Bogging down when accelerating in my 89'

My Runner has always, kinda hard to explain it, bogged down while accelerating when its cold, when its warmed up and cruising at a constant 70mph, and has now started doing it randomly when accelerating over 40+mph. It's starting to get worse and worse and need to get to the bottom of this. It seems like its drowning or something. Like its not getting enough gas or air or too much of both.

I recently got a tune up on with with valve adjustments, replaced head gaskets, timing, new plugs, wires, repaired wiring harness, and fluids and what not....

I kinda feel like it might be the mass air flow sensor, but wanted to hear from you guys before dropping the $200 on a new one. Any Ideas????

 

Need a little more info.

V6? I'm assuming from you replacing the "head (gaskets)"
Is your t4r equipped with California emissions? (Egr valve).
Last time you replaced the thermostat, and have you ever replaced the coolant temp sensor (if you have one).
How does it idle? Any random little shakes or miss fires? Ever stall out?
Does it have the orginal cats? Any exhaust work done?
Any notice in power drop over the time you have owned it?
Does it have the original fuel pump?

 

Its a 4 cylinder, with all Cali emissions, however it has an aftermarket Cat (since some a-hole decided he wanted to chop mine off a few years back). I have NEVER replaced the thermostat or coolant temp sensor. Still has original fuel pump, but I know that works fine cause I just dropped the tank to check the other month.

The idle has always been a little strange. Some days it idles just fine (independent of outside Temp) and other days it will idle high and/or low. These are also the days when the bogging occurs the most....

 

You never have an issue maintaining operating temp? how many miles are on it?

 

It has a little over 200k on it. It has never had any real issues with operating temp by that I only mean it has never overheated or has ever really burned up oil. However my temp gauge does act up. It will randomly bounce from cold to hot and back and forth on some days. And other days will work just fine and always be running at a good operating temp. Never though this would be the cause of it, just thought is was a bad sensor or something. What are you thinking?

 

Check out the 02 sensors, espeically Sensor #1.

Thats my random stab in the dark.

 

If you are getting erratic signals from a coolant temp sensor, the computer can run the engine too rich. When its at operating temp and the ecu sees the motor as being cold it will dump an insane amount of fuel in and give you all kinds of driveability problems. If the temp gauge sending unit that's bouncing all over the place is tied in with the cts the ecu sees, that could be your problem. Try putting one of them in and see what happens. I doubt they are expensive. I'd put a new thermostat in wile your at it.

 

O2 Sensor, Themostat, I wouldn't doubt that they could us replacement since they are still the OEM from 89'. I'll check them out and see what they run.

When you say "a coolant temp" it sounds like there are many. Do you know how many or which one you think I should start from? I've always thought I needed to get the temp sensor repaired...the real funny thing was that after I got the tune up they told me there was "nothing that could be done with that". haha! Obviously I didn't believe him, but it forced my brain to move it down on the to-do-list. Not smart on my part. I should always stay with my initial thoughts.....

Thanks guys any other thoughts? If not, I guess I'll see how it runs after they are replaced. Is it a good idea to reset the ECU after installing new sensors??

 

I'm actually not very familiar with the 22re. I've done some parts replacement but never had to diag drivaability issues. I'm pretty unfamiliar with Toyota obd I as well. I would recommend looking in a repair manual, if you dont already have one, to get an idea about where the sensors are located and what kind of sensors it actually has. Some repair manuals have testing procedures for certain systems and sensors.

The thermostat is definatly a place i would start. Not sure what toyota recommends, but they are not designed to do 200k miles of duty anyway. I looked them up on autozones website and their heavy duty one is $8.99. And their coolant temp sensor is $20. I like stealer ship stuff personally.

Up to you, but I think its a better place to start than the maf. I'm sure if it was bad you would be having issues with it running at all. I believe its a vein type maf sensor. Which is pretty easy to check with a multi meter if you have one.

 

Yeah that's where I was going to start. I have the complete repair manual that does show everything including some trouble shooting but it's on my work computer and I haven't been into the office in a few days so I don't have access to it. I'll have to go in tomorrow and get a soft copy. When this issue first sprouted up I did run through the trouble shooting with the air flow sensor but got inconsistant readings which was a result of my faulty multi-meter cables. Since then I have repaired the problem that was at hand (intermittent connect in my wiring harness. The runner wouldn't start on random days but I was getting spark, and the fuel pump was working.....long story with that one ) so I haven't checked it with my new meter.

I'll be checking the dealership tomorrow to get some prices and hopefully get some parts ordered. Thanks for the ideas

 

No problem. Good luck.