Hot start issue, won't start right after turn off the engine.

[madstudios]

Hi everyone!

I'll describe my hot start issue:

If I turn off the car with the engine hot, and try to turn on right after (or within a minute or 2), it won't start... and If I try to crank for a couple of times it smells like the engine is flooded. I have to wait a bit, like 5 to 10 minutes and then it fires up.

If the car sits for more than 10 minutes, I don't have hot start issues, just very occasionally.

I'm running open loop, dwell was set properly, no vacuum leaks, accumulator was replaced (1000 miles on it).

Any thoughts?





Fernando Silotto. Sao Paulo - Brazil
Delorean Vin 3772

[Bitsyncmaster]

I would bet your cold start valve is running on a hot engine start. Try unplugging the CSV and see if the problem goes away.

[madstudios]

I was looking for bad connections, and I found out that a wire on my CPR connector has bad connection, only one thin wire was holding, and broke...https://uploads.tapatalk-cdn.com/20170515/c9f7d3bb17dcd162f4934013143c695e.jpg
Now I've disconnected the cold start valve and fired right up.


Fernando Silotto. Sao Paulo - Brazil
Delorean Vin 3772

[Bitsyncmaster]

The heater in the CPR would not cause your hot start problem unless it shorted. If it shorted your lambda may not get powered.

I've found I need the cold start valve if my car sits for more than a week. I guess the injectors leak down in that time to make starting hard.

If disconnecting the CSV fixed your hot start problem then it's time to find out why the CSV is firing on a hot engine.

[David T]

Verify there is NOTHING plugged into the hot start relay plug. Make sure the cold start system (the cold start valve and the TTS) are hooked up correctly and operating correctly. The cold start valve should NOT operate if the engine is warm-hot. Next time try unplugging the cold start valve before trying to start a hot motor and see if that improves things. If it does, it means the cold start valve is squirting when it shouldn't.

[madstudios]

The heater in the CPR would not cause your hot start problem unless it shorted. If it shorted your lambda may not get powered.

I've found I need the cold start valve if my car sits for more than a week. I guess the injectors leak down in that time to make starting hard.

If disconnecting the CSV fixed your hot start problem then it's time to find out why the CSV is firing on a hot engine.

After another round of tests yesterday, disconnecting the CVS didn't "fix" the problem.
So it's something else.
What else could I check now?



Fernando Silotto. Sao Paulo - Brazil
Delorean Vin 3772

[madstudios]

Verify there is NOTHING plugged into the hot start relay plug. Make sure the cold start system (the cold start valve and the TTS) are hooked up correctly and operating correctly. The cold start valve should NOT operate if the engine is warm-hot. Next time try unplugging the cold start valve before trying to start a hot motor and see if that improves things. If it does, it means the cold start valve is squirting when it shouldn't.

Hi David!
Nothing is plugged in the hot start relay, and after few more tests, unplugging the CSV had no improvement.


Fernando Silotto. Sao Paulo - Brazil
Delorean Vin 3772

[Bitsyncmaster]

After another round of tests yesterday, disconnecting the CVS didn't "fix" the problem.
So it's something else.
What else could I check now?

Fernando Silotto. Sao Paulo - Brazil
Delorean Vin 3772

Is the problem consistent and not a random thing?

[madstudios]

Is the problem consistent and not a random thing?

Consistent, it happens only with the engine hot and if I try to start right after shutting off.
If I wait 5 minutes or more, the car starts normal.


Fernando Silotto. Sao Paulo - Brazil
Delorean Vin 3772

[Ryan S.]

O-ring?

[madstudios]

O-ring?

I've put a new oring recently too.


Fernando Silotto. Sao Paulo - Brazil
Delorean Vin 3772

[David T]

Three more tests. Before trying to start it see if there is any resistance when you try to push the air sensor plate down. Now try starting hot again but check for spark. If you have spark then try the plug swap and see what difference that makes.

[DMC5180]

Hi everyone!

I'll describe my hot start issue:

If I turn off the car with the engine hot, and try to turn on right after (or within a minute or 2), it won't start... and If I try to crank for a couple of times it smells like the engine is flooded. I have to wait a bit, like 5 to 10 minutes and then it fires up.

Any thoughts?

Fernando Silotto. Sao Paulo - Brazil
Delorean Vin 3772

This may not fix your issue, but try depressing the gas pedal 1/4 - 1/2 while cranking the Hot engine. It should help clear the excess fuel and help it to re-start it.

It is stated in the owners manual to depress the throttle a 1/4 travel to aid in starting. We are so used to modern EFI vehicles we tend to skip this step and don't touch the pedal when cranking most of the time the engine fires right up this way but not always for some situations.

What is the Ambient Air temp when the problem occurs most of the time?

[madstudios]

Hi everyone!
Today I've figured what was going on.
My Ignition coil gets too hot, and does not provide the spark needed to fire the engine. That's why if I wait for about 10 minutes, it works, I think it cools down and works.
The coil installed is not stock, was put by PO, cause we don't have the same one from bosch here in Brazil, so I had another one from a friend and now its working.
https://uploads.tapatalk-cdn.com/20170524/2858ba7c92ae4289bf847332252de8c6.jpg
I've already ordered one from DMCH, waiting to arrive.


Fernando Silotto. Sao Paulo - Brazil
Delorean Vin 3772

[David T]

We have seen similar problems before with none-stock ignition coils. People try them thinking it will give them a boost in performance. That doesn't happen BUT they do often cause problems. Make sure all of the connections are clean and shiny on the ballast resistor and it is connected up correctly, ie, all of the wires are where they are supposed to be on it. Sometimes it gets rewired or even bypassed to make the coil even hotter. In fact, on some performance coils, you remove the stock ballast resistor and use a special one that comes with the coil. Mallory did that back in the 70's.

[madstudios]

We have seen similar problems before with none-stock ignition coils. People try them thinking it will give them a boost in performance. That doesn't happen BUT they do often cause problems. Make sure all of the connections are clean and shiny on the ballast resistor and it is connected up correctly, ie, all of the wires are where they are supposed to be on it. Sometimes it gets rewired or even bypassed to make the coil even hotter. In fact, on some performance coils, you remove the stock ballast resistor and use a special one that comes with the coil. Mallory did that back in the 70's.

Thanks David!
Do you know the resistance of the stock ballast resistor, correctly wired?
This Bosch coil requires a 0.8ohm ballast.
The primary resistance is 1,2..1,6.



Fernando Silotto. Sao Paulo - Brazil
Delorean Vin 3772

[Bitsyncmaster]

Thanks David!
Do you know the resistance of the stock ballast resistor, correctly wired?
This Bosch coil requires a 0.8ohm ballast.
The primary resistance is 1,2..1,6.



Fernando Silotto. Sao Paulo - Brazil
Delorean Vin 3772

Stock resistors are 0.5 ohms each and connected in series. So you get 1.0 ohms during normal running and 0.5 ohms when your starting the engine.

[Ron]

...
Nothing is plugged in the hot start relay, and after few more tests, unplugging the CSV had no improvement.


Fernando Silotto. Sao Paulo - Brazil
Delorean Vin 3772I would suspect one or more injector(s) leak while at rest, at this point.

[madstudios]

I've installed a new ignition coil, and apparently the old one was causing the problem. Tested and everything is working great!


Fernando Silotto. Sao Paulo - Brazil
Delorean Vin 3772