Quote:
Originally Posted by qwerty333
Car has 335,000km and is a 1987 420SEL
When I cold start the car it will run like crap and the engine will run very cool no matter how you drive. It will stay under 80 degrees celsius the whole time and feels like 1 or 2 cylinders might be missing, but not misfiring out of time or anything. While this is happening, the transmission refuses to kickdown properly. 0-60mph time in this situation is around 11.5 seconds
After driving it around, and letting it idle a bit, if i turn off the car and let it sit for 2 minutes, then turn it back on, it will then fire on all cylinders and idle very smoothly. The temperature then goes to 90-100 degrees celsius. Kickdown works properly and the car has full power again. 0-60mph in this situation is 8.5 seconds.
I've run out of ideas for what may be causing this weird pattern.
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We might well ask, "What would respond to a period of heat soaking?"
Among other things, mostly mechanical, there is also a group of thermal switches and vacuum valves mounted in the water outlet manifold at the upper front of the engine, the highest point in the engine of the water system. The water at that point in the engine will rise in temperature when the engine is stopped. One of those valves controls vacuum to the EGR valve. If the EGR valve is being held open by faulty vacuum control, or is itself sticking open, the result will be 1) rough running, 2) low power output, 3) low water temperature due to low power.
qw, try this: pull the vacuum line off the EGR valve on the left exhaust manifold, and plug the vacuum line. Start engine, and if running rough, tap on the EGR valve to see if it will close (if stuck open).