Question On the cold-start problem, these are interesting ideas I've never heard before - thanks. Questions for my own education - are the sparks being flooded by the too-rich mixture? If so, why would this cold-starting problem be ambient-temperature-related? Maybe because the cold start valve is in fact opening when the engine is cold? Car starts fine in warm weather, and okay when the engine temp is warm, even if it's cold outside. Battery voltage problem in the cold?
I recently put in new Bosch Platium plugs, dual spark I believe, not NGK but that should be sufficent, right?
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Thanks for the advice, Stephen. Regarding the cold-start problem, you have an interesting idea. I've recently replaced the plugs and wires though, and once in the middle of winter my mechanic trickle-charged the battery, but the only effect was that the starter cranked FASTER, but the engine started no quicker. I could try replacing the coil. Any other thoughts? If it's the electronic ignition causing the problem, why does pumping the gas pedal when cranking help it start? (In fact, if I didn't press on the gas pedal it would just crank forever and never start.) Again, this is only true for temperatures below about 50 degrees. Above that, or if the car was recently driven and is still warm, then it starts right up.
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Thanks for your fast response to my previous question (head gasket oil leak?) My other pet peeve about my much-loved 1984 Alfa Spider (110k) is cold starting. In warm weather, it starts right up. In colder weather, 50s and below, it will crank and crank and crank forever... If I press on the accelerator while cranking, it'll start up, and then run perfectly. I thought you weren't supposed to have to do that on a fuel injected car. I didn't used to. I know of some likely suspects: Cold start valve? Thermo-time switch? What's the most common/likely cause in your opinion? How best to troubleshoot? Thanks in advance.
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It is the ignition system. And the battery.
Clean the battery terminals. Put in new NGK plugs and an MSD Coil and ignition wires.
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The mixture is too rich for the spark and opening the throttle momentarily leans it out. Did you replace with NGK spark plugs...
There are 2 cures. I prefer putting in an MSD 5A or 6A unit and an MSD Coil. But, for a lot less money you can put a resistor in parallel with the temp sensor for the ECU. Depending on your altitude you can use a 1k ohm or 2k ohm resistor. But, even with the resistor trick I would still install the appropriate MSD coil.
Answer The cold start injector operates at or below 50 degrees F.
Yes, the rich mixture floods the weak spark. Bosch coils have always had weak spark.
Years ago, with the aid of an ocilliscope and a smog machine I determined that the best Sparkplugs for my uses were NGK and Champion. I also found that with the addition of an MSD spark box (5A, 6A or Blaster) regular NGK and Champion plugs would last way too long. The only automobiles I found Bosch plugs to work well in were German. Times do change but NGK and Champion were way ahead with dyno research then and probably still have an advantage, at least for me.
Lastly, modern automobiles require good clean electricity. No dirty/corroded connections and very little ac ripple. So I have come to rely on the Optimus battery and keeping connections clean--as a result, I find that components last longer than they should and that connectors are the wear items. But, change the O2 sensor every 30 to 40 K miles.
