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Matt
Matt, Engineer
Category: VW
Satisfied Customers: 20805
Experience:  Mechanical Engineer with 20 years experience in the auto industry, 8 yrs in formula 1 engine testing
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2001 Jetta GLS. I just changed the plugs and wires, and now

Customer Question

2001 Jetta GLS. I just changed the plugs and wires, and now it won't start.
JA: Have you checked the battery, particularly the terminal connections? Are they corroded?
Customer: battery is fine. it started before I changed everything.
JA: Are you fixing your Jetta Glis yourself? What have you tried so far?
Customer: yes. one of my plugs was bad, so I change all six and put new wires too.
JA: Anything else you want the mechanic to know before I connect you?
Customer: no. that's it.
Submitted: 5 months ago.
Category: VW
Expert:  Matt replied 5 months ago.

Hello

1st thing to check is that you've gotten the plug wires all back in the right order

I'm assuming that this is the V6 so check the lead order against this image

Customer: replied 5 months ago.
they are all in order.
Expert:  Matt replied 5 months ago.

Hello

OK in that case

I'd pull a plug out and check that you have a spark

If there is a spark and its still not starting then its likely that the ECU isn't opening the fuel injectors, if the injectors are working you can hear them click - its difficult to hear them with background noise so use a long screwdriver like a stethoscope, placing the handle end in your ear and the metal tip against the body of the injector whilst your assistant turns the engine over.

If you can't hear anything check the ECU power is present by measuring voltage at the fusebox and on its relay socket if OK then check the connections to the crank speed sensor and consider replacing this sensor if the wiring / connections look OK

If the car will start using a squirt of quick/ easi start into the intake then this confirms the problem is lack of fuel

Also its worth checking that the electric pump that feeds the injectors is working correctly, it should run for a few seconds then switch off when you first turn the ignition on. If you remove the filler cap to the fuel tank and listen inside while your assistant flicks the ignition you should hear it clearly

If the connections to this are corroded or damaged then the pump could stop at any time. Check that its relay switches in and out and the relay contacts are clean and bright – replace the relay if in any doubt and do the same for the fuse, ideally measure the voltage at the pump and check its getting 12V.

You should be getting around 3 bar measured at the injector rail check to see if the plugs are getting wet indicating fuel is flowing – if not and the injectors are opening then there’s a problem with the pump or the filter or even the pressure regulator

Expert:  Matt replied 5 months ago.

Hi

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