Engine Slow To Start When Hot

[Longboarder]

Going down the ECU route. Most ECU's have cranking settings for engine speeds below say 400rpm. There is certainly a cranking fuel correction setting shown in the instros. There may be a cranking ignition setting also but it is not shown on a quick read through (or I missed it). There will be a section of cranking settings in the maps. Fuel is there. A basic cranking ignition setting may be there. If so check its set to something sensible like 3 degrees advance. If there is a cranking ignition correction setting degrees/temp/load check that is sensible also.

Also the ignition map you are using will have ignition advance figures plotted against rpm and load. Check the ignition figure for all loads at or below 500rpm is set for 3 degrees advance.

 

I did have a stage after a rolling road tune when I couldn't start if I touched the accelerator. The RR operator had advanced all the ignition settings at 500rpm and any load above zero. Put them back to 3 degrees and all was well.

 

Nigel

Edited April 7, 2015 by Longboarder

[Guest mower man]

In the dim and distant past several competition cars I played with exhibited these symtons finaly found the cause - heat soak into starter motor !!! you say it works ok cold and if you let things cool down then realy its obvious the thing gets tight and doesn't want to turn many cures bucket of water , ducted fan to cowled starter ,wrap starter in exhaust wrap are but three [ we used water !!!!!!!]

mick

[richardm6994]

the more I think about it the more I dont think it would be the charger. That things sucks so much air through it that when Terry and I was fitting it to the engine for the first time, the inlet sucked-up my hand from 6inches away.... and that was at engine idle speed!

 

I'm still thinking its more ignition timing problem.

 

ps.....how long does it need to cool before it starts again?

[Tazzzzman1]

Usually 5 mins or so Rich. Dave at CANEMs has suggested unplugging CAM sensor and cranking over. If still slow then definately not ECU related. Gonna try a few things later. I'll keep you all posted..

[richardm6994]

Usually 5 mins or so Rich.

 

That's plenty of time to cool down whilst you're waiting for everone else to catch-up!!!

[femster87]

My money still on starter motor as discussed on monday

[maccavvy]

http://www.demon-tweeks.co.uk/motorsport/heat-shielding-protection/cool-it-starter-heat-shield

[femster87]

http://www.pistonheads.com/gassing/topic.asp?t=748327

 

Found the above, might be of some use

[alanrichey]

Interesting. I tried adding an extra earth strap some months ago and it made no difference. But I am now thinking I added the earth strap from the inlet manifold/fuel injector to the chassis. Might the manifold gasket be preventing it from acting as a decent earth to the engine block ?

 

[Guest 2b cruising]

Interesting. I tried adding an extra earth strap some months ago and it made no difference. But I am now thinking I added the earth strap from the inlet manifold/fuel injector to the chassis. Might the manifold gasket be preventing it from acting as a decent earth to the engine block ?

 

No not really. The earth would be carried through the fixing studs and nuts.

[Guest mower man]

As my previous post I saw several teams using water bucket method at Le Mans over the years and know Jaguar had probs right up to the last cars they ran mick

[alanrichey]

Can you buy cans of 'freeze' spray anywhere. That would be worth trying.

[Bob Tucker]

Plumbers sell a freeze spray for freezing either side of a damaged length of pipe

so you dont have to drain the system.

 

A CO2 extinguisher would do the same thing.

[sj-bradley]

The sheer mass of the starter would mean a huge heat capacity so you would need a fair number of these to cool it down whereas a bucket of cold water is cheaper and more effective in this case.

 

Electric motors are designed to run at elevated temperatures. Have you felt the heat pumped out the back of any conventional hoover? Does it run any slower when hot?

 

I still think a simple check to see if the engine is tight when hot with a long wrench turning the engine over would prove useful and takes less than a minute to do.

 

Simon.

[Tazzzzman1]

Ok update..

I have done as instructed by CANEMS and disconnected CAM sensor ( basically disabling ECU) engine spun over faster. So looking like aapping issue for hot running. Hopefully a simple fix...