Cold Start Issue

[DMC VIN 6639]

I am struggling to get a car to start cold. It requires the pedal to be pressure slightly to open the butterfly. I have to hold the pedal for 10-20 seconds and she will run on. The car came to me this way. The car had not been run much and struggled to accelerate and start. I found the fuel distributor plunger sticky, contaminated fuel system. Everything had been jacked with, including timing and idle screw. I replaced the fuel distributor was replaced, fuel lines replaced, fuel tank cleaned, fuel injectors, accumulator, filter. Reset timing to 13. After proper warm up i set Dwell to 15-20 on V8 scale, set idle and microswitch screw. Fresh battery and o2 sensor. The new set up still required the pedal to get it started. The car is an automatic. It runs great once it is running, idles smooth, accelerates well, and holds temp. It clearly needs to be leaner to start initially, but everything is set.

[Bitsyncmaster]

Does your car hold the idle at 775 RPM? The idle ECU opens the idle motor at power on so that should provide enough throttle to start without using the gas pedal.

The warm up regulator makes the mixture rich on a cold engine. That is required to keep the cold engine running with enough power to drive it.

[painterdave72]

I see you checked the dwell .. but did you actually have to adjust the mixture screw?? sounds like its slightly lean.. also on the back on the sunvisor the startup sticker says to actually hold the pedal slightly down on start up to assist,......

[David T]

Sounds like the fuel system is still not operating correctly. I would start with having the fuel injectors cleaned and tested and replace the seals. Then test the cold start system to see if the Cold Start Valve (CSV) is spraying during cranking. Probably a good idea to check the fuel pressures to see if the CPR is working.

[dmcman73]

Check your Idle Speed Motor to see if the valve inside of it is stuck, not uncommon. If you pull it off the engine, apply 12V to the center pin and then briefly (don't keep it connected) touch one of the outer pins with Ground, the valve should move one way with ease. Then tap the ground wire to the opposite outer pin (again, briefly) and the valve should move the other way with ease. If the valve doesn't move or only moves in one direction or partially moves, you can try and clean it with brake cleaner by spraying it into the valve body to flush out the carbon. If that doesn't work, you'll need a new idle speed motor. If you do, these work well as I've used them before: https://www.ebay.com/itm/304362808513

[82DMC12]

Check your Idle Speed Motor to see if the valve inside of it is stuck, not uncommon. If you pull it off the engine, apply 12V to the center pin and then briefly (don't keep it connected) touch one of the outer pins with Ground, the valve should move one way with ease. Then tap the ground wire to the opposite outer pin (again, briefly) and the valve should move the other way with ease. If the valve doesn't move or only moves in one direction or partially moves, you can try and clean it with brake cleaner by spraying it into the valve body to flush out the carbon. If that doesn't work, you'll need a new idle speed motor. If you do, these work well as I've used them before: https://www.ebay.com/itm/304362808513

Unfortunately those idle motors need a different clamp to hold it on (narrower than stock) and being from China they have a high failure rate. Better to get a good used OEM motor. With all the engine swaps and EFI swaps they are definitely out there.

[dmcman73]

Unfortunately those idle motors need a different clamp to hold it on (narrower than stock) and being from China they have a high failure rate. Better to get a good used OEM motor. With all the engine swaps and EFI swaps they are definitely out there.

I just use a piece of coolant hose trimmed down and slit down the middle, holds it perfectly. As for High failure rate, I've had it on the car for quite some time and it's been working fine. If you can find a Volvo or Bosch one, even better but at $39 for the Chinese ones, it's a no brainer.

[r00b]

It looks like some BMW 5 series might have a compatible idle speed motor. I'll pick one up next time I'm at a wrecking yard and let you know if they work.

[DMC VIN 6639]

After testing and swapping parts I found my idle speed motor was not moving. I swapped to a good motor and this helped starting but I had to crank for about 6-8 seconds to get it to start. I swapped out the cold start valve to one from a running car. Now the car starts right up. The old CSV was squirting at cranking. Maybe the old CSV was not squirting enough fuel. I may never know.