Hot starting issues

[slewinson]

Hi all, not too sure where this one fits. Stock barina with 60x crank trigger and multec-m ECU. Starts almost immediately in the morning but seems to require up to 5-6 seconds more cranking when hot. Fuel pressure looks fine and doesn't seem to leak down very fast. Battery is good and cranks consistently hot or cold.

I think that the crank trigger (standard delco reluctor style) might be the issue. ECU has been replaced for VSS related issues but no real change in starting. Engine was out for a rebuild and I cannot recall this happening beforehand.

Thanks in advance.
Simon

[vlad01]

not leaky injectors? my cars behaved this exact way when they leaked. Perfect start first thing in the morning. Takes a ton of cranking when left hot for 10-30min or more good again after several hours or overnight.

[slewinson]

If that was true, then using the "flooded start" wide open throttle would make for a faster start. I will also try to be near the exhaust when getting the car started to see if it stinks of fuel.

Simon

[vlad01]

in my case, WOT didn't help it start any faster. The leaky injectors in a hot manifold fumigated the whole manifold out.

[slewinson]

The multec-m ecu has a "flood start" mode that injects bugger all till the engine lights off. Buggered if I know why they would include this - sorta says that the engine can easily be flooded. I borrowed a fuel pressure gauge and even when hot the fuel pressure did not seem to leak down over an hour or so; the hot start issue seems to be after 5-10 minutes sitting. I will try to get a log of a hard start with OPCOM and see what it says.

Simon

[VL400]

I think that the crank trigger (standard delco reluctor style) might be the issue.

Now you can log it, if its the crank trigger will show as no RPM while cranking.

On commodores if the fuel pump relay fails, an oil pressure switch provides power to the fuel pump. But it meant longer cranking times as you needed oil pressure to get fuel happening. Maybe something similar on the Barina?

[slewinson]

I think that the crank trigger (standard delco reluctor style) might be the issue.

Now you can log it, if its the crank trigger will show as no RPM while cranking.

On commodores if the fuel pump relay fails, an oil pressure switch provides power to the fuel pump. But it meant longer cranking times as you needed oil pressure to get fuel happening. Maybe something similar on the Barina?

Nope, fuel pump is only controlled by ECU and there is no input to ECU from oil pressure switch. Will try to get it to play up while logging. Might try to depressurise fuel rail when cold and see how quick it starts.

Simon

[VL400]

The pressure switch operates independently of the ECU, it bridges the fuel pump relay which the ECU does have control of. Its part of limp home mode, so even during normal running could remove the fuel pump relay and the engine would continue to run.

Have a look here .. http://pcmhacking.net/forums/viewtopic. ... 2&t=12#p30

Not saying the Barina is wired this way, but if you have a wiring diagram something worth checking.

[slewinson]

Nothing like that on the beep beep. Relies only on the ECU for pump control. Oil pressure switch is vanilla type only for the idiot light.

Simon

[slewinson]

Managed to capture a hard start this afternoon. Sorry for the crappy graph but best I could do in excel. I have attached the datalog as well.

start log.xlsx

(32.06 KiB) Downloaded 262 times

start log.csv

(151.81 KiB) Downloaded 248 times

Interested in your thoughts

Simon