LImped home

[Gary]

After a year of relatively trouble free motoring Vera has decided to only drive at 10 MPH without warning she lost power (Limp mode) and just got us home. Idle is ok she starts, but will not respond to accelerator inputs.
I have the leads reccomended by Phill, but there are 4 out of the obdII lead and only 3 pins in the diagnostic plug. is there a common fault or will i need to interrogate?

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Registrynr. 317

[phade]

Hiya Gary,

The only 3 wires you will need are the following:-

- +12V (red wire on 1600i diagnostics socket)

- Ground (brown wire on 1600i diagnostics socket)

- K-Line (grey/white wire on 1600i diagnostics socket)

The other wires such as L (line), K-Line 2 (second control data wire), Lamp Lead etc can be ignored.

Did you get the OBD II socket from SK Pang Electronics? If so, all you will need to do is to wire them up according to my 1600i to OBD II adaptor's wiring.

In my car's case my VAG 1552 didn't show up any faults when my car behaved like that (my car had to be recovered from the M25 in rush hour !!), but it may be a good idea to interrogate your ECU's fault memory anyway.

From the fault you have just described it looks like that either of the following could be faulty:-

- Engine oil temperature sender.

- Hall sender inside the distributor.

To check the engine oil temperature sender, you can very easily do the following:-

- Disconnect the engine oil temperature sender's plug and measure the engine oil temperature sender's resistance (engine cold). Make a note of it's resistance value (at 20 degrees C the resistance of the engine oil temperature sender should be approx. 900 Ohms).

- Reconnect the engine oil temperature sender's plug

- Disconnect the air temperature sender's plug (at the back of the throttle body at the top). Now measure the air temperature sender's plug resistance and make a note of it. The oil temperature sender's resistance and the air temperature sender's resistance should be about the same value. Reconnect the air temperature sender's plug.

- If the engine oil temperature sender's resistance is either open circuit or is of a very high resistance (eg. mega Ohms) then the engine oil temperature sender should be replaced.

- Now wiggle the engine oil temperature sender's plug. If there is significant movement from the engine oil temperature sender's socket then the engine oil temperature sender should be replaced.


To test the hall sender is more straight forward. There are two methods of doing this. The first method is documented on the 1600i website, which is the following:-

- Switch on ignition, but do not start the engine

- Rotate the alternator or crankshaft and you should hear a click from one of the injectors. This will indicate one of the cylinder's firing points.

- Repeat the process for the other three cylinders. The crankshaft should be back in it's original position.

- Switch off the ignition

The second method of doing this is the following:-

- Start up the engine

- Use a pair of insulated pliers and wiggle the hall sender's connector (but not too hard !!). If the engine then cuts out whilst you are doing this then the hall sender its self is faulty.

If the hall sender inside the distributor was proved to be faulty then the distributor must be replaced.

Unfortunately on your car (just like it was on my car) the impulse rotor (the metal disc below the rotor arm) is machined onto the distributor shaft, thus making it's removal impossible.

As for parts, both the distributor and the engine oil temperature sender are both unique to the mexican beetle. They are available from the following sources:-

- Manfred
- Atonio Trejo ( partsvw@hotmail.com ). Beware of his occasional sky high prices !!!
- VW Classic Parts Center ( http://www.vwclassic-parts.de )

The part numbers are the following:-

- Engine Oil Temperature Sender:- 113 906 161

- Distributor:- 043 905 205 N

Good luck with fixing your car.

Phil

[Gary]

Thanks Phill, I think I'll get a replacement temp sensor just in case, let the trouble shooting begin!

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Registrynr. 317

[Gary]

Hi Phill, the Oil Temp sensor was 927 ohms, but the Air temp was in the 3,000's, the reader also gave a fault code for a spurious vaccum problem. Can the ECU be at fault, the vaccum pipe holds good -ve pressure even when wiggled. I will order the oil temp and air temp tonight. There were no other codes on the ECU.

Gary

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Registrynr. 317

[phade]

Hiya Gary,

Did you check the resistances of both senders when the engine was stone cold (as in left overnight) ?

What air temperature did you measure the senders at ? If it was cold (eg. about 5 degrees C) then the air temperature sender's resistance was about right.

What sort of condition were the sockets on both senders ?

The vacuum error sounds like a perished vacuum hose or a vacuum hose that isn't fitting onto a vacuum port properly. The ECU its self very rarely goes wrong (if at all). If you are concerned about the ECU then you can remove it from your car and check all of the solder joints on it's PCB (that's what I did to mine when that error came up).

Check the ends of all of the vacuum hoses for splits, cracking or chaffing and replace them if necessary. These vacuum hoses are 3.5mm in diameter, but a 3.2mm hose (available from any motor factor) will also fit those vacuum ports.

Have you also checked the fuel pressure regulator? This could cause that symptom as well. See my testing the fuel injection system documentation on http://www.1600i.de/1600i-mechanik/FuelPumpRemovalandRe-installation/FuelPumpRemovalandRe-installation.htm for further details.

Another thing to check as well is the air filter unit for sludge (usually caused by heavy rainfall). If any sludge is present within the oil breather pipe or the air filter unit its self then the best thing to do is to get rid of that muck with kitchen towel.

Good luck with your car and happy beetling,

Phil