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Discussion Starter · #1 · (Edited)
Okay, I have had the car for almost two weeks. 1.8T 2003 B5.5. No CEL on, Car starts right up with the key turned, smooth idle and looking at the RPM gauge it's very steady at idle. Seems in the mornings when the car is cool it accelerated smooth and good power, but after the engine warms up or been driving for a while I have to push the pedal down at least half way to get good acceleration, it I push it further it takes off really fast. I live in Phoenix and as you know it's hot as hell here, 106 today. The car has 101K, Timing belt and water pump just replaced as well as cam and crank shaft seals, and two new axles. No oil leaks as far as I can tell. Temp stays right in the middle. The mechanic that did my brakes last week took it out right after and when he came back says I need new plugs as he was feeling the power loss. I realize it can be many things, I hope it's no issue with the Turbo... He will be replacing the plugs with the OEM NGK's next weekend as well as a new PCV and air filter. Do you think it may be another issue?. The car has been well maintained as the exterior and interior of the car is immaculate as well as the engine bay, very clean. This is my first VW so I am learning that Maintenance is critical on these cars, I knew that it would be somewhat costly to maintain but did a little homework before buying and also had a mechanic take a look before I bought it. After I figure out the power issue I am going to have all the fluids flushed as I don't know what the previous owner has done. Thanks for any input and advise.
 

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I doubt the power loss is spark plugs; you should be getting a CEL if they're misfiring that badly. Still, if they need to be changed, do it. Most times, though, a loss of power translates to a loss of boost - whether diverter valve, intercooler problem, boost leak, or turbocharger remains to be seen.

Also, on your engine the PCV system is fairly complex - you don't just replace "a" PCV valve, you service the components of the PCV system. Do you have a part number for what was replaced?
 

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Discussion Starter · #4 ·
The acceleration issue is mostly from a stop and after about 25mph it will boost smoothly. Seems to act-up the hotter it gets, Accelerating when the car is cold is very smooth with very noticeable boost and power. I will post back after the NGK PFR6Q plugs get installed
 

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I agree with Scott that the plugs won't be the problem. If they are lighting the charge on all cylinders, every time, new plugs won't change anything. A boost gauge, even a temporary hookup, would be helpful.
 

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Discussion Starter · #6 ·
Land vehicle Vehicle Car Alloy wheel Volkswagen
I decided to test the power issue with no A/C, Believe it or not I have ran the A/C full blast here in Phoenix it's really hot, so today I took off out of my driveway with the windows down and no a/c, the car has absolutely no power issues at all. The boost kicked right in even with somewhat light acceleration. I drove around for about 2 hours with no a/c, and no power issue at all. Smooth acceleration, good turbo boost. There still may be a problem but ruining the car with the A/C off is a totally different driving experience. I'm still going to do the plugs cause it has 101k and they should be changed.
 

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I have this issue as well. I even resort to turning the AC off when at a stop before the light turns green so that I can get some of that acceleration back. I also tried switching to an electric fan instead of the belt driven fan yet that did not seem to help the problem. Maybe someone else can give us some clues as to how to mitigate this. I feel your pain though. I live in Georgia and while it doesn't get nearly as hot as AZ, the humidity will make you sweat through to your seats.
 

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There's not much to do about this cost of horsepower. The AC compressor uses circa 10 HP by itself; and the AC raises under hood temperatures somewhat, expanding the charge air at least a bit. On my Passats, the loss of power is noticeable, but not dramatic. More so on the 150 HP ATW engine in the 2000.
 

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You may want to check your battery and alternator voltage when the a/c is running. If it is low, it can affect engine output.
 

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I have a full-framed GT28RS turbo and a front mounted intercooler installed yet it is still noticeable to me! Especially when the turbo is not fully spooled. I think it is just parasitic drag from the compressor like scotts13 said but what PZ said also makes a lot of sense. I know some Passats came with a 90 amp alternator while others came with the 120 amp. Maybe those running the higher amperage alternator do not feel it as much...?

Passat2016, do you feel a loss of power with the heat on? I do not. It is only with the AC on cold.
 

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I know some Passats came with a 90 amp alternator while others came with the 120 amp. Maybe those running the higher amperage alternator do not feel it as much...?
The 120 Amp alternator can absorb more power from the engine than the 90 Amp, so if anything, the higher output alt could cause more drag. But even working at maximum output, say with a dead battery, the 120 Amp is only taking about 2.25 HP to run. The 90 Amp is just around 1/2 HP less.
 

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Discussion Starter · #13 ·
Temp's have been down today in the mid 90's, you may say wow that's still hot, but not for us here in Phoenix, Windows down most of the day, Drove the VW morning up to about 1pm with no A/C and no power issue at all. I have also been looking at this inner cooler thing on the 1.8. I am learning about all of the regular maintenance things that need to be done on my car, so bare with me. I am going to have the coolant flushed next week with some fresh g-12, and I asked about flushing the inner cooler and they said the flush does not include this. What do I need to do to be sure that the stock inner cooler is operating normally, or what maintenance needs to be done on the inner-cooler?
 

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The 120 Amp alternator can absorb more power from the engine than the 90 Amp, so if anything, the higher output alt could cause more drag. But even working at maximum output, say with a dead battery, the 120 Amp is only taking about 2.25 HP to run. The 90 Amp is just around 1/2 HP less.
Good info. I didn't know the drag of the alternator was so low.

When the AC kicks in, the engine is going to have to work harder to provide the power to the condenser. I feel this sometimes on my AEB with the 90 amp alternator. The engine will rev up a little at idle when the AC is on. I'm wondering if the 120 amp alternator can provide enough power at idle that the engine does not have to do this. I think this would mask some of the performance issues I've noticed with the AC on cold. It's just a theory. I'm not going to swap alternators over this.
 

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What do I need to do to be sure that the stock inner cooler is operating normally, or what maintenance needs to be done on the inner-cooler?
The stock intercooler is an air to air intercooler meaning that the charge air coming into the engine is cooled by the outside air passing over the fins of the intercooler. So there isn't any fluid that you have to service with it. Make sure that the fins are free of debris though. You can check it by looking at the driver side of the front of the car. There is a plastic cowl that scoops air into the intercooler fins. To clean the inside of the intercooler is difficult because of where it is located. You have to put the car into service position so that you can remove the intercooler and even then it is difficult to remove. You could try removing the intake hoses that go into the intercooler to see if there is any oil in the intercooler. I hope that helps.
 

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Discussion Starter · #16 ·
Great info Mr. Smiley, I had kinda read up on the inner cooler and I read that it can become blocked with leaves, derbies, etc .. I was confused about coolant running through so I guess it's a totally separate system. When I do my 4200k fog lights I can have a look in the drivers side area, under the fog lamp panel? I am pretty sure (as you read the first part of this post) that my Turbo is working good, so I can scratch that and go on to flush all the fluids and install new plugs.
 

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INTERcooler, not INNERcooler. There should be no way for it to be blocked with "leaves and debris", you're thinking of something else. It's fairly normal for a small amount of oil to collect there (maybe a tablespoon or so); more, and you have a turbocharger oil seal failure. Anything else in there and the boost pipe isn't connected and you'll have almost no power at all.
 

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Discussion Starter · #18 ·
So here I am a week later. excuse the French but I'm really Freaking disappointed. I started this thread over a week ago, and also searched the forums for power issues in hot weather, and I have read all of them. To sum it all up, bottom line is this 1.8T has serious power issues when running the A/C in hot weather. I almost didn't make it through the intersection after flooring my car, very dangerous I have to say. Most of the posts I have read are stating that this is normal. There is no way these cars came off the assembly line with this issue, otherwise no one would have brought the cars. Let me say, I don't have an issue with the temps below 90, even running the A/C, but in stop and go traffic, it sucks. My Saturn SL1 SOHC was way faster than my Passat. I know they test cars in the Serra Desert. As you all know it's darn hot here in Phoenix 6 months out of the year. We have to run our A/C's here when the temps are 105 and above, but I'm afraid to drive this car. I guess I have to take it in to see if there are any issues with the turbo because it does not operate with the A/C on. What is the fix for this? and It can't be normal. The car has great turbo boost when cool out side, so I am assuming if it did not have great boost when cool there would be an issue with the Turbo. What is the FIX for this.:banghead:
 

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I'd suggest that you check the MAF readings with and without A/C on, at idle, and also throttle percent in both cases. Post those and see if someone can compare what their car measures. Perhaps there is some serious resistance to turning that A/C compressor. Another thing I'd consider trying is disconnect the A/C clutch wire, and then turn on the A/C (without the compressor actually running) and see if you still get the power loss.
 

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Discussion Starter · #20 ·
Just got off the phone with a guy that works on VW's, he was refereed to me by a friend and he is going to do a Boost leak test next week. At least I can start there. BTW still have not got the new plugs in yet.
 
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