Cold starting

[theweaver]

I have no problem with starting from cold, but the engine 'hunts' for about a minute or so . The engine revs to about 1500rpm then back to 1000rpm and keeps doing this, and then settles down to a smooth tickover after a minute or so, Any ideas. It is a 1980 SC.

I also have a slight misfire at about 2000 rpm which disappears after that range.
I have replaced the Spark plugs..HT leads. checked operation of advance mechanism. Could it be an injector. Compressions are all 10.5 Bar

The car has stood for 10 plus years, and I have recently finished the rebuild of both the car and engine following twelve broken headbolts.

Photo attached. It is a little disappointing after spending so much time and effort doing all the restoration work. . Any ideas would be appreciated

[Scott R]

Just to be sure, this is of course a ROW car correct? If so I would advance the distributor a bit when it's hunting to see of the hunt goes away. If it does it's time to inspect the internals of the distributor for issues.

[AVDCAV]

I just tighten my intake bolts when it hunts " and it goes away
For another 2 months , seems they work themselves loose. Takes 5 mins
Check for leaks with starter fluid no rev all good.

Hope yours turns out to be simple also, not debating but ie owned 4 3.2 cars
And never had to add advance. Others will jump in but try the simple stuff first.

[Scott R]

Originally Posted by AVDCAV

I just tighten my intake bolts when it hunts " and it goes away
For another 2 months , seems they work themselves loose. Takes 5 mins
Check for leaks with starter fluid no rev all good.

Hope yours turns out to be simple also, not debating but ie owned 4 3.2 cars
And never had to add advance. Others will jump in but try the simple stuff first.

Says he has a 3.0...

[Bob Kontak]

Originally Posted by Scott R

Just to be sure, this is of course a ROW car correct? If so I would advance the distributor a bit when it's hunting to see of the hunt goes away. If it does it's time to inspect the internals of the distributor for issues.

+1 Scott is pretty sharp regardless of what folks say about him.

On my US 81, a member named psalt suggested I plug the vacuum retard hose which essentially advances the timing about five degrees at idle and helps overcome some of the age issues with the various components in the CIS system. It worked wonders for helping my car start in the expected fashion. Meaning, fire up and idle at 1500 plus for a minute or so then drop to 900.

Disconnecting and plugging the decel valve hose may also help eliminate some fluctuations.

As always, make sure you have eliminated vacuum leaks. You can use carb cleaner or starting fluid on the vacuum connections (AVDCAV is right - intake runner base fasteners may loosen and suck air and cause "things" to not be right with idle.) I had one loose and I had a little backfire putting from the exhaust. Once found and tightened, no issues.

As to the distributor maybe being tired, I cannot comment as I purchased a new one in the late 1990's and I think it is still operating properly given the few miles I have put on the car 30k-ish.

[theweaver]

Hi, I am unfamiliar with ROW, please explain.

[flatsixjunky]

Hi, I am unfamiliar with ROW, please explain.

from theweaver

Rest Of the World as in a car manufactured not for USA market. Like yours, that's a RHD '80 SC.

[Bob Kontak]

There is also a Japanese model that is separate from USA and ROW models.

On pdf page 499 of 503 you can see the variations at the macro level. There are probably sub-variations based on country of destination given law differences.

This is the US parts catalog. There is a separate ROW catalog available.

http://www.porsche.com/all/media/pdf/originalparts/en/E_911_83_KATALOG.pdf