Power Loss with each Upshift?

[V8-X]

1999 Explorer AT 5.0L/302ci

I am experiencing a loss of power which becomes more noticable with each upshift and when the TC locks up.

When I am accelerating through 1st gear, the X seems restricted or lacks power but picks up speed decently but not normal.

When it shifts to 2nd gear, I notice a deeper tone to the engine (almost bogging down type sound) the RPM's don't rise like in 1st or like they should (basically sits at 2000-2300 RPM's throughout this gear) and you can feel the X is hesitant.

Once it hits 3rd gear, the engine tone sounds the same as when in 2nd (deep tone & bogging type sound) and the RPMs still don't rise properly (RPM's sit at 1800-2100 RPM's throughout this gear).

After 3rd, the TC locks up and the engine tone gets even deeper with the bogging down type sound becoming even more noticeable. This drops the tach down to 1200-1500 RPM's and acceleration power loss is really severe at this point. At this point while still trying to accelerate, the 4th shift will come around 1800-2200RPM's. If I'm at this point keeping a cruising speed, I have to force the X to down shift if I want to increase speed.

Once in 4th the engine tone & bogging down type sounds are just as bad as when the TC locks up and the acceleration power is at it's worst. The RPM's will be around 1200-1500 when it shifts into 4th, and while the RPM's are under 2000, I get a vibration through the gas pedal.

To make a long story short, my X is having a problem with lack of power. With every upshift and TC lock up, the power decreases dramatically. At times it sounds like the X is in to high of a gear and the engine is straining.

This has been happening for over a year now, with 6 shops and myself unable to determine the issue. It's such a loss of power, I am unable to keep up with 1st Gen OHV X's or 1st Gen Caravans. I can be on a flat surface, incline or decline, and these vehicles still blow my doors off.

Please help, any and all advice would be appreciated!

 

[oldwrench]

Power loss

If a vehicle came into my shop with this complaint, I would automatically assume we were looking at an exhaust restriction.
I unfortunatley have to ask some questions, is there a check engine light? The electronics will monitor many different , but not all areas that can cause this type of concern.
From your post I need to know your feeling about the trans, are you saying you think it is the trans causing the trouble or not?
The answers you provide can maybe shed some light on the direction of the trouble shooting. Sorry for the ambiguity, but there are several possiblities.

 

[Ak LTD Xplorer]

hmm..that's odd my dad's v8 get's more and more power the higher you go in gear's..and it blow's the door's off everything!!

 

[IAmTodd]

Another helpful tidbit of info would be anything maintanance that has been done recently.

 

[V8-X]

oldwrench:
1) 3 seperate Ford Service Centers & 3 Independent shop have checked the exhaust. They have each stated the exhaust is not restricted.

2) No CEL. It did come on about 1.5yrs ago, which was caused by a bad #4 plug. I have since replaced the plugs twice & wires once. Now to let you know, this is when the problem started. Since replacing the plugs the 1st time, the CEL has never come back on.

3) I personally don't beleive it is the trans. I've had a trans shop check it out, and they seem to say all is okay. At times it seems as though the trans shifts properly, but most the times it does not. The X runs better when cold than at normal operating temp. I beleive some sensor may be telling the trans to shift when it does, kind of like going into a limp mode. When accelerating, you can hear the engine strain at times and the fuel injectors pumping their life's away.

Ak LTD Xplorer: That's what I'm sayin! This thing used to fly up the mountains here in Denver like a typical V8 does. This thing strains to keep a constant speed on a slight incline now. Hate driving home from work, cause it's 35mph on a very slight incline and the X can't keep a steady speed. It will either continue to loss speed or I have to make it down shift to increase speed. Usually I have to make it downshift to pick up a little speed just to end up back in the next gear or with the TC locking up and losing speed again. Very irritating and Ford either can't find a problem, say it's usual or that the X is just getting old. What a line of BS!

All parts which have been replaced within the last 12 months: Plugs (twice), Wires, IAC, Alt., T-Stat, Fuel Filter, all 4 O2's, Both Ignition Coils, EGR, FPR (twice), Battery, S-Belt, TPS, K&N drop-in Filter.

Services performed: 10K miles since Trans Service, Normal 3K mile Oil Changes, MAS/MAF cleaned twice (once by myself & once by Ford), Front Dust Seals replaced twice, Radiator Flush with T-Stat replacement, Shocks Replaced & Brakes Inspected (brakes determined to be okay).

Parts currently own and thinking of replacing: DPFE, PCV Assembly, ECT.

I was informed by 1 of the 3 Ford Centers & 1 Independent shop that I need to replace the front hubs. I think they are correct, since when I coast next to a concrete barrier doing about 40-50mph I can here a slight scraping/metal to metal type contract. I've had the brakes checked, and these are not the culprit. Other than that I am starting to get the Chirp/Squeal from the belt area no matter if it's warm or cold, so I may need to check the tensioner or a pulley as well.

Since this is an AWD, what type of affect do you think bad hubs would have on the performance?

Hopefully this answers all the questions so far. Please let me know if there are any suggestions or other questions, I do appreciate it!

 

[old mechanic]

If I understand what you are describing my thoughts would a problem in your distributor less ignition, spark control OR distributor if you had one. This will make your engine rev perfectly good with the car in nutural. But when you put a strain on by putting it in drive it won't have any power.
Now if your describing a power loss with a load like giving it more gas to climb a hill then I would lean towards it being a fuel problem. Check your flow rate at the engine.

 

[ipozestu]

Did you do the plugs and wires yourself? Do you know what kind of plugs you have in there? The reason why I am questioning the plugs is because of the possibility of the gap being open to much. Have you checked your plugs since you put them in? As you accelerate the phase angle and and current that is sent to each plug changes. At the lower RPM You are getting much higher current in the timing advance \, as your RPM increase the current and phase angle change to provide higher current later in the spark /. If your gap is open to much it will cause misfires reducing power and fuel economy. Has your fuel mileage dropped off a bit? Try this, pull your plugs, check to make sure they are in good shape, meaning electrodes have sharp edges, no rounding, and there is no fouling. If they look like they are getting worn change 'em. Set your plug to stock gap then reduce it -.01 I.E. stock gap .054, corrected gap .044. This allows the ignition to provide a more stable spark at the higher RPM with the lower current. This is in therory now, but try it out and let me know how it goes.

 

[V8-X]

old mechanic:

Thinking about it, I beleive that the problem is connected to either the ignition, the spark control or a fuel distrubution problem. The engine sounds like it is starving for gas at times or not getting enough spark, which makes the engine sound strained while the fuel injectors are pumping away at a lot louder and more noticable rate than prior to this problem occuring.

I have had the Fuel Pressure Regulator replaced twice already by two seperate shops, which determined the problem to be fuel related (Neither shops were Ford). After having the FPR replaced twice, there was still no change in performance. Both kept reading a low fuel rate, and even when they replaced the FPR the fuel rate didn't increase to spec. How would I be able to check the fuel rate?

Now the problem is noticable at all times, it's just the most severe when trying to climb any form of incline. Also, when you drop the trans into D or R you notice the RPM's drop and the engine tone get deeper. This will also drop by battery gauge if this makes a difference.

ipozestu: I replaced the plugs once while an independent shop replaced them once. Each shop I've been to has checked the plugs, since this is a common Power Loss diagnosis procedure. None of the shops have found the plugs to be at fault, except I did have 1 cracked plug. Which is why this one shop changed the plugs again. I have since checked the plugs and they are all gapped properly and in good shape since they were last replaced.

I only use strictly OEM/Ford/Motorcraft parts, so every part I've replaced has been direct from the dealer.

I have had a considerable loss in Gas Mileage since this occurred. I used to average 15-19mpg, but now I get 12-14mpg. This is with mixed city & highway driving. I try to do as little highway driving now, since it takes so long to get up to highway speed. I've almost gotten run over a couple times cause the X can't get up to speed quick enough. I don't chance pulling out in front of anyone, cause it feels as though I'm carrying a ton of gravel in the back of the X.

Ideas and suggestions?

Again, how would I test the fuel rate at the engine?

Also, when I let off the gas from accelerating it seems to give a little buck forward. You feel a little jerk forward like the X just downshifted or you hit the brakes very lightly, but all that was done is letting off the gas. Kind of like the engine isn't getting gas or any spark. When I coast now, the decrease in speed while coasting is a lot quicker than before the problem. IT used to keep speed well when you let off the gas and coasted, but now it immediatly starts to slow down like something is pulling back on it.

I also have to give it a lot more gas now to accelerate than ever before. Sometimes the gas pedal is firm and is hard to press down while at other times it's kind of spungy and soft and is a lot easier to push down. Now when the gas pedal is spungy and easy to press down is when I get the worst of the symptoms.

Hopefully these additions may help.

 

[Robert]

Are you sure the plug wires are on the correct plugs? Maybe everyone keeps putting them back on the same incorrect plugs when they change them.

How long has it been since your fuel filter was replaced?

Another possibility (other than what has already been tried or suggested) is the fuel pump.

Testing the fuel flow rate will confirm if it is a blocked filter or faulty fuel pump. It takes a special fuel guage that connect to the underhood fuel service port.

 

[oldwrench]

power loss

I am perplexed, it looks like a few parts are being shotgunned to try and solve this to no effect. The fuel system seems to not be the problem, although the talk of fuel pressure is interesting. If the fuel pressure or volume are not where they should be the computer will continue to increase the pulse width to compensate. If the system is pushed too far it will turn on the check engine light . I feel the fuel is not the problem. Ignition could cause the vehicle to be down on power, but what is the cause, most of the components that could cause this have been replaced. If this is not fuel or spark and I dont feel this is trans related, it leaves me to believe that there is something dragging on the drivetrain. Possibly brakes or hubs, I have run across a vehicle that was applying the brakes as the car ran down the road. It was very difficult to prove but your gas mileage could be a result of something like this.

 

[V8-X]

Robert:
1) Yes the wires are connected to the correct plugs. This question about foul plugs and misrouted wires are the 1st item everyone advises. I've checked these time and time again, which the wires are routed correctly and the plugs are in good shape. I bought a Haynes manual to double check that the wires were routed correctly.

2) Fuel Filter was replaced just over a year ago when I started having this problem. The new Fuel Filter made no difference.

3) The Fuel Pump could be the culprit, but I'm trying to narrow down my options. As you've noticed, I've already spent some $$$ on parts which were recommended, but not one of the parts have corrected this problem.

oldwrench: Like you, I truely can't determine what the problem area is.

I've been to 3 Ford Service Centers ($100 each visit @ 5 visits), 3 Independent Shops ($90, $65 & 95 dollars on visits) & 1 AAMCO (Free diagnosis), then parts and labor on top of the above mentioned diagnosis fees. All stated different problems or stated there was no problem, except for the 2 shops which thought it was the FPR. The price just keeps on rising, and no one is able to find the issue.

I'm trying to save money for the hubs, since they are $200+ each plus the labor charges. I have basic tools for basic work, but not all the equipment to do every job myself.

What about the VSS? Could this be sending an inaccurate speed reading which is throwing off the trans and is not tripping the CEL?

I've heard there is a sensor in the hub assembly, is this true? If it is true, could this be causing a problem?

One last piece. When I release the E-Brake I am unable to go in reverse. I can put the trans in reverse, but the X won't move anywhere. Now if I drive forward a couple feet, then I am able to go in reverse. Also, sometimes when I do this, it will make a bad screeching sound going forward or backwards like the E-Brake is still engaged. If put the X back in park and wait a couple moments and try again, then the schreeching will be gone. I had one of the shops look at the brakes, but they just stated the E-Brake Drum Pads are getting low but nothing to worry about at the current time.

 

[Ak LTD Xplorer]

have you replaced the fule(sp? it's a long day) filter?

EDIT..OOp's sorry dident read that far down

 

[ipozestu]

There seems to be something wrong with the ignition. It's not often that new plug insulators crack under normal wear. In a lean condition with serious detonation, this is not uncommon. Has the AWD been acting up at all. Your last post about the shifting into rev and all that... I don't know a whole lot about thses auto tranny's and AWD. I prefer the manual 5spd. It weeds out a lot of variables. Do you have a vac. gauge? WHat kind of vac do you have at idle? What about your tail pipe? Is it sooty? Are the plugs sooty or white?

 

[V8-X]

ipozestu:

What do you mean by "It's not often that new plug insulators crack under normal wear"? Nothing I've replaced has been determined to be the problem. I've just replaced parts based off recommendations from this site and mechanic friends. If this is in reference to the cracked plug, I just think it was cracked on installation or when one of the shops check it they cracked it. Either way, all the plugs currently in the X are in good condition with no cracks.

I don't beleive the reverse issue has to deal with the AWD, only the E-Brake. Since I only have the problem if I engage the E-Brake. As long as I don't engage the E-Brake I don't have this problem with Reverse.

Plugs are as clean as to be expected and the same goes for the tail pipe. Not really sooty or white. Our 1996 Sentra is tons worse than the X in this sooty area. But the Sentra runs smooth with no problems.

I as well prefer a stick, but the V8 (which I wanted) only comes in Auto Trans so I had to settle.

No I don't have a Vac. Gauge, do you know if Auto Zone loans these out? If so, what would I need to hook the gauge up to and what readings should I come out with?

Thanks again for the further investigation advice!

 

[ipozestu]

Auto zone should loan these out. They are pretty cheap none the less. I am not familliar with the 5.0 off hand normally they should be < 16"vac at idle. This should be steady and not bouncing around. You can hook it up just about any where on the vac tree. A good place I hook up at is on the line for the fuel vapor . Best place for you so your not messing with any vehicle function is the break booster that connects to the master cylinder. What I mean by the spark plug comment is, porcelin is pretty tuff stuff. It takes quite a bit it get it to crack. This will happen under extreme lean conditions, and detonation. Under mildly lean conditions your plugs will be super clean, and kind of whitish. This e-brake thing is interesting. This may be a whole different problem entirely, it's hard to tell. Section525, Expo5.0, jamesT, and a few others have the 5.0 you might want to PM them to get them involved with this. Maybe they have experiences like yours. I'll keep my gears turning and will fire some more suggestions out when they come to mind.

 

[oldwrench]

Perforance Issue

First your two questions, the VSS or Vehicle Speed Sensor is located on the tailshft of the transmission. This sensor is for shift timing and Quality. I cannot imagine this causing your problem but it should be easy enough to unplug it and see if the symtom changes. It only has 2 wires and is on the back of the transmission just in front of the transfer case.
Second the hubs may have wheel speed sensors on them and any problem with them would turn on the ABS lamp almost immediately.
Now for my idea, something in your last post about the noise when you engage the parking brake. This should be eliminated as haveing anything to do with your problem, the noise on the fromnt hubs needs to be checked to. This AWD type of setup provides power to all wheels and conversly when anything is dragging it will attempt to pull al;l the wheels down too. The more you comment about this the more I think your problems lie in this area.

 

[old mechanic]

I just realized that you had said that when your Ex is cold it seems OK! When you have a fuel delivery problem it is usually pretty noticable when the engine is cold because the engine works with MORE fuel than air when its cold. So if it is working OK when cold I would usually say its NOT fuel related. HOWEVER the pump could be worse when it heats up and that would explain your problem on those hills. You give a telltale of poor fuel delivery when you say "its just the most severe when climbing hills".
STEP 1---Have it checked to see if you have enough fuel being delivered to the engine first! Make sure they check it when it COLD and HOT. That would be where I would start. That way you can determine if its a fuel problem or not. If you have more than 100,000 miles I would change the fuel pump anyway. This will save you from being stranded somewhere. Fuel pumps are like starters. They get FLAT spots on them. If you bang them (or the gas tank) they sometimes will work until the next time you go to start the truck. The worse thing that you can do to a electric fuel pump is to run the tank low. It stresses the pump.
Get that fuel pressure checked out first.

 

[V8-X]

ipozestu:

I will go to my local Auto Zone this weekend and purchase or rent a Vac. Gauge. I will check my Haynes manual for the vac. specs and best location for checking.

So it should read steady and not bounce up or down? If it does bounce or is low, I will check back here for advice on what I should check for next.

oldwrench:

I beleive my VSS is located on the rear diff rather than the T-Case. I'll have to double check, but I thought that Ford had changed the location of the VSS some where around the 1998 or 1999 year. I'll take a look at it, but like you I don't think this is the problem.

At times I do get a moaning & grinding type sound from the front end when the problem is most severe. Like when the X locks up the TC or shifts into 4th. It doesn't moan & grind every time, but does here are there. So I'm wondering if the hubs are so bad that when the power band is at it's lowest (right after a shift or TC lock up), the X has trouble keeping the hubs spinning at that particular rate of speed. Only problem with that assumption would be, why or how would this affect the tach/RPM's & engine tone?

Now since the X seems to work better when cold than hot, do you think it could be due to the idle? Like the MAS/MAf or IAT is not reading correctly once the X gets warmed up? I would think the CEL would be tripped if they were not working properly, but just thought I'd ask.

Would I be able to check the Fuel Pressure myself? Does Auto Zone loan this tool by chance? If they do not loan them, what is the average cost of a Fuel Pressure Gauge? I can check my Haynes manual for the specs on the Fuel Pressure, just need to know what type of symptoms to look for when I am testing the Fuel Pressure.

The X is only a couple hundred miles over 75K, but I will keep in mind to replace the Fuel Pump around 100K. When I test the Fuel Pump (key on/engine off), you can hear the Fuel Pump pressurize. Don't know if it could still cause a problem even though it sounds normal.

Now I usually never run my tank under 1/4, unless I'm totally broke or trying to make it to a station to fill up. I am aware that running your tank below 1/4 puts undue stress on the Pump, so I do this as little as possible.

Thanks for the great advice everyone. Please let me know the answers to what questions I have so far, so I can check the Fuel Pressure & Vac. Pressure this weekend to hopefully rule these out as the culprits. Of course I will let everyone know what the outcome is after testing.

Again, you help is greatly appreciated!!!