Misfire Issue - Injectors?

[coreyemmons]

Hey all,

I'm hoping this is unique enough to warrant its own thread; if not I can do a deep dive search. I have a 2000 SC 5spd that is giving me major engine headaches. It started misfiring only when starting warm a couple of months ago. I replaced the coils, spark plugs, wires, and passenger side valve cover gasket. I didn't mess with the driver's side because I was not feeling taking off the SC. Anyway, it stopped for a while, but now it is misfiring all the time. I took it to my trusted mechanic, who checked all the things I replaced and also did a compression test, and said that was all good. He was uncomfortable diving deeper into the engine because he's not familiar with the SC (didn't charge me so bonus).

Anyway, does anyone know of a surefire way to diagnose this? The engine is sitting at about 175k and I'm thinking worst case I'm just going to replace all of the injectors and the rails and hope that does it. I need this thing for DD'ing so I'm thinking I'll tackle it this weekend. Any thoughts or suggestions are welcome. If anyone wants to recommend a good shop in Northern NJ that's welcome too.

Thanks in advance!

 

[brillo_76]

Any maintenance on the fuel system itself. Like the Fuel filter? Pressure good at the rail? Also why wouldn't you do both sides if doing anything to the engine?

Coils can test good and still be bad. Can you get it narrowed down to which cylinders are misfiring? No check engine light of pending codes?



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[Down by the Water]

Any Check Engine Light? Codes?

 

[Bad Luck]

Anyway, does anyone know of a surefire way to diagnose this? The engine is sitting at about 175k and I'm thinking worst case I'm just going to replace all of the injectors and the rails and hope that does it. I need this thing for DD'ing so I'm thinking I'll tackle it this weekend. Any thoughts or suggestions are welcome. If anyone wants to recommend a good shop in Northern NJ that's welcome too.

Thanks in advance!

No need to replace the fuel rails when doing this. You'll need to remove the supercharger to replace the fuel injectors though so it would be a good time to replace the other valve cover gasket you didn't do. I replaced my injectors a few weeks ago and went with these: 5VZ (V6) Equalized Fuel Injector Set (99-04) They are OEM remanufactured and there was a $60 core. They come with all new seals and dust boots. I would start with a fuel filter if you haven't already and check the resistance on the injectors.
Here's a link to a 2000 FSM to help you out as well: 2000 4Runner FSM - Printable - Google Drive

 

[JohnMc]

Is it a consistent miss on one cylinder?

If so, figure out which of the three things it's missing:
1) Compression - already tested by your mechanic, not an issue
2) Spark - try moving things around to see if the problem moves with either the coil (which would usually kill one cylinder on each side), spark plug wire (the left side plugs), or the plugs themselves.
3) Fuel injector - if the miss stays in the same place - you're pretty much down to that. And you have to pull the upper and lower plenums off to get to them. Not too hard of a task, but it's not trivial.

Beware the crappy knockoff 'new' injectors for sale cheap on eBay. I tried a set on mine and while it wasn't running on 5 cylinders, it was very hard to start and getting worse, so I took them back off after about 100 miles. I just put on a set of factory injectors from a junkyard after that.

 

[VernySanders]

When my Injector was severely clogged I could reset the CPU by disconnecting the negative terminal and then reconnecting it. the truck would run perfectly fine untill the CPU collected enough data to recognize there was an issue with an Injector. With my truck it would completely stop running. Loss of all power. Reset CPU drove fine. Not saying this is always the case though. Personally I would go to a junkyard pull 6 Injectors out of another 4runner make sure they're not cracked with a quick visual inspection. Take them to your local shop ask and see if they clean and flow test Injectors. I paid 15 bucks per Injector and they performed like brand new after cleaning and flow testing. I bought a kit on Ebay for all new o rings and filters caps etc but the shop I went to said they could have supplied those. Going to the junkyard is nice because instead of having down time on your truck you can avoid that by getting additional injectors. And this way is far cheaper than anything I encountered online as far as new or reman injectors and quite frankly i dont trust ordering any new or remans unless they're from Toyota as there is a lot of injector fraud out there. Hope that helps.