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Volkswagen Jetta Engine Questions



  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,412
    we need to get some codes to know where to start I think. A simple fuel test would be to measure fuel pressure in the injection rail, if you had that type of gauge.


  • iyoulowiyoulow Posts: 4
    You're correct. I just didn't want to run into a huge bill. I cut the cat out today in anticipation of the new cat being delivered Monday. Still the same issues with the engine. It is still misfiring. I still think the cat was bad but there is something else wrong as well. How do I find out if either of the O2 sensors are bad? I looked at the hose from underneath; didn't see anything obvious. If I can get the new cat installed on Monday at least I avoided having to pay someone to do that. Then I can take it in and have it looked at if no one on this board has an obvious cause for me.
  • I am having some trouble. If i hook up the alternator, it will start but runs rough and if i push on the gas, it shuts off. However, if i disconnect the alt. it will run fine. I have replaced the coil, rotor,plugs, wires, distributor, starter alt ans battery. Could someone help me with this.
  • mk4wemk4we Posts: 2
    i have a 2001 wolfie that has 140000 miles on it i run strictly shell v-power and always couple valvoline syn power 5w 40 with a bosch 3421 filter and she still drives like new i just want to encourage people to not be cheap with preventative maintenance for example YES shell is more expensive than most BUT with a 14.5 gallon tank you look at a maximum of TWO dollars more at the pump each time multiply that by 50 and it costs 100 dollars A YEAR more to run v-power than the "best price" 91 octane which is the recommended fuel i have replaced the timing network on my car as per maintenance since i have owned it and that is the extent of the cars time spent in the shop.................just a thought if you are truly a v-dub lover its the least you can do for your car
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,412
    02 sensor is hard to test. It has to be (well, should be) done with the car running and with a special type of voltmeter attached. Probably not something you are equipped to do.


  • bpeeblesbpeebles Posts: 4,085
    The O2 sensors are much easier to test with a VagCom. Just plug your laptop into your VW and run diagnostics.

    Dont forget that there are 2 types of O2 sensors. Some have a digital (on/off) type of output and other have an analog output. VW uses BOTH kinds of O2 sensors on some enginecodes.

    If you REALLY want to test out the O2 sensors, you can collect data as you drive then graph the results on the screen when you get back home.

    In the hands of a skilled user, the VagCom system can be used to efficently isolate almost any issue with your VW. I have diagnosed everything from bad MAF to burned out glowplugs and popped-off hoses. Even burned-out heated-review-mirrors can be located quickly. Faultcodes can be diagnosed and reset....etc etc.

    You can even enable/disable any of the programmable options such as auto-door locks, beep when armed...etc.
  • Update, it is the voltage regualtor wire doing this to the car.
  • I have a 2002 Jetter 1.8T. The check engine light keeps coming on. The code is P0171 running lean. One dealer had the car for three months replaced all kinds of parts. Carried to another VW dealer and they have replaced cat coverter, pulled the head and checked it (it was fine), have replaced several sensors and usually before we get home from the dealership the light is back on and with the same code. This time we drove the car for 166 miles before the light came back on, but it is back on again. I am getting really tired of it. It is getting very expensive. The car runs perfect, just the check engine light. Can you help me?
  • wow, thats a lot of money to toss into it and it not fix it. Have you tried cleaning the throttle and Mass Air flow sensor. I just put 1000 into my jetta just to find out that it is the voltage regulator wire bad, and i cant find another one. Really dont want to have to go thru the dealer if i can get out of it. A nieghbor wants to trade a 2001 dodge neon for my jetta, not sure about it though.
    Your problem could also be something in the fuel system too, always check the spark plugs gap too.
  • I have read through some of the other comments and tried the "throttle adaptation" that was discussed but it didn't really fix my problem. When I hit the accelerator my car takes off like a rocket and my tires squeal (my neighbors probably think I'm crazy) The engine seems to lope and then I loose my throttle completely. The car does not totally shut off, the throttle pedal just no longer works. This happens sometimes when I first take off and sometimes when I'm driving down the highway. Lately, it is happening non stop. I took the car into the dealer and they told me it was the MAF and oxygen sensors. The MAF has been replaced as well as both oxygen sensors and nothing has changed. The dealer also said the battery was bad so I replaced that also. I tried the "Throttle adaptation" that someone here described and it seemed to help the idle (the idle goes up and down erratically when I start the car). Does any one have any suggestions? I was going to go out and try checking on the vacuum hoses. Any input is appreciated. Also, I took the car over to Auto Zone on Friday and the following codes P1116 (Oxygen sensor heater circuit, open, P1118 Oxygen sensor heater circuit, open, P1542 Throttle actuator sensor,range or performance problem, P1545 Throttle valve actuator malfunction. Thanks to any input!!!
  • bpeeblesbpeebles Posts: 4,085
    Since "Throttle adaptation" did not seem to correct your problem. There is really only a couple possibilities left, (not the MAF nor O2 sensor that your dealership suggests)

    The P1542 Throttle actuator sensor,range or performance problem, P1545 Throttle valve actuator malfunction. are the clues.

    EIther the potentiometer in the throttle-pedal assembly or the throttle-valve actuator itself is your problem.

    If you are on a tight budget, any scrapyard should have both of these components.

    Personally, I would remove and throroughly clean both of these components and then do another "Throttle adaptation" BEFORE spending any money.
  • jkartcrazy, thanks for the advice, i will try this again. And the other problem is the voltage regualtor wire, it went bad and i cant seem to find the little wire anywhere.

    Will let ya know how the cleaning goes.
  • For my 2000 Jetta, not VR6 but 2.0, catalytic converter was recalled and replaced by VW- I hope you didn't pay for replacement! Check into it!
  • bpeeblesbpeebles Posts: 4,085
    Lets not forget.... on a 2000, - recall or not - ALL the emmissions-equipment is coverd for 10-years/ 100,000 miles by federal law.

    The catalytic converter is part of the emmissions system and is thus covered by this federal law.

    so... when we say "check into it"...we really mean READ YOUR FEDERAL EMMISSISSONS WARANTEE!!
  • I was wondering if anybody knew the price range to get new turbo in my 2001 VW Jetta. The turbo that is in there right now is going out and is making a really nasty noise when the turbo should be kicking in. I received an estimate and they told me it would be about $1,000 to have it fixed. I was wondering how hard of a procedure is this to do and why does it cost so much? I know nothing about cars and I already had to spend about $2,800 to get it fixed because my timing belt went out and messed up all the valves... I am so disappointed. :sick:
  • bpeeblesbpeebles Posts: 4,085
    This is what I suspect happened... when the TimingBelt broke, the pistons crashed into the valves and some debris from this collission got into the exhaust thus damaging the turbocharger.

    If you continue to drive it, and the turbocharger decides to self-distruct... then pieces from it could get sucked into the engine thus damaging the engine again. (It is a visious circle)

    Here are several online websites that specialize in Volkswagen parts.
  • jeffyscottjeffyscott Posts: 3,855
    I know nothing about cars and I already had to spend about $2,800 to get it fixed because my timing belt went out and messed up all the valves.

    You don't need to know all that much to avoid problems like this. You really just need to follow the maintenance schedule. It is in the owners manual, if you don't have one you can also find the schedule on That schedule would include replacing the timing belt, had you done that you'd have saved at least $2000.
  • bpebbles, thank you for your input. I had all of my codes erased(which had not been done since the MAF and O2 sensors were replaced. I did the throttle adaptation but it didn't last very long (5 min) and it now only threw two codes, the P1542 and the P1545. I have taken out the throttle pedal assembley and cleanrd the potentiometer and will be getting that back in the car this morning. One other question however dawned on me as I've been reading. I have also replaced the battery recently. Could that be messing up my throttle control module? I have read that it the ECM needs to be reset to it's basic codes after a battery replacement? If so, how do I get the basic codes and do they come with a Scan Tool if I purchase one at Autozone or other auto parts store? Thanks for any input!!
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,412
    that's not a bad price to replace a turbo. Even if you took it off yourself and shipped it out for a rebuild, that would cost maybe $350. Not sure about labor rates to R&R this. I would think an independent shop might be able to do it somewhat cheaper.

    Sounds like you need to step up the maintenance on this car. I hope you are using synthetic oil on that particular engine.


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