4runnerFireman

First of all, I wanna say thanks to the people who post good stuff and actually help people, you know who you are. And those who don't know how to put a socket onto a ratchet, please stop typing!!! Hopefully what I am about to say will help some of you, I know how frustrating this problem can be.

I had the infamous 4runner miss, scanner showed cylinder #5 misfire, but no other info. If the motor was cold, after sitting for a couple hours, or overnight, it ran fine. It was when you shut it down to run into the store or something, fired it back up, it would lope at idle up to about 300 rpm's. SOUND FAMILIAR? Of course it does!! I spent 2 months on forums, emailing and making phone calls, no one had DEFINITE answers. OK, so first, I changed the plugs & wires, didn't help. Then, I swapped the coil pack from cyl 5 to cyl 3, scanner still showed the misfire to be in cyl 5, so that rules out the coil pack. So, I kept researching since I didn't want to drop $100 or more for a fuel injector and it not be the problem. I spoke to the head mechanic at my local stealership, he said he deals with it all the time and that he would check it for $45....Sounds like a good deal right? NOT!!! He had my truck for 5 hours, then called me to tell me it was the coil pack, so then my foul language started. I already ruled out the coil pack, remember guys??!! He said 9 out of 10 times it's the coil pack, and that the injectors have a very low failure rate....Hmmmmm, yes I know that, but this guy does not understand my failure rate with luck!!! Luckily, he found it in his soul to search through his tool box....GUESS WHAT, he found a fuel injector!!! He gave it to me, told me to swap it out (I guess I could have swapped out the injectors like I did with the coil packs to see if it threw another code, but hindsight's always 20/20!!) and pay him what I thought it was worth if it solved the problem. He also stressed that I was pretty much wasting my time, since the injectors rarely fail. He said it was probably a burnt valve (EVEN THOUGH HE DIDN'T DO A COMPRESSION CHECK) ARRGGGHHHH........So, I went home and started pulling the motor apart, throttle cables, intake, vacuum lines, intake manifold, fuel rails etc. Swapped the injector out and put everything back together. Switched the ignition on for 10 secs to let the fuel pump prime the rail, turned the key and BAM......cranked up like it never missed a beat!!! BUT, not fixed for sure yet right? Right!! Let it idle for 10 mins, shut it down, started it back.....still running good. Drove it for a few miles, shut it down, started it back....still A ok!!! That was 3 days ago, driven 200 miles since with no problems....IT WAS THE FUEL INJECTOR!!! I hope this help some of you out there, feel free to ask me any questions and I will reply as soon as I get a chance!!

Moral Of The Story.....If I didn't do any testing/reading (or if I was a woman) before taking it to the yota shop, they would have charged me $300 or so for coil pack, diagnostic & labor....then the next time I shut the motor off and restarted it, I would have realized that it didn't fix the problem....That's how people get hurt, haha....have a good day and good luck!!!

brian2sun

He's just a dumb mechanic and should know that injector failure isn't that rare. You definitely ruled out the coil pack when the miss didn't move after you swapped them. He should've known (or remembered that you told him that). I've been dealing with a miss problem myself and I ruled everything else out but valves and/or injectors. It took me a while to find a good diagnostic tech and he was smart enough to ask what I had already ruled out and how. I guess it helps that I was a service manager for a long time and know a little about turning wrenches and can explain the previous diagnostic work I had done. Right now my engine is getting a BG cleaning for the valves, FIs, piston heads, etc.. hope it works.

4runnerFireman

Well good luck Brian, nice 4runner by the way....how many miles? Have you tried to swap the injectors like I swapped the coil packs? What code(s) is it throwing?

4runnerFireman

Oh yeah, in the original thread, where I said 300 rpm's......that was supposed to say 3000 rpm's....typo

brian2sun

Thanks 4runnerFireman, I haven't swapped injectors yet although I did test them and the voltage was good on all of them (did not flow test them yet though). I wanted to do the cleaning first and if that doesn't help, my next step is to swap em. Luckily, my miss has always been isolated to cyl#3 (code P0303), so if the miss moves when I swap them, then I know it's injectors, but if it doesn't move, I'll know it's valves. The hard part is sometimes my CEL won't come on for months so I still don't know what cylinder is missing until I get lucky and the damn thing finally throws a code. It will run like crap and get 9-10 mpgs for months without a CEL!

It's got 197K on it and has ALWAYS had regular oil changes and recommended maintenance. Amsoil or Mobil 1 synth oil and filters for the last 105K. We will see....

4runnerFireman

Yeah, I use mobil1 as well....not too sure about the ohm reading being correct if there's some trash in the injector...also, the reading may change at different idle speeds & temperatures, the ohm reading was just barely off the normal range on mine....and of course it was bad. Mine is running fine but seems to idle around 900 rpm's sometimes, when it should be around 650...I'll have to check the throttle cables and vacuum lines again, and whatever else if you have any other suggestions.......

hross14

good job

Brutus

Mine has baffled me too. i'm not the wrench head you guys seem to be, but I've been around. My 98 started acting up last fall. My mom was sick and I was driving about 350 miles every weekend. I noticed on the interstate going up a hill it would nock and feel pretty rough. I changed plugs, wires and bought 1 coil pack recently to change out and see if I can isolate. I'm not throwing a CEL but there still seems to be a miss. MPG doesn't seem to be affected nor does power, just a occasional chugging thats drivin me crazy.

I reckon I'll keep the injector thing in my mind now.
Thanks.

hross14

every 100k you should send your injectors off to be cleaned. I havent seen a pair yet that didnt need cleaning at 100k....

There are also those wear items that should be changed around the 100k mark---O2's/AFR's, TPS, MAF cleaned and checked, IAC cleaned and checked.....and so forth.

I agree though with the original post--sometimes people let thier bottoms talk for them.......Instead of testing--everybody just starts guessing.......

and think a certain type of grease is the cure for all....

I am no genuis--but i do know my way around.........

b0n3mast3r

i had the same problem too but mind was injector # 2 i still have the bad injector in tool box. you can test the injector with a noid light kit or with a ohm meter any thing over like a 1000 ohm is a bad injector i think cant really remember the ohm of my head right now

4runnerFireman

Yeah Hross14, I forgot to mention that I cleaned the MAF sensor, that didn't help either. I haven't messed with O2 sensors yet, there are two of them right?

hross14

Yes, depending on whether your truck is Federal emissions or Cali--it will have an AFR before the cat (Cali smog) and an O2 behind it.

Injectors are high impedence (16-18 ohms I do believe).

When my truck hits these bench marks i just set aside a weekend and go to town. better to spend the money on new parts versus a tow bill. So the mentality of well i dont want to just start replacing parts--is kinda mute.....$.02

quinsdad

Hi guys,

Very good info here. Thank you 4runnerFireman. I have this same issue, though slightly different...

My truck started running very rough, missing. Light came on, so I borrowed a friend's scanner to check it out. I had a mature code for a misfire on #2, and a pending code for a misfire on #5. I checked the haynes manual, and found that those cylinders share a coil (as you can tell, I'm not a "work on my own vehicle" kind of guy).

With this info, I figured the first place to start was the coil pack. Replaced it, and the truck ran fine... for 3 days. Misfiring again. Checked the code (had cleared the previous codes), and it was #2 again. Okay. So I figure it's due for plugs and wires. It has 150k miles. Yeah, I know I should have done that sooner... but I'm not a auto guy... so... you know.

Anyway, replace that individual plug first just to be sure that's what it is. Bingo! Starts up fine, take a little test run. Figure I'll do the rest of the plugs and wires on the weekend. Everything is okay. Right?

Wrong. 2 days later, same thing. Checked the code.... #2 again. Okay, maybe I need to replace these wires. Might as well do all the plugs while I'm in there. Done. Start it up. Bingo! Take a little test run. Everything is okay. Right?

No. Misfire. #2. Okay, I'm thinking injector... but again, I'm no work on my vehicle guy. Try some injector cleaner. BAM! That's it. Test run, a-okay. 2 days later, a-okay. 5 days later, a-okay. Must've been it, right?

Nope. Not yet. Misfire. #2. Okay, I'm done. Take it to a friend of a friend that has a shop. Checks it out for me. Bad injector. Okay, figures. At least I was on the right track. Not bad for a guy that knows nothing about autos I guess. So, he replaces the injector. Everything back to normal. For one week.

Misfire. #5. Now.... I'm about to buy another injector, and put it in myself since I can probably get to it without taking the intake plenum off... but does this sound right to you guys?

I know I'm a n00b and all, but any help would be appreciated. I don't want to hijack your thread either, so I'll start a new one if you like. I only posted here to avoid redundancy.

So... what do you think, am I on the right track here, or should I start looking at valves?

Thanks again 4runnerFireman for posting your experiences with this problem!

4runnerFireman

THANKS QUINSDAD, I'll type you back tomorrow when I have more time.......there seems to be a naked woman in front of me right now!!!

brian2sun

quinsdad

Yeah, what he said

4runnerFireman

Oh jeez, ok......no #2 now? just #5 right? pugs, wires, swap the coil packs to see if the scanner picks up another cyl miss.....also, was the plenum gasket removed when he changed the #2 injector? if that gasket is not new, replace it, it's only $12.........If it's not the gasket leaking air by, or the injector, then yes look at the valves. Have your mechanic dude do a compression test.....I am just rambling on a monday at work, did this help you?

quinsdad

Not sure if he changed the plenum gasket or not. I do know he replaced all the o-rings in the fuel rail on the drivers side though. I am probably going to put the injector in tomorrow, because it won't hurt, and if it isn't that, at least I'll have a spare when I do need it.

Thanks a lot for your advice, and will let you know how it goes. I appreciate you taking the time!

quinsdad

Not sure if he changed the plenum gasket or not. I do know he replaced all the o-rings in the fuel rail on the drivers side though. I am probably going to put the injector in tomorrow, because it won't hurt, and if it isn't that, at least I'll have a spare when I do need it.

Thanks a lot for your advice, and will let you know how it goes. I appreciate you taking the time!

Double post. Sorry about that, I'm using my phone to reply.

4runnerFireman

No prob, good luck, We'll check back to see what you find out!!!