... something to look at:
https://www.google.com/url?sa=t&sou...ahUKEwj2v4TUzo3RAhVM34MKHUngBzMQuAIIIzAD&usg=AFQjCNHzaiVF9aTsJXToEqW12pad0llJGg

 

Already saw that, but I already know that cylinder #1 isn't working. I can unplug the spark plug and the engine idle doesn't change. Now does anyone here have a schematic?

 

For injector #1, the 12v power wire is black with a red stripe, and the ECU wire is solid light blue. You can test continuity across the coil.
... Hook up a scope probe between the light blue wire and chassis ground and you should see some sort of blip on the scope.
Injectors 2,3,and 4 are red, yellow, and white. ... red with black stripe is power.
... not too sure about posting wiring diagrams, though.

 

+1 on dc...definitely check the resistance on the injector to see if it's within specs of the haynes or fsm.
also, you can put a 9v battery across the injector's terminals and it should click if the mechanical part is working.
lastly, you can pull the injector, hook up air or blow through the injector with the 9v battery across it and that will tell you if it's clogged up or not. it won't tell you whether the patter is correct or not but in this case, it sounds like your hunting down a go/no go situation.
also note that some contact cleaner on the connector halves will help ensure you get a good connection cause sometimes a little oxidation is all that's wrong to begin with. that happens after 20 years.
and certainly your scope will catch the injector being grounded out by the output driver in the ecm too, if you want to watch the square wave for correctness.
tony

 

OK, so if I understand everyone correctly, the car's computer switches the ground. That is what I am looking for. And yes it's a go-no go situation since cylinder #1 isn't doing anything (car is running on 3 cylinders). I tried unplugging the spark plugs on each cylinder individually while it was idleing and when I did for cylinder #1 the idle did not change.

I am pretty sure the car has CA emissions (common in the northeast) and I was also wondering what the difference between the CA and non-CA fuel injectors is. Don't I have to remove the fuel rail and the valve cover to do this? I am also interested in testing fuel pressure, but there is no scrader valve on the fuel rail like I have in my other car.

 

No difference in CA fuel injector wires on 5s-fe.

In a sense, the injector control wire can be looked at like a garden hose with a trigger type hose nozzle on the end. Water pressure is in the hose as long as the trigger grip is closed. That is analogous to your 12 volts when the scope signal is high. When you pull the trigger grip on the hose, the water pressure releases and a stream of water flows out. In the fuel injector, a transistor acts like the spray valve on the hose end. An electronic signal goes to the transistor inside the ECU. This signal is just a voltage pulse. It turns the transistor on, or causes it to allow current to flow, just like the garden hose nozzle lets water come out when the trigger is pulled. The thing to understand here is that when the electric current turns on in the injector control wire, that current charges the injector coil, making a magnetic field ... just a magnet ...that opens a small valve opening in the injector, letting a measured amount of fuel into the cylinder, at just the right instant of time.

 

So you're not sure if it's spark or fuel yet?

 

I only had a very limited time amount to look at it today, but my stethoscope suggests that the fuel injector on #1, #2, and #3 ares working. I could not reach #4 and am not sure if I could get a stethoscope to it. Assuming that #1 is on the side of the engine with the belts. I probably should have mentioned that there is an oil leak in the #4 spark plug tube, and when I pulled that spark plug wire out it was covered with oil (as in drowned in oil), and so was the plug. I cleaned that up and put it back together and was amazed when that wasn't what was causing the problem (it was the first thing I thought to do, and at the time I assumed #1 was on the drivers side). Since #1 and #4 do use the same coil, I do have to wonder if that was somehow damaged.

Searching the internet on P0301 hasn't been particularly helpful since most of the time the problem does not get resolved. Literally once or twice it's a fuel injector or coil, but people seem to not follow up on their original post with a resolution or they sell the car. Often lots of parts are thrown at the car too.

This car only has 138K miles in it too.

 

Injectors are negative switched.

 

Have you pulled the plug and grounded it to see the type (if any) of spark you're getting?

Also do compression test.

 

I will pull the #1 plug next time I work on the car. It's going to be very rainy this week and the car is outside. I can't use the garage to fix this yet because I have another car in the garage waiting for a timing belt that I mail ordered. Yes, I am getting a spark at the #1 spark plug wire, but still want to look at the plug (which is maybe has 13K miles on it and is an exact Denso replacement. I still want to get an ohms reading on the #1 injector, but I was unable to remove the connector so far.

Question: could a bad timing belt cause this? It's still the original at 138K miles. I would think so, but I would also think that it would afeect more then just one cylinder.

 

Yes, I am getting a spark at the #1 spark plug wire, but still want to look at the plug

If the spark is bright & blue then it's not a spark issue. Yes, remove the plug and ground it to see actual spark at plug.

Question: could a bad timing belt cause this? It's still the original at 138K miles. I would think so, but I would also think that it would afeect more then just one cylinder.

Stretched belt or jumped tooth will affect timing - but all cylinders, not just #1. You may be getting spark but at the wrong time. A timing light would confirm if spark is on time. 138k for belt is pushing it.

Can you check compression?

Getting at the injectors is easier with valve cover removed.

 

I have to replace the valve cover gasket anyway, but I'm going to glue it on with RTV to make it leakproof. But anyway, I pulled the #1 spark plug and it was fine. I even swapped it out with one of the old ones and the code came back pretty quickly. What fixed it was when I swapped in the old spark plug wire for cylinder #1. So, as far as I can tell, it was a crappy aftermarket plug wire. Autolite Professonal to be exact. They lasted 80K miles in my Escort and I thought that they would be OK here too (they were still working fine in my Escort when I replaced them on the Camry, I subsequently replaced the ones in my Escort with Motorcraft plug wires). The thing is the defective wire did measure 6K ohms, which makes no sense to me. If this fix holds, I'm just going to replace all of them with a new Denso set of plug wires.

 

Update: Changing the spark plug wire cleared the P0301 code AND the EGR insufficient code!!!! So the car just went through emissions and passed!!!! It's been months trying to figure out the insufficient EGR code (P0401). This EGR thing being the spark plug wire makes no sense, but the GF is very happy about not having the CEL light on all the time.