After the tranny shop rebuilt my 48RE tranny and replaced the TC (after less than 1,000 miles) there were a few problems with the truck. One was that the tachometer didn't work - that turned to be a sensor that somehow been obliterated. But the biggest problem is a significant loss of power.

The batteries had been disconnected for about a week and when they tried to start it the first time it would not start, but after a quick charge it did.

I re-programmed to Smarty Jr #2 but that didn't help.

I re-programmed it to Stock and it drives the same as it did with #2.

In fact it seems to be slower than stock, there's accelleration until you get about half way into the pedal, and there is no more. It used to a rocket ship on which putting the pedal to the floor was a scary experience requiring your complete attention, now it's no big deal.

So, what could happen that would negate the Smarty programming. Do I need go out and get a fuel pressure gauge?

Peter

 

Well Wait a minute here, Where is this sensor at? If its on the side of the crank shaft and its black and it has one bolt holding it in Thats the CPS. Maybe thats why there is no tach and no power, You would probably have a CEL if you had a light in the dash.

 

How would the truck run with no CPS? Would it run at all? I'll take a look. I'm pretty sure what I replaced was just for the tach, but if it was destroyed by something, there's a good chance the CPS was damaged too.

Peter

 

Check the CPS, it is still there and does not appear to be damaged. Anyone know what code it would throw? I checked the codes and there is nothing new, just the 3 transmission codes that it throws because of the ATS tranny controller - anyone know how to get rid of those?

Peter

 

OK, should I post this somewhere else? I need some help here. Is fuel the only thing that can cause a power reduction, or is there anything electronic I can check - other than the codes which I have already checked.

Peter

 

Fuel pressures would be the first thing to look at, a quadzilla rail pressure gauge with the fuel pressure option (for the lift pump) would be a good choice. What are you using for a fuel pump? Can you hear it running? Try changing the filter?

 

Thanks, I'll get the quadzilla.

I can here the FASS running - should I also be able to hear the pump on the block running? I will also change the filter, havn't done that yet, it looks impossible to get at on my truck, plus I need to acquire the 'tool' for it - we'll see.

Peter

 

OK, I got the Quadzilla installed today. It max's out at about 1800+ psi at about 40% throttle - lost power to the ScanGauge so I can't see the exact TPS position. Is there a table or a curve somewhere that shows what PSI to expect for various rpm and/or TPS positions?

Peter

 

OK, I should have said 18,000 psi, the Quadzilla reads in 10's. And I can get low 19,000. How are those numbers? I searched for a description of correct psi readings for the fuel rail but couldn't find anything.

Peter

 

Sounds ok, idle should be between 5k and 7k, cruising down the road 10k to 14k, wot 24k to 26k.

Lots of things affect the rail pressure. You need good lift pump pressure for one. If your injectors are leaking, I've read it will limit max rail pressure. Also, if you run any performance boxes or large injectors, you essentially can drain the rail of pressure when called upon. So if you get on it hard, the rail pressure will spike up and then drain down as rpms come up. The cp3 can't maintain the pressure due to larger injectors or longer duration from a box.

Any codes?

 

Thanks for the info. that's helpful.

No, codes, stock programming, stock injectors. I idle/cruise at 6,000, as I run up to 50% to 60% throttle the pressure rises to about 19,000 but never exceeds that. I have no increased acceleration after about 60% throttle and 19,000 psi.

Peter

 

OK, changed the fuel filter today to see if that was contributing to the problem - but no, pressures only seemed to go up a couple thousand psi. From maxing in the low 19,000's I am not hitting 20,000 occasionally. It's kind of hard to see what is exactly going on since, as I read elsewhere, the pressure spikes and then drops off as the engine uses the fuel. That would seem to imply to me that the max pressure isn't that important.

This is all happening in front of the regulator - right? What psi does the regulator regulate the pressure to?

Now that I know my pressure and have a clean filter installed, what's the next step in diagnosing a loss of power above 60% throttle?

Peter

 

That pressure (20,000 psi for example) is the pressure in the fuel rail, directly attached to the injectors. No regulator on it. The engine monitors this pressure and has the FCA (fuel control actuator) (little round thing on the cp3) adjust how much fuel is allowed to enter the cp3 to increase or decrease this pressure as needed. The FCA can't really decrease the pressure, but if it doesn't let any more fuel in, the injectors firing will cause the decrease...

Did you have to feed a speed signal to your ECM?

 

5.9, thanks for that info - that's very helpful. I don't know how it was wired, it was done by Autoworld in Montana. My impression was that the speed sensor was only going to the ATS controller. And it wasn't really speed it was off the driveshaft. Does the ECM need speed? And where on the big connectors would it be connected? And what flavor speed input would it require. My understanding is that the ECM is only looking at TPS and RPM - but as I have already proved, my understanding is very, very crude. Without this site I'd have given up on this truck a while ago.

The tranny was recently worked on and I wonder if the speed sensor got hooked back up incorrectly. The loss in power coincided with the tranny work exactly.

Peter

 

Without looking at the 05 wiring manual I won't be much help, but some years required the signal or the engine would defuel. The ford speed signal is output to the ABS system, the speedometer, the cruise control, etc. so there are many places to tap into it and then it is fed to one of the ECM inputs.

Scott at Destroked.com would be a great resource to talk to. He has all the wiring manuals for diff years and could tell you what color wire to look for to find it or where it should be connected on your engine wiring. Hope that helps...

Will it currently rev like normal? I seem to remember if no speed signal is present, it won't go above 2000 rpm maybe...