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engine question for those that know

def

Monkey
Feb 12, 2003
520
0
knoxville, tn
Haven't posted here in years, but I'm looking for some help as I'm mildly retarded. I've developed engine hesitation recently and I'm looking for a little help to see if I can handle this before I run it to a shop.

2001 Tacoma 4wd
3.4L
Auto trans
190k on the clock

I've developed low rpm hesitation/sputtering between 1500 and 2000 rpm. Its mostly noticeable at highway speeds, but only in that range. The trans will downshift fine and then pull through, but slight accelerations w/o downshifting causes the problems. The truck idles fine. No warning lights on the dash. This issue came on all of sudden. The truck has had no other issues aside from a bad O2 sensor a couple years ago. Regular maintenance is performed.

There it is. I'm decent at turning a wrench and can perform basic to moderate stuff. Any ideas or suggestions on where to look? I'm not up on car message boards so suggestions there would also be helpful. Thanks-
 

ALEXIS_DH

Tirelessly Awesome
Jan 30, 2003
5,492
272
Lima, Peru, Peru
does the tranny slips a bit or something? does this happen only when you slowy accelerate between 1500-2000rpm in any gear?

how does the engine run while cruising at 2000 rpm? any hesitation?

since the cars idles fine, i`d assume the thottle body (and isc valve, assuming your car has one) is not very dirty. anyway, i`d start by cleaning that.

how does the car respond at say 4000rpm? any hesitation when accelerating hard could mean a problem with the fuel delivery, from a clogged fuel filter to dirty injectors.

i´d start by checking that first.

i once had a problem just like yours with a 4runner, that only happened at certain temperature and altitude after a couple hours of driving. it was VERY tricky, we could never replicate it at the shop at sea level. we had to drive it for hours at 150000ft above sea level hooked to all sorts of data-acquirisition crap... and it ended up being just an o-ring the fuel lines that froze and choked the injectors, did not trigger and warnings or lights, but just enough to cause hesitation.
 

MMike

A fowl peckerwood.
Sep 5, 2001
18,222
86
just sittin' here drinkin' scotch
But with no Check engine light, it could anything really. It's actually a little weird that therer's no check engine. Of course I'm use to ALWAYS seeing my check engine.

(But FWIW, I just have my thottle position sensor changed in the Jeep last week, because it was doing something similar....but again...check engine was on).

Oh and TRY IT NOW!!
 

ALEXIS_DH

Tirelessly Awesome
Jan 30, 2003
5,492
272
Lima, Peru, Peru
But with no Check engine light, it could anything really. It's actually a little weird that therer's no check engine. Of course I'm use to ALWAYS seeing my check engine.

(But FWIW, I just have my thottle position sensor changed in the Jeep last week, because it was doing something similar....but again...check engine was on).

Oh and TRY IT NOW!!
if there is no check engine light. 99% of the time, there is something worn or dirty.

more information would be good. im still not very clear on whether its an engine or transmission problem.

any smoke coming out? engine oil level ok? tranny oil ok? funny noises in the tranny? only happens in one gear? can the symptom be duplicated at will?
 

buildyourown

Turbo Monkey
Feb 9, 2004
4,837
0
South Seattle
Try the Toyota board at Expedition Portal. There are lots of guys running that motor and they aren't blowhards like TTORA.

The lack of a check engine light all but rules out electrical things. Not completely, but I would start with some simple mechanical stuff.
Air and fuel filters. Plugs and wires. Clean throttle body. Etc. Simple, cheaper stuff that will be good to get done even if it doesn't fix the problem.
 

Mr Jones

Turbo Monkey
Nov 12, 2007
1,483
0
My 2001 4 runner melted the catalyst at 190k. Gradual loss of power over a period of 2 months till it started rattling. Doesn't sound like anything wrong with your trans because if you downshift, you bring the motor closer to its power band.

Basics to cover:
spark plug gap incorrect
PCV valve stuck open?
Fuel Filter dirty
MAF sensor contamination
carbon build up on Idle Air control valve (needs to go full open at 1500+rpm)
carbon buildup on throttle bore
 

trib

not worthy of a Rux.
Jun 22, 2009
1,173
103
I have nothing to add except for I read the thread title as 'equine questions' and thought this was about horses.
 

Kanye West

220# bag of hacktastic
Aug 31, 2006
3,475
194
Spark plug gap, fuel pump/clogged fuel injector, bad spark plug wires or coils (forget which that engine has), dirty MAF needle. Those are the places I would start and see if it goes away.
 

def

Monkey
Feb 12, 2003
520
0
knoxville, tn
No smoke, all fluids okay. Troubles started yesterday (fri).

Today - hesitation/jerking/rode like complete sh!t at all rpms. Check engine light finally came on, codes read = cylinder 3 misfire. Autozone pulled it up and stated either bad plug, wire, lean or loss of vacuum.

Jesus, there is a lot of plastic/wires/lines to get out of the way just to access the plugs. Visually, things look okay. Guess its time to grab a beer and go out into the humidity and get dirty.

On a semi-related note, there was a nest (bird or mouse) in the valley next to #3. The truck did sit for about 4-5 weeks this spring/summer due to out of town work, but it never showed any issues and nothing looked eaten.
 

stringcheese

Monkey
Jun 6, 2002
360
0
Golden, CO
No smoke, all fluids okay. Troubles started yesterday (fri).

Today - hesitation/jerking/rode like complete sh!t at all rpms. Check engine light finally came on, codes read = cylinder 3 misfire. Autozone pulled it up and stated either bad plug, wire, lean or loss of vacuum.

Jesus, there is a lot of plastic/wires/lines to get out of the way just to access the plugs. Visually, things look okay. Guess its time to grab a beer and go out into the humidity and get dirty.

On a semi-related note, there was a nest (bird or mouse) in the valley next to #3. The truck did sit for about 4-5 weeks this spring/summer due to out of town work, but it never showed any issues and nothing looked eaten.


Loss of vacuum... in the cylinders? That could mean your oil pressure is inconsistent, which would explain the strangeness during acceleration.

Maybe next time you're driving it try to take your foot off the accelerator really quickly while you're in the higher rpms, because that creates its own vacuum and will force more oil to be sucked into the cylinders and if it temporarily behaves better then that could be the problem.
 

splat

Nam I am
i once had a problem just like yours with a 4runner, that only happened at certain temperature and altitude after a couple hours of driving. it was VERY tricky, we could never replicate it at the shop at sea level. we had to drive it for hours at 150000ft above sea level hooked to all sorts of data-acquirisition crap... and it ended up being just an o-ring the fuel lines that froze and choked the injectors, did not trigger and warnings or lights, but just enough to cause hesitation.
150000 feet! Dam, what kind of fuel are you using ?
 

def

Monkey
Feb 12, 2003
520
0
knoxville, tn
Simple as a burned-up plug. Spent most of my time removing the intake and a bunch of other stuff just to access them. Test run showed no problems through the full rev range, reset the warning light and nothing new pops up. Not sure if I feel like the idiot who asks how to change plugs or like Clarkson for changing a tail light...

Thanks for the help
 

kickstand

Turbo Monkey
Sep 18, 2009
3,444
392
Fenton, MI
No smoke, all fluids okay. Troubles started yesterday (fri).

Today - hesitation/jerking/rode like complete sh!t at all rpms. Check engine light finally came on, codes read = cylinder 3 misfire. Autozone pulled it up and stated either bad plug, wire, lean or loss of vacuum.

Jesus, there is a lot of plastic/wires/lines to get out of the way just to access the plugs. Visually, things look okay. Guess its time to grab a beer and go out into the humidity and get dirty.

On a semi-related note, there was a nest (bird or mouse) in the valley next to #3. The truck did sit for about 4-5 weeks this spring/summer due to out of town work, but it never showed any issues and nothing looked eaten.
cylinder 3 misfire is great, but WHY is it misfiring? Sounds like you have a bad plug wire, but one bad cylinder shouldn't affect the overall power/ride/drive THAT much. Something else is happening, find a good scanner (Snap on or similar) from a good mechanic and go for a ride, it will show you EVERYTHING and will tell you why you are misfiring, of course I could be completely off, and it could just be the one wire.
 

snowaddict91

Chimp
Sep 8, 2008
69
0
Gunnison, Co
cylinder 3 misfire is great, but WHY is it misfiring? Sounds like you have a bad plug wire, but one bad cylinder shouldn't affect the overall power/ride/drive THAT much. Something else is happening, find a good scanner (Snap on or similar) from a good mechanic and go for a ride, it will show you EVERYTHING and will tell you why you are misfiring, of course I could be completely off, and it could just be the one wire.
one cylinder misfiring most of the time will definitely affect power, but I agree there are so many reasons it could be misfiring. Plugs/wiring starting to go is a good place to start
 

thebornotaku

Monkey
May 19, 2008
359
0
Northern Bay Area
Loss of vacuum... in the cylinders? That could mean your oil pressure is inconsistent, which would explain the strangeness during acceleration.

Maybe next time you're driving it try to take your foot off the accelerator really quickly while you're in the higher rpms, because that creates its own vacuum and will force more oil to be sucked into the cylinders and if it temporarily behaves better then that could be the problem.
Vacuum is measured at the manifold (typically), compression is measured in the cylinders.

Low or inconsistent vacuum could be any number of things. A bad intake manifold or throttle body gasket, any number of problems with the valves, a restricted exhaust, bad rings, etc... none of which sound like particularly feasible problems given the fact that most of those cause your vacuum to fluctuate and behave strangely through the whole rev range.

Also, for the record, the only oil that is supposed to make it's way in to the combustion chamber in the majority of engines does so by filling the tiny grooves in the crosshatch pattern of the cylinder bore. Engines are not designed to suck oil in to the combustion chamber any other way. Oil control rings and well-fitting valve guides are designed specifically to keep as much oil out as possible.

There are people who like to add a little bit of 2 stroke oil to their gas to help the engine run a little smoother (I happen to be one of those people) with decent success, but that's neither here nor there. Low oil pressure in no way affects engine performance as a result of the combustion chamber failing to receive lubrication. It can cause excessive friction between the crank and the mains, or the cam and it's mains and such, causing performance to suffer, but not like you said.


cylinder 3 misfire is great, but WHY is it misfiring? Sounds like you have a bad plug wire, but one bad cylinder shouldn't affect the overall power/ride/drive THAT much. Something else is happening, find a good scanner (Snap on or similar) from a good mechanic and go for a ride, it will show you EVERYTHING and will tell you why you are misfiring, of course I could be completely off, and it could just be the one wire.
A single cylinder misfiring on what is more than likely a 4cyl engine (can't be bothered to look it up though) can affect performance a hell of a lot. I had a clogged injector on my '87 Volvo, and it ran like crap. Pulled the rail off, put in a set of cleaned and flowed injectors, popped it all back together and it ran wonderfully. Boosts like a charm, no hesitation or lurching or anything strange now. :thumb:
 

kazlx

Patches O'Houlihan
Aug 7, 2006
6,924
1,808
Tustin, CA
Does that truck have coil/wires or coil packs? My dad was having an issue with the engine missing slightly on a 2001 Ford Escape, so I ended up doing new plugs and OEM coil packs on it. He says it runs better than it has in a long time. Probably wouldn't hurt to change the ignition system if you have a little extra time/cash. Ignition seems to be one of those things that degrades slightly over time that you don't really notice anything is wrong until it starts missing enough like yours....
 

Mr Jones

Turbo Monkey
Nov 12, 2007
1,483
0
Simple as a burned-up plug. Spent most of my time removing the intake and a bunch of other stuff just to access them. Test run showed no problems through the full rev range, .....

Thanks for the help
Glad it was a simple fix. Those 3.4L engines are such a step up from the 3.0's they replaced. My dad still has a HiLux with the 22R in it. Damn thing refuses to quit at 285,000 miles.
 

thebornotaku

Monkey
May 19, 2008
359
0
Northern Bay Area
Glad it was a simple fix. Those 3.4L engines are such a step up from the 3.0's they replaced. My dad still has a HiLux with the 22R in it. Damn thing refuses to quit at 285,000 miles.
22Rs are awesome engines. If I ever need a truck, I won't hesitate to pick up an older tacoma/hilux.

I drive Volvos primarily though, and the Redblock engine is one of the most famous engines for longevity -- my wagon just rolled over 275k recently, the turbo 760 is at 207k and the turbo 940 is at 325ish. pretty crazy. :thumb:
 

kickstand

Turbo Monkey
Sep 18, 2009
3,444
392
Fenton, MI
A single cylinder misfiring on what is more than likely a 4cyl engine (can't be bothered to look it up though) can affect performance a hell of a lot. I had a clogged injector on my '87 Volvo, and it ran like crap. Pulled the rail off, put in a set of cleaned and flowed injectors, popped it all back together and it ran wonderfully. Boosts like a charm, no hesitation or lurching or anything strange now. :thumb:
when did toyota make a 3.4 liter 4 cylinder for the tacoma's?

The last misfire I had was due to an O2 sensor downstream in the exhaust manifold, it caused one cylinder to misfire about .75% of the time , and 3 others to misfire about 25% of the time and power was down a fair amount. If it is just one cylinder (like recently on my dad's truck 4.3 v6 for reference) power is noticeably down, and you will feel a slight stumble but it wasn't ungodly.
 

thebornotaku

Monkey
May 19, 2008
359
0
Northern Bay Area
when did toyota make a 3.4 liter 4 cylinder for the tacoma's?
I dunno, I was just assuming since I couldn't bother to look it up.

The last misfire I had was due to an O2 sensor downstream in the exhaust manifold, it caused one cylinder to misfire about .75% of the time , and 3 others to misfire about 25% of the time and power was down a fair amount. If it is just one cylinder (like recently on my dad's truck 4.3 v6 for reference) power is noticeably down, and you will feel a slight stumble but it wasn't ungodly.
Depends on the engine. A 6cyl or more, yeah it'll still be pretty smooth. But like I said when my 760 turbo had a misfire due to a clogged injector, it was pretty rough.


this is common. clean the thing with some alcohol and a q-tip. there's plenty of videos if you google it.
Don't. AMMs are pretty sensitive equipment and I wouldn't trust most people, including myself (bear in mind I am a certified mechanic) to clean them with a q-tip. Go to the parts store, pick up a can of CRC AMM cleaner, and spray down the AMM. Then turn it over, and spray some more, then repeat. I like to empty a whole can just to be sure. Let it dry out in the sun for a few minutes, pop it back in and voila, clean. And you didn't have to touch any of the sensitive parts. Most of the AMMs I've worked with anyways had screens on either side anyways to protect the components.
 

golgiaparatus

Out of my element
Aug 30, 2002
7,344
41
Deep in the Jungles of Oklahoma
Spuddering = Fuel or air or spark issue. Could be a number of things. I'd get someone to hook you up to a diagnostic to determine exactly what the issue is.

Easy things to check out. Check air filter. Check spark plugs & wires. Some cars are easier than others to check the fuel filter... not sure about yours, but that's another thing to check.
 

Kanye West

220# bag of hacktastic
Aug 31, 2006
3,475
194
this is common. clean the thing with some alcohol and a q-tip. there's plenty of videos if you google it.
No and NO. You don't want any fibers on the MAF, and you want to use a specific MAF cleaner, not carb cleaner. Electrical parts contact cleaner is the same thing as MAF cleaner.

Spray at the needle in short bursts and let it air dry. Do not touch it.