bain

OK..The truck idles really really smooth.. But during acceleration it surges or hesitates and doesn't seem to want to wind out and it doesn't have the power it should. I have new plugs and fuel filter and it didnt fix it. Could it be the coil packs? Thanks

Elton

what plugs did u go with did you also replace the wires ? how about cleaning the maf sensor air filter good too ?

BajaRunner

Check/Clean MAF (Air flow sensor which is directly behind air filter) with electro-contact cleaner, and clean your throttle body with throttle body or carb cleaner.

Any vacuum lines disconnected or leaking?

Check all the simple stuff first!

bain

I pulled my packs and one plug looks brand new and the other looks used...must be the pack

hross14

As always we need more info. Miles, auto or manual, year of truck, mods----details man--details.

But here is my initial diagnoses--i will assume it has over a 100K

**Replace both O2's or in later models AFR and O2
**Replace the TPS switch--its cheap, just do it
**Clean the MAF, Throttle body and IAC
**Take out the injectors and have them sent out to be tested and cleaned
**check resistance values on your coils
**Plugs and wires (Hint: the only reason Toyota used dual electrode plugs was because of the wasted spark system--they fire twice as often)

**Do a leak down or compression check to get a general idea of what condition the engine is in. You can get this all done in a day less the return time for the injectors.

LAST BUT NOT LEAST--SEARCH--there is tons of people with this same issue and our suggestions

bain

First off..thanks for the help..Ive searched for a week and didnt learn anything helpful so I thought Id try a new topic with new input.. Its a 98 3.4 4X4 5 speed 103,000 . Its got new O2 sensors,new plugs and now new wires and coil packs (all Toyota). The MAF has been cleaned. I just replaced the coil packs,plugs and wires and it got worse. If you set and rev it , its smooth as hell but when you take of it feels like a light case of running out of gas. You can floor it in 3rd gear and it will stay the same speed with the hesitation.. Would a bad injector across from the plug that always looks new cause it not to fire?

bain

and does a TPS have to b calibrated in any way or do you just put it on?

hross14

I suggest the injectors because every set i send out at about the same miles comes back with a poor pattern and less CC's flowed.

The TPS just bolts on with no calibration. Also, if it got worse maybe rechecking the firing order might help--they might have gotten mixed up.

You might also want to sweep the Knock Sensors--just saying

check OHMs on the fuel pump also--but i put that one low on the list....

904_runner

it needs to be adjusted properly..

Look up specs in a toyota manual..
You need to use an ohm meter to get it proper.

Google "toyota FSM" and a result will be from ttora and they have factory toyota service manuals uploaded that you can use...

Yota Runner

Check the boots on the coil packs for cracks. It doesn't take much of a split to make it run crappy. Roll the ends between your fingers while squeezing. There should be no splits, cracks or anything.

bain

coil packs and wires are brand new.. cleaned MAF again and checked TPS (it was good). I checked the new plug just now and it still looks new..could it be a dead cylinder? I'm confused because it runs smooth until i accelerate up a hill or get on it....I'm getting a compression test done Wednesday..

904_runner

Yes do a compression test to see whats going on internally. If everything turns out good there and the TPS and all the other sensors are good, the only thing i could possibly think of is maybe a clogged cat.


So your saying when your pushing it it just falls on its face? NO power??

bain

pretty much. if i have to give it gas to get up a hill it has no power nd you can fill it missing

904_runner

if you can feel it missing, i would seriously check your plugs/wires/coil packs

there is a possibility it may be bad, even though its new. Are you sure all the wires are connected all the way?

bain

yea..triple checked.. I just got to figure why #5 isn't getting any fire...gotta be a bad injector or a dead cylinder...that's all i can think of..guess ill find out Wednesday..

vital22re

iTrader: (2)

Do a compression check on 1,3,5 that will help rule out a lost cylinder.

bain

im pretty sure #5 is gone...thats the luck ive been having with this truck...

FJHammerHead

iTrader: (1)

After I took out my MAf and cleaned it, then reinstalled. I had the same problem because I didn't have the MAF plugged in all the way. Worth another look.

bain

ill double check that tomorrow..thanks... would that cause the #5 plug to look unused and the rest look normal?

hross14

Unless your 3.4 is different from the ones i have worked on--they dont need to be adjusted. There arent any provisions for them to be adjusted. Only the 4 cyl

The compression and or leak--down (this is the one i prefer--more consistent) will let you know what is happening as far as valve leaks and etc. But if all sensors check out and etc...you are just going to have to keep digging. I am assuming you are mechanically inclined and checked all the small stuffs. Take a look at the injectors.....

Did you pressure check your Fuel pump/system?