Adjust idling after install high duration camshaft

[CHB]

i just run in my new camshaft and valve springs in my 3TC. it is 284 degree, 114 lobe separation, 0.475" lift. i can't get it idling after the run-in period. i have to put my right foot slightly on the gas pedal just to keep the engine running. i've tried to adjust the idling screw and it reach it's max position but the engine will dies off too..
before i do such replacement, everything was working fine and smooth. any tips?

[oldcorollas]

first, rasie the idle speed, then try to tune it a bit, then lower idle sspeed and tune... keep going until it is as badly behaved as you can stand

maybe the cam needs to be dialled in.. ie advanced or retarded a bit?

[af300e]

Have you checked ignition timing? Have you upset it?

[CHB]

everything was set accordingly back to the setup before the camshaft change. idling at 12BTDC.

[af300e]

hmm, might be a little retarded for the lumpy cam. Try swinging it forward gently, you should find it idles up. Do you know what vac advance it runs?

[CHB]

i installed my cam straight up. it only want to idling at 50-60kpa, previously it sit pretty at 40kpa.

[Rodger]

Is this the Turbo 3T-C in your profile?

If it is a carb version and it is the stock Toyota one then it will not be able to flow enough fuel to even idle with that cam.

More info please

Regards

Rodger

[CHB]

yes it is for turbo 3TC. i'm using Megasquirt 2 EFI and previously runs fine with my stock cam and valve springs. now i installed my new cam straight up without using an adjustable cam gear.

[oldcorollas]

are you using alternating squirts? try using 2 squirts alternating, or other combinations (1 squirt simultaneous, or 2 squirts simultaneous) and see if it affects idle quality.
you may need to change the idle table, and a bit more timing will help, since you have lower dynamic compression with the larger cam.. - needs more advance...

[CHB]

i'm using 2.883 code. do we need to reconfigure the whole setup if we change the injection mode from alternating to simultaneous? how high is the ignition advance to start with? now it is 12 BTDC

[oldcorollas]

no, you should just be able to swap the modes around, and it will change ReqFuel to suit.
ie, if you double the number of squirts, ir will have the pulse width
it can make some engines idle better.

how high is it to start with? i'm not sure what you mean.
but, at idle speed (and no load only) you can adjust up to maybe 20deg reasonably safely... i am nto sure of exact number, but as you advance, it should idle smoother or increase rpm... just fiddle around with it..

[Rodger]

Yep I agree with oldcorollas. You need to offer up more fuel and change the timing curve with more advance at idle to try to burn more of it.

Gotta love EFI for this. I cannot do this with carbs as easily.

The cam is now long opening and has more overlap that causes a lack of vacuum/air speed to suck in the fuel.

Regards

Rodger

[CHB]

ok i'll try to change the injection mode and see how stuffs goes.

[af300e]

Sorry, I didn't know you were turbo. My bad. Just make sure you are not going to over advance the ignition if you are running vac advance before you go too far on the idle ignition timing.

[thechuckster]

CBH's ECU is running fuel and spark.

Personally, i had better luck with 4 simultaneous injection events per cycle. Also, i run lots of advance at Idle with a section at much lower RPMs (~600 from memory) to help bump up the idle speed when the motor got too slow.