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Discussion Starter #1
Hey guys, same as the title says. I recently did the Blend Door fix to try and get some cool air flowing and noticed my compressor isn't turning on at all, however I'll hear the engine start working harder or something when I hit the AC button. I also had my intercooler pipe put back onto where it belongs to fix a really bad hissing issue, but i still hear a slight hiss on heavy acceleration, however not nearly as bad as it used to be. Lastly, I have a rough idle on startup and those two error codes. I just replaced the spark plugs and am having the same issue, but the CEL hasn't come back on yet. I'm trying to save money so I was going to do a smoke leak test, and figure out the AC myself, because I don't think anyone else will be able to help me and the VW mechanic I like isn't available for 3 weeks. Anyway, any help is appreciated. Thanks!
 

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Looks like you have a specific misfire; for cylinder #3. You replaced the spark plugs; was there any oil on the top of the plugs, when your removed the old ones? If there was, the inner valve cover gasket; is probably leaking and these can cause misfires, eventually kill off coil packs (grounding out). If it is leaking, replace it with a quality gasket set, from brands like Felpro, Victor Reinz or Elring.

Otherwise, you might change the location of the coil pack and see, if the misfire trouble code, travels to the new location (e.g. #3 coil pack to #4 cylinder; then, you end up getting a p0304, indicating a misfire in cylinder #4). If this is the case, then you have a bad coil pack; stick with genuine vw coil packs (or equivalent oem: eldor, bosch, bremi, etc), do not buy typical aftermarket versions sold at most auto parts stores, they will prematurely fail.
Beyond that, you could have a compression issue, clogged or malfunctioning fuel injector, etc. Read the ross tech misfire code definition; for a list of things to check.

As to the a/c issues; you need to confirm the clutch is engaging. There is a common problem with the fuse panel; on top of the battery, the a/c compressor fuse will get hold and end up not making good contact.


Beyond that, I would hook up some gauges and see what the high, low side freon pressures are. There is a issue, where the compressor will kick on but the internal pressure valve sticks open (failure), causing low pressure in the system (the pressures tend to equalize on the low/high side).


These are just two common issues; there can be a wide range of possible things, as to why the a/c isn't working. You might check out this thread; for troubleshooting technqiues, testing steps to possibly find the problem.


For new beetle specific service manual info and testing steps, here are some free online manuals here:


For the boost/vacuum leak; there can be a wide range of areas/hoses, that can leak and cause a hissing sound. You might get a helper; to rev the engine and you could try to find the source of the hissing (a piece of hose to your ear or a mechanics stethoscope, can help isolate the source of the sound).

So, there are some things to try; let us know, the resutls of your testing, troubelshooting things and we can go from there. Thanks.
 

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Discussion Starter #3
Hey there,

So I did what little I could today, and found that upon pressing the AC button and running the internal fans on high, the coolant fans did not run. They only ran after i had driven the car in high heat for a while. This tells me the culprit may be the fuse box on top, or the Fan Control unit.

As for the coil packs, there was no oil when I took the plugs out, and I can't get the engine light to come back on even when switching the coil packs, so something tells me those aren't the culprit. I have yet to have time to test for vacuum leaks, which was the next most common cause of those codes.

Any thoughts so far?
 

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For the a/c: you might check the fuse in the battery top fuse box, sometimes cleaning the fuse contacts, bending them for better tension, can be a temporary fix.

So, is it still running rough and misfiring? What scan tool are you using? With VCDS/OBDeleven, you can view a misfire counter but typical obd II scan tools, there should be a trouble code, being read.

(Later 2.0T shown but principles are the same):


What have you done; to check for misfiring in #3 cyinder, aside from new plugs?
 

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Discussion Starter #5
For the a/c: you might check the fuse in the battery top fuse box, sometimes cleaning the fuse contacts, bending them for better tension, can be a temporary fix.

So, is it still running rough and misfiring? What scan tool are you using? With VCDS/OBDeleven, you can view a misfire counter but typical obd II scan tools, there should be a trouble code, being read.

(Later 2.0T shown but principles are the same):


What have you done; to check for misfiring in #3 cyinder, aside from new plugs?
Not very much, I just did the plugs and a visual check, I havent had the opportunity to test the coil packs themselves, and I only have a generic OBDII scanner right now. I'll look into the AC this weekend, see what I can get into.

Again, it only ever runs rough on startup for about 2 minutes, then stops. Its more of a small surge every couple seconds 2 or 3 times, then it smooths out and I don't really seem to have any other problems afterwards.
 

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If it is only at a cold start, rough idle and hesitation, then goes away once it reaches normal operating temps, it could be a bad coolant temp sensor. That issue, typically throws a specific trouble code; from what you are saying, it is only a #3 cylinder misfire code at this time? Meanwhile, I would swap the #3 coil pack to a new cylinder and then, you can check, to see if the misfire trouble code, moves to the new location.
 

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Discussion Starter #7
If it is only at a cold start, rough idle and hesitation, then goes away one it reaches normal operating temps, it could be a bad coolant temp sensor. That issue, typically throws a specific trouble code; from what youu are saying, it is inly a #3 cylinder misfire code at this time? Meanwhile, I would swap the #3 coil pack to a new cylinder and then, you can check, to see if the misfire trouble code, moves to the new location.
Hey again, so I swapped around the coils and didn't get any specific coil issue, just the P0300 Random Misfire, which I think may just require new coil packs, so I ordered them in. The AC is likely the Fan Control Unit as the fans don't come on at all when the AC button is pressed, and the loud whirring noise on startup I've determined to be the secondary air pump since the fans aren't on at all when the noise starts.

My only thing now is the turbo boost hiss/leak, and the vacuum leaks. Where do I start with doing a smoke test? I don't know where I should specifically be blowing smoke to get results, and the boost hiss I don't know what could be causing that.

Thanks!
 

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The random misfire code; may or may not be the ignition coils, when a specific coil fails, then it typically shows a specific cylinder as a misfire. Most misfires we see, typically come down to ignition or fuel delivery related issues. For the fuel side of things, you might look at your live data for fuel trim, see if they are in the normal range (+ or - 10%); a larger unmetered vacuum leak, could cause misfires or a weak fuel pump/pressure, etc.
Good info here; from ross tech:



On the new coils, what brand did you purchase; be sure to buy oem coils like genuine vw or oem bremi, eldor, bosch, etc. We have seen aftermarket coils; sold by your typical auto parts store, cause problems out of the box and prematurely fail.

For the fan issue; I would be following the specific testing procedures, check for voltage, etc; as noted, fan control modules, have been known to fail. Jumpering the pressure switch; at the a/c, is one way to bypass the a/c system, as a check for fan operation isolating the compressor. I would be checking the basics: hook up a pressure test gauge kit and see, if the freon is in the normal range on the low/high side of the system, as a low freon condition can cause the compressor to not kick on. You can typically rent a a/c gauge set; from your local auto parts store and save money that way, confirm the conditions that need to be met for the a/c to operate normally. Other issues, such as a bad compressor clutch, bad internal pressure valve; bad compressor, many other things could be a issue, more testing is needed.

As to the pressure and smoke testing; you might check out some of these videos for testing procedures:




Most show the use of making your lown smoke test kit and using plumbing parts, soup cans, to block off things like the rubber intake hose from the airbox, etc.

Let us know, how the results of your testing, troubleshooting, parts replacements turn out and we can go from there. Thanks.
 

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Discussion Starter #9

The random misfire code; may or may not be the ignition coils, when a specific coil fails, then it typically shows a specific cylinder as a misfire. Most misfires we see, typically come down to ignition or fuel delivery related issues. For the fuel side of things, you might look at your live data for fuel trim, see if they are in the normal range (+ or - 10%); a larger unmetered vacuum leak, could cause misfires or a weak fuel pump/pressure, etc.
Good info here; from ross tech:



On the new coils, what brand did you purchase; be sure to buy oem coils like genuine vw or oem bremi, eldor, bosch, etc. We have seen aftermarket coils; sold by your typical auto parts store, cause problems out of the box and prematurely fail.

For the fan issue; I would be following the specific testing procedures, check for voltage, etc; as noted, fan control modules, have been known to fail. Jumpering the pressure switch; at the a/c, is one way to bypass the a/c system, as a check for fan operation isolating the compressor. I would be checking the basics: hook up a pressure test gauge kit and see, if the freon is in the normal range on the low/high side of the system, as a low freon condition can cause the compressor to not kick on. You can typically rent a a/c gauge set; from your local auto parts store and save money that way, confirm the conditions that need to be met for the a/c to operate normally. Other issues, such as a bad compressor clutch, bad internal pressure valve; bad compressor, many other things could be a issue, more testing is needed.

As to the pressure and smoke testing; you might check out some of these videos for testing procedures:




Most show the use of making your lown smoke test kit and using plumbing parts, soup cans, to block off things like the rubber intake hose from the airbox, etc.

Let us know, how the results of your testing, troubleshooting, parts replacements turn out and we can go from there. Thanks.
Alright, I managed to replace the FCM today which instantly fixed the AC issue and turned on the larger of the two fans. The smaller one is not turning however, and I rotated it by hand and noticed it didnt free spin at all. I will likely need to replace that as the bearings have definitely gone bad, which hopefully won't be a big problem.

The car also starts much nicer and runs smoother with new coil packs, though I still smell a slight gas fume smell on startup with that. However, I found no vacuum leaks, so until the CEL comes on I'll have to just deal with it.

How hard is it to replace the fans myself?
 

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I replaced the passenger side fan on my 2002 new beetle; i went through the bottom but the car was on a lift. The oem fans for VW; were made by VDO and it was doable without removal of the shroud. I got a VDO fan and it was identical to the original. VDO sells the individual fans or the whole assembly with the two fans and the shroud. If the other fan is old and worn; it might be worth replacing both. Check amazon (usually free shipping) and rockauto, fcpeuro has a lifetime warranty on all their parts; you can look up the right part numbers, for your particular application here.

 

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Discussion Starter #11
Hey all, I'm just updating with some new unique things.

First off, I got the error code P0030 after I got the beetle APR tuned, which is the O2 sensor which needs replaced anyway. Will an O2 sensor cause crappy gas mileage and acceleration slowdown?

Next, ive noticed that normally my cooling fans will cycle on and off like the car is breathing, and lately the AC has been shutting off and on (I hear the refrigerant hiss through the expansion valve and then stop) and after I turn off the car the fans aren't on and the AC doesn't sound like it depressurizes. Is the FCM I got bad already? It was a cheaper 20 dollar one off Amazon but I couldn't really find any exact OEM matches.

Thanks!
 

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Discussion Starter #12
Another thing to note, at idle the AC will produce the loud hiss, then the compressor shuts off, then starts again, and i only get cool or warm air. Then at speed it stays consistent and cold. Whats the reason behind this? Thank you.
 

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You might check the wiring and a basic continuity test of the 02 sensor heater circuit; if bad, replacement is required. Stick with a quality oem sensor from Bosch.

For the a/c, have you hooked some gauges and checked pressure ( most auto parts stores; will rent them for free)? As to the fan control module; like so many parts on these cars, we have seen problems with aftermarket versions, causing problems, not working or prematurely failing. I believe, the oem is by Stribel. Did you replace the bad cooling fan? The passenger side one; can definitely, affect the performance of the a/c condenser, so both fans should be working as they should, for best a/c performance. I noticed a improvement; in a/c temps, when I replaced my passenger side fan, that was failing.

What year and model; is your 1.8T New Beetle? We can give you some links; to 02 sensor testing info, from the service manual.
 

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Haven't had a chance to rent gauges yet, but I will soon. Now for the O2 sensor since I've had the original for 107634 miles, it's likely due anyway, so I'm planning on replacing it either way. I was just curious to know if that may have been causing bad idle and acceleration problems
 

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The history of your car and the repairs, adding of the APR tune, has added allot of variables to things. Tunes, tend to exacerbate; problems, that existed before the tune, as they add more stress on the engine and the turbo/boost systems. Ideally, it is recommended; to get the car running correctly, before adding a tune. I don't know, if you have the APR "Program Switching" capability but switching between the stock and upgraded software map, is one way to check things while troubleshooting. Tune's typically, increase boost levels substantially over stock; so, if you already had a boost leak/hiss noise; it makes sense, the tune caused more boost problems and in worst cases, will kick things, into limp mode.

As to the 02 sensor; I replaced my B1S1 sensor with a correct oem Bosch version, my acceleration, fuel trims, gas milage improved but the car was running ok, overall and I just replaced the spark plugs as well. There is a whole list of things; that can impact performance, covering all the basics and checking everything, to rule them out, can take time and multiple troubleshooting sessions, to get these pesky 1.8T's to run right in stock form, then the added variable of a APR tune, adds more complexity to things.

After you test and replace the 02 sensor; you might want to go review, all the things you have done and we can re=evaluate things and you can tell us, how the car is running currently.
 

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Will do. I've taken care of all the previous issues, so now I have to focus on the O2 sensor and the AC for now, and report back.
 

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Discussion Starter #19
My bad, I have a 2004 VW Beetle Turbo S, with engine code AWV. 1.8, 20V engine. 107730 miles.
 

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02 sensor testing info; advance pages, goto bank 1 or 2 sensor and "generic obd II" testing pages:

 
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