Time function is controlled by a temp sensor (thermistor) in the relay, but I believe current draw is also invovled.

2 ohms GP resistance is way too much -- won't get hot enough at that resistance, to say nothing of only having 4 sec of current!

If they don't stay on properly (20-90 sec cold) with new plugs, it's relay time.

Check the strip fuse on the relay, too -- it may be cracked and opening up with heat.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!