98 Ex lost power - need help please

[darkowy]

Need some advice to get 98 Ex Sport VIN. "E" into drivable condition.
Vehicle lost almost all power; it's very hard to start driving it from stop. With just a little acceleration applied engine starts to choke and car is braking instead of accelerating, however when not in drive position engine revs fine without any problems. "Check Engine" light is on so, I was able to pull those DTC's:
P1747 Pressure Control Solenoid "A" Short Circuit
P0743 Torque Converter Clutch System Electrical
P0750 Shift Solenoid A Malfunction
P0755 Shift Solenoid B Malfunction
P0760 Shift Solenoid C Malfunction
P0765 Shift Solenoid D Malfunction
P1451 Evap. Emission Control Sys. Vent Control Valve Circuit Malf.

Pending Codes:
P0141 Heated O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 2)
P0161 Heated O2 Sensor Heater Circuit Malfunction (Bank 2, Sensor 2)
P1409 EVR Control Circuit Malfunction

Seems like transmission problem but I doubt there is anything wrong with it mechanically. Looks more like electrical problem to me.
Any suggestions where to start?

Thanks in advance

 

[Blee1099]

Sounds like you got all sorts of problems. Does it atleast idle right when you start it up? When was the last time the truck had a tune up? The shift solenoids can be replaced from your local Ford Dealership however I would recommend testing the solenoids first to make sure they are really bad. In situations like yours, I recommend taking it to a reputable shop and let them assess the situation. Everything in regards to the transmission problems could easily be caused by a PCM problem or just a failing transmission.

 

[darkowy]

Yes, car idles ok and reacts to accelerator fine when gears are in "P" position. As for solenoids I think they are ok as no mechanical fault codes are present. Besides transmission is shifting ok once I get the car moving. I can reach normal driving speed 40-60 Mph but have to be very gentle on accelerator.

 

[dogfriend]

I think the first code P1747 is a huge clue - if your EPC solenoid is malfunctioning, the line pressure may be low and it won't shift right.

I also think it is likely an electrical problem - the EPC and the shift solenoids all share the same power source.

I would have a shop check the line pressure to see if it is abnormal.

 

[dogfriend]

--

 

[darkowy]

Ok, I was able to find a cause for all those DTC's. It’s 15A fuse in Power Distribution Box, that's getting blown. However I couldn't trace the problem any further.
According to Ford guide this fuse covers: Heated Oxygen Sensor, EGR Vacuum Regulator, EVR Solenoid, Camshaft Position (CMP) Sensor, and Canister Vent Solenoid.
Now, if I replace the fuse and start engine everything is fine as long as car stays in (P). In my opinion this eliminates problem with shortened wires because the fuse should get blown right away. As far as I was able to check it seems that fuse is being blown when I accelerate. It also appears that very gently acceleration keeps the fuse "alive" and pushing pedal to the metal blows it. Any suggestions what can cause that?

 

[budwich]

The EVAP canister purge valve is cycled... in idle / low speeds, it is probably 0 but at load / high speeds, could be "cycled" to 100%. Perhaps that solenoid is "weak". Its an emmission thing so if it doesn't work (unplugged) for a test drive, it shouldn't be a problem although maybe codes will be generated. what's the fuse number that you were blowing???

 

[darkowy]

It's fuse number 13 in Power Distribution Box.

 

[budwich]

Thanks... that helps a bit as it clears up any misunderstandings. Anyways, I only 96 schematics but hopefully they are close / the same perhaps. As you indicate 13 powers a lot of stuff thru the PCM power relay. The good thing is that there is a secondary fuse (#24) that powers the oxygen sensors... since its not blowing perhaps those can be elliminated ... again in 96.

I assume you are a 4.0 engine... right???

PS... I guess Ford is not superstitious about having a "13" fuse...

PPS. of course, I have two different references that don't agree on things, one a chilton 91-99 and a "96 cd manual" (of ? origins)... so I am not sure how much help things are.

 

[darkowy]

Thanks, I'll try to unplug canister purge valve nad see what happens. My engine is 4.0 L SOHC. I don't see a fuse #24 in power distribution box, or any other fuse powering oxygen sensors so I guess they can't be eliminated based on that

 

[budwich]

On the chilton, it shows fuse 11 going to the oxygen sensors (15 A).... so there you go. Anyways, I would pull the EVAP canister purge value and also maybe the vapor management valve connectors since these deal with emissions and shouldn't harm brief test periods. Good luck. Hopefully some one else will also pipe in.

 

[dogfriend]

I think you are on the right track - unplug sensors or solenoids until you find the one which is shorting out.

Looking at the schematics I have (97) I wouldn't rule out a shorted O2 sensor because the power for the O2 sensors comes from a 15A fuse in the Power Distribution Box which is supplied power from the PCM power relay. The circuit which supplies the 15A fuse is 361 (R) which also supplies power to the EPC solenoid. The fuse is labeled #11 on my schematic.

 

[budwich]

I have this same picture in my 96 cd... the "confusion" / uncertainty is circuit numbering... if the actual circuit is correct.... that #11 fuse basically only powers the oxygen sensors.... its a fuse behind a fuse link (#2 in this case... which I think is labelled #13 in my 96 case). The fuse link actually powers most / all the stuff and isn't a problem. Certainly need a 98 picture of the same stuff.

 

[dogfriend]

Another thought that I had was that it could be the PCM Power Relay. If you have high resistance in the relay, then you would get lower voltage at all of the components powered by the relay. Also, this would explain why the fuse keeps blowing - the voltage is low, so when a powered solenoid (EVAP) turns on it will draw more current than normal.

You could test the relay with an ohmmeter - you should get an open circuit with no power, very low resistance with 12V applied to the control side.

 

[budwich]

Hey Darkowy... as you pointed out from your list of things that the 98 has on the fuse, egr vacuum regulator / soleniod is also a possibility as the egr is made to open up under load / driving conditions to feedback NO2 gas. Again unplugging it for test drives shouldn't be a problem.... it is a good candidate.

 

[darkowy]

Thank you all for suggestions. So far I checked PCM Power Relay (tested fine) and I think I unplugged EGR valve. I haven't checked other sensors/solenoids because I don't know where to find them yet. However as far as I know, O2 sensors work continuously (after they warm up past 600-degrees F), so if they are shorted, the feral fuse should be blown also when transmission is set in P position. Am I right? Where I can find some reference to all those sensors/solenoids? My Haynes Repair Manual doesn't cover them too good.

 

[dogfriend]

EGR Info

 

[dogfriend]

Evap System Info

 

[darkowy]

Sweet, this is what I was looking for Thanks a lot

 

[iggybrevet]

MR DOG FRIEND

thanks so much for your great help
regards
iggy