scott d

Hi guys. I'm having trouble with my 97 4runner with the 3.4. I have had an intermittent miss here and there. It never lasts, so I have not been able to do much diagnosis with it faulting. First time it happened was upon restart after a very short trip (about a mile), it ran rough for about 10 seconds and cleared up, no code. About 2 weeks ago, upon restart after a 30 mile trip it started missing again, and ran that way all the way back home. I shut it off in my driveway, came inside for about 30 min, and when I went out to work on it the miss had cleared. Code P0305 stored this time. Plug wires and plugs are new, and since I didn't have a code for 2 cylinders, I didn't suspect coil, and focused on the fuel injector. I changed the cylinder #5 injector with one from a salvage yard, and upon restart it missed badly. I used a mechanics stethescope to listen to the injector and it was not operating at all. While the truck was still running, I pulled off the injector connector, and checked resistance through the injector, 14 ohms-- normal. Then I plugged the connector back in ant the truck immediately ran smooth again. Now the injector was firing. I shut the truck off an tested the voltage at the hot side of the injector connector-- 12.23 volts-- normal. I wiggled and moved the connector to try to make it fault with no success. Connector and wires look perfectly normal with no corrosion. Does anyone else have experience with this? Do you think my next step should be to unwrap and trace that wire to see if I can find a fault somewhere? I was thinking about changing the injector connector first, to see if that helps, but it looks good to the eye. Any other ideas or help would be greatly appreciated.

scott d

By the way, the truck has 200K on it and the problem hasn't happened yet while in the middle of a drive, if it is going to fault, it seems to only happen upon start up. I am going to pull the fuel rail again first and change position of the injectors just to be sure I didn't get a bum injector from the salvage yard. Then I plan to wait for a fault again and see if I get a different cylinder misfire code. It seems unlikely to me that my old injector and the one I replaced it with would both fault intermittently, so I'm sort of thinking that it is probably either the injector harness or the wires going to the injector. Also both injectors have a normal resistance reading when checked with a multimeter. With the key on, the hot side of the injector has proper voltage(12.2), but I haven't tested the ground wire. Anyone have a suggestion about how to test this wire without physically unwrapping the whole bundle and tracing it? Anyone have a link to a wiring schematic for my truck? Anyone have any other ideas what could be causing my problem? Would really appreciate some help here, Thanks.

scott d

Anyone know how to get an answer on this site?

eddieleephd

sounds electrical to me, and the plug sounds to be culprit...
to get a response on this site the right person has to look at the thread.
Some times a PM to some one you have read posted good things for electrical or the specific issue is an option!

I would think your plan is a good one to see if the symptom moves with the injector.
But my first suggestion is to change the plug if it does not move.

eddieleephd

links to FSM is here https://www.yotatech.com/forums/f123/

scott d

Thanks for the link and the response, Eddie. By plug, do you mean spark plug? If so that has already been done. As stated above the fuel injector was confirmed too not be firing by mechanics stethoscope, no clicking at all, and when plugged back in a couple minutes later it started to click and operate normally. The problem is definitely that the fuel injector does not operate intermittently. The question is why? Is the second injector also intermittently bad or is there another issue causing it to not fire. Anyway, would love to get some advice on what you and others would do next to zero in on the problem. Thanks again

brian2sun

I think a lot of people see those huge paragraphs and just pass. I think more people will respond if you break up your main points a little bit. Not that I care, I'm no english teacher, but I clicked past this one this morning because I'm admittedly lazy sometimes and tonight I guess I felt like reading it more thoroughly. It's easier to soak up all that info when it's broken into separate thoughts (at least for me).

I'm sure Eddie was referring to the electrical plug (connector) for the injector and I agree. Not that I'd put a lot of faith into a junkyard injector, but if it was bad I would expect it to be clogged or not work at all - not copy the symptoms of the original injector. I think swapping it and chasing the miss is the logical next step, but make sure you lube all the top o-rings on all 3 injectors good w/ Vaseline or oil. Otherwise you will damage them when you keep taking the rail on and off (or better yet, but new o-rings each time you have to mess with them).

eddieleephd

Brian2sun is correct I did mean the electrical plug.

and if you couldn't tell I agree about the huge paragraph, Break it up !!!!!!!
It is a lot easier to read if you separate the different sections like Symptoms,

Things Done..........................

Thoughts to do next,

I honestly had to read it like 3 times to understand it fully and may have passed at other times..

About the only reason I do not pass is I saw the frustration in your third post!!!!

I haste having that frustration.

Next time I think to PM some body I will also think to PM Brian2sun!!!

eddieleephd

heat increases resistance so this is another reason I am thinking electrical plug, as well the vibration could move around a loose plug!!!!!!!!!!!

eddieleephd

This is some thing I believe Brian and I were thinking like.......

Anyone have a suggestion about how to test this wire without physically unwrapping the whole bundle and tracing it?
I was going to wait to see what the next step turned out to say this but OHM METER!!! if the resistance is too high when the truck is warm the wire is likely broken or has a bad connection on the other end!!!

did you find the link I was mentioning to the FSM, I would have just posted the actual link but I really didn't even know where it was till some body pointed it out and had been posting a link to TTORA's Tech section.

scott d

O.k., Thanks Brian and Eddie, I am going to change the electrical connector going to that injector, and swap injector positions.
I did get the link to the FSM, but haven't actually found the info I need yet, haven't had time to look thoroughly.
I will also try and do some testing with the Ohm meter and see if I can pinpoint a bad wire.
Thanks again for your help, guys. I will keep the post updated as soon as I have more info or a solution.

brian2sun

I'm not sure about how to trace that wire either (without unwrapping the whole bundle). I think you're on the right track. I doubt it's the injector, but if/when you rule that out I suggest putting your original injector back in and not using the junkyard one. I would send that one out to get cleaned/rebuilt and either sell it or hold on to it for the future.

scott d

I agree, Brian. I will install the original injector when I pull the fuel rail next time. Thanks again for taking the time to try and help me. Hope to have some new information soon.

brian2sun

Good luck, keep us posted...

scott d

I removed the salvage yard injector and re-installed the original injector in a different spot. No faults for a while, then today upon re-start the truck missed badly. I checked it with the stethoscope, and it was the original injector which was now in a different position, so the injector is definitely the problem. I am changing it this afternoon.

I believe that the salvage yard injector was gummed up from sitting around on the shelf, and that's why it didn't work immediately after installation but started to work after a couple minutes, when the fresh gasoline started to un-stick the valve inside.

I believe this one is solved. Than you to Eddie and Brian for the help. It is appreciated very much.

eddieleephd

you are welcome Scott happy days!!!