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Discussion Starter · #1 ·
I would like to ask you experts how often does throttle body fail on our car. I have a 2002 turbo s, currently has 166K, the throttle body has been replaced about 3 years ago when it was at 138K and now it starts to fail again. When the RPM goes above 3000, the speed would drop and the turbo is trying hard to spool up. No check engine light, no codes, but I had a mechanic scanned it via VCDS and he stated that the throttle body does not respond to the computer and suggested it could be the electric module that's failing. The throttle body was purchased through VW dealer, not a third party part. I'm just shocked how quick a throttle body could fail. I thought it was ignition coil that's causing the problem but after having it scanned, it appears to be the throttle body. Can anyone help address/solve the problem? Your help would be greatly appreciated.
 

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We have had some members; who have replaced their throttle bodies over the years and some who did repeatably but those were aftermarket rebuilt units. I think; it is also possible with many others, that there could have been electrical problems; possibly, harness issues but these were with codes that indicated a loss of communication with the throttle body. I guess; one would have to see the data behind the mechanics statement: " the throttle body does not respond to the computer ". Most of what we are seeing; is that they work or they don't work but anything is possible.

The characteristics of the drivability problem; that you are describing, could possibly be something else. I had a long term problem; that the engine @ WOT would rev up and then the rpms would fall and then recover, like a big hesitation. In my case; it ended up being combination of a bad diverter valve and other boost related electrical valves: Wastegate Bypass Regulator Valve (N75). If you have never replaced the diverter valve @ 166k; it is most likely bad, plus other things should be checked as well (boost leaks). I tested my DV with a Mityvac vacuum pump and it held vacuum but it was sticking, that caused the hesitation issue under boost. Check out this thread; for more info and see if this sounds like your problem, be sure to check your DV. Note: I did not have any trouble codes; related to this issue.

http://newbeetle.org/forums/1-8-lit...ock-motor-apr-aftermarket-vs-stock-bosch.html
 

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Discussion Starter · #3 ·
Thanks for the information. I made an appointment with the shop tomorrow and hopefully they'll figure out what really went wrong. As for the hesitation you mentioned, my symptom was a bit different. The turbo tried to kick in but whenever the rpm reached above 3000, it immediately dropped speed and then picked right up. I hope it's boost leak instead of the throttle body. As for diverter valve, it has never been replaced. Do you know if it's an easy DIY? If I had it done by the shop, how much will it cost in general? Thanks.
 

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Yes, it is definitely a diy; there are a couple of clamps and that is it. I wouldn't pay someone to install it; it is that easy. My situation and drivability problem; sounds similar to what you are saying.

Here is a diy; showing how to do it, in this case he is replacing the stock one with a aftermarket version:

http://newbeetle.org/forums/1-8-liter-turbo/69745-how-install-new-dv-n75.html

They typically sell online; in the $45-$60 range.

OEM: 06A145710N
MPN: 06A145710N
By Kayser

Quote from a online vendor:

New and improved VW Audi diverter valve (a.k.a. 710N valve, overrun cut-off valve). The 2.7T motor needs two of these, while the 1.8T needs one. Use clamps with 23-35mm clamping range (see related products). This version was originally used on the 225hp Audi TT so it's a great upgrade for the 2.7T and 1.8T motors. Upgrades and replaces the weaker 06A145710P and 034145710B valves. This "N" version is so much better, we stopped selling the "P" and "B" versions completely.

This VW Audi diverter valve is manufactured in Germany by Kayser, Genuine OEM manufacturer. Bosch valves were prone to defects and were replaced by these stronger and improved Kayser ones.
 

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I'm sorry to interrupt, but will someone please tell me where to find the "new thread" icon so I can ask my question. THank you.
 

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Discussion Starter · #7 ·
New update: The shop scanned the car and no codes were found; checked vacuum leak and no leak was found. They test drive the car with over 3000 rpm, car ran fine, no hesitation whatsoever. They did re-adapt the throttle body, other than that, car runs perfectly fine.

As for diverter valve, I checked all options you listed and couldn't decide which is the best way to go. Any opinions? Car is stock, no mods. Should I just stick to the OEM part or an aftermarket part?

Thanks.
 

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I would stick with the Kayser oem part (be sure to get the oem KAYSER brand); 710N Diverter Valve
VW part #06A145710N, doesn't require any maintenance, like the aftermarket ones. Looks like the latest revision; is vw part # 06A145710P.

https://www.google.com/#q=06A145710P
 

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Discussion Starter · #9 ·
Thanks. I will order the oem Kayser brand from ECS or other vender and swap the old one out.
 

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Discussion Starter · #11 ·
Update: I had my timing belt job done last month at 167K, also had 710N diverter valve replaced, but the hesitation/surge upon acceleration still exists. It's like driving in higher gear when the rpm is too low. It is intermittent and only happens when I try to accelerate. One thing I have noticed is that I've been having difficulty shifting to 3rd gear in the past couple of months when accelerating fast or going up hill, it is as if the teeth in the gear isn't matching up perfectly and I would hear this horrible grinding sound, but during normal in town driving, it's shifting fine.

My question is what could cause the surge problem upon acceleration? Is it possible that my transmission is not working properly?

I had my spark plugs replaced 6 months ago with Bosch Platinum Plus, I wonder if the mechanic gapped it correctly (I asked if the plugs were gapped to spec and the response was they came factory pre-gapped and shouldn't be changed).

Other things I can think of that could possibly cause the hesitation is bad coil packs or bad O2 sensor.

Any suggestion and advice? By the way, car has no CEL and was scanned last month when I had it in for the timing belt job.

Thank you.
 

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I had long term hesitation problems and I ended up having to replace a number of valve(s) (e.g. N249, n75 etc.); that were related to boost. I would also, check for any boost leaks. Again, check out my thread:

http://newbeetle.org/forums/1-8-lit...ock-motor-apr-aftermarket-vs-stock-bosch.html

Keep in mind; that I did NOT have any trouble codes, when the dv and other valves, were in "soft failure" mode and they were working but not to the level that they needed to be for the car to run well.

As for coil packs; when they fail, the car runs badly and the cel with come on, flash. I would discount this as a possibility; as you say, the problem is ONLY when accelerating, failed coil packs are all the time and cause misfires, the engine shakes and there is hardly any power. You will KNOW, when this happens and sometimes, the car can be almost not drivable.

As for the Bosch plugs; the oe plugs that are recommended are NGK and the gap to spec is .031". You can look up the correct plugs; for your car here: www.ngksparkplugs.com

I just installed the NGK: PFR6Q NGK Part #: 6458; they work excellent and my old ones, had worn electrodes.

As for the shifting problems; you might check all your shifter bushings, check the gear oil levels (possibly change the gear oil) and try adjusting the shifter linkage. Bushings wear out over time and can cause shifting problems; check out dieselgeek for replacement bushings:

Dieselgeek Shifter Bushings

pivot corrosion problem:

https://www.youtube.com/watch?v=NPLk45AmcPk

linkage adjustment:

https://www.youtube.com/watch?v=sheTKD03hmo

For the shifter issues; pull up the shifter boot and look for anything broken or worn. Inside the engine compartment: look at the shifter ends (bad rubber or wear), you can remove them and try shifting by hand and see if there is any stiffness or problems getting into gears.
 

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Discussion Starter · #13 ·
Thanks for the prompt response, billymade.

As mentioned above, what is N249 valve? I was told by the shop that N75 valve usually throws a code when it's bad, but I'm definitely leaning toward the "soft failure" theory, especially after experiencing a few failure symptoms on the car without having codes. Does it require VAG-COM to adapt the new N75 or does it adapt it on it's own after driving for a while?

For plugs, is it difficult to replace them? I had the shop replace them a few months earlier and it cost $150 for all 4 of them.

For shifting problem, I'll probably have my gear oil replaced since the last time I've had it done was 40K ago. Is it easier to get the whole short shifter set from Dieselgeek or get the bushing replaced if it's torn?

Thanks.
 

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The plugs are not that hard to install; more time consuming, than anything. I just did mine and it made a difference but my electrodes were worn, so the gap had gotten bigger. I recommend, using a torque wrench; if available, as the threads/head are aluminum. You will need metric hex bit sockets; to remove the vacuum bracket.

There are quite a few diy's and videos: most are for Jetta/Golf/Audi but the procedure is the same, the New Beetle just has a bracket on top of the valve cover, that is a little different.

https://www.google.com/search?q=1.8...ome..69i57.10638j0j7&sourceid=chrome&ie=UTF-8

I'm disgusted to hear; how much the spark plugs cost you to change by a mechanic! Just realize, many VW shops; are getting to the over $100 an hour labor rate, so it doesn't take long to get a big repair bill! You need to start doing, many of the simple maintenance procedures yourself! You can save a TON of money; in the process and learn more about your car. :)

The valves do not, need to be adapted; the ecu will make adjustments, to adapt to the new parameters of the new parts.

As for "soft failures", I was tearing my hair out; trying to find, the culprit of my boost lag/flutter issue and all the conventional testing methods were not really helping. Most testing is more of a "works or doesn't work"; way of thinking, as noted in my thread, HEAT is another factor that we don't always think about when testing things. One thread, I was readings; was adding a hair drier to simulate engine compartment heat and then testing, to see if that made a difference.

I don't like to throw parts at a problem or waste money but for me, I did the best testing I could with my understanding and test equipment. Then, I started replacing parts; each new part, reduced the lag, boost hesitation/flutter, until it went away. The DV helped but it was still there, when I replaced the N249/N75 it was eliminated.

You need to look thing up in the manual and that way you can see their locations, do testing and start understanding how the system works.

locations:

#7 - Recirculating valve for turbocharger -N249-

#9 - Wastegate Bypass Regulator Valve -N75-

http://workshop-manuals.com/volkswa...turbocharger/component_information/locations/

testing:

DV:

http://workshop-manuals.com/volkswa...ection/charge_pressure_bypass_valve_checking/

N249:

http://workshop-manuals.com/volkswa...component_information/testing_and_inspection/

N75:

http://workshop-manuals.com/volkswa..._and_inspection/with_manufacturers_scan_tool/

As for the Dieselgeek Sigma 6 shifter; it will replace the cable ends (they are eliminated by the shifter), the whole shifter mechanism on top of the trans but the bushings under the shifter boot, will still need to be checked for damage and they do wear out, break, cause play and even shifting problems when bad. I would also; make sure, that the pivot point, is not corroded or binding. Check the dieselgeek video; for more info about bushings and cleaning the pivot point.
 

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Discussion Starter · #15 ·
Sorry, it's been two months since my last update, life has been crazy.

A month ago my car quit on me when it was 90+ degree out, it was fine on the first start in the morning but once it's been driven and parked it would only crank but no turning over. It turned out the fuel pump was failing, which was replaced and all was fine. And I also managed to get the shift linkage rubber bushings replaced and shifting is more precise now.

However, last weekend I noticed another hesitation when sitting at the lights, it felt like misfire and the car wanted to die. Finally, the CEL, EPC and traction control lights came on, which indicated a failing crank position sensor judging from my past experience. I had the car towed to the shop and for some reason the car denied scan for codes but they eventually got the codes which pointed to crank position sensor.

My question is, what could possibly cause the car to deny scan for codes? Lose wire?

Thanks.
 
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