almost zero power mounty 5.0 with codes | Ford Explorer Forums - Serious Explorations

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almost zero power mounty 5.0 with codes


Active Member
February 20, 2013
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City, State
West Coast
Year, Model & Trim Level
2000 Mounty 5.0 AWD
I have my excellent running 2000 5.0 AWD mounty.
lol well, it WAS running excellent.

I noticed a trans leak a while back but I put trans fix in it since i wanted to keep driving it and planned to pull it for a full performance rebuild anyway, just not yet.

Coming home one eve it almost completely lost all power. I have to practically idle around.
It also will start to surge generally.

My codes were related to EVAP leak of some sort and 2 or 3 transmission codes.

I am just surprised transmission problems could limit the engine so much, I will assume it may be in some sort of protection mode?

I'm ready to pull the engine and trans and have my buddy build the trans and i'll build the motor but i'd be heartbroken if I do all that, get it all back in and it is behaving the same way.

I'd like to fix it now so it's running normal again before I pull everything for rebuild BUT I understand it just may not be possible and it's just time.

Any suggestions?

Thanks all!

p.s. I do not have the actual codes at the moment but I remember one mentioned a solenoid for trans.

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60 views and not even some guesses?

nothing guys?

I had constant engine surging/ pulsating when accelerating (not cruising at highway speeds) and had no codes and it turned out to be a faulty 02 sensor....they can be failing and not trigger a CIL / code in early stages. I only confirmed it by unplugging them causing the PCM to go on default settings which upon surging then DISAPPEARED.

When you get a chance, post the actual codes.

To add, I would look into a fuel pressure test.... possible failing fuel pump...


P1747 - EPC solenoid short circuit
P0755 - shift solenoid b
P0743 - tcc circuit electrical
P1451 - evap emission ctrl system
Vent ctrl circuit
P0135 - o2 bnk 1 sensor 1
P0141 - bank 1 sensor 2
P0155 - bank 2 sensor 1
P0161 - bank 2 sensor 2
P1409 - egr vacuum regulator solenoid. circuit

Keep in mind. I left in.the morning and got home and all this occurred. Very strange. I dont see a correlation since it's two separate systems have problems. Strange.

Gut instinct is to see if there's a common source, like a bad ground.

Gut instinct is to see if there's a common source, like a bad ground.
Trying to fix my new 98 sport but that's an excellent idea. I just need to go over the whole thing with a fine tooth comb. No expense just time, see what I see.

Anyone else have any ideas?

Excellent running throughout day then as I approach home it start to lose power.

It sounds super healthy at idle. Then I go to give it some throttle and it sounds horrible, super weak, almost misfiring or something of the sort.

I don't feel my engine problems and trans problems are related.

I don't see a transmission problem causing the engine to run so poorly. Unless its dying like in the other thread maybe due to the TC locking up immediately when placed in gear.

I'm going to check all my wire connections when I can. check and clean. I'll check some fuses and relays as well.

Check the main electrical connector above the back of the engine, the computer also, right behind it. Barely snug those two bolts that hold them tight. If not much servicing has been done lately, it's time to do a lot of basic things. All fluids, filters, plugs, wires, coolant hoses, idler pulleys, and belt should be relatively new. It's much easier to find a problem when it's not related to basic maintenance items.

"Aside from the activation of the Check Engine light and the registry of the Error Code P1409 into the system (EGR Vacuum Regulator Solenoid Circuit Malfunction)
, vehicles affected with this error code usually experience a pinging problem, which makes sense for vehicles with EGR valve issue. Other symptoms typically include
  • Decreased power
  • Rough idle "
Article here:

EGR issues can also cause some surging..

With that many error codes, I'd suspect a wiring issue first, and/or if the vehicle has not been serviced in years, it could be multiple items. I'd first hope for a simple wiring problem, plus do maintenance stuff that needs to be done anyway.

Wiring harness, 100%. CDW nailed it. Trace the harness from the PCM down to the sensors/trans. They are all bundled together, I believe. You probably have chafe, burn through, etc.

Someone had this exact issue a few months ago.

well I found no physical damage to the harness anywhere. It's quite clean and tidy considering age/mileage.
I started it yesterday for the first time in a while and started right up and sounded great however I applied no throttle.

I will try to use my cheapo OBD tools live feeds and see if anything stands out. I was considering a new DPFE? sensor and a new EGR valve solenoid since they're pretty affordable.

But i'm trying to get out of the habit of replacing parts before being absolutely certain they're faulty.

I would get a can of electronics cleaner spray and thorough spray off connections on PCM and connector (make sure to disconnect battery first and let thoroughly dry--dries quick though) ... as stated running fine one day and then bad the next with all those codes sounds odd.... maybe your PCM itself is on the brink,...but give this a whirl and see what happens..

Check fuel pressure! Had similar issues on a 98 grand marquis today. It would idle ok but will die out as soon as you hit the gas over 10%. 10psi is all it had for fuel pressure, spec is 38-42.


was experimenting with my OBD scanner and did some live viewing. My fuel trims were crazy high so I'm fairly certain, among other problems, my fuel pump has failed. Would explain lean in all 4 O2 sensors as well. Just makes sense. I have a new fuel system tool kit somewhere I ordered maybe I should find it and play with it.

Luckily I have a new walbro spare so i'll swap it up along with the strainer and see what happens. nothing to lose except some time I suppose. I followed wires as best as I could, used my bore scope where I couldn't really see as well as a mirror. Still no visible damage anywhere.

replaced in tank assembly and fuel filter and still same problem. 9 trouble codes as before. Fuel trim will start at 0-5ish then go up to 40. causing it to surge at idle. I will try to unhook harness from engine bay down and inspect it better and clean connections. Could a failed purge valve cause all of this? It is the one mounted in the driver front fender area near battery...

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What fuel pressure are you getting with the new pump?