cold advance solenoid

[A M A]

if the cas gose bad how will thy motor run please help thank :confused: u

[catmandoo]

it will only be affected when cold ,first thing in the morning,when you start it should hammer hard ,mine usually does this for about 2-3 minutes or so and you will notice when it pops off it will get quiet and the power will drop off a little

[A M A]

this dose not drop more fule when it is cold

[A M A]

iis the c.a.s only on cal motors or are they on all 48s

[catmandoo]

yes they all have it and it does give it more fuel.

[britannic]

There are 2 solenoids:

The fast idle solenoid raises inj. pump idle to 800rpm (if set to factory spec) to enable more fuel and prevent stalling when cold.

The HPCA drops the inj. pump housing pressure to advance the timing and thus compensate for the slower burning combustion in the cold engine.

[POINTERMAN]

Where is this hpca solenoid located and if it were to go bad could it keep your timing advanced ?

[britannic]

Originally posted by POINTERMAN:
Where is this hpca solenoid located and if it were to go bad could it keep your timing advanced ? The HPCA solenoid is in the IP housing, it pushes up against a check valve which releases the IP housing pressure. The pressure drop activates the servo advance mechanism by simulating the higher consumption of fuel at high engine speeds.

The HPCA solenoid is most likely to fail by not releasing pressure and is easily confirmed when no change in diesel clatter is heard when it's energized with 12v.

Less common, is an HPCA failure in which the valve remains open. When the HPCA solenoid is energized, the diesel clatter doesn't change and sounds like an erratic Cummins engine at idle. At WOT, the engine's power is slightly reduced (assuming timing is spot on and the timing chain is within spec) and will feel more powerful if the accelerator is gradually backed off.

Both conditions are best checked using a timing meter. Expect around 6* of advance with an energized HPCA in good condition.

[POINTERMAN]

My truck all of a sudden seems to idle a little high than normal and seems to have louder clatter when you give it a little pedal but if you mash it and put it under load it quiets down. I am going to be pulling heads on it in a month and checking timing chain in anticipation of banks turbo I am going to install.It has 155,00 miles so I want to put new gaskets on it.

[A M A]

will any of these make the truck blow white diesel smoke very rich in dieswel smell

[A M A]

what is a hpca

[britannic]

HPCA=High Pressure Cold Advance

[Peter J. Bierman]

Sorry to interupt, but HPCA= Housing Pressure Cold Advance.

If activated the housing pressure drops a little and as a result timing advances.

Peter

[britannic]

Thanks Peter! I recorded it incorrectly in my DB2 article and copied it from there. I've asked More Power (a.k.a Jim Bigley) to correct it in the article I submitted to him.

[Peter J. Bierman]

Your welcome.

Peter

[A M A]

hello i got to play today and i did alot i did take off the i/p cap today all springs and stuff seemed to be sloppy if i put 12v to the hpca the rpms jumped up and ran with little to no smoke ithink it was the hpca the wire ran from a temp sens {on left side in rear on head} to what i think is the hpca and on to the c a s is this the hpca i tkink it might be the i/p pump i hope not $$$$$$ not good wear can i go to get a i/p pump or rebuild thanks ama merry x-mas to all

[britannic]

On top of the IP pump are two connections:

The front one usually has a pink wire and is the fuel shutoff solenoid.

The rear one usually has a green wire and is the HPCA, there is also a wire connected to it that goes to the fast idle solenoid plunger on the accelerator bracket.

Before spending $$$$ on an IP, get the timing checked and also check the timing with the HPCA engaged.

If it finally proves to be the pump, after you've checked all of the suggestions in this thread's previous messages, I can recommend Tim Wagner @ www.accuratediesel.com. (http://www.accuratediesel.com)

[A M A]

thank u for the ref. i pretty sure its gone a be a i/p pump it could not be a cheap thing it x-mas ha ha