3VZE Hesitation

[clunker]

I'm hoping that members with more Toyota experience can help me out. My recently purchased 1992 4runner has some issues that I want to resolve. I researched a little and uncovered some common throttle hesitation solutions, but I think I need to look at the big picture of all possible causes.

Here's what I know. The V6 sometimes hesitates (or bogs) when increasing throttle. It happens more often before the engine has warmed up but still happens sometimes when warm. I installed a new fuel filter, which managed to help a little. I also have an NGK tune up in the mail, and I have a new throttle position sensor that I'm planning to install this weekend. I just don't want to keep throwing money at the problem.

Symptoms:
-Starts and idles beautifully
-Temp is perfect, even on hot days up a long steep grade
-Engine seems to occasionally have sudden bursts of power at higher RPMs
-The new fuel filter seems to have actually made the engine slightly quieter
-Fuel injector treatment has made zero difference

I'm really hoping that it is not the fuel injectors (expensive). Can someone make suggestions of what the possibilities are and how to diagnose before randomly replacing more parts?

 

[willyt4r]

Egr

please research the EGR system - a dirty carboned up EGR valve causes the exact:girl: issues that you post.
Good luck

 

[89FourRunner]

Before you do any of that - check the intake tube that connects to the throttle body, a cracked or leaking one will cause every single symptom you mentioned, especially the sudden burst of power in the rpm band. This is due to the leak happening after the MAF sensor read.

 

[clunker]

Thank you for the great suggestions. I had actually considered both of those things. There is a crack in the throttle body boot, but it is mostly covered up by the band clamp. I will change it out anyway just to rule it out.

I just noticed the large canister connected to the EGR system last weekend and wondered if I should take a closer look at it. This thing has been abused, so it would not surprise me if the EGR valve is toast.

Still welcoming any other suggestions.

 

[clunker]

Replaced the boot, and it helped reduce the hesitation by about 50%. Considering that it helped at all, I'm wondering if the leaking valve cover gasket is letting in some air (like the cracked boot was probably doing).

Is an EGR delete possible or even recommended?

 

[clunker]

I just discovered something while looking into the EGR system. The stem located just upstream from the EGR valve does not have anything connected to it. After a quick google search, I discovered that there is supposed to be a temperature sensor, but it is not there. Could this have something to do with the hesitation? It would explain why the engine seems to stumble a bit less after it warms up.

 

[FJRunner23]

I just bought a 1992 T4R 3VZE and it is having similar issues, It will start and idle great but after only 30-45 seconds will lose rpm and stall and not restart. I advanced timing to max to adapt rpm to about 900 rpm and it will run fine with the timing advanced to the point it is driveable but still lacks any considerable power on acceleration. This is not however proper timing so I too am wondering what to do next. I was thinking the Crank position sensor or Cam position sensor. Has a new fuel sending unit, filter, plugs, wires, cap, rotor, fuel pressure regulator and I checked the EGR for fouling (appeared to have flowing passages) Keep me posted on your progress.....Im stumped here until someone tells me what to do next...

 

[Darkyoda727]

Seems common almost..

I got a 94 4 Runner V6 2 wheel drive. I change the water pump and the radiatorlast week and I can't get it running at least how it was before I started. when I pulled the water pump off of course the timing belt and the timing belt tensioner had to be tampered with so all and all after putting it back together 3x I'm at this bAugie hesitation nonsense. I have already changed plugs wires cap and rotormass air flowand one of the sensors on the right. most of my vacuum linesmy oil and tranny gasket. it was running better before I fudged with it. I'll keep up with the tread. Good luck guys n gals

 

[Hutch77]

89 3 liter low compression in two cylinders adjacent each other

I did a compression test solid compression on front two cylinders and rear to 150 to 170 middle two are 50 + 70 put a couple ounces of oil in each with same results

I'm just wondering what the next step is and how big of a job it is to determine :thanks:

 

[fixitagain]

Hesitation

Hi am having issues with my 92 3.0 4 runner vrz as well..RE original post may be TPS worn on first area of travel..it is a variable resistor that controls timing and is sconnected to ecu..IF power is best at high end maybe due to less wear on that portion of metallic strip in TPS? most driving would be at lower ends I suppose and higher end might be in better condition providing more accurate info to ECU..did yoy connect ohmeter to tps and observe smooth change in ohms as tps was rotated? any breaks in this might explain issue especially if smooth increase at end of travel/rotation..

In any case maybe someone can help with my situation..ran out of fuel and had no start no run due to no pressure on line..replaced pump and filter obtained start and run bt somewhat rough,,examined plugs were black soot..checked cap rotor wasted away on 4 contacts firing on only 2..replaced cap rotor wires coil and plugs..obtained good start good idle and great operation while COLD..

as soon as warms up rough idle and hesitation on acceleration..ouch..

cleaned MAF, replaced intake hose, replaced TPS, no change..replaced pressure reglator same..

disconnected EGR, same..ajusted TPS mltiple times..same..disconnected cold start injector..same disconnected ecu temp sensor..same..

engine looks great with all the parts changer parts..Oh replaced O2 sensor too..same..

PS tried reading codes at first was eppileptic..then stopped flashing thats why changed so many parts also un plugging parts caused no change so I figured they werent working in the first place..wrong..

Any ideas? soon I will have a new engine at this pace..

again runs perfect cold for about 5 minutes then rough idle and poor acceleration..

ANY ideas?

 

[bearcat90]

I just discovered something while looking into the EGR system. The stem located just upstream from the EGR valve does not have anything connected to it. After a quick google search, I discovered that there is supposed to be a temperature sensor, but it is not there. Could this have something to do with the hesitation? It would explain why the engine seems to stumble a bit less after it warms up.

Before this thread gets hijacked any more, did the OP find the solution? Also, did you verify that the timing and idle speed are within spec? That's probably the first thing I would check and while you're in there, make sure the timing is advancing with increased RPM. The situation is that you're getting a rich condition upon acceleration so that could be too much fuel, not enough air or retarded timing. EGR, temp sensor, MAF sensor are all involved but you gotta check the easy things first...