Cold start map / injectors firing on ignition on??

[royal]

http://www.skylineowners.com/forum/showthread.php?t=107699
Non VEMS but I'm interested in an answer as I'm reading and learning lots at the moment. Some guys having cold start up issues with skylines. One says his injectors squirt on turing the ignition on and fouls the plugs, another guy has had similar issues since having the ecu chipped althougth the garage say they don't touch the cold start part of the map. Anyone here got any ideas?

[gunni]

Are those Skylines standard?

I do know some manufacturer do not actually map some aspects.
Alot of KIA cars that came to iceland in the mid 90´s did not start.
Koreans came over and the cars where held in climate controlled cells in Iceland.
And they had to remap them to make them work properly.

I could imagine that if the injectors aren´t the originals that they are not flowing in the same manner as the originals and
that means that the warmup would need retuning.

[royal]

I'm pretty sure they are more or less standard, perhaps air filter and intercooler with a chip sort of setup. Maybe boost increased in a few cases.

[gunni]

Then it can only be down to faulty sensor/s
or bad tuning of the warmup.

[rob@vems.co.uk]

So they're fouling on priming pulse?  I'd be a man who was bust measuring coolant temp. sensor's resistance and checking the MAF voltages.

[royal]

What does primary pulse mean Rob? do the injectors fire on key turn?

[gunni]

Yes,
When you put your car to ON and nothing more. Alot of ECU´s do a quick injection shot.

[royal]

Thanks Gunni. Is the amount of fuel injectored on the primary pulse adjusted by the temp sensor in the same way as cold startup adjustment? just trying to make sense of the guy who said the primary pulse was fouling the plugs and giving startup problems, or whether its more likely a red herring and actually a temp sensor issue or something else?

[Sprockets]

Without knowing the exact mods, it's hard to say but everything that has been said so far has been correct.

One thing I wish to add tho, is if when it was chipped with added boost some owners/tuners feel the need for a colder/harder plug when all it will do is make warm up a real issue and cold fouling a regular thing!  Had this problem numerous times with cars coming in, a plug change to either OEM specs or 'Iridium' style but correct heat change cured everything.

Remember guys, a spark plug is critical thing, don't change the specs without really understanding why

Just speaking from experience.

-Gavin