hello ive got Ford Ranger 2003 manual transmission 4 cylinder pickup. generally runs fine except i cant get it to go above 75 mph and must be in 4th

[laurakatejohnson333@gmail]

hello ive got Ford Ranger 2003 manual transmission 4 cylinder pickup. generally runs fine except i cant get it to go above 75 mph and must be in 4th gear to do it. if i'm in 5th gear and go below 70 it feels like i must go back to 4th to get it to go back up to 70. is this normal? i've owned like 4 rangers so far and never had this problem. no shifting problems or clutch problems and no overheating or excessive rpms, doesn't idle weird or anything like that. maybe ive just never owned the 4 cylinder before but i would think going 70 mph shouldnt be that hard. any suggestions?

 

[Mbrooks420]

Are you sure the speedo is correct?

Mileage?

Factory sized tires?

It shouldn’t struggle to hold 75.

 

[RangerX]

I could see a tired high mileage engine maybe doing that. Or if you drive around with hundreds of pounds of cargo in the bed.
Potential issues could also be a clogged cat, a fuel pressure problem, maybe a vacuum leak.
Do you have a check engine light on? Have you checked for codes?
Answers to Mbrooks’s questions would help a lot.

Welcome to the forum!

 

[RangerX]

Also, how long have you owned it, and is this a new problem and it used to run good, or no?

 

[laurakatejohnson333@gmail]

Are you sure the speedo is correct?

Mileage?

Factory sized tires?

It shouldn’t struggle to hold 75.

*Pretty certain speedometer is correct but not 100%. When i pass one of those mile per hour digital signs on the freeway construction sites, it reads the same as my speedometer reads.
*Mileage on the engine is around 105,000
*Factory tires? No. Not factory tires, in fact they're fairly beefy. They look good, but i was thinking they might be the problem. I thought they might be a little too much for a 4 cylinder manual trans. There's some noise from them on the freeway but nothing extreme really. I asked around a bit for the educated opinion of some car saavy people i know, including one whom used to be a mechanic and now works in the tire department at Costco. They both said they dont think it to be the problem, but none has taken it for a test drive themselves.
*No check engine light. At least not in the time span i've owned it. About two months ago i bought it from a small dealership.

 

[Mbrooks420]

If the tires are oversized and heavy the 4 banger might just not have the ass to turn them.

 

[Mbrooks420]

What’s the tire size/model?

 

[laurakatejohnson333@gmail]

*Pretty certain speedometer is correct but not 100%. When i pass one of those mile per hour digital signs on the freeway construction sites, it reads the same as my speedometer reads.
*Mileage on the engine is around 105,000
*Factory tires? No. Not factory tires, in fact they're fairly beefy. They look good, but i was thinking they might be the problem. I thought they might be a little too much for a 4 cylinder manual trans. There's some noise from them on the freeway but nothing extreme really. I asked around a bit for the educated opinion of some car saavy people i know, including one whom used to be a mechanic and now works in the tire department at Costco. They both said they dont think it to be the problem, but none has taken it for a test drive themselves.
*No check engine light. At least not in the time span i've owned it. About two months ago i bought it from a small dealership.

*Current tire size on vehicle are 31x10.50R15LT (m+s--- not sure what m+s means but it was on the tire next to the size)

 

[laurakatejohnson333@gmail]

What’s the tire size/model?

*Current tire size on 2003 Ford Ranger 5sp manual trans. 4 cylinder (no 4x4) are 31x10.50R15LT (m+s--- not sure what m+s means but it was on the tire next to the size)

 

[MrQ]

*Mud and snow

235/75/15 is usually the right size for 15's on a Ranger. Those 31's are roughly 2" larger in diameter and at least 2" wider, which probably explains your struggle. Your speedo is also probably off unless you were re-geared or the speedo reprogrammed. Those roadside speed radars are not horribly accurate.

 

[Mbrooks420]

I bet that’s too much tire.

 

[domct203]

I bet that’s too much tire.

+1

 

[laurakatejohnson333@gmail]

*Current tire size on 2003 Ford Ranger 5sp manual trans. 4 cylinder (no 4x4) are 31x10.50R15LT (m+s--- not sure what m+s means but it was on the tire next to the size)

And it looks to have a tow package? the bar and hitch ball capability anyway/ idk if that's helpful info necessarily but maybe.

 

[laurakatejohnson333@gmail]

I bet that’s too much tire.

Thanks very much for taking the time to reply. It's so nice to get several opinions on this. I think you're right about it being the tires. So does this mean i'm working my transmission much harder than i should be? This will likely decrease the lifetime of my transmission by a substantial amount, am i correct? Are there other problems that can occur as a result of driving on oversized tires? And if so, how urgently should i stop driving it in its current state?
I am so thankful for anyone's hypothesis (educated guess, that is).
Sending out a, "Happy New Year" to all you folks out there.

 

[Mbrooks420]

And it looks to have a tow package? the bar and hitch ball capability anyway/ idk if that's helpful info necessarily but maybe.

The tow package on these did not include any hitch. Oversized tires are harder on the entire driveline. How much harder? It’s hard to say.

 

[RangerX]

There’s a plate on the door jamb area that will tell you and what size tire came on the truck from the factory, see if you can find that. I’m pretty sure it wasn’t 31s.
There’s also an axle code listed on that plate. That info would help us too.
Larger tires are harder on an automatic trans, but you have a manual so it’s less hard on it, but still not a great thing.
No need to stop driving it immediately just for that reason, though.

Years ago, decades actually, I had a 4 cylinder Nissan that I put 31s on. Same thing as you, had to shift to 4th when on hills on the freeway, etc.
The axle gearing and the tire size have to be in a certain friendly compatibility for the truck to have the power and performance it was built with.