Expert: Sean Halliday - 4/10/2007

Question
QUESTION: For the last several months I have had intermittent problems starting my 2000 S-10 (180,000 miles) when the weather is cold and/or wet - primarily wet, though.  When the engine is already warm, though, it always starts regardless of weather.

Last week I replaced my plugs (Bosch Platinum-Iridium), wires (Bosch), distributor and rotor, and used plenty of dielectric grease on every connection and boot, but the problem remains.  As long as the weather is dry, it starts just like it did when new, but throw some moisture in the air, and it has to generally crank an awful lot before it starts, and after starting it feels like it misses for a couple of minutes.

Around the time I first noticed the problem I also had a lot of trouble starting in cold weather, even when dry.  I replaced the coolant temperature sensor, and the cold start problem seems to have gone away, but wet starts remain a problem, even after the changing out plugs, wires, and distrib/rotor.

Any thoughts on what I should check next?  Could there be an electrical problem further upstream from the distributor?  My gut still tells me it's an electrical issue, but I just can't imagine where.
ANSWER: This is a Chevy s10,then you need AC DELCO  plugs as i have learned these s10s only run good with these plugs and only these plugs.I would also look for a vacuum leak especially around the intake for the idle air control and the air filter.Look at the vacuum system itself and check all the lines.This is a HEI ignition and as you know the electricity will take the easiest way to earth when wet so i would start the engine and spray some water on the ignition components to see if the engine misfires then you will know what part is shorting out.It may be hard to get at the distributor but worth a try.Did you change the distributor or just the cap and rotor?Dont use a hose pipe but a small bottle filled with some soapy water.

---------- FOLLOW-UP ----------

QUESTION: I actually was using DELCO plugs all along, but switched to the Bosch only last week, partly because of this problem.  I'm not saying that the DELCO plugs couldn't be a new problem, but it certainly wasn't what caused the starting problem in the first place.  Hopefully I won't have to change them again, because besides being a pain in the a--, those suckers ran me $60.

I will look at the vacuum system and try spraying some water on some components to check for shorts.  After changing out the plugs, wires, etc. I looked for signs of arcing and didn't see much, although there may have been some tracks in the distributor cap.

To answer your question, no I did not change the distributor itself, but rather just the cap and rotor.  To be honest, it never even occurred to me to change the distributor.  Is this something I should consider doing anyhow, considering I have more than 180,000 miles and have never changed the distributor?          

Thanks again for all the help.  

Answer
It wouldnt do any harm to have a spare distributor.As for the plugs,if the engine was hard to start before you changed them,then just leave them in there.I know theyre a pain to change and not much room.There isnt much more to the igniton system as far as electrics go and maybe this isnt a spark problem at all.The car will be hard to start with a fuel problem also.Chevys are notorious with bad fuel pumps and filters so maybe change the filter.It is a problem which is a real pain and apart from the plugs,wires,cap,rotor,ignition module and distributor there isnt much more to look at.Best way to see is when its damp pull one of the plugs and see if its sparking any plug will do as long as you can get at it.