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    Thread: 98 a3 golf hard cold start

    1. Junior Member
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      98 VW Golf
      10-18-2011 08:28 AM #1
      My 98 a3 golf has been difficult to start in the morning for a couple of months. Plug wires are about 18 months old and were high quality german wires bought from GermanAutoParts.com. I replaced cap and rotor thinking it was a condensate problem, but this has not resolved the problem. Typical hard start is that it takes up to 15 seconds of cranking to get it to fire up. A couple of times, it refused to start at all for an extended period of time, and I left it alone and came back to have it start right up.

      After the 'wouldn't start at all' incidents (two in one weekend), I started to think back to previous A2 cars that had starting problems like this that turned out to be a flaky fuel pump relay. I replaced the relay with another one from a parts car, and this seems to have alleviated that problem.

      I still have hard starting, and I note that I do not hear fuel pump run when I turn key on. I note that the A2 fuel pump relay was a 5 pin affair, which had circuitry to do a pre-ignition pressure up. I see postings indicating that A3 cars should do the same, but the relay apparently doesn't provide this function, since its only got four terminals: 2 high amp terminals that cause the fuel pump to run, and the signal terminals that cause the relay to close the circuit on the other two.

      Do A3 cars run the fuel pump for several seconds to pressure up? What provides for this function? What should I be checking? I presume that the car would probably start if I jumpered the fuel pump run terminals.

    2. Member
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      1998 GTI 2.0T
      10-18-2011 12:23 PM #2
      Turn the key on and leave it on for a few seconds before cranking. If this alleviates the long crank, then the check valve (built into the fuel pump) is suspect. The fuel pump should prime with key-on.

      Also, get a VCDS/Vag-Com on it and pull codes. Check the readings on the ECT starting stone cold and watch it (via graph in measuring blocks) as the engine warms up.
      1998 GTI 2.0T
      1993 Jeep ZJ 4.0

      World Automotive
      Need any VCDS (VAG-COM) diagnostics or coding in the North NJ area? PM me.

    3. Junior Member
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      98 VW Golf
      10-18-2011 04:31 PM #3
      I'd thought it was implicit that I had turned the key on and let it stay on for several seconds in my statement 'I note that I do not hear fuel pump run when I turn key on.', but having stated that clearly, lets move on to the ECT.

      ECT = Engine Coolant temperature? I don't have VAG-COM, but I have successfully used scantool.net older version with a generic ELM USB, and while it doesn't graph, I can monitor the temp with it. Can you elaborate on why I'd want to do that? Does ECT influence fuel pressure?

      How would I tell if check valve in fuel pump was non-funcional? I presume with some sort of fuel pressure gage in-line. Is the any sender that reports fuel pressure? I'll have to check in scan tool to see if it can see anything there.

      You imply that the fuel pump should run for x seconds upon signal from ignition switch (which I replaced a couple years ago because it had worn out), and I'd presume that it stops at some point if it does not see signal from engine that it is running. What controls that ECM? Another relay? Some other circuitry?

    4. Junior Member
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      98 VW Golf
      10-18-2011 04:35 PM #4
      This may be relevant (and perhaps a key) as well: I have pulled codes with scantool and I've only seen one in it that began to be intermittent and has now become persistent. I can't cite the exact code right now without looking it up, but it was one of the ones that speaks of evap leak, and could implicate something in the fuel tank or lines.

      Perhaps a smoke generator test will sort the code and the hard starting out, because it would make sense that this would allow leak down of pressure, but it doesn't address the fact that I don't believe my fuel pump runs at ignition before you key the starter.

    5. Member
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      1998 GTI 2.0T
      10-18-2011 04:41 PM #5
      Yes, ECT is Engine Coolant Temperature. The ECU will adjust fuel mixture differently for a warm engine than a cold engine. If it thinks the engine is hot when it's actually cold, you'll have cold start/cold running problems. I'm not 100% convinced that this is your problem though, you've gotta check it with a scan tool capable of showing a datastream. Look at the value of ECT vs IAT after the engine has been sitting overnight, before the first start in the morning. They should be within a couple degrees of each other.

      The fuel pump should hold pressure after the key is turned off. To verify, put a mechanical pressure gauge on the supply line, turn key on, pressure should build. Turn key off, pressure should hold steady.

      EVAP leak shouldn't have anything to do with a starting/drivability issue, unless the purge solenoid is stuck open (would create a rich code in most situations) or the vacuum line is broken off creating a large vacuum leak (lean code usually).
      1998 GTI 2.0T
      1993 Jeep ZJ 4.0

      World Automotive
      Need any VCDS (VAG-COM) diagnostics or coding in the North NJ area? PM me.

    6. Junior Member
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      98 VW Golf
      10-19-2011 08:25 AM #6
      Thanks for the direction. I probably won't have any significant time to spend with it until this weekend....

    7. Junior Member
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      98 VW Golf
      10-25-2011 08:25 PM #7
      This morning, the car wouldn't start, so I took the opportunity to hook it up to my scantool.net, and here's what I saw:

      IAT started at 50 (ambient) and warmed up a little bit to 75 under the hood by the time I got to work.
      ECT also started at 50 and warmed up to 190 within 5 minutes, which seems normal.
      I did note that the O2 sensor showed up some sort of fault a few times while running but stayed in closed loop status most of the time.

      I pulled the fuel pump relay and jumpered it. I could here it running -- something that doesn't happen when I turn the key on.

      The codes that were present in my car this morning were:
      P0442 (small evap leak)
      P1500 (fuel pump circuit issue) - This was AFTER I'd pulled the relay and jumpered it, so I don't know if this has any meaning. I'll keep an eye on it.

    8. Member
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      1998 GTI 2.0T
      10-26-2011 10:20 AM #8
      Those IAT and ECT values seem to be good.

      Have you checked the fuel pressure with a mechanical gauge to verify that there is indeed a fuel pressure problem to begin with?

      Will it start if you crank it with the fuel pump relay jumped? Better yet, re-install the relay and see if you've got power at the pump while cranking.
      Last edited by Anony00GT; 10-26-2011 at 11:01 AM.
      1998 GTI 2.0T
      1993 Jeep ZJ 4.0

      World Automotive
      Need any VCDS (VAG-COM) diagnostics or coding in the North NJ area? PM me.

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