2000 Tacoma Starting issue

the TPS sensor job is to tell the ECU exactly where that throttle plate is, using simple
metal contacts on resistor paint. a potentiometer. they wear out. when worn any type of strange anomaly can
occur. so, if it is original, may need replacing all I'm saying.

 

Hey Chris...

A few thoughts, I am sure I am missing some items in this list...

1. Battery - Sounds OK to me if it keeps cranking the starter
   1. Ground Test?
2. Starter - Sounds OK
3. Fuses and Relays - Sounds OK
4. Sensors - (If some of these were a problem you would get a check engine light)
   1. Crank - OK
   2. MAF - OK
   3. Cam - OK
   4. ECT
   5. TPS
   6. Knock
   7. AF
   8. Oxygen
5. Spark - Sounds OK
6. Fuel
   1. Maybe pull a spark plug after trying unsuccessfully to start, can you smell a lot of gas (you might want to disconnect the battery for safety)? Is there a lot of gas at the exhaust?
   2. Injectors on the passenger side are visible without removing the plenum. Remove the wiring clip and measure resistance on the injector. I think it should be around 14 ohms.

Also, you asked me a while back how I connected a fuel gauge. This is a photo of my 3.4 after installing the fuel regulator. In the upper left you can see where I removed the regular union bolt and replaced it with a brass version that includes a schrader valve to connect the fuel gauge. Once the fuel gauge is connected you can test running fuel pressure and do the leak down test mentioned by BldEgl2.

 

What is this and whats its purpose? I figured it was some sort of buffer for when the throttle snaps back to the closed position or is it something more? I just tried to start it and a buddy was messing with it by opening the throttle and it started after 4 failed attempts. But if i give it gas while in the driver seat it doesnt start it. Also after about 4 more tries of messing with it being separated it finally didn't start like normal. He also went to the exhaust and said he could smell gas.

 

The things I haven't checked are all things that seem to take a lot of work to get too that I would probably end up causing more problems than I already have. What is the AF Sensor? Also once again no codes are being thrown.

 

AF sensor = air/fuel sensor. Some modern cars use them in place of o2 sensors but I believe our newer first gen model Tacomas use both, someone correct me if I'm wrong.

I had my air/fuel sensor replaced by Toyota when I was throwing a P0171 "system too lean" code.

 

Ok so besides where the O2 sensor is where would the AF sensor be located? Also it's not throwing any codes.

 

Check out this thread on Yotatech from awhile back, I think it's in regards to a 4runner but from the same era/same drivetrain.

http://www.yotatech.com/f2/directions-replace-air-fuel-sensor-119618/

Sounds like the af sensor is between the catalytic converter and the engine

 

Thanks. I'll look at it later but I dropped it off at the dealership for them to do their diagnosis hat doesn't call for them to start pulling stuff off. To get their input. I'm hoping it's just something stupid that we all have checked and deemed it working fine. If nothing comes of that I might end up selling it cause right now it's become a huge stressor on the wife and I sharing one car 6 days a week. I bought it from a friend for super cheap and didn't think it was going to be this bad/hard to figure out. It runs good and I actually enjoy driving it when it's running so I hate to see it go if it comes to that. And I'm the guy that's really picky about the car I drive and am not really into trucks, more of the sport kind of guy. Butt here is just something about the 1st gen Tacoma I'm enjoying about driving (when it's running), well at least for this one. But at this point it almost seems like a money pit/huge time waster. I've been troubleshooting it for about 4 to 5 weeks now. If I had another car to drive then I don't think it'd be an issue but sharing one car is becoming a pain.

 

And and about the picture above, is that just a buffer like I think it is or is it actually something?

 

Once you figure out the problem you will be happy again...

 

Hope the fix turns out to be easy and cheap! Also, that part on your throttle body... I do not have that on my 3.4. I looked at photos of 3.4s last night and found a couple with the same part. I am not sure what it is though.

 

I think the part is the 'throttle opener'
throttle opener should be functioning correctly if the vacuum is applied and released

I have no idea but it may be the idle control tied to power steering, which
keeps engine from conking out while power steering when stopped or at idle

 

That is called a Dashpot. It functions exactly as you thought. Found on the man trans trucks, absent on the autos.

The "Throttle Opener" is the vacuum actuated device on the rear of the throttle body. It holds the throttle plate open a tad via light spring tension to allow a bit more air for starting. As soon as engine vacuum develops (few seconds), the spring is overcome and the plate is allowed to close to the normal position against it's stop.

 

By "Throttle Opener" do you mean the Throttle Position Sensor or is there something else on the rear of the throttle body that's the opener you speak of?

 

I'd be really happy. So far it's started every time for them and I said they could hold it till tomorrow to test it out some more. After I installed the cam and crank sensor I thought maybe it just needed to be driven a long time so the computer could readjust to the new parts so I was going to drive for like an hour yesterday morning but couldn't get it started so I gave up that idea. Maybe the drive to the dealership fixed it or something. Who knows but there was 1 full week where I had no issues and I thought I fixed it so let's hope this isn't the case.

 

Two different things.
Throttle opener is low center of the pic, shiny round thing with the small vacuum hose attached (no wires), just to the left of the main intake tube. A hose that plugs into the main intake has been removed for clarity.
Throttle position sensor is dead center, black plastic (with wires). Secured to the t-body with 2 screws.

 

Ok I see what you're talking about now. Hmmmm so do you think maybe it's not opening up like it should but wouldn't me pressing on the gas open that up more so it can get the air it needs?

 

Not suggesting the throttle opener is your problem at all. They are nearly trouble free.
Without my eyes, ears and hands involved, your symptoms fit leaky injectors pretty well.

If you want, the t-opener is simple and quick to test. First, with the engine off (no vacuum) the throttle should be open just a bit, you should be able to close it with finger pressure, it should then spring back open a bit. We are not talking much, maybe 1/16"-3/32" off the stop. Next, with the engine running, warmed up and at normal idle speed, momentarily pull the little vacuum hose off the t-opener and plug it (the hose). Your finger will do. The engine speed should bump up noticeably to between 900 and 1900 RPM.

 

Leaky injectors as in it leaking partially out of the injectors where the o-ring is? Like where the fuel rail connects to the injector? There's no smell of fuel that any one or I've noticed when the hood is open coming from the engine bay. Also wouldn't That cause a misfire or something?

 

When an injector (s) leak, it leaks into the cylinder from the tip, which is internal, flooding the cylinder when shut off, as the engine cools back down the extra fuel drains past the rings and into the pan area, thus the reason you have better chances of starting after sitting all night, warm starts can be a biatch, like you are describing....you need to have a leakdown test done, along with the fuel pressure check....