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Discussion Starter · #1 ·
Hi,
I drive a New Beetle Bj.2004 with an unchipped 1.8t (AWU and 175 tKm). For years I have the following problem. When I drive off and get on the highway, pretty much after about 10 minutes of driving, the engine cuts out for 1-20 seconds. This announces itself as follows: it starts to jerk briefly and then dies off. It feels like stepping on the brakes. I then let it roll with the gear engaged as it resumes after 1-20 seconds (jerks first and then starts). Per trip (round trip), this usually only happens 1-2 times and never in city traffic. To be precise, if I first drive 10 minutes in the city and then on the highway, this error does not happen. The error memory is empty, of course.

I have already tried the following:
1. While driving, I have VAG-Com display the readings for the (electric) throttle (opening angle), accelerator pedal position, injection timing and ignition timing. When this error occurs, I give e.g. full throttle and in VAG-Com the values change accordingly.

2. When the error occurs, I switch the ignition off and on again (with gear engaged) => can not be started.

3. I measured the current consumption of the fuel pump in idle for about 15 minutes, because I have the feeling that it doesn't get any fuel => constant 5.8 A and no loud noises from the pump (only a quiet whirring).


The car also has the following errors. Maybe this helps:
1. The idle current after 30 minutes of parking is about 120 mA => should be about 20 mA.

2. The car can only be helped to start via the door lock (silver counterpart on the frame). If the ground terminal is connected to the engine block for example, this will not work. I have already measured with a multimeter. There are 0.01 ohms between the engine block and the ground terminal of the battery.

3. Even with a new battery, the starter does not turn as rich as before.
 

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Well, you might try doing some traditional testing; that may help pinpoint he problem, for example a fuel pressure gauge and use a tie wrap, on the wiper arm, etc. This could help you see the pressure; as you drive the car.

For live data: watching fuel trims might be good to view as well with + or - 10% being considered in the normal range.


Many fuel pumps, start malfunctioning; as they get hot, when the fuel level is lower, making them overheat faster and can cause the engine to cut out on the highway, die and cause a hard or no start condition.

If the charging system is suspect; a whole system test, would also, make sense.



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Fuel pressure specs and testing:


If you end up needing a fuel pump; stick with oem quality pumps, we have found Bosch and VDO, to provide solid performance, while cheaper aftermarket versions cause drivability problems. While, replacing the pump; be sure to replace the tank seal, filter and fuel pressure regular as well.

The Bosch pump, is a better bang for the buck; as it includes, a integrated fuel level sending unit and a replacement tank seal.


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Discussion Starter · #4 ·
Don't you think it can be a voltage related issues because of a bad engine ground connection? A few months ago, I had problems with flickering lights. The solution was to replace the secondary air pump, which had too much initial current because of faulty bearings.
 

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It could be many things; hopefully, some testing, when the problem happens, can help you pinpoint the issue.

The video has great testing info; for charging problems and other typical related issues.

The other symptoms, sometimes are typical; of a failing fuel pump and so, testing that, is worth checking as well.


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Discussion Starter · #6 ·
Ok, I will start with charging system. Do you know where are the ground connection of the engine block, the starter and the ground connection of the battery to the chassis?
 

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There are lotz of grounding points in the car but one of the main ones that i know causes issues is the chassis ground under the battery tray. there's one on the tranny near the shift cables and one behind the drivers headlight. Those symptoms you are describing can be caused by the fuel pump relay also. There is also a signal that comes from the drivers door to the fuel pump relay and i believe it disables the relay just in case of a crash.
 
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