I thought I was facing a tranny problem, and had mixed emotions about getting my '03 Ex's tranny rebuilt and put into my truck while my truck's tranny would then go to the Ex... it was going to be a BTS job, complete with 6L tranny coolers for both vehicles. My only caution was related to the cost, but a man's gotta do what a man's gotta do!!

Anyway, I've ruled out the tranny as the problem tonight, and would be grateful for insights from those more experienced than I.

PLEASE... be patient with my long write-up and PLEASE read the ENTIRE post before jumping to any potentially premature conclusions. I've tried to cover the basics and address potential issues to the best of my knowledge.

SYMPTOMS...
Once the engine and tranny are warmed up, when I start to climb a steep hill at low speeds, the Excursion acts almost like the tranny is slipping very, very badly. Upon closer observation and repeated runs, what happens is this...

- vehicle is running through the bottom between two hills at about 30 mph and then starts the climb...
- about half way up the hill, the tranny downshifts and then the vehicle starts losing power altogether...
- the engine RPM's do not climb at ALL even though I am pressing the accelerator harder and harder, and the vehicle begins slowing tremendously...
- as the situation progresses and I shove the throttle to the floor, the vehicle starts pulsating and shaking and the engine sounds like it's missing very badly, and I can't get more than about 10 mph out of the vehicle...
- once I have crept to the top of the hill and let off the throttle to stop at the stop sign, the engine smooths back out and runs seemingly normal again.
- aside from this situation on a steep uphill climb at low speeds, the engine runs normally and smoothly, and the tranny shifts like normal under normal acceleration.

TEST RESULTS and FINDINGS from running AutoEnginuity...
1. Cylinder 8 shows a balance fault on the cylinder contribution test
2. Injector Buzz test indicates that cylinders 1, 3, 4, and 5 are the weakest sounding, with 7 and 8 being the strongest. I would guess that the buzz volume on the weaker injectors is about 60-70% of that on injectors 7 & 8.
3. Upon starting up, Injector Pressure hits around 800 psi (IPR valve replaced with a brand new unit about a year ago)
4. No misfires indicated on any of the cylinders.

ADDITIONAL OBSERVATIONS from idling and running the engine in the driveway...
5. When pushing the throttle down progressively harder and harder, all the way up to 3000 rpm, the engine seems to run smooth and steady.
6. After letting the engine run at or higher than 2500 rpm for 10-15 seconds, and then punching the throttle up and down for rapid acceleration and deceleration, after about the third or fourth cycle the engine starts puking tons of white smoke from the exhaust and begins to run very roughly, just like when under load and trying to down shift on the hill in my driving test.
7. Batteries and alternator are good and providing ample voltage.
8. When turning on the key on and letting the fuel pump run while waiting for the WTS light to go off, the fuel pump sounds like it may be struggling... nothing like the steady sound I get from either of my other two 7.3's.
9. NO white smoke on startup at all, and no indication of a bad GPR.

RECENT WORK on vehicle...
- oil and filters were all changed about two months ago
- air filter has low mileage and is good
- fuel filter has low mileage (changed back in the spring)
- the tranny was flushed and new fluid installed per Mark K's flush procedure... no change in symptoms, and this flush was done after the symptoms started showing up but BEFORE my discoveries tonight.

PLANS for TOMORROW:
1. Pull valve coves and check for tightness on all injectors.
2. Complete the 50-cent mod while I'm under the covers.
3. Take the fuel pump off my F250 and see if it makes any difference in running conditions on the Excursion.

What else should I be looking for??

Like always, I am grateful for your help.

 

check the fuel psi sounds like it is running out of fuel. i think that would be the first thing to do.
i dont think it could happen but is the air filter clogged?

 

Air filter is in good condition.

Fuel filter has low mileage on it.

Oil, full-flow filter element, and byass filter element all changed two months ago.

Oil level is where it should be.

 

my truck would do the same pulling a camper up a steep hill...The trans for whatever reason would not downshift....RPS drop,temps climb,truck sounds horrable....i learned to let it down shift before the climb and all was well....my BTS doesnt have the issue..

 

I should note that this is something new, and I am not pulling anything with the Excursion while thsi is happening. The tranny has had no problems with downshifting on this hill for the past two years. If I were seeing clutch slippage, I would see the rpm's building while losing speed, and I'm not seeing that. Also, I have tried downshifting manually and the exact same symptoms exist. If it were a tranny problem, then I know that the BTS unit would be an ultimate solution for me.

 

could lack of fuel pressure cause it????just throwing it out there..on flat ground if you romp on how does it act??

 

Have you noted the fuel level when this happens Pete? I'm wondering if fuel is sloshing away from the pickup in the tank coupled with a bad mixing chamber?

 

Hello Pete,

I'm with Matt. I would concentrate on fuel pressure. That's want it sounds like to me.

 

I'm thinking it's fuel related altogether due to the white smoke I've observed in repetitive tromping sessions in the driveway and what sounded like a struggling pump on start-up. t isn't fuel sloshing with low fuel level because I can create the same running condition on level ground in the driveway without the vehicle even moving around.

I'm expecting that either the UVC inspection, fuel pump swap, or both will reveal what's really happening in the morning. Like I said in my opening post, while I'm under the covers, I'm going to be checking/tightening up the torque on injectors, rocker arms, and also doing the 50-cent mod to boot.

I know this has been asked before, and I simply can't remember... can I start and run the engine with the VC's off, and if so, what do I look for in terms of leaking injector o-rings?

 

i wouldnt waste your time pulling the valve covers until you have verified its not the fuel pump or another fuel restriction.

You can run the engine with valve cover removed but it will splash a little oil. Bad injector orings will not cause what your describing. You are describing a situation where your engine only runs out of power at a situation where it is under load, i.e. driving up a hill. It has plenty of fuel for normal driving but when you put it under load and it calls for more fuel and its not there, it will start losing power due to being underfueled, and therefore, causing some white smoke

 

Pete
Do you have a fuel gauge you can hook up and see were your fuel pressure is running at before you switch pumps?

I'm with Matt and Robin on a fuel prob.

 

X2 on what they said with the fuel pressure, I think you will find that under load you will not have what you need. It doesn't look like from your signature that you have done any of the in tank mods. At the mileage you have it could very easily be plugged up screens in the mixing chamber. Remember there is also a small screen in the intake side of the fuel pump. If your getting your pressure (55-65 psi) but it drops off under load, my first place to look would be in the tank. If your not getting that I would check your FPR next.
I know this from experience, I put off dropping the tank till the very last and it cost me a whole lot more since I put in a new FPR, and pump and then still had to drop the tank.

 

Pete, I have a spare fuel pump if you wanna try it and see if it eliminates your problem. Just say the word and I'll ship it out to you.

Stewart

 

Fuel issue. When I did the in-tank mod on mine, the fuel line got twisted when we put the tank back up. The pump was making the angry bee noise when you turned the key on (which I didn't notice at first). I had the same loss of power when trying to climb a hill too. Made it up the gradual part just fine, but when I gave it more pedal to go up the short 9% grade, it started shaking missing horribly. More throttle made it worse. If I backed out of the throttle, it smoothed out but was still loosing speed. After cresting the hill, it drove fine all the way back home. We un-twisted the line and it ran perfectly after that.

 

I Forgot to say that my truck was starving and struggling like this when all my troubles started. It got progressively worse to the point that it was struggling just to remain idling. I ended up limping the truck home on the freeway 30 miles at less then 20 mph, it was all it could do just to make it up and over the freeway overpasses. I know what you are going through, I limped it home to save the tow charges, cause if it moves on its own it was still faster then waiting for a tow truck.