Poor running

[bertdejut]

Hi there,

I've got a 72 2.4E and love it. With the help of this bulletin board I changed the timing and mixture etc. and got my car running well.

I'm quite new to driving Porsche so need to learn a lot.

However, last week my car started hesitating on the motorway after about 10 miles and it desn't go away anymore.
Also, when accelarating it's hesitating. I bit like my earlier problems after which I moved to a leaner mixture.

What I've done in the meantime is:
1. I used an injection cleaning additive.
2. While you can't buy the old fashioned leaded petrol anymore in Europe, I put some lead additive in the car before I left (first time). Here you can get RON95 or RON98.

Any ideas whether this could have caused the poorer running?

Also, I understand from reading all the other messages that I can use unleaded petrol. Would you recommend RON95 or RON98 on a European model?

My car is now with the Dutch Porsche importer, because I'm going on a classic car rally on Wednesday. Unfortunately my experiences with official dealers are not very good. It looks like they don't know how to fix these cars anymore and we need to rely on each other.

Many thanks in advance!!

[stlrj]

Ignition?

[bertdejut]

I replaced the ignition wires, put a pertronix in it, replaced vacuum hose, new distributor cap, new rotor, new plugs.

Could it be the vacuum unit being worn out??

My initial thoughts were that maybe because of cleaning the petrol system with the petrol additive, some things have changed because of the cleaning. More air? More petrol?

[fred cook]

Had the car been sitting unused for a while? If so, trash (dirt, rust, etc.) in the fuel tank may have partially blocked the fuel filter. You may have bought some gasoline that had been contaminated with water which could cause a misfire or skip. An anti-freeze additive (breaks down or absorbs water) added to the gas tank might help. Also, check to see if the advance is working in the distributor. You can check this by removing the distributor cap and lighty twisting the rotor. It will turn slightly in one direction and then spring back into position if the advance weights and springs are working correctly. If the rotor will not turn under finger pressure or turns and won't spring back, the advance mechanism will need to be removed, cleaned and lubricated.

Good Luck!

Fred Cook
'80 911SC coupe

[bertdejut]

I'm not using the car that often in the winter (half an hour drive every 2 weeks on average). So I'll check the fuel filter. Is that a simple thing to do?
When accelerating quickly there are no problems. On the motorway I was driving around 70mph and then it is misfiring etc.

Advance seems to work fine.

[keithdog72]

dwell angle?