Stroker in and running.. but noise and lean condition.

[Mgardiner1]

You get a fuel PSI reading during the problematic area?

Also, try to think of what else has changed besides the internals of the engine. You were running this truck before with no issues (other then a crap built motor)

[SilverXJ]

PSI is 42 psi idling, revving in neutral, and off.. holds steady for 5+ minutes when off. Hose on fuel gauge was not long enough to be routed outside of engine bay for driving analysis.

What else has changed with this engine, besides 100% of the engine (still have same PN cam as last one): battery cables and alternator. Oh.. and I picked up an extra IAT sensor someplace, but I put the one that I was using in the old engine in the air box and am now using that one. I swapped out all the sensors today with spares (except the O2 and coolant sensor) and tried to find see if there was a bizarre vacuum leak and didn't find anything.

I really think I need larger injectors. I was able to run the scan tool long enough yesterday to determine that long term fuel trim is at +35%. Maybe the long rod versions just need that much more fuel at that point.. they are supposed to make more torque than the short rod versions.

[Mgardiner1]

I just have such a hard time believing that it would act like that at part throttle. If the throttle body was wide open and the general trend showed a lean condition, then i'd agree. However, i am not a fuel injection EXPERT

[1bolt]

I'm fond of repeating that I run stock sized injectors, with no problems... Chris are you sure that the lean swing isn't part of the typical averaging process that narrow band O2 equipped fuel management systems use? It's hard to say why but my Air/Fuel often shows protracted lean swings at warm up, yet it runs down the road well within an acceptable range of stoich, a tad lean of ideal on average. Once i put my foot in things it fattens up instantly and is just a little rich.

[Edit] I just re-read your first post... mine does the same thing and always has, until it's warm. I believe it's got something to do with the ECU's default "warm up" not being Rich enough for the new .6 or 7 liters that were added. and the fact that your O2 sensor is ignored until the coolant sensor warms up to normal temp.

For what it's worth I've run like this for over 60,000 miles and the plugs never show lean. It goes away once the engine is out of warm up mode.

[SilverXJ]

I'm sure this isn't normal behavior for OBD II. I expect it to be lean, but leaning it to 18-19:1 under a load for a sustained period of time isn't right. If you look at the graph I posted it shows an RPM drop when it hits that point, that isn't a shift. That is on a flat load with nearly constant throttle (~40%). In any iteration of the titan strokers it never had that issue either. I do believe it is going in to open loop and ignoring the O2 sensors at that point.. I have most of it dialed out with the apexi, but I don't like adding that much with the Apexi as such a low throttle opening. I rather be taking fuel out instead of adding it. As for stock injectors, I have ran them in the past but you need some modification on top of that such as upping the fuel rail pressure or a piggy back. And I know that I had to have the apexi add a bunch of fuel at WOT to keep the AFR where it should be, especially after I p&p'd the head.

[hatem61]

SilverXJ, I am glad the sound went away.
Now the lean condition, I am just thinking loud:

I tend to agree with 1bolt and Mgardiner1 that the injector SIZE is not your problem, the OBDII compliant PCM on your vehicle is capable of altering the base injection pulse width by +/- 33% fuel quantity based on O2 sensor data ( short term correction ), and another +/- 33% based on O2 data under certain RPM and MAP conditions ( long term correction ), this is a lot of correction combined.

You mentioned the fuel pressure at idle is 42 psi? if you typed it right and I read it right then it is too low. Specs calls for 49 psi +/- 2 psi for your vehicle ( 2000 year model, right ? ), also it is equipped with a returnless fuel system and fuel pressure will not change with vacuum.
Good Luck

[SilverXJ]

I know the factory pressure is 49psi. I thought that 42psi was with in range. However checking the FSM, the minimum fuel pressure is 44.2 psi.. ^@#*&#%&%# I'm going to check it with another pressure gauge before I replace the pump. I really wasn't wanting to replace the pump. Some dipstick engineer decided it would be a good idea to put it on top of the tank instead at the front like previous years.

[SilverXJ]

If I do need to replace the pump, should I get the whole assembly with the regulator, or just the pump and strainer?

[hatem61]

SilverXJ, I thought these things only happen to me
You are probably right for the pump pressure but not for your particular year model.
Pump is expensive so please doublecheck before you replace it.
If the test gauge is confirmed good and the pump condemned, there should still be chances that the problem could be the regulator for instance.
I you want I can try email you the complete procedure to check fuel delivery system, very well explained but I am not sure I can post it here. I already PM my email address. You also better check what can be sold separately for THIS model year pump, I know it is different than some other years.
Good luck

[ARH]

If I do need to replace the pump, should I get the whole assembly with the regulator, or just the pump and strainer?

If I were you I'd shell out the extra coin for an adjustable FPR and a Walbro pump.

[hatem61]

SilverXJ, have you got the 2000 FSM? it gives the pressure test specifics, pump amperage draw test, pump capacity test and leak down test. your problem could be anything from a leaking or kinked fuel line to a pump motor.
And yes, you are correct, the minimum pressure in most instances in FSM states 49.2+/-5 psi. The one I mentioned actually states 49.2+/-2 psi from the specs of the same FSM .

[SilverXJ]

Well, the fuel pressure is back up, but the lean spot is still there. Other than that it is running well.

[Exos]

Maybe you need to wait for the ECU to have enough cycles and it will correct it by itself?

[SilverXJ]

Perhaps, but using the old learned fuel trims it should then be running rich in the same area.

[Exos]

If your ECU had no power for more than 30 secs, as I imagine it did, it's learning all over again.