Big oil and duty cycle... need advice

Pocket · #1 Sat, June 12th, 2010, 07:27 PM

For years I've run the oil crossover tube, and kept it when I went to big oil. Recently I worked on tracking down an oil leak, and one of the leaks I found was coming from the crossover. So I removed it, and re-installed the plugs back into the oil rails.

As a result, my truck will sometimes stall as it returns to idle... such as coming to a stop sign or a stop light. With the crossover tube, it always had a very slight dip as it returned to idle, but never enough to stall the engine, and hardly enough for anyone else to notice (my wife never once noticed it in all the years she's been driving my truck). Now the idle dip is extremely pronounced every time I come to a stop, and the stalling is starting to piss me off. It does this in any tune, including stock. And it started immediately after I removed the crossover tube.

I haven't decided if I'm going to put the crossover tube back on. It's in the way when I'm working on my truck, and I'm about to tear into it again anyway, so I don't feel like hassling with it.

Basically I need some help on which direction to go with the duty cycle table to try and smooth it out, and help it return to idle without being jumpy, without dipping RPM's really low, and without stalling.

TIA for any help!

***907DAVE*** · #2 Sun, June 13th, 2010, 05:14 AM

Subscribing.

I have monkeyed with the Duty% quite a bit, not for stalling issues, instead for a rolling idle.

My first thought would be to raise it in the Idle range, but logically it does not make much sense to me why you would need to.

Have you tried to raise your ICP?

***cleatus12r*** · #3 Sun, June 13th, 2010, 09:58 AM

Can you post a screenshot of the current values? The F6 and F10 views would be great.

Pocket · #4 Sun, June 13th, 2010, 02:27 PM

Here ya go Cody. The first image is the stock DC, the second image is one of the tunes I'm playing with, but I'm simply using Bill's table that I copied from I believe his 120hp extreme tune. Both are VDH2.

***cleatus12r*** · #5 Sun, June 13th, 2010, 04:55 PM

Oh... Yeah....
Put the stock map back in there. Your IPR duty cycle base map is WAY too high at an idle (3-4 MPa). Big oil should love that stock map!

The thing that really bothered me about "brand-x" tuning was the IPR duty cycle would cause a HUGE dip in RPM once the transmission downshifted and the engine dropped to an idle at 35 MPH. This was simply due to the high IPR duty cycle and the lag time required for the PCM to decide that the base duty cycle was way too high to maintain 600 PSI once the RPM dropped quickly.

Put the stock map in your programming. Your truck will thank you.

***cleatus12r*** · #6 Sun, June 13th, 2010, 05:00 PM

Here is said map (black) and stock map (blue). This caused a near-stall condition many times on decel when the transmission would drop out of 4th gear at 40-35 MPH. It would always cause a big dip in RPM.

Pocket · #7 Sun, June 13th, 2010, 11:35 PM

Cody, I've also had it try to stall in the stock tune too. It never fully stalled in stock, but the idle does dip quite a bit until it settles.

Should I lower the DC a bit more on the bottom end of that stock table and see what happens?

Shaw · #8 Mon, June 14th, 2010, 12:14 PM

Pocket, what big oil do you have?

Pocket · #9 Mon, June 14th, 2010, 05:14 PM

Quote:

Originally Posted by Shaw

Pocket, what big oil do you have?

Termy pumps. I've had them for about 3 years now. Problem I have right now is I think one of the HPOP lines is leaking. Probably a bad o-ring. They are the original lines. I just can't seem to pinpoint which line is leaking, since it only spits out oil above 2500 psi.

***907DAVE*** · #10 Mon, June 14th, 2010, 06:30 PM

Ground out your IPR for a few seconds while watching for leaks, should be able to find it.