Quote:
Originally Posted by AndreasK
Hi. Recently bought a 77 911S. Has the original 2,7. Rebuilt some time ago, with SSI headers and 964?? cams. Sweet car and engine. Starts and runs great when warm.
Starting cold, not so good. Very predictable, but, I have to give it some throttle and it fires up. Wonīt idle for about a minute. Shuts right of. With the throttle i can keep it steady at 1000 rpm. After about a minute, with the same amount of throttle it suddenly (takes about 5 seconds) revs up to about 2000 rpm. I can then let the throttle go and it idles fine. Rides a bit jerky until fully warmed up. Especially around 2000-2500 rpmīs. Some backfires, especially when changing gears at lowish rpmīs.
Porsche shop, checked fuel pressures, when i bought it. Not so good. Changed accumulator and fuel pump. Pressures fine after.
Where do I start looking?
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The bold in your post needs a bit of clarification.
Without using the throttle, will the engine
start and immediately die? If so, your CSV
is working. It's not clear in your post that you are using the throttle to get initial firing of the engine or to just keep it running. This is an important distinction.
Even if the CSV is
not working, once started and running, your use of the throttle to keep the engine at idle is indicative of
another issue, likely out of spec cold control pressure--that's why you need a gauge set before anything else. The CSV only works when the start circuit is engaged, meaning when the engine is being rotated by the starter motor. Once you let the key move from the START position, the CSV stops injecting fuel.
Let us know about the cold start without the throttle. Does the engine fire and immediately die?