I can get my car to rev past 4,000 rpm in gears 1-4 but in 5th gear it wont pass 3,000. It used to be fine, but one day it was just like this and hasn’t changed since. This is annoying because where I live some of the speed limits are at 75mph. When I’m in 5th gear at 3,000 rpm I’m only going 65. What can I do to fix this? Reset ECU? Clean MAF sensor? Is it related to an approaching timing belt failure (I’m at 94k miles and it needs to be replaced before 105k)
Is it related to an approaching timing belt failure
Has NOTHING to do with the timing belt. When the belt fails…the engine doesn’t run…PERIOD…
How about going down hill??
Does it run well before it reaches 4000 rpms???
Sounds like it could be fuel starvation. When was the last time you changed your fuel filter??
I was thinking about a clogged cat converter (which may still be covered under your emissions warranty depending on the year of your truck)… Can you bring the truck to red line in the other gears, or does it putter out around 4,000?? Does the truck lack power untill 3-4,000 RPM when it stops reving?? Try this, go for a drive and when you park imediatly take a look under the truck, if you cat is glowing its clogged… GOOD LUCK !!
Check for vermin nesting inside your air-cleaner housing, blocking airflow into the engine. Have a shop check for a plugged CAT by removing the front oxygen sensor and replacing it with a pressure gauge…
I’d find someone who has a vacuum gauge and the ability to read it. Check for a clogged converter. With vacuum gauge in hand this involves just mere seconds of time as it’s so easy to do.
If no converter clog is present then it could be a fuel starvation problem. This may not necessarily be due to a clogged fuel filter but could be related to abnormally low pressure due to a fuel pump that is weak but not dead.
Is there a yellow light that looks like and engine or a yellow check engine light lit up on that dash?
I’m going to go with the vacuum gage suggestion, but would like to suggest that it might have a relationship to the timing belt. If the timing belt has stretched and slipped a tooth, it will limit the vehicles ability to rev, and of it is a slipped belt a vacuum gage will show it.
OK, so, No lights are on on the dash. I have reved up way past 3k rpm in other gears with it still going strong before an upshift. Just yesterday I was driving down the freeway just under 3k rpm in 5th gear and the cruise control turned itself off. I have a feeling that there is a blockage somewhere. There are a bunch of rats/mice where I live and we (my family) have had trouble with them nesting in the engine bay, so we keep our hoods up at night to keep them out. Once again, with 94k miles, I will be needing a timing belt soon. And it looses power right as it reaches 3k rpm, but only in 5th gear. I also got it up to 70mph but that was going downhill. All of the filters/belts/fluids were changed just over 1000 miles ago (except the timing belt).
I just cleaned out the area around the air intake, however it just had a few twigs in it. I’m looking into just taking the baffle and two air resonators off to increase performance and sound and hopefully fix the problem if its an animal of some sort living in there.
You may have a disintegrating Catalytic converter…and this would create more back pressure in your exhaust system. If the engine revs fine in the lower gears then …hmmm This points to the engine not making proper power and not being able to pull the tallest gear… Can be MANY things that would do this… Does the engine run smoothly? NO engine missing? NO vibrations? That engine is pretty smooth in your truck so any odd behavior will only compound at higher speeds and loads. If you have a spark plug or wire issue…creating a miss…then it will not be making full power… YOu should be able to figure this out fairly easily… When was the last tune-up? Plugs? Wires (if equipped)? Could be as simple as needing a tune up…and if you haven’t had one in a long while…then do it and see what you get…
To test my Cat theory…just loosen the exhaust pipe at the exhaust manifolds…Then test. It will sound like crap, but it will also rule out any back pressure in the exhaust as the culprit. After that…if that wasn’t it…we can go on from there with more info…
Blackbird
Connecting up a vacuum gauge, even if you must buy a new gauge, is MUCH easier than disconnecting the head pipe…All evil possibilities will be revealed…
I’d second the vacuum gauge. Mine cost me $40 and I probably overpaid but holy cow is it useful.
Alternatively, if one does choose to try to open up the exhaust, pulling the upstream O2 sensor(s) is also probably easier than the pipe - that will vary, of course.
The engine runs smoothly and with little vibration, both at idle and at speed. It was at the mechanic’s about 1000 miles ago for an inspections since I just bought it.
Where is the best place to get a vacumm gauge and how do I hook it up and use it?
Any parts store will have a kit with instructions. You can pick up a Haynes manual while you’re there too. That’ll help you know where to hook it up and what to look for.
No…That would be why you can’t find a decent mechanic…There are much easier ways to make a living…
On second thought, forget the vacuum gauge…Pay an exhaust system shop to do a back-pressure test on the CAT(s)…
I third and Fourth the vacuum gauge…Does he know how to read one?
Unfortunately, no…And interpreting a vacuum gauge is a learned art…
alright ill have that checked out by a professional…
I was also suggested that it could be a clutch problem since its only in 5th gear. Could this also be the problem?
Which is why I posed the question about actually READING a vacuum gauge. I was trained by 3 people who were absolute Aces in this discipline…first, a guy who was born in 1898…then a man born in 1903…then a guy from 1934…So I was trained from the OLDEST of OLD SCHOOL… You can bet i have my i’s dotted and T’s crossed…and I wish we were there to help the guy, let alone my Si-fu’s. HOWEVER… You can have an encyclopedia of instructions…But like Caddy said…this is an Art…and I FULLY agree. It actually is…
I severely doubt that this is a clutch problem…just my 2 cents…but what do I know eh? I tend to think…quite a bit…and so do the guys on this forum…collectively we are the Grand Master Kung-fu champions of Automotive repair… At least thats my opinion
PLEASE look into the simplest things first…such as tune up items…sometimes even these things can really F with your mind if you haven’t seen the symptoms B4. I will be here to help further if needed ad I am sure most others will be also…
Blackbird