2000 expedition 35mph and nothing more

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jochre

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greetings everyone

this is a whole long spiel and im gonna tell u all of it. my father has a 2000 expedition he bought from the neighbor. he bought it knowing that it was running a bit rough, but he needed a car. now, a few days after owning it, he loses the only set of keys there was for it. wonderful! now the car sits for another month in the driveway until he saves enouigh money to have a locksmith come out, cut the key and re program it. so now he has the keys in hand, and the car wont start. idr why exacyly, but he has some lame shade tree mechanic come out to fix it, which he does, but not quite. for some reason the mechanic switches out the speedometer cluster for another one, which i have no clue why because the original one was fine. he also puts in a new to us ecm, after a day or 2 of trouble shooting he manages to get it to fire over.

now it runs and drives, but at 35 mph, the speedo reads 100 mph @ 2400-2500 rpm, and then it cuts out sorta like when my grandmas safari van would at 95 mph. tonight i downloaded a speedometer app, and i find out the expedition quits accelerating ones it hits 35mph..now to me thas a pretty square number, meaning theres more than likely a reason it cuts off at 35mph, and not just a coincidence. maybe if it were 29 or 33 or some weird number but 35 mph is what it is.

so after a few months of trying different things, shifting through the gears, driving with overdrive off, driving with over drive on, driving with the shifter in 2nd, OD on and off. now, 35 mph is the number right, so when i have it in the lowest gear on the gear selector, and i punch it, the car takes off! but it cuts off at 35 mph!!! if i'im in drive, or 2nd and i punch it, nothing! the car is a slug it sputters and surges, and if i punch it going uphill it completely shuts off.

driving this way is extremely un economical. my dad is old ok, so he doesnt like to have to shift gears znd what not, so he keeps it in 2nd, which is steady @ 2000rpm. when i drive it i get it to cruise around at 1500rpm. i found if i turn over drive off and put the gear selecgor on Drive, its a lot more fuel efficient. anyways i might be forgetting a thing or two. please help! also that ******* mechanic i told u about, well he charged my dad $900 for a transmission most likely from whack af pick n pull, which he still hasnt put it, even though i'm pretty daggone sure theres nothing wrong with the trans thats currently in it.

if you have any ideas or suggestions, please shoot them my way.

-jochre
 

jr1under

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Just speculation on my part because I'm not an Exp expert but I was a computer programmer my entire career and this might be the GIGO syndrome - garbage in, garbage out. Corrupted data can produce wildly unpredictable results, kinda like when NASA lost the Mars Climate Orbiter in 1999 because one component was transmitting data in English units while the receiver was expecting metric.

How to prove/disprove this idea and what to do about it is beyond my understanding but maybe someone else can provide further insight.
 

Hamfisted

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Do you still have the original PCM and instrument cluster ? If you have a laptop you can use the free ForScan app to program the newly cut key to the original PCM and be good to go. Sounds like your dad is really being taken advantage of. Or you live in a really shady area, with no reliable or honest mechanics available.

ForScan App Download Page






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jochre

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@Hamfisted u know i'm not sure if we still have the original pcm. the 35mph cap was a problem even before we got it and the day my dad lost the keys, was maybe the only time it was ran smooth and shifted properly, according to my dad.. i know for sure we still have the original instrument panel in the garage, and like i said i have no idea why he would switch it out for another one. do u think the mech had to install the instrument panel from the car he pulled the pcm from? like they work as a pair only? there was also a new something for the transmission. im pretty sure its in limp mode, but i dont know why yet.. i've hooked an obd2 reader to it and there were a few codes none of which i can remember. i will hook it up again and update shortly.
 

jr1under

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im pretty sure its in limp mode, but i dont know why yet.. i've hooked an obd2 reader to it and there were a few codes none of which i can remember. i will hook it up again and update shortly.
Pull off the air intake hose and take a look at the throttle body valve. If it's really dirty, that can cause limp home mode with P2106, P2135 and a few other codes. Removing that part of the TB and cleaning it is easy and will only cost about $15 for a new gasket and a can of TB cleaner.
 
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jochre

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i forgot to mention, at 2400-2500 rpm the speedo reads 100mph and then it loses power..could it be a governor that’s keeping it from accelerating any more cuz the computer thinks it’s going 100mph? i used a speedometer app to clock the speed, so i’m really going 35mph @2400ish rpm
 
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