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Discussion Starter #1
Just got this 99 beetle, didn't have power when I bought it so I knew that it had some problems. I have put on a tb kit. Cleaned intake, replaced vacuum hoses, turbo vanes seem to function correctly by pushing on actuator while still hooked to turbo. I took the top hose loose n75 there was increasing boost pressure going to turbo. The power when driveing seems to stop at about 2000rpms and does no good to increase rpms above that. I don't know yet what max rpms should be but it only goes to about 3200 rpms. Also car is hard to start, has to crank over several times to start, seems to be worse when it's hot. I do have a scan gauge and the only code I've seen is 1550 ocassionally. I know 1550 has to do with boost. What's the problem????
 

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Discussion Starter #3
I've read through the whole low power thread. Couldn't find anything that sounded exactly like my problem. Fuel filter is good. I disconected the MAF sensor and went for a drive no differnce only a code showed up P1144. MAF sensor problem is my best guess.
 

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Sounds very likely but datalog the MAF sensor if you want to test it instead of buying a new one and hoping that it's the problem. Normally, such a severe power loss is maf, boost, or fuel.
 

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Discussion Starter #5
I'm pretty sure fuel is not problem. Boost I'm sure is a problem, why it's a problem I don't know. I thought that if you had fuel and turbo wasn't working correctly there would be lots of black smoke. If the MAF was bad you wouldn't get enough fuel to build boost. How does the N75 affect fueling? Or does it just moniter boost level and control it by vacuum pressure to open or close vains on turbo.
 

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The N75 just controls vac to vnt can, it's controlled by ecu. Does not directly control fueling. You could also increase the boost, will not directly increase fueling.

Fueling is controlled by ECU. If MAF fails in normal fashion the ecu thinks there is little air so why would it overfuel? There are other problems that could cause black smoke from overfueling but a MAF which reads low isn't one of them.
 

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Discussion Starter #7
What I was thinking was if the MAF was good and N75 was bad then it would smoke. If MAF is bad and N75 is good you wouldn't get any smoke because there is not enough fuel. Also the motor rpms don't go to red line only 3200rpms so there's a shortage of fuel. N75 wouldn't restrict rpms when there is no load on motor. Would a bad MAF cause hard starts?
 

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Discussion Starter #8
Disconecting the MAF is supposed to prove if it's bad based on performance change. I did disconect the MAF and there might have been a little more power but nothing impressive.
 

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Disconnecting the MAF doesn't bring the car up to normal. It brings it up to a low limp mode power. If it's unchanged or the same, it's probably bad, although if there's a reason why the MAF isn't pulling air in like a clogged exhaust, it will mimic the symtoms of a bad MAF.
 

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Discussion Starter #10
After hearing another car like mine running, the turbo isn't spooling right. I know the cat isn't plugged but the turbo does have some build up in it. Guess I'll do a chemical clean on the turbo today and see what happens.
I guess once I get the power up to normal, I'll have to figure out the hard starting. Who knows maybe one will solve the other.
Thanks for your advice. CCBB
 

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Discussion Starter #11
Chemical cleaned turbo still no power but now I have full rpms when no load is on motor 4k+rpms. Went for a drive when I finished cleaning turbo about 5min into the drive I felt a surge of power for a couple of seconds. Mybe bad electical wires or ground.
 

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Discussion Starter #12
To many little problems with VW cars.

my two centsAfter doing hours of research and working on car my conclusion is. VW enginering is a joke. To many little quirks about wireing and mechanicals with these cars.
Has anyone compiled all the things that have been found to be the cause of limp mode or low power?
I disconected the MAF and turbo boost control valve and egr contorl valve and drove the car for 5min and never got any codes. Now that's real helpfull, codes don't show up when they are disconected how could you know if something was wrong when they did show a code. Started it up in drive with everything still disconected and reved it a couple of times and then the codes show up for everything being being disconected. my two cents
 

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Most of the causes are in the FAQ. FYi, I don't know why you didn't get any codes...what code scanner are you using? You said earlier that you know hte cat isn't plugged, how do you know this? Did you disconnect the exhaust upstream of the cat to test for this?
 

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Discussion Starter #14
I'm useing a scan gauge II, and the cat suddendly developed a hole through it. I'm going to pull the exaust pipe off and go drive it, maybe I'll get an over boost or some thing. I'm been watching MAP on the scan gauge going from 14.1 to 21 so about 7psi is all I'm seeing. I think whoever had this car couldn't find the cause of the low power and sold it.
 

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Discussion Starter #15
Went for a drive with the exhaust off. Lots of whistleing, got louder and higher pitched but still no power. About 21.1psi on map now that's from 14.1 or atmospheric pressure 7psi total boost.
While I was under car again I disconected the vacuum line to torbo, pushed the arm down into the actuator and stuck my finger where the vacuum line had been. Sucked my finger tight to it, I held it there for a little bit and then release it, I could hear the actuator pop back up from the spring pressure.
 

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Discussion Starter #16
New info

I went ahead and changed fuel filter and that didn't change anything got a new MAF and that didn't change anything either. Only thing that seems odd it at 2200-2300rpms in 2nd and 3rd I get a power surge for about 1sec. It doesn't do it everytime it goes past 2200-2300rpms thought. Makes me think it's electrical. I'm hopeing to get a VACOM dignostic this week. I'll keep you informed.
 

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Discussion Starter #17
Did get to the diagnostics done. Going to replace N75 seems the most likely problem. I am going to replace the starter to help or fix the hard starting. Cranking over to slow to fire right up. Battery is fine according to tests.
 

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Discussion Starter #18
Replaced N75 no change. Did the MAF mod, now I have full rpms all the time. A little more power from 1300-2000rpms no power till 2300rpms then it takes off. I did replace the starter and that fixed the hard starts.
 

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Discussion Starter #19
Went a road trip finally. 520mi. I found that if I went above 2200-2300rpms the computer reset and no more boost. Turn off ignition and restart boost (to 8psi.) came back as long as I didn't go above 22-23k rpms. In town the first time I ran it hard it would boost (to 13psi) above 2300rpms for a little while and then no more boost untill ingnition was turned off and back on. Did get the P1550 code intermittently.
Also since I fooled the maf I get P0101 Mass air flow implausable signal. (didn't use right diode, couldn't find right diode so used a simillar one, maybe why boost dissapears)
Also got p1248 maybe since I have a 1k resistor hooked to the pump. (Start of injection timeing contorl deviation)
I'm still studying on how to fool the MAP sensor.
 

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Discussion Starter #20
Finally figured out he problem. Turbo was bad. Replaced turbo and power is up boost is up 13+ at times. Haven't had any codes since I changed turbo.
 
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