136 code (Fuel Trim: Bank 1 : System too Lean). I have not measured the boost, but I suspect it is low. Please let us know what you find.
 
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