pre 99.5 CCLB auto DRW

Initially brought to me as it was communicated it was cutting out and gutless. T plenums were resealed, rebuilt turbo/billet wheel, new boots and a new MAP, truck went from 9 psi to 23 in stock form. I had my computer plugged in the short time it was in the shop and test driven, never hiccuped. As soon as he plugged in the edge unit it was cutting out anytime when hitting the throttle. Since then that has been removed. N issues for a month.

Fast forward a month to today. Truck is returned and gutless, had a 1211 and 1209 stored. At cold idle icp and IPR DC are in check. It's torquey as it should be down low when on the throttle and then it falls in it's face as RPMs go above 1800. I can spin the dual tires on dry concrete brake loading up till 1800 and then nothing. It weird it like the power transfer stops and the motor still spools up and builds terrific boost.

Now here is the part I am questioning, once it warms up a tad the D.C. Goes through the roof, 40% to hold idle pressure -480, peaks at 65 anywhere on the throttle AND ICP FALLS OFF AFTER AN INITIAL SPIKE. When accelerating the ICP pops to 2600 psi down low then sits below 1000 at wot and 65%, the part that has got me is the truck is making 23lbs of boost... and is not moving as it should. I don't understand how it could have such poor oil delivery and appear to be fueling very well and building terrific drive pressure and boost. It has been verified Mechanical and at the MAP sensor. Due to what I'm seeing in oil I went ahead and replaced the IPR and ICP, the internal plug on the shaft was loose aSeen it dozens of time without ill affect but either way, the IPR was replaced and same with the ICP with no affect. I can't imagine the pump crapping the bed instantaneously. Truck made terrific pressure on a stock pump a month prior.

I am asking for your thoughts on the issue with oil, which is the opposite of what I'm seeing with boost... usually they go hand in hand and are not polar opposites.

Its an odd problem I have not seen before in this sequence. I have never seen a boost number like that, no oil, and the truck that is a turd in putting the power to the ground.


A healthy 7.3 at this altitude puts 18-21 psi on fresh everything in stock form data logged in AE, his motor had healthy compression when purchased and the charge intake has been tested to 60 psi and turns the motor over.

All I can think of is a mass oil dump, I'll take the valve covers off and see if there is anything that is obvious, otherwise dead heading the pump is next.

Any thoughts?

 

If the fuel filter is black, injector O rings are the usual suspects.

 

Its not, and its not consuming past the mid tier ring either.

 

Try it with A/C turned off? Any problems there will grow with rpms.

What is oil temp? Maybe tstat isn't opening?

 

My guess is dead heading the pump tests out fine. Be sure to also check volume. While there's no technical way to measure, other than eyeball comparison, we've seen pumps that can build pressure, they just can't supply the required volume. A weak pump will eventually get weak enough that it is noticeably low on output when a line is disconnected, but still pressure tests fine when blocked off.

That might explain your boost levels. Works great until not enough oil can be provided and then falls on it's face. Got a spare HPOP you can swap around for testing purposes? Does the existing HPOP have a reman tag on it? Those are notorious for having these type of low volume failures.

 

I am not knocking your suggestion but AC or not it will not affect the oil issues I'm seeing. AC was not on.

Oil is up to temp, or at least as up to temp as it can be for test drives. 150+, thermostat is opening fine.

 

I do have a spare to swap over. Its not a reman, and I have never seen one fail this way but hey you learn something everyday.

I am going to re-ring the injectors for safe measure and hope when the valve covers come off there is something apparent, if not I guess we can move onto a pump.

I'm frustrated and in here asking questions as I have never seen this in this sequence, I'd rather not be stabbing at the dark with swaps, but outside of that I am not sure what else to do and test on the oil side.

 

Never took it that way

But if you have trouble with the A/C pulley, compressor, etc, it can add a substantial and uneven load.

Ask me how I know, lol

It can be enough to stutter the truck, like bad gas, so it can be significant... And sneaky

 

Blindly swapping parts sucks, I get that, but at least the HPOP is much easier on the 7.3 than the 6.0.

And the only reason I suggested it is it fits your symptoms. I've even seen a reman from Terminator suffer low volume issues. Works great down low, but as the IPR goes up and the injectors use more oil, the volume just isn't there and the power falls off. Injector o-rings usually show symptoms on hot starts but not cold starts, or leave signs of oil somewhere.

Good luck with your search, and be sure to let us know how it turns out.

 

Nick, sounds just like my HPOP failure/debacle right before the truck quit. It seems HPOP failures are not common, but lately I have seen a few threads where they are taking a dump. Don't rule it out. I thought "no way" when mine failed, but it did.