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Date: 7-9-08 09:33
From: mikael 
Subject: Strange behaviour - help needed!  
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Hello,
I am experiencing some trouble with my 2002 '71, and I am wondering if some one out there could give some hints on what to do.
Symptoms: When the engine gets warm (after driving for maybe 15 min) the car starts choking itself, almost as if it is getting to much gasoline. It has an almost normal idle, but when I release the cluth and give it some more gas it starts to stutter. I then push the cluth all the way down and rev the engine - this clears the stuttering, but when I try to drive away again the same problem occurs. This appears mostly in the 1st and 2nd gear, and isn't that noticible in the 3rd and 4th, although it isn't running very smooth at high speeds either.
When the car is cold I have none of these problems - it starts fine and idles great and there is no problem driving in the city, i.e. until the engine gets warm.
Changes preceding the symptoms: New oil-, air- and fuelfilters plus a new Hot Spark installation (electronic ignition ).
Free speculation: Could it be the Hot Spark installation? I would think that either the ignition works (which it does when cold) or it doesn't. Please correct me if I am wrong.
Could it be the new inline fuel filter that behaves strangely when the engine gets warm? To me this sounds very strange, but then again you would know better than I.
Thank you in advance!
/Mikael
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Date: 7-9-08 09:46
From: Inka2002
Subject: The easy answers are...
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Is the choke stuck?
Might you have dislodged some dirt in the fuel line that's now clogging the idle jet?
I'm not sure what your new ignition system is, but is there any chance the timing or dwell are off? Is the condenser (if you still use one) attached tightly (for a good ground)?
David Roach
"Molly" (Inka 1973 2002)
"Nick" (Schwartz 2004 330xi)
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Date: 7-9-08 09:53
From: mikael
Subject: Re: The easy answers are...
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Thank you for a quick reply!
No the choke moves as it should.
The filter looks clean, and it idles fine when the engine still is "cold". It's only when driving the car for about 15 min that the problems starts.
The ignition system is Hot Spark ( http://www.hot-spark.com/ - similar to Pertronix I suppose. No the condenser is replaced with the Hot Spark system.
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Date: 7-9-08 11:12
From: mike in Beavercreek, OH 
Subject: Are the symptoms accompained by black smoke from the
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tailpipe? If so, this sounds like it could be an overly rich condition once the engine's warmed up. As David said, check your choke. I presume you have a 1 bbl Solex carb since your car's a '71. Keep in mind that the choke on these carbs operates both the strangler valve at the top of the carb's air horn, and also activates a linkage that increases the idle speed.
With the choke knob fully pushed in, the strangler valve should be vertical in the carb's air horn, and the idle speed should be back to normal. Have someone pull the choke knob in and out while you observe how the linkage works and you'll see what I mean.
My other suspect would be trash in the idle jet. It actually provides fuel flow up to about 2000-2500 rpm, so a partially plugged one would affect engine performance well above idle speed.
Other than your disturbing ignition timing while installing the new system, I can't think of any of the recent work you described as causative factors.
cheers
mike
_________________
'69 Nevada sunroof--"Wolfgang"--bought new
'73 Sahara sunroof-- "Ludwig"--mine since '78
'87 eta E30 coupe--"Johannes"
+ Fiat Topolini (Benito & Luigi), Renault 4CVs (Anatole, Lucky Pierre, Brigette)...
and Kermit, the Bugeye Sprite
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Date: 7-9-08 12:37
From: Tiko
Subject: Re: Are the symptoms accompained by black smoke from the
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Mike is always right - except when he is given bad information.
Why don't you confirm the type of carburetor you are using including whether the choke is manual or water activated. IF you had gunk in the idle jet or even have an idle jet solenoid that has been disconnected or not working (accessible from the side of the carburetor) it may be that you are really running off of the fast idle cam and the choke. When the engine warms up or when you open the choke the idle circuit is still plugged or handicapped and this would account for a crappy idle and poor low speed running.
Brakes that are dragging, bad cracked motor mounts, bad transmission mount and/or a worn or maladjusted clutch might account for or magnify a poor running engine. The fact that you claim everything runs fine when cold would seem to vitiate this possibility.
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Date: 7-12-08 11:28
From: mikael
Subject: Re: Strange behaviour - help needed!
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No I haven't removed the resistor. Do you think that I should? I have the setup that can be seen below.
How can I measure the strength of the spark? Would the spark be weakend as the engine warms up?
I forgot to mention that the car has also "back-fired" once after turning of the ignition.
I haven't had a chance to inspect the carburator and the choke yet, but I will on Monday. Happy Weekend!
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Date: 7-15-08 12:58
From: mikael
Subject: Re: Strange behaviour - help needed!
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Mike, Bob, themoose, Daniel, Tiko and Clydeg!
Once again for all your insightful suggestions.
Having checked the choke (manual) and the jets on the Solex 36-40 PDSI everything checked out and was functional. The resistor was also removed as suggested but didn't improve performance at all.
Unable to figure out the fault, I had a mechanic remove the new electrical ignition, and reinstall the old pointers and condenser, and Whola! The engine works as it should once again...
I am very confused as to how the ignition could cause the above described symptoms, but then again I am new to all this. Maybe it is a faulty electrical ignition kit?
Cheers!
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Date: 7-16-08 01:42
From: mikael
Subject: Re: Strange behaviour - help needed!
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| Clydeg wrote: | | what type of electronic system were you trying to use? |
It was the system from Hot Spark (see the link to their website in one of my previous postings above). I believe that it is a magnetic-type sensor.
I had it installed correctly, according to the manual, and everything worked fine; smooth idle and good behaving through the rpm's. I drove it after installation for about one hour (mostly 90km/h, 55mph) without any problems, had a longer stop, and then again for about 40 minutes on average roads and then when I came to a city (with stops and slow driving) the above stated symptoms appeared, and they would do so everytime after when the engine had gotten warm - thus it performed like normal when it was cool.
Anyway I am glad it is running again, although with the old points put back in, but I am wondering if anyone else had had similar problems with electronic ignition?
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