Will not start when cold...grrr

Just looking for a direction to going in

I have a hard cold start problem, after cam install, the cam is a touch smaller than a MS3(lift wise).

when doing a cold start I get brief fire than dies, then hit key again I get a longer cranking with brief fire(couple of cylinders). more cranking leads to me having to put my foot in the gas.

Now when I put foot on the throttle(30-40%), right away, is fires up but have to use the throttle for about the first 5-10 seconds, then idles on its own and continues to run rough until warmed up. Plus when I drive away when its still cold it will run rough until 2000rpms then cleans up.

Hot start is fine, wish it had more snap, but fires up then goes to idle rpm.

This condition gets way worse when temp drops down to 50*f or below. Stock cam had this condition,but was only very slight.

Tune drives great, idle great, little choppy around town. :drivin:


I think couple bad injectors leaking down?
I did change spark plugs to tr55s...problem?
Plus get a alot of misfires(scanner wise) at idle to 2500rpm
And yes I running maf only(Dynamic air disabled)...problem???

PS I think I have fixed the idle surge when coasting as seen in my log. Have yet to flash this tune into the car.

:worship:
Thanks:drivin:

It sounds like you need more startup airflow and possibly a higher idle. I can't look at your file right now, so this is just a guess.

Try some more base idle airflow, start up airflow. Add 2-3 grams.

Ian

funny thing about startup airflow, I found if there to much, ETC postion goes 1% during startup. And I am getting close to the 64g limit in some colder areas. I have never been able to get ETC postion over 20% at startup, but it only takes 15-16% to idle.

ok set all your ol/cl settings back to stock, set your etc tps settings to 100 across the board this will allow the throttle blade to open 100% at any speed if your looking for better throttle response.

in your dynamic airflow set your high rpm disable to 100 and your reenable to 50 if your doing away with the ve tuning.

And if that fails and your WB is showing lean as soon as it fires and under 2krpm then richen your OL tables up for the ECT and intake valve temp area you are at for cold start. This should help to bridge between crank fueling and run fueling. Maybe also some additional crank fuel as well given your second crank attempt is a little slow to light up. :)

okay will do shortly...thanks guys!!!

ahh still a no go.

ETC went to 1% again, and remaining starts attempts stays at 1%.

I even added 5% to crank fuel. it was commanding 10.15 AFR at first start.

oh heavy fuel smell not to mention nice little spray patten from the exhaust tips on the driveway.

dont know why the ETC want to be "closed" for the first few seconds..grr:shrug:

Also looking at the log file why is bank1 inj at 60 some milisec?? and bank2 at 40 some milisecs?? at times.

Okay tried few other things

Restored stock startup airflow...and added 30%
reflashed...ETC stays open at 19-20% during cranking

Also notice the its commanding 4.05afr on my first start after re flash.

Then I pulled 20% crank fuel out..reflashed command 8.09afr.

I think thats my problem, flooding the motor when cold. Cause I notice the commanded cranking afr goes higher when motor get warmer,

Well motor is getting warm now, until next morning. oh is was about 58-60*f outside this morning.

Sorry for not posting earlier, but as soon as you said you were approaching 64 g/sec in the startup airflow, it was kind of a dead giveaway that the engine was getting way too much fuel.

Next time, share the setup so we know exactly what we're dealing with. :D

so anybody know why its commanding so much fuel at cold start....? Sorry may have a mental block here...lol

Quote:

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Originally Posted by WorkingManPerf.

so anybody know why its commanding so much fuel at cold start....? Sorry may have a mental block here...lol

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Its the equivalent of choke on a carb motor. Because there is no vaporization extra fuel is used to ensure a mix that will fire.

It also goes richer when warmer to compensate for hot motor and too much vaporization.

well got it to start with no intervention, and on the first twist of the key when cold.

except have no clue what did it, all I did is pulled out 20% out of cranking fuel and smoothed my maf table a bit.
still runs pretty rough though. I notice that commanded afr goes up from 10. to 13.3 over the course of 30 secs.

Can someone explain... what tables are being used to calc first 30secs of fueling.

thanks??

Oh the setup is cam and headers ls2 (236/242 .580/.590 on a 112 lsa)

Just thought of something....I bet its one of those OL tables doing that....

sorry speaking out loud...lol

It sounds like you need to start over from a stock calibration, because that isn't a terribly wild setup.

well its starting like a gem now, just need to smooth out low speed fueling, fix a few other things.

Thanks again

CT