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Missing some ooomphhhh!

Lechuga

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'98 XLT
I've owned a 92 Ex with the V6 OHV, which with its 160 bhp was a mean beast. It would climb up slopes in 4x4 High no sweat. I now own a 98 Ex with the SOHC V6. Even though it is spec'ed with 210 bhp, it is unable to climb up the same slopes as the 92 Ex, unless I put it in 4x4 Low. Is this normal? Or is my 98 Ex missing some serious oomphh???

Needless to say I've just finished a complete tune up including: air filter, MAF, IAC, inlet manifold gaskets (upper and lower), spark plugs, oil and oil filter, fuel filter, VB rebuild...
 


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Lechuga

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I think the lack of power may be due to a cylinder not working, however no DTC misfire codes are raised. I will be checking ignition wires later today
 




rickybobby

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the difference could be in the axle gearing, and the ohv made better low end torque iirc, which is needed to climb a hill
 




Lechuga

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Not sure. I also noted that when cruising on the highway at 70 mph it will pop out of OD at the slightest incline..
 




gmanpaint

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Completely different drive train from engine to axle gearing. Not all Explorers are created equal. This can differ not only from generation to generation, but in the same year as well.

Your 92 EX...
4.0L OHV (low/mid end power range engine)
1354 gear driven transfer case
Gears ranging from 3.27 to 4.10
Either open or limited slip differential

Your 98 EX...
4.0L SOHC (mid/top end power range engine)
4405 clutch driven transfer case
Gears ranging from 3.27 to 4.10 (3.55-3.73 being the most popular)
Either open or limited slip differential


Check the door tag and find the code for the gearing under AXLE. This will clue you in about your vehicle. The smaller the gear size, the smaller the tires need to be. Numerically speaking here....The larger the gear size, the larger the tire size can be. If you have small gears and large tires, it will be a dog with a low power feel to it.

You can change these up to get more low end power by changing a few things from other Explorers such as manual Trans, t-case, & gearing. Tire size being another thing.
 




Lechuga

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Thanks. It's a stock Ex. I was expecting a little more get up and go. I'm surprised it has to drop out of OD to roll up a very modest hill, which more modest cars can drive along no sweat. There's no tag on the driver's door nor is there any evidence there ever was one. This is a European spec Explorer. I know its OBDII because I've used a scanner with it, but there is no tag under the hood confirming it is OBDII. Vin code E.

The tires are standard approved size (265x70R16).

Also I was expecting about 20-21 mpg (as I did with the 92 Ex) and in the weekend 300 mile trip, I got 15 mpg (US gallon).

There is a slight chain rattle from the front top cam that disappears after about 2 miles, but I refuse to believe that could be causing so much power shortage and increased fuel consumption. Nevertheless I'll also get round to fixing that.

Last night I unplugged ignition wire from #2 and it ran (to the best of my experience) exactly the same as with it plugged in.
 




gmanpaint

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265 is a pretty big tire size. Look for the tag on the differential to figure out the gearing if the door jamb tag has gone missing.

My $$ is on the wrong gears for those tires causing your lack of power and the O/D issue. ;)
 




Lechuga

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Agreed. I remember putting 31s on the 92Ex and it was quite a dog from traffic lights. I'll look at the rear axle later tonight and get back to you. Thanks again
 




Lechuga

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This is what I've found. The official factory tire specs for my 98 Ex is 255x70R16 (not very different from the 265 I've got). On the rear axle I found two tags: one said to use some kind of oil and the other had a code ("631C" I think) and below it said 88. Both tags are mostly unreadable. What am I looking for? Sorry but this part of the car is newish to me. TIA
 




Turdle

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Downshifting on inclines leads me to wonder if the rear emergency brakes are sticking.
 




colintrax

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Never driven a SOHC but it's a top end motor. The OHV is a bottom end motor. The 92 might have had 4:10s and the 98 might have 3:08s.
If it's driving fine and has a smooth idle then I doubt there is motor issues.
 




Lechuga

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It has a fairly good idle and runs pretty smooth except around 1500 rpm. I would believe the car is fine, if it weren't that when I floor it, it just doesn't have much power. Flooring it from 60 to 80 mph takes a long time, and it jumps around the various gears (5th->4th->3rd->4th->3rd->4th) to accelerate, which is weird behaviour in my book; in 3rd it revs up to 5000 rpm and sounds like the pistons are about to fly out through the hood.
 




Lechuga

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Downshifting on inclines leads me to wonder if the rear emergency brakes are sticking.

This could be. I've checked the coil pack and ignition wires and they look ok. I mean I saw sparks from each wire and I just installed new spark plugs less than 600 miles ago
 




XLT

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It could really be the gear ratio hurting you. Those are 31 inch tires you are running and if you have a high gear ratio you will feel it you try to punch the gas. My 98 sport with the sohc and 4.10 gears made my 93 ex with ohv and 3.27 gears feel like a dog. The 98 has a lot more zip then my 93 did. Check the driver side door jam for a sticker that has your vehicle info on it. The axle code should be listed on there.
 




Lechuga

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From watching SOHC V6 Ex videos on Youtube I can tell my engine isn't right. I'm running out of ideas but I'm determined to get it going as it should. Would clogged/bad injectors raise a code? EGR? Can the timing chain rattle make the timing go so bad?
 




Lechuga

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It could really be the gear ratio hurting you. Those are 31 inch tires you are running and if you have a high gear ratio you will feel it you try to punch the gas. My 98 sport with the sohc and 4.10 gears made my 93 ex with ohv and 3.27 gears feel like a dog. The 98 has a lot more zip then my 93 did. Check the driver side door jam for a sticker that has your vehicle info on it. The axle code should be listed on there.

Thanks. I don't have 31s on. That was with my former 92 Ex and they hurt bad. This is something I picked up two months ago, and it comes factory fitted with 255x70R16 (I've got 265x70R16 now, so no real difference).
 




gmanpaint

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Do you have a GPS unit to check the actual speed compared to the dash speedometer?

This will tell us if your ECM needs flashed for the proper ratio for those larger tires. Yes it really does make a difference. ;)

If your speedo is off, the trans shifting points are off as well. This will mess with all aspects of the shifting, weather it be up or down, unlocking the converter, or passing gears.
 




Lechuga

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Do you have a GPS unit to check the actual speed compared to the dash speedometer?

This will tell us if your ECM needs flashed for the proper ratio for those larger tires. Yes it really does make a difference. ;)

If your speedo is off, the trans shifting points are off as well. This will mess with all aspects of the shifting, weather it be up or down, unlocking the converter, or passing gears.

I did some reading on the rear axle and saw what the tag layout is supposed to say; got a wire brush, some solvent and cleaned the tag properly. I could just read "73 88 (and something else)" on the lower line. So I guess the gear ratio is 3.73

I have a GPS and the variation between the dash speedometer when running at 75 mph, the GPS reports 71 mph.

I insist, these are practically the same tires the car was originally sold with (255x70R16).
 




ponyfreak

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265 is a pretty big tire size. Look for the tag on the differential to figure out the gearing if the door jamb tag has gone missing.

My $$ is on the wrong gears for those tires causing your lack of power and the O/D issue. ;)

My 97 calls for 255/70 16, or 235 75 16, 265 is a little big, and they weigh more too......
 


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Lechuga

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Thanks guys for your help. I am learning a lot. My feeling is the engine is not quite right in addition to the slightly bigger 265 tires instead of 255. I will get some 255s. I think the o2 sensors may be malfunctioning mainly because although it idles well, I'm getting poor mpg and poor(ish) throttle response. When I got the car it had been left untouched for at least two years, it has 140k miles and apparently never done a service.
 




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