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1999 Ford Expedition looses RPMs/power at any speed, then resumes running. Local mechanic cannot diagnosis the problem. When tested on a diagnostic machine by dealer, the car did not send any code. Anyone else with this problem? EJ

Optional Information:
1999 Ford Expedition 5.4

Already Tried:
Car has been to dealer 3 times, local mechanic 5 times.

Customer (name blocked for privacy)

Status: Closed Value: $8

Thanks for your question. At any of the places you've taken it, was there any codes at all? So when you say looses RPM's, do you see the tach just drop to zero, or does it go to an idle RPM? How many miles on the Expedition? Also, if you have a VIN # I would like to check it out further.

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Reply to Fordanswerman's Post: The tach drops to zero. Speedometer, RPMs all drop to zero, then, resume. No codes were recorded when at repairshops. VIN#1FMRU17L3XLB83903
Sometimes when driving at slower speeds, as in making a turn, it will loose power,then die. I have to put it in neutral, restart to continue the turn. But, the problem of loosing power for short periods of time happens at ALL speeds. Thanks for responding. EJC

No problem, thanks for your questions. Sounds like to me you are losing battery power. What I would like for you to do is while the vehicle is idling in PARK, open the hood and start to wiggle several different items.Start with both battery cables, but do it slowly so to see if the wire you move, causes it to stall or even miss a beat. Then on the firewall just behind the battery, there are a mess of connectors there. Try to wiggle all those wires connectors. This is your main battery feed area. This may take a little time to do. Also just to check this. If you can get under the vehicle and just check the crankshaft sensor and wiring to see if it is rubbing on the A/C compressor. I've seen all these cause issues and will not leave any codes.

Reply to Fordanswerman's Post: All the suggestions you gave were done by a local mechanic. I have received online suggestions of a possible idle air valve problem. At one time, rerouting of some wires near the windshield wiper fluid holder corrected the problem for a while. This didn't last long, and would not correct the problem when re-done. Unfortunately, the car did not have a 'glitch' when on the diagnostic machine. Thanks. EJ

So, other than the suggestions given.....any other ideas?

When this stalls, does it stall like the key ign key was shut off, or does it stall like it might be running out of gas? It still sounds like a power problem. Especially if rerouting the wire loom like you said took care of it for a while. That may have been just a bandaid fix for a while.If I had it I would be chasing that loom you're talking about until I found something. If it was an IAC it wouldn't stall or quit at speeds above idle. That is only for idle conditions.

Another thing I had one time was a bad EEC relay. This relay is in the power dist box under the hood on the drivers side. If these go bad they just shut down like turning off the key. At any speed. This powers up the computer only, but I thought you said the speedo and tach just went to zero right? Another thought is bad ignition switch, this controls power also to those items. Has anybody checked the ign switch by wiggling the wires to it?

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