You do not need a scanner to read your codes. You just jump two ports in the diagnostic port box under the good and turn the key to on and the CEL will flash the codes for you. Have a look on here for the factory service manual for your truck and it will explain in detail .

 

Welcome to YotaTech! You've come to the right place.

Ah, the scanner. Yes, many "local" shops just don't have the right tool for a vehicle of this vintage. But here's where you can get one: https://www.staples.com/Staples-Jumb...product_525923

Here's how you use the tool: http://web.archive.org/web/201211190...85diagnosi.pdf (Toyota calls the tool the "SST.")

I'm guessing you'll find code 71. This code (all codes) will keep you from passing smog. You have a California vehicle (how do I know?); so there is a good chance you will NEED to pass smog. Even if not, you don't want to be THAT guy poisoning the air around us.

Just so you know, the gas cap won't throw a code. That's on more modern vehicles.

Invest (?) in the tool, check the code(s), report back.

 

 

Part of the EGR system.

http://web.archive.org/web/201204061...77exhaustg.pdf

 

Some misguided souls defeat the EGR system in the mistaken belief that the truck will then magically have increased horsepower and better fuel economy. While it's true that an improperly working EGR system will cause power loss and mpg decrease, if it's working correctly you'll never notice it's there. Get it plumbed up correctly, make sure the valve moves freely and the ports aren't plugged with carbon, and keep that smog-causing nitrous oxide out of our air.

Keep coming back here for advice and learn to do your own troubleshooting and work. Most mechanics will charge more than the truck is worth for repairs you can easily do yourself. It's the only economically viable way to keep these old trucks running in top shape.

BTW, congratulations on your new ride. It looks like you got a good clean vehicle. It should give you a lot of good times ahead.

 

 

A day without a red 1994 Pickup is like a day without sunshine.

 

Timing belt is supposed to be done every 60-90,000 miles or so. Since you have no records, that should be on your list. Figure $800-1200 for a dealer to do it - there's a fair amount of labor involved. The 3vze is a non-interference engine, which means a broken timing belt won't result in further damage - the engine will just stop running. So, if you're staying close to AAA country, it's not absolutely urgent.

Unless the existing O2 sensor is rusted badly into place, changing it is a 15 minute job. Get a Denso (which is what went in at the factory). $40-50 from Rock Auto. Worth doing, especially if you have to pass emissions. (If it's a California truck, there are two sensors. The upstream one is the most important for emissions and running well.)

While you are changing the plugs, do a compression test. Look for uniformity across cylinders.

The valves are probably due for adjustment, but that's also a fairly big job. There are some good writeups about it on this forum.

 

Do you have the owner's manual? It contains this Service Schedule. http://web.archive.org/web/201210210.../1maintena.pdf

Don't worry about past service records; there aren't that many items that are replaced just based on mileage/time. For instance, you'll inspect your brake pads; if they're close to the 1mm (!!) limit, you replace them no matter how many miles they have.

This is a common misconception. "Read the code, replace the part it says to replace." Kinda like a big Lego. But it doesn't work that way. The code tells you what system is not responding correctly. Often there is a "most likely suspect" part, the replacement of which will cure the code. But this forum is full of desperate individuals who replace one part after another, without testing anything, until they go bankrupt. (and specifically to the O2 sensor, you're going to replace that just based on mileage, no matter what code you have.)

Speaking of bankrupt, if you think $60 for an oil and air filter change is a good deal, you may not be happy with where this is all going. As you can guess, many (most?) of the individuals on this forum are here because we do the majority of our own work. You have an old (but good lookin!) truck, and even those at the dealership are not going to be familiar with it. Nursing it along is very rewarding, but it can take time and a good ear, and subcontracting all of that out can be expensive.

The timing belt is sort of the dividing line. If you can do everything short of that (replace the O2 sensor, the belts, plugs and wires, adjust the valves, etc.), leaving the timing belt to a professional won't break the bank. But lots of us have changed ours, and I can assure you I'm no professional mechanic. A desire to learn (and the Factory Service Manual) is all you need.

 

 

 

Check out that FSM section that scope103 referenced in reply #6 above. That shows how to inspect and test the various parts of the EGR system.

First thing I'd do, though, is plug the hose back into the valve where it belongs, clear the code, and see what happens. Might just work fine.

 

^^ Hopefully this is the case! Another possibility is that the diaphragm is bad, and just plugging off the line was the previous owner's quick fix.

You will not know until you try.

 

So if I plug the EGR back in and it runs like pooo (which Im guessing is going to happen since the previous owner made this plugging the wire move) is the next step replacing the EGR. (140ish bucks). Is the diaphragm in that unit … Im thinking you will be right on with this guess. I have been reading around that people will throw a resistor in the mix to kill the code. The truck runs fine as far as I can tell for now but I want it fixed right if this is part of the motors design.

 

Again, you need to read the FSM section that's been referenced and do the tests that are indicated there. The EGR system isn't complicated, but there are multiple components and just throwing parts at it isn't the most efficient way to fix it. A stuck EGR vacuum modulator could also leave the EGR valve open at all times causing the engine to run poorly.

Basically, the EGR (Exhaust Gas Recirculation) system, under certain condions, recirculates exhaust gas into the intake manifold to reduce high combustion temperatures which are the cause of NOx emissions. However, too much exhaust gas at the wrong time will cause the engine to lose power or stumble. So, the EGR system closes off the recirculation during cold engine operation and/or idle or low throttle operation, or (I think) at wide open throttle. At all other times the recirculation is active. The valve is what controls that.

I do not know where you would put a resistor to kill the code - I'm not sure how the ECM determines that the EGR system is not working properly.

 

Nice truck. I've seen many newer trucks, but I prefer my '94 Yota and the $0 per month payment.

Haha! Well, maybe a lil hyperbole in your comment, but we see things the same way basically. Mine is black.

 

There is a thermistor in the duct that goes to the plenum. If it's dead cold (at the wrong time), the ECM knows that no exhaust is flowing to the intake.

You don't want to throw parts at anything, Your guess of a bad diaphragm is just a guess. Your prior owner wouldn't be the first person to fear everything under the hood, and think that he's improving things by mucking up the plumbing. It's not hard to actually determine what's wrong by running the diagnostics.

Remember that the EGR system (significantly) reduces NOx pollution. If you're in an area with smog checks, you'll never pass with a disabled system. If you don't have smog checks, you still breathe the air, and NOx turns to nitric acid on contact with water vapor. It's not something you want to be putting into the air for a few bucks. (a complete EGR valve is as little as $80 from RockAuto -- but DON'T order it until your testing shows the current one IS bad.)

 

I am unable to load that guide. But I will run a few Tess and report back. The truck is only being driven about once a week till I get a few things done. (things not related to the truck )