Truck Tech

I finally got out wheeling again in mid-February.Joined up with a group in Death Valley (California), for 3 days of desert fun.First day saw a couple of sliced tires and one 4Runner with a leaky radiator hose.On the second day, I had to fire up the Premier Power Welder and reinforce a steering box that was pulling loose from the frame on another 4Runner.All in all it was a fun trip.


Hi Roger;

Got any suggestions on a throttle body (TB) upgrade for a 95 Toyota 4x4 22RE engine? Getting ready to add a LCEngineering header and would like to perk up the TB too.†† Also could you tell me how much anti-freeze the radiator holds?I donít have the ownerís manual.

Randy Hembree

Hi Randy;

Several companies offer bored out TBs:

LC Engineering is one:

DOA Racing Engines is another:

A 3mm over-bored TB will help the engine breathe better, especially when combined with a mild cam and exhaust headers.You already have the improved TB and intake on your Ď95, so you would probably see less improvement than I did on my earlier Ď85 engine.

Radiator should hold about 8.9 quarts of coolant:

[A reply from Randy]

Hi Roger;


Thanks Roger for the quick response! I have another question for you, how much oil does the manual transmission and rear differential hold?†† Also, you think with the LCE header, Hotshot cold air intake, and 2 ľcat-back with Flow-Master muffler, the cam would be better than the bigger TB?Which cam would you recommend?Rando

Hi Randy;

The web page that I sent earlier lists all the fluid types and quantities, including the 3.2 qt. volume of the 22RE 5-speed transmission and 2.3 quarts for the rear differential:

Never tried the combination of engine upgrade parts you list, so canít comment on them specifically.Making the engine breathe better is the whole idea.You need to get air to the engine (intake), then you need to get the air into the engine (cam and valve train) then you need to get the exhaust gas out of the engine (header and exhaust).Improve 2 of the 3 and you only get part of the benefit.I documented my 22RE engine buildup on my web page:

I installed a larger TB, TRD Level 1 cam, LC Street Performer header and a 2Ē stainless steel exhaust. 2-1/4Ē is supposed to be a good size for a 22RE engine, I went with 2Ē to preserve the low end torque and I also had all the material to fabricate it left over from other projects, outside the muffler.


Hi Roger;

I have a 1985 4WD pickup, 22RE engine and a camper shell.Every time I fill the tank, I check the mileage. I always got 25-27 MPG on the highway and never less than 22 MPG. Then, at 54,000, I filled the gas tank once again. To my horror, the gas mileage had dropped to 15 MPG!Since then, I get 19-21 MPG with a few 22 MPG tanks.I shorted the test plug under the hood and read the Check Engine Light (CEL) in the dash. According to that, nothing was wrong.The tires have always been the same size as stock.

At 110,000 miles, I had to replace the head gasket. The coolant in the overflow reservoir was disappearing quickly and there were exhaust gasses in the radiator. I got a valve job, had the head shaved, replaced the exhaust valves, new timing chain and gears, and new plastic chain guide. The oxygen sensor was replaced with a Bosch unit.Gas mileage remained the same but once the CEL came on indicating the Air Intake Valve was faulty.I performed the field test on the valve and it checked out OK.Iíve since checked every electrical connection for corrosion. The only questionable connection was the plug on the Mass Airflow Sensor. I cleaned the tabs and put it back together. Still no change in gas mileage.

Someone suggested checking out the Throttle Positioning Sensor (TPS). I do believe that a smog technician adjusted it one day (I canít tell you if it was before or after the initial drop in MPG). I adjusted it according to the Toyota manual (the adjustment screw was turned in a couple of turns too far) and tested the resistance at different points as noted in the shop manual.No change in MPG.It seems there is some room for interpretation as to the correct gap between the adjusting screw and the sensor plate.

Page FI - 60, Toyota Truck & 4Runner 1985 Repair Manual

Clearance between†††††† Between termsResistance††††††††††††††††††† My Results

lever and stop screw

0.00 mm (0.000 in.)†††† VTA - E2††† 0.2 -0.8 k ohms†††††††† 0.482 k ohms

0.57 mm (0.0224 in.)††† IDL - E2††† < 2300 ohms†††††† Infinity

0.85 mm (0.0335 in.)††† IDL - E2††† Infinity††††††††† Infinity

Throttle fully††††††††† VTA - E2††† 3.3 - 10 k ohms†††††††† 4.61 k ohms

open position ††††††††† Vcc - E2††† 3 - 7 k ohms††††††††††† 4.58 k ohms


I tried turning the screw Ĺ a turn out and driving it around for a few tanks. No change in MPG. I repeated this test again turning the screw out another Ĺ turn, still no change in MPG. Then I turned it in 1-1/2 turns, still no change in MPG.

Last week, with 128,000 miles on the truck, I was driving the truck in first gear 2wd, on asphalt, for Ĺ mile and the CEL came on, and then went off.I looked around under the hood and saw nothing strange. I have not shorted the test plug to test the system.

Dan Goulet

Hi Dan;

There is no adjustment screw for the TPS.You loosen the two screws that hold it to the TB, rotate it on the TB and then tighten the screws.I have the full description of the testing and adjustment procedure on my web page for your reference:

Which screw(s) were you adjusting?From the sounds of it you are adjusting the bypass air screw on top of the throttle body.This screw is used to adjust the idle speed.Also, you should pull the new check engine trouble code and see what it says.

I would also test the O2 sensor, especially with the Bosch sensor.While the Bosch O2 sensors are good, Iíve heard of folks having trouble with them in Toyotas, Denso and NTK sensors are most like OEM.You may have had some bad gas in there, or even something as simple as having some silicone sealant used that was not O2-sensor-safe.This sensor has the most impact on gas mileage, unlike the TPS, which will affect idle speed and throttle response a bit.The Factory Service Manual has the instructions on testing the O2 sensor, but in a nutshell, you get the sensor hot (2500 RPM for a few minutes) then use an analog voltmeter on a 1-volt scale and observe that the needle twitches from near 0 to near 1 volt at least 8 times/second.




If you are searching for, building, modifying, or maintaining a Toyota 4WD truck, send your Truck Tech questions to Roger Brown at <>.Iíll try to answer your questions with authority!