VW Golf Mk3 poor pick-up from idling - car_driver
My ?92 (Mk3 petrol) Golf 1.4 CL has done 118k miles. It recently failed on a journey with horrible misfiring, unable to idle, frantic switching of the fuel pump relay. VW dealer found and corrected a short in the wiring loom, which allowed the car to idle but it was still nowhere near driveable - basically no power at anything below 3000rpm. Quoted £700 to replace the fuel injection (throttle body etc), but with reservation that there might be other components at fault, which would cost extra to diagnose and fix. They hinted that the wiring fault might have caused damage to the throttle valve potentiometer (which is integral with the throttle body).

Their quote is way outside my budget, so I?m back to DIY - I have bought and installed a secondhand throttle body/injector and the car now runs nearly perfectly. It starts first time, idles at normal speed, and can be driven. The remaining problem is that it loses power when I open the throttle quickly from idling ? if I open the throttle more slowly, it will behave. When driving, I can?t open the throttle too much when revs are low, or the car will impersonate a kangaroo. Basically it?s driveable only if I slip the clutch a lot and keep the revs right up.

I have subsequently checked the fuel pressure regulator ? clean and no visible damage to the rubber membrane. The injector itself has the correct electrical resistance as per Haynes manual.

What else can I look at? Haynes doesn?t show me where to find the ECU ? where do I look (under the bonnet?), and do the symptoms suggest it might be faulty? What about the fuel pump itself ? I was wondering if the repeated switching of the fuel pump relay might have damaged it?

Haynes also says this car?s fuel / ignition system can only be investigated by a garage with a diagnostic system, yet my local VW dealer was quoting £300 of labour to replace the throttle body and investigate the problem. Hardly sounds like the diagnostic process is time-efficient, that?s 4 hours?

The engine type is ABD and the fuel injection is Bosch mono-motronic. Recent repairs have been new HT leads and new plugs, and a new oil pump.

All suggestions welcome



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