hesitation while driving?

[toyo924x4]

ok....ive got a 92 pickup 22re and for the last week i've been having some problems once i reach 45mph or 4th gear if i accellerate my engine starts to sputter like it wants to kick off on me. this was the same problem i had when my fuel pump went out ( 6months ago ) but it felt alot worse then. so yesterday i replaced my fuel filter thinking that might fix the problem (it didnt) i also seafoamed the truck last night in hopes to clean the injectors (still having the problem) also, i bought cheap gas the day before it started this problem i thought i might have had some water in the fuel so i drained what was left and refueled (still having the issue) im now thinking its a ignition problem


IM LOOSING MY MIND AND CANT FIGURE IT OUT

should i start with the plugs now and work my way to the sensors

or replace the pump again

[fourwd1]

My first thought was fuel filter, but you already did that.

If you think it's still the pump, I'd check the pressure at the engine before replacing it again. You can probably borrow a fuel pressure tester from the local parts store.

[maxpower_hd]

Have you tried to pull the codes from the ECU yet? I would do that first thing. There are many things that can cause hesitation in these things. I would start with the codes and then go from there.

[toyo924x4]

doing that this friday ,also going to replace plugs and wires ive read alot of posts about this problem and no-one seems to re post once the problem is fixed assuming they do get it fixed i'll make sure to update my progress on this issue. also my check engine light is NOT on and the only time i have ever seen it on is when i unplug my o2 sensor and being that its not on now it shouldnt be the o2sensor RIGHT?

[toyo924x4]

just ran my codes i got 4 blinks then 1 blink i m guessing thats code 41?

[maxpower_hd]

On the codes: As you have found, you do not have to have a CEL to have codes stored in the ECU.

I had a similar issue and also noticed that many people either didn't post after they fixed their problem or simply never fixed it. This hesitation issue seems to be a symptom for several potential issues so it isn't just cut and dry "replace your xxx".

I ended up running all kinds of tests, changed loads of parts only to have it still hesitate. Finally I found a troubleshooting guide for the O2 sensor. I checked it several different ways until I finally determined it was bad. I replaced it and everything has been fine since. BTW, I had no codes or CEL. I just had hesitation and poor mileage.

Code 41 may be your TPS. It could be out of adjustment or just bad.

[toyo924x4]

well im still getting good mileage between 18 and 20mpg around town, and i have pulled my o2 sensor a couple of times and my check engine light always comes on while its pulled and goes off once i plug it back in and my check engine light isnt on right now so i dont think its my o2 sensor

im going to replace the tps this week if it solves the problem ill be sure to post ...if it doesnt, ill be posting that as well

[toyo924x4]

i also noticed that many people with this hesitation issue seem to be having the problem in the low rpm range then it corrects itself accelerating like a rocket in the higher rpm range mine is just the oppisite i leave in first and second great its only when i accellerate above 35mph or in third gear and above i get the hesitation and any little push on the throttle causes it almost like the ECU isnt sending a signal to send more fuel and the TPS regulates that RIGHT?

[BigRedTruck]

Why do people insist on just replacing parts .. with no idea if they are bad or not.

Why not buy a FSN ( Toyota shop manual) and test the it out... refer to the FSN if you are with in specs..
get a good volt meter, fuel pressure gauge , timing light.

pull codes, pull codes

Check for vacuum leaks as this engine is particularly sensitive.

Fuel pump- test the output pressure, test the electrical load at idle or running..

Check fuel pressure at the rail when idle or higher..

TPS - test to make sure you are see proper voltage at certain throttle angles..and no dead spots thru out the range..

Check voltage, dead spots or resistance at the VAFM , door and temp vane.

o2 sensor - test with a volt meter, if reading are slow/wrong or not there , get a new one.

Coolant temp sensor ( if you have one) - check resistance

Cold start injector- is in on when engine is hot..??

Check all electrical grounds


idle control valve ( it goes by many diff names)

etc etc etc


However, this sounds like a sticky door or dead spot in VAFM (vane air flow meter) (usually incorrectly referred to as the MAF or mass air unit, as this measures volume with the door and temp with the vane.)

In the VAFM there is a potentiometer that tells the ECU the door angle sometimes there are dead spots in the POT coil or an open contact in the circuit board... all of which can be tested with a volt/ ohm meter and a manual ..


Test , refurbish and then replace.. dont be a friend to the parts store if you dont have to..

[maxpower_hd]

I did as BigRedTruck stated. I did replace a few parts out because I had them and it was easier than testing, like the AFM. However, I ended up having to replace the O2 sensor. Mine did NOT throw a code or CEL unless I unplugged it but it WAS bad. It failed only PART of the test procedure.

I would also check the TPS according to the manual before replacing it since it is expensive. You can also sometimes adjust them.

Do a search hear for on line manual and you should find one for $0.

Good luck.

[toyo924x4]

i have a manual and also have tested almost all the things i need to i pulled the TPS last night last night and the case was cracked in 2 and it split apart in my hands so i know thats not good.

as for the o2 sensor i have not checked , i will get on that tonight

[toyo924x4]

PROBLEM IS FIXED!!!!!

first i want to say thanks for all the help guys

i fixed the problem in the parking lot of autozone i ordered my TPS yesterday and picked it up this morning i installed it and drove it to work this morning the hesitation wasnt to bad but still there so once i got to work i pulled the plugs i just put in last month and they were completely destroyed just really bad so i replaced them at work and the problem is totally gone

once again thanks for all the help

[89hilux]

How did you know which one to order? Autozone is posting two different kinds, TPS436 and TPS 432.

Thanks

Originally Posted by toyo924x4

PROBLEM IS FIXED!!!!!

first i want to say thanks for all the help guys

i fixed the problem in the parking lot of autozone i ordered my TPS yesterday and picked it up this morning i installed it and drove it to work this morning the hesitation wasnt to bad but still there so once i got to work i pulled the plugs i just put in last month and they were completely destroyed just really bad so i replaced them at work and the problem is totally gone

once again thanks for all the help