Very weird running problem

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David Pettengell
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Very weird running problem

#1 Post by David Pettengell »

So, since I have had my car back in the UK I have had weird running problems. Car was running great before it was put on the ship to the UK.

So the car starts badly, turns over fine but will not fire. First time I had this I changed everything. Plugs, Rotor, Distributor cap and HT leads and then she started. Had the same problem a few times since and every time I change the plugs and she starts, plugs - especially number one are always very coked up.

So I thought my timing light was plying up so I got another but now realise only one in maybe 3 sparks are getting through HT lead number 1. I changed the lead and it had no effect.

So today I had the same problem, the car was running but very poorly, pulled the HT lead off of spark plug one and noticed that holding the HT lead cap close to the spark plug (but not connected) made number 1 fire much more consistently.

All very strange. I have a 123 distributor and the car is 6V. The engine was rebuilt by Cliff Murray just before I left the states and was running perfectly to Hershey etc.

I am lost. Booking the car into PRS to look at it but wondering if anyone has some ideas?

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Martin Benade
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Re: Very weird running problem

#2 Post by Martin Benade »

It sounds like a weak spark, either caused by the distributor electronics or the coil, assuming that your plug wires are in good health. This also assumes (never a good idea) that you have good batter power feeding the ignition system.
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Re: Very weird running problem

#3 Post by David Jones »

David, you mention that the plugs are coking up which suggests to me that you are running very rich and probably excessively so at idle. Are you by chance seeking out ethanol free petrol after your engine was tuned on 10% ethanol in the states? Just a thought as some engines can be particularly sensitive to fuel changes especially well tuned ones. Did Cliff dial it in on a dyno?
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Martin Benade
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Re: Very weird running problem

#4 Post by Martin Benade »

As my reward for commenting here, I just drove to Trader Joes, and when I got into my car to come home, it is now a 3-cylinder S90. I prefer the 4-cylinder version.
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Re: Very weird running problem

#5 Post by Doug McDonnell »

Must be very virulent problem-it made it across the Atlantic.
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Jim Liberty
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Re: Very weird running problem

#6 Post by Jim Liberty »

Contact Cliff direct. He'll walk you through the fix.
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C J Murray
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Re: Very weird running problem

#7 Post by C J Murray »

We have been talking. I really wish I was there to help and I am very concerned that Dave be happy with his engine. We have become friends and I value that friendship very much. Mike will get to the bottom of things and the mystery will be solved. I drove Dave's car quite a bit breaking in the engine and sorting out the tune and then Dave drove the car to Hershey and as much as he could before escaping to the UK and the engine was great. We did replace the fuel tank to fix a dirt problem and we also replaced the ignition switch to fix a starter problem so I am hoping that those issues may have popped up again and can be easily repaired once the exact problem is identified.
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Re: Very weird running problem

#8 Post by John Brooks »

CJ Murray, a little off topic... but is the engine number in your 1300S Race car P50118 by chance?

Thanks
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Re: Very weird running problem

#9 Post by C J Murray »

Hi John, the number was 50106 which was offered to me as an engine case only for a lot of money which I declined because the car is not likely to ever be restored to original. I would have bought it if the price was anywhere close to market value though. It was for sale at the swap meet during the lit meet a couple of years ago.
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Re: Very weird running problem

#10 Post by Jim Liberty »

CJ., is there any significance the the title of this has the word "Weird" in it. Just say'n.
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Re: Very weird running problem

#11 Post by C J Murray »

356 running problems and "weird" in the same sentence is redundant.
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Re: Very weird running problem

#12 Post by David Pettengell »

Let's be clear. CJ has been absolutely awesome. As he states we are friends and always will be. The first person I spoke to about this was Cliff and he has been incredibly helpful but only so much you can do 3000 miles away. I love the car, I love the engine and CJ actually inspired me to love my car. I have plenty of classics but CJ made me recognize the car I have wanted since I was 20.

So on the running rich question.. Unless something is going wrong the mixture screws are only a 1/4 turn out on all pots so not sure I can lean it out much more. My thoughts about the spark plugs coking up is more about lack of firing than over rich mixture but happy to be wrong.

My current thoughts are definitely ignition related, could be lack of voltage from ignition switch to coil. I have changed coils and made no difference or something wrong with the distributor causing a weak spark.

I am arranging transport of the car to Mike Smiths place (PRS) as CJ pointed me his way originally and after my visit, I am completely assured that Mike and the guys will be on the case,

Just to be clear, none of this is a criticism of CJ. IF an absolute disaster has happened and something is fundamentally wrong, we will sort it out and still be having beers at the Whip next time I am over there (if Trump lets me in)

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Re: Very weird running problem

#13 Post by JohnLiles »

Good morning David .
I will be very interested in what you discover.
I imported my 356 from Australia earlier this year , since it was shipped it is hard to start and does not run so well.
I blame the pre shipping procedure of draining tank and disconnecting battery , although there are no electronics or engine management system in a 356 !
I guess the car was run till it stopped to drain tank so maybe the carbs collected some muck in spite of in-line fuel filter.

PS mine is 912 engine and Solex P40 II s , 12 v and has had electronic ignition fitted to eliminate contact gapping
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Re: Very weird running problem

#14 Post by Neil Bardsley »

david pettengell wrote:Let's be clear. CJ has been absolutely awesome. As he states we are friends and always will be. The first person I spoke to about this was Cliff and he has been incredibly helpful but only so much you can do 3000 miles away. I love the car, I love the engine and CJ actually inspired me to love my car. I have plenty of classics but CJ made me recognize the car I have wanted since I was 20.

So on the running rich question.. Unless something is going wrong the mixture screws are only a 1/4 turn out on all pots so not sure I can lean it out much more. My thoughts about the spark plugs coking up is more about lack of firing than over rich mixture but happy to be wrong.

My current thoughts are definitely ignition related, could be lack of voltage from ignition switch to coil. I have changed coils and made no difference or something wrong with the distributor causing a weak spark.

I am arranging transport of the car to Mike Smiths place (PRS) as CJ pointed me his way originally and after my visit, I am completely assured that Mike and the guys will be on the case,

Just to be clear, none of this is a criticism of CJ. IF an absolute disaster has happened and something is fundamentally wrong, we will sort it out and still be having beers at the Whip next time I am over there (if Trump lets me in)
David I have a spare 009 distributor I could lend you to swap over the the 123 if it would help? I could post it to you. However, you will probably have the car at PRS before you can use.

Sorry to ask some stupid questions but have you checked and cleaned the distributor cap and rotor? What 123 setting does Cliff have you on? If a special tuned one it might be worth reverting to 022 to see if it helps? Might also be worth checking for a loose wire on the ignition that was the cause of a similar problem I had.

David Pettengell
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Re: Very weird running problem

#15 Post by David Pettengell »

I am on the non-tunable Porsche vacuum version of the 123 and have tried with multiple caps and rotors, all the same problem. I think I have a 009 as I am a VW guy historically but not had a chance to try it.

The comment about a good + from ignition switch to coil is a fair call. I will have a better look at that as well!

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