Cold Start problems
 

I've checked out the other "cold" and "no start" topics but didn't see a fix that fit my problem. As soon as the weather dips below freezing my 1990 Bonneville refuses to start. It cranks fine but coughs and sputters as if the spark isn't adequate or timed properly. The temporary fix is simple -just plug in the block heater for 1/2 hour and away it goes. Once it starts, and burns off the excess fuel, the car purrs like a kitten.

I have two other Bonnvilles, one that I am transplanting an engine into and another parts car. Yesterday I had both Bonnevilles in the driveway, I cranked the problem car until the battery died and it wouldn't start. I hopped into the one I'm working on and it fired up right away. I plugged the problem car in (along with a battery charger) and was able to start it 1/2 hour later.

Since I have a parts car available I am able to swap parts easily and, so far, have replaced the following items in an effort to solve the cold start problem.

ECM, Crank position sensor, coil pack, plugs and wires (new ones) and a temperature sensor. I read somewhere that the ECM uses the temperature sensor and the crank position sensor to determine the fuel mixture and spark timing during the cold start process so I swapped both, no improvement. There appears to be two temperature sensors on this car located beside each other, one has a two terminal wire harness and the other a single post threaded terminal. I changed the two terminal unit, does anyone know which sensor is used by the ECM? (Yes I plan on changing the other one now).

I haven't checked the fuel pressure, the car seems to be getting lots of fuel and I suspected ignition / timing was the problem but perhaps the low pressure will cause fuel to be delivered but the spray pattern isn't proper? Any ideas.

The strange thing is that the car starts and runs so well after a short period on the block heater.... Any thoughts

Duke Orr

I never had any problems starting my 89 SE in the winter, You have a block heater? Might want to use that in extreme cold conditions and continue to use it...

hmmm, sounds like you covered a lot of items so far to this problem :?

I have some cold start issues (difficult cranking, initial rough idle, occasional stalling). Undiagnosed so far :|

I have a 89 SSE that began having the same problem during the winter of 1996. Luckily I had just changed jobs and moved to indoor parking. It acted like it was flooded almost imediately when trying to start at any temperature below about 30 degrees. Those temps last along time during the Minnesota winters. I first tried injectors since it always seemed to flood and seemed like gas was just dumping in the cylinders. I gave up and just made sure I didn't park outside when it was cold.

The problem continued for 6 years, and never got worse or better. Finanlly during the winter of 2002 in anticipation of my son taking the car to college, I parked the car outside and would change one part a day. I brought a bunch of electrical parts home from the junkyard and started with the ECM, and sensors and each morning it wouldn't start. Then I changed the ICM (ignition control module), and that was it. He has been driving the car for two years, about 20,000 miles, and obviously parks it outside all the time... and has not had a problem since.

I hope this helps.

Did you pull the MAF from the good starting car and try it in the bad starting car ?

Do the old parts back on the other car still allow that car to start well ?

You mentioned swapping the coilpack. Was it just that (six screws) or did you swap the entire ignition module (three nuts on bottom of bracket) ?