Poor running problems on bug

[mazmich]

Hi can anyone help.
I have a 1997 Mexican beetle 1600i with fuel injection. Struggles to start from cold and then when it is running it has a flat spot just off idle. It idles okay and drives okay once you are over the flat spot. It almosts dies when you accelerate. So far we have changed the idle stabbiliser, had the injectors sonic cleaned, complete service including leads, cap and rotor etc. All pipes have been checked for air leaks and reclamped. We dont have any garages near us that have the equipment to diagnose. We have swopped the hall sensor for another 1600i beetle which we have and is okay. Fuel pressure is fine.
Many thanks for any help or advise.
Location Warwickshire in the UK
Michelle

[phade]

The first question I'll ask is have you checked the condition of the vacuum hoses and pipes ?

The (cheap) plastic vacuum pipes themselves fracture over age (one of the pipes on my car shattered into 3 pieces as soon as I touched it). They will be the very first things to check.

Also check the resistances of the oil temperature and air temperature senders when the engine is stone cold. They should be about the same as each other.

Another quick note as well. If you had replaced the HT leads with Bosch ones then it would be a very idea to change those back to the old ones. I used to run a set of Bosch leads on my ones until the spark plug ends started to fall to bits after only approx 12,000 miles (they contain carbon film resistors rather than metal film resistors).

When one of the spark plug ends failed on my beetle, I ended up with oil steam from the engine (I thought it was a slow puncture at first until I tried to pull away from a motorway junction).

[nopap]

Hi,
If you have another 1600i around, try to swap the Digifant ECU to see if the problem disappears.
I had a similar erratic idling problem on mine, checked everything without success, from vacuum leaks to fuel pressure and of course relay problems.
I finally changed the ECU and the problem disappeared. The pressure sensor on the ECU was probably faulty.

Cheers,
Emmanuel.

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N°205