99 Tacoma pukes, gags at 2000 rpm

I have worked on lots of toyota's but I must admit I am new to the 2rz/3rz and 5vz specifically, but it isn't the first time I have encountered an rpm wall.
It is usually related to the ecu not being able to read the timing correctly, whether cam/crank sensor is bad or something is loose or dirty etc..

the 2rz/3rz is showing the cam sync is in the distibutor, until they went coilpacks and then there is a separate cam sensor on the drivers side of the cylinder head.
I just assumed on the distributor engines that the crank sensor was also in the distributor, but I forgot in 1996 with obd2 toyota moved the crank sensor to the crank on almost all their engines.

I usually mess with older engines so I forgot about that part. Some of the engines in 96 and 97 like the 2jzge that I am currently building, had 2 crank sensors.. one in the distributor and one on the crank. the ecu runs off the one in the distributor on that engine, and the one on the crank is used for misfire detection only.

I found this online:

 

Looks good to me, but in the FSM they make no mention that it is the Cam position sensor, not a word. unless there is more in the dist then
whats in the FSM, guess Im going to tear apart the old dist. Would the Signal Generator be the Cam sensor, I was understanding that the
signal generator relayed to the Igniter that the plug was fired, and in turn the igniter told the ECU, otherwise if it gets no signal, then
the ECU cuts fuel and Injector power, maybe it does both. maybe its the same thing to the ECU.
Thinking they moved the crank sensor earlier, mines a Jan of 95 build and the crank sensor is in the block under the alt bracket, and I have
OBD2 and even stranger its has OBD1 also. Even if he checked the OHms on the Crank and Cam sensor, electronic parts are not static,
they can malfunction with heat/cold/ vibrations. I wonder if he gets the problem just sitting and revving up his engine to the problem
rpm zone. guessing 2 to 3 thousand. or is it just under load. Mine was just under load, made it double hard to find.

 

Generally the late 1995 models started to get the crank sensor on the engines, in preparation for the switch to obd2.

So the signal generator is the "cam sensor". it tells the ecu where tdc#1 is in conjunction with the crank sensor.
those signals (crank is "NE" and cam is "G" or "G+") go to the ecu, and the ecu returns an "IGT" (think ignition trigger) signal to the ignitor at the proper timing.
The ignitor takes IGT, and fires off the coil. In the ignitor is a secondary circuit that picks up reverse voltage from the coil firing, and this is returned back to the ecu as "IGF" which is the ignition confirmation signal.
IF the coil does not fire for whatever reason, the ecu will see that no IGF was returned for its IGT it sent out, and it will start to accumulate those errors, and if it happens for long enough, will trip an obd2 code.

You can see on the ecu pinouts for the 2rz and 3rz ecu have the same IGT and IGF signals.
On the later engines with coilpacks, you will see an IGT1, IGT2.. etc.. and one IGF and that is because there is no distributor to send it to the right cylinder, so the IGT signals are seperated by the ecu and the ignitor has multiple outputs to the respective cylinders.

Basically all the toyota systems from the early 90's on work that way so the ecu can control timing advance and pull timing for knock control.

In the 70-80's on the 22r for example the distributor was like what you are saying, it controlled the spark and had a mechanical vacuum advance system. nothing comes from the ecu cause there wasn't one.
Then they went to the 22re, and they started adding the crank sensor etc.. into the distributor to get knock control and electronic timing advance.

Then in 1995 for obd2 they discovered that the old way of the crank sensor in the distributor was not super accurate for detecting misfires, as they usually have a 24 tooth trigger wheel and the resolution was fine for running the engine, but couldn't detect a hiccup very well that obd2 required by law. So they started putting finer resolution crank sensors on the crank.

Like the 2jzgte that came out in 1993.5, had a 12 tooth crank gear on the crank which was way ahead of its time, but when they went obd2 on the later 2jzge and vvti variants, they changed that 12 tooth wheel to a 36-2 wheel which is a 36 tooth wheel missing 2 teeth at TDC, so the ecu has 3 times the resolution and could easily detect even a small misfire without relying on IGF as much.

My 2jzge vvti that I am building right now that will go in my taco, has a 36-2 crank trigger wheel and 1 cam sensor in the head.
Toyota made so many different combinations of cam and crank trigger setups, but the whole IGT and IGF system never really changed except on some later engines they put the igniter into the coils.

 

Thanks so much for that explanation, clears up alot. And all along I never got a Trouble Code, maybe cause it only happened for a sec or 2.

 

Good explanation 2JHilux.

A code won't be throw unless there are 4 consecutive missed signals back to the ECU, but maybe the ECU cuts fuel with only 1 or 2 missed signals.

 

When I spun wrenches for money I always laughed at the last line in the factory's diagnostic procedure... Replace with know good unit. Yeah, sure, the parts department is going to order a 1000.00 ECU so I can "test" against it.

 

I loved reading this post. You explained this so clearly it's mind-bottling. Thank you for taking the time to type it out.