Loss of power, acceleration issues... | Ford Explorer Forums - Serious Explorations

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Loss of power, acceleration issues...

SteveRosenow

Active Member
Joined
June 25, 2019
Messages
64
Reaction score
7
City, State
Shelton, Washington
Year, Model & Trim Level
1996 Ford Explorer XLT
After I'd replaced the water pump and timing chain (as well as putting a new timing cover on), I thought I'd have better acceleration issues.

This too, was also after I had installed brand new spark plugs and a new air filter.

However, I have noticed that I still have acceleration issues. For those in the Pacific Northwest (Washington state, specifically), if you are familiar with Highway 101 and Highway 104, you're likely familiar with the long climb out of the southbound Highway 101 exit to eastbound Highway 104 towards the Hood Canal Floating Bridge. For those not familiar, it is a long, uphill climb of roughly 10-15 percent grade (Google Earth pegs the grade at 21%!) for roughly two miles.

You begin the climb on an S-curve exit that crosses over Highway 101 approximately 20 miles south of the town of Sequim, after which the highway follows a broad curve to the left to begin a steep, straight ascent with an elevation gain of almost 600 feet. The total distance of this particular stretch (from exit to peak elevation) is approximately 2.19 miles.

Last night, when I was driving home from the town of Sequim, I took this exit and maintained the posted speed limit of 60 miles per hour, in fact I managed to exceed that by about 5mph for one half of the climb up to the top of the hill (I had been passing a slow-moving truck). At about halfway, however, I suddenly experienced a loss of power. The engine did not rev which to me, did not indicate a transmission slippage, even in spite of having my foot to the floor to try and engage the passing gear. By the time I had got to the top of the hill, my speed had reduced to 35 miles per hour and I had resorted to driving on the shoulder to keep from impeding both the truck I had just passed, and another vehicle following behind it.

This was not a 'new' scenario, too. For months I've noticed that my acceleration isn't as robust as it used to be when I bought the Explorer three years ago. When I try to pass slow-moving vehicles, the passing gear will engage, however my speed does not reflect it. In fact there have been times when I try to pass other vehicles (and seemingly engage the passing gear), however my speed sometimes slows down and in those cases, my engine RPM will often stay constant , increase slightly, or act like it's starved.

My Explorer is a 5.0L V8 with the 4R70W transmission. I am at a loss for this and I really hope it isn't the transmission.

What could cause this?
 



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Pop in a new TPS - throttle position sensor.... had similar issue/ symptoms and that resolved it - $20
 






Pop in a new TPS - throttle position sensor.... had similar issue/ symptoms and that resolved it - $20

Where are you sourcing it for $20? I work at O'Reilly and the part we have in stock is $63. even with my discount it's not even under $35.
 






Many things can cause low-power issue. You might have a partially clogged exhaust (catalytic converter or muffler). This typically causes a situation where the engine runs fine at lower speed, but lacks power at higher RPM. I had a clogged muffler on a Chrysler mini-van (cheap-ass Midas muffler). Something inside had broken off and was impeding the exhaust flow. The van ran and drove fine, but wouldn't go over 40-45 MPH.
 












Where are you sourcing it for $20? I work at O'Reilly and the part we have in stock is $63. even with my discount it's not even under $35.
Make offer here for $20 ....granted of course could be other issue ...but worse case scenario you're only out $20+ and you have a new sensor for your 23 year old rig which was probably close to failure anyway. Also, codes don't always pop up at beginning of issues....hence my suggestion....
Throttle Position Sensor 1996-1998 FORD TRUCKS, VANS, SUV'S 5.0L, 5.8L and 7.5L | eBay
 






Does the check engine light turn on with key? does it turn on or flash while driving?

Yes. CEL illuminates both at key flick and while running.

Last time I pulled the codes, it was an ABS code followed by P0171, P0174 lean codes, and at one time was throwing P0402, EGR excessive flow detected.
 






You really should fix your codes. OBDII is an amazing engine controller and if it tells you something is wrong, it should be repaired. The lean codes could be a vacuum leak, which would cause loss of power. Excessive EGR flow also would cause loss of power. Just because it has had those codes a while does and it ran better before does not mean it is not those things causing the problems as the vacuum leaks could be getting worse and the EGR flow could be getting worse over time. Have you done a compression check and vacuum check? Cleaning the MAF sensor is pretty cheap and could be causing the lean codes... failing fuel pump, faulty fuel pressure regulator and or clogged fuel filter are also suspects for the lean codes (along with vacuum leaks). Replacing the filter is cheap, you can check fuel pressure as well. I am not familiar with the 96 EGR system but on the 2000s I have, there are just three parts, the EGR valve, the flow sensor and the EGR regulator. The flow sensor (DPFE) and the position regulator. The EGR throttles in exhaust gas, the DPFE measures the flow and the regulator sends varying vacuum to the EGR to control the amount of valve opening of the EGR valve, all controlled by PCM. There are simple tests for all of these. While it may be the TPS causing sudden loss of power, you can check/test this too before buying one. I rarely just go start replacing parts, generally you can test just about everything and know it is bad before replacing.

You also could look into downloading FORSCAN, you can see how things are interfacing with your PCM and you can have it do various simple tests to check inputs to the PCM. I use it with a laptop, you can get a Bluetooth interface for you cell phone as well.
 






Yes. CEL illuminates both at key flick and while running.

Last time I pulled the codes, it was an ABS code followed by P0171, P0174 lean codes, and at one time was throwing P0402, EGR excessive flow detected.

Your EGR valve issue can easily be causing your problem. Maybe your EGR valve is stuck in the open position.

As far as the P0171 and PO174 codes they could be a vacuum leak or that you're not getting enough fuel. If a vacuum leaks, they don't usually cause severe power loss, but if your fuel filer is clogged or your fuel pump is failing you will very likely have power related issues. I find the the Ford OE pumps start acting up at aroind 150-200K and should be replaced. Fuel filters should be replaced at least every 50K (Ford recommends 30K). Also clean your MAF, especially important if you use oiled air filters (like K&N).
 






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