Sometimes diagnosing engine trouble is the hardest part

I'm trying to discuss and get help with a classic engine (2001) on another forum, but they're not very helpful. The HAMB usually has the desire to help people figure these kinds of things out, but this engine, which has similar mechanical components, has electronic components that older engines don't have. The engine was running fine, then not. It's a tired engine (335k miles on it), but it seems that it should at least start.

She was accelerating after changing lanes to the fast lane, and the engine completely "lost steam." I got to the car and tried to start it. It'd barely start but wouldn't run. I got it home and tried starting it and, of course, the same happened. Then I took the intake stuff off and removed the plugs, and on a whim I put in new fuel injectors (because one plug was soaked in gas, so I thought it was stuck open). Since then, the engine doesn't even try to start. Maybe I'm overlooking one of the many connections, but I don't think so. Maybe a fuse, relay, or something electronic like that went bad in the meantime. Anyway, let's see how this goes.

I'm not hearing any noises like there's a rod or piston problem. It's getting spark. I tried starting fluid sprayed past the throttle plate and it still didn't even try to start, so I think that more or less eliminates the fuel system being the problem. But, with those "extra" components, it's hard for me to tell if that's true. I guess the "air" part of the equation is that it's getting and keeping enough air to compress. The compression test yielded 150 psi, 150 psi, 185 psi, and the last spark plug is stuck. So, the compression difference is 2.5 times what the manual says the worst should be, but it was running good and should still run. It'd just be sluggish. Unless there's something more that happens to the engine when there's a large compression difference.

So, the questions that come out of this are:

1. Does spraying starting fluid eliminate fuel system problems, keeping in mind that it's a complex fuel system?

2. Does a large compression difference make the engine not start?

3. Blown head gasket?

4. Any other ideas?

If I can't figure it out soon, we'll probably tow it to get it diagnosed. Then I should be able to fix it from there.

 

Is the Check Engine Light on? Have you put an OBDII reader on it to check for any codes? What vehicle/engine is it?

 

I'm trying to keep it a bit hush hush, for obvious reasons. No DTCs. 3RZ.

 

Have you researched if those engines are prone to ignition module failure?

 

No, but it's getting spark on the three I was able to remove. Let's discuss air, fuel, and spark. Air seems like a given, but I'm not sure. Does starting fluid eliminate the fuel system?

 

Oooh , I have a 2001 3RZ as well! I'd start by looking at Crank & Cam Position Sensors. Coil packs, ground wires, etc. This sounds like an electric issue more than fuel/air.

 

Well alright! It has spark, so the coils (on the plug) and ground wires should be good. I'd think that a bad sensor would throw a code, but that's the thing, the systems are much more complex, and I don't know how they all interact. That's the beauty of engines with simple systems.

5. How about the timing chain? Maybe it's slipped and slipped further, the more I've cranked the engine? But then again, it's an interference engine, so I think that would result in lots of mangling metal noises.

Summarizing, again: The engine was running good. Then it quit but would try to start. Now it's not even trying to start.

 

Seems to me 335k miles on gas 4 lot of miles pretty worn engine. Why that last plug will not come out, aluminum head? Water in that cylinder? Oil milky? Radiator level still up? Above texashardcore ask good questions. Sure would like to get last plug out

 

Yes; yes. I don't know about the head gasket fluids questions; I didn't see any signs, but I didn't look that hard; I plan to borrow a head gasket test kit, soon. I'm trying to figure out what's wrong before taking the head off. Maybe I should just dive in and plan on ~rebuilding it or getting another engine to ~rebuild.

I'm going to start looking into the mentioned sensors.

 

Timing chain isn't likely. If it were a V6 with the timing belt, yes, but the 3RZ's all have chains and are not prone to those issues.

Have you tested all of the fuses & relays?

With the cam & crank sensors, either test them or replace them to rule them out. They're not very expensive and they're simple to get to. MAF Sensor, IAC, TPS...all of these send signals to the ECM that could possibly lead to this no start.

Could be an ECM, bad wire in the harness, etc. I'm just spit balling here, as I'm lucky to not have had any issues with my 245k miles 3RZ Tacoma over the last 13yrs. It has been the best vehicle I've ever had, and I have vowed to never sell it.

 

I like carburetors, you guys are giving me a headache…

 

This is the first engine problem [that I am aware of] at over 335k miles, and it [seems like it] hasn't been maintained well at all. I plan to check fuses and relays, and if I missed plugging something back in or in the wrong spot, but I don't think so. There [was] a 3RZ at the local pick-it-yourself, and maybe I'll see if it has various sensors on it. I'm keeping that long block in mind, too, but nothing seems catastrophic with this long block. My daily driver is also a 3RZ. I'll probably swap my upper intake components to eliminate those. The fuel filter's probably original, but I don't think it'd go from running to not, to not trying [to start].

 

Will someone please try to answer the numbered questions?

 

If the engine is not getting fuel, but it has spark and compression, it should run with starting fluid. But if it's flooded, or had been flooded and the plugs are fouled (which you can't always tell by looking at them), then starting fluid won't make it run.

Usually having 3 cylinders with adequate compression will let a 4 cyl engine run.

The compression numbers don't indicate a blown head gasket, but a blown head gasket can do interesting things.

Ignition...fuel...it's all controlled by a computer that relies on proper signals from sensors.

 

Heres some potential causes / fixes.

 

1. Does spraying starting fluid eliminate fuel system problems, keeping in mind that it's a complex fuel system?
It bypasses the fuel system, so it doesn't eliminate the fuel system problems, but will help eliminate sensors/electrical issues.

2. Does a large compression difference make the engine not start?
That variance of compression across the cylinders doesn't seem to be enough to cause a no start. It'll still run

3. Blown head gasket? You'd see a bigger variance across the cylinders in the compression test, or water in the oil/oil in the water, really bad spark plugs, or smoke out the tailpipe. it'll still run.

4. Any other ideas? If that pick & pull long block is decently priced, I'd jump on it and save it for if and when it's needed. A pullout 3RZ is expensive, a rebuilt 3RZ is even more expensive.

 

There's a strange thing happening when I hook the battery back up. The left front marker light flashed a couple times. It's not a turn signal.

 

Does the throttle plate move when you turn the key on and try and start it?

If you plug it in to a reader can you ‘see’ the crank sensor?

 

I had her step on the gas pedal some when I tried starting fluid. Other than that, I haven't looked at what the throttle plate does.

I only have a basic code reader. I've thought about getting a live data dongle.

 

I've had problems with 3RZs. Part of me wants to get away from them. I'd probably be doing better with a couple Rancheros running on propane. They might run cleaner than the EFI 3RZs. But she's not going to go for that. Then there's airbags and air conditioning.

 

The light flashing sounds like anti-theft. OE or aftermarket, they would normally interrupt spark and fuel (still crank).
Compression is high enough in the 3 tested to pop, if sprayed with fuel and has properly timed spark.
Disconnect the battery, charge it if low, then try again after a while, making sure to actuate any keyless entry or alarm before entering.
If it still will crank but not even pop and still has a spark, it's either timed wrong (cam/crank=chain, most commonly tensioner) or spark timing is wrong (cam/crank sensor) and the computer is unable to trigger spark at the right time.
If you can pull codes after this test, they may help.

 

Basic code reader should register rpm (live data) when it’s turning over on the starter that’ll confirm the crank sensor is working.

 

Customer Concern: It will not stay running but it does crank up and it will not idle.
Average Reported Mileage: 190213
Tests/Procedures: 1. When the vehicle is cold and the problem is occurring, open the throttle slightly and check to see if the engine will start and stay running.

2. Check the idle air control valve opening voltage. The Black/Red wire should read approximately 3.5 to 4.5 volts during crank and slowly go towards 8 volts when warm.

3. Remove the idle air control valve and monitor the opening angle of the rotary valve when the key is turned on and off. The valve should move.
Tech Tips: There is a bimetal element built into the idle air control valve that forces high idle when cold. The valve can work perfectly fine by electrical control but not operate mechanically. This will cause a start and stall situation when cold.

Saw this, If you haven't checked the Idle Air Control Valve yet.

 

Customer Concern: The engine starts and then dies after a few seconds of running. It seems to have injector pulse and spark when it dies.
Average Reported Mileage: 156637
Tests/Procedures: 1. Eliminate the vehicle's fuel supply and then run the engine on external fuel to see if it will stay running. If the engine stays running, check to see if they are clicking when running it on external fuel. Check the injector on time. Normal idle on time is close to 3.0 M.S.

2. If there is no injector pulse, monitor the IGF signal from the ignition coils to the Engine Control Module (ECM) to see if it is steady signal. If the signal is cutting out, disconnect one coil at a time to see if the pattern changes. One faulty coil can affect the signal from all the coils.

3. Check the crankshaft position sensor to see if it has a good pattern. It should produce 3 volts peak to peak on a lab scope.

And this one for the crank sensor.

 

Is there a schrader valve on the fuel feed so you can just see if you’ve got fuel by pressing it, put a cloth over it so you don’t get it in the face.

 

No.

 

Yeah, the flashing light could be the remnants of the alarm system that hasn't been used in ages.

Thanks for the reminder to unplug the charger.

When I feel up to it, I'm going to turn it to TDC and check the chain.

 

Something you might consider is looking up "miniVCI" on ebay. I got one of these cables for our 2GR Toy and it's saved my bacon a couple of times when the check engine light came on. You need a laptop or Windows tablet to run the software but it is the real deal when it comes to interfacing with the computer system in the vehicle. The cable is around $25 but there's a couple of things to look out for when installing it.

Rather than posting the info here (Ryan may not want it) just look up forums where people are using the miniVCI cable to read and alter the computer in your Toyota. Look up "Techstream" on Youtube for more info. I have the drivers on hand for the v1.4 cable and they've been extracted so there are no nasty surprises hidden like there were in the downloaded drivers.

 

Headache? Easy remedy

Ben.

 

Thank you very much- I really appreciate it. This is the information and motivation I needed to get me to get a laptop and get data instead of "flying blind."