I bought my 99 4runner 3.4L a few months ago. I was aware of some obvious problems when I bought it. i.e. new brakes, new tires and a very small intake gasket leak. The first two issues have been addressed. I haven't replaced the intake gasket yet. Today I got in it to take my son to school and it was fine on the way there. After the engine warmed up completely I noticed a miss when I slowed down or idled the truck. Pulling into the driveway the check engine light came on. Pulled the codes and got a cylinder 4 misfire and a tps code. I cleaned out the throttle body and replaced cylinder 4 plug. It was a little burnt, but I've seen much worse. I also added some fuel injector cleaner to the tank. Upon driving it to test if the spark plug worked it idled fine, but when I accelerated it missed horribly. I couldn't get over 40 without the entire truck shaking violently. All my wires and coils are fine..The only thing I can think of is that it could be the injector. Is there anyway to check this? Should I wait to see if the injector cleaner works? What are possible problems I'll have if I continue to drive it with the miss? I've only been doing my own mechanic work for about two years, so I'm still new at this. Any help would be greatly appreciated. I don't wanna shell out a hundred bucks to replace an injector and then that not be my issue.

A bad intake gasket could cause the symptoms you're describing. If that's already a known issue, I'd start there.

I'd replace the TPS since you got the code for that as well. They're about $70 from Toyota and take 5 minutes to install.

I meant valve gasket not intake. Sorry I was distracted when typing the first post. I ordered the TPS from work. (parts store, discounts come in handy) I'm going to go ahead and replace that. But only one cylinder is misfiring. That's why I'm sort of stumped. I wish I could get to the fuel injector easier to have it tested.

before you go shelling out some money..... Try swapping cylinder 4's injector with another Cylinder's injector. Clear the code, and when the code comes back, see if the code goes to another cylinder....

Chances are, it's your cylinder #4 injector. I've recently gone through this, and can say that it's really not that hard to do. You should definitely follow a good step by step, but it's not hard to do.

If you chose to do the job, get a New OEM injector from the Dealership. I made the mistake of ordering a set of Remanufactured units off of E-bay, and had 2 bad sets sent to me, before I opted to just use one of his, and run my 5 other old ones.

Again, if this is your issue, and you decide to do this job, send me a PM and I can walk you through some of it... I've done it 5 times (thanks to the bad injectors I bought from that seller!).

Good luck with the diagnosis.....

I ordered an injector today along with the tps. After cleaning out the throttle body and resetting the engine light the code didn't come back up though. The throttle body had a LOT of nasty junk. The only thing I'm worried about at this point is driving the truck until I'm able to do the repairs next Wednesday. No time off work before that. I found a place that will test my injectors. So I can get it checked without having to disassemble and reassemble a thousand times. The brand injector I ordered is Denso. So what are the potential issues if I drive it with the misfire? I only drive about four or five miles to work. And I can go through town and drive slower which is what I did today. I just don't want to screw anything else up along with this problem.

When the truck is misfiring... that cylinder is not running very well... if not at all. So if that's the case, you're running it with only 5 cylinders, and the engine is working that much harder to try and maintain speed.

I'd try to use it as little as possible.... until you can get it fixed...

no offense but have you had it looked at by someone who really knows Toyotas or a Toyota mechanic?
( I expect to get flamed for asking this)


Injectors, TPS, ect - you could swap parts out all day and not find the problem. You also could make the problem worse by buying non-Toyota parts and create new problems. If you do swap out the injectors, it seems like re-manufactured OEM is the only legit way to go.


Misfires can be SO many things. It is not the type of problem I would want to troubleshoot only via forum knowledge.

Injector problems are not that common, based on the forum posts I have seen over last year, they are much LESS common than even a head / head gasket failing, plugs or wires. Injectors are also really expensive.


Do you know what codes it was throwing?

-- Good luck BTW.

I took it to a mechanic friend yesterday. He seemed to think it was the injector. I've got a guy that used to work at a Toyota dealership that I'm going to call today. He helped me with my tons of Camry issues last year. The only code it's pulling up is a cylinder 4 misfire. The tps code is gone. The code scanner belongs to the mechanic I went to yesterday. I used a little pocket scanner and got the same code he's getting. The plugs are new. I'm going to swap wires today. But if it were a wire wouldn't it make more than one cylinder misfire since one wire and coil runs two cylinders? Or is it possible for only one to misfire? Again, bear with me. I'm new at this stuff. I've also heard that injectors rarely go out. But since the truck is new to me, I don't know how well the previous owner took care of it. So I'm trying to look at all possibilities.

First, I should tell you that my E-bay injectors, were Remanufactured OEM's. If you go that route, get them from a local store, not over the internet!

As far as injectors not being a common issue??? Brian.... there were a ton of people over the course of this winter with Injector issues.... myself included. I know of at least 3 other people on here that had the same codes coming up, and the cause was a bad injector.

I'm not saying he should throw parts at it, but simply taking things apart, and swapping one injector with another one from a different location, will cost him nothing, and is a sure fire way to find the culprit. When I did so, it went from a Cylinder 1 misfire to I believe cylinder 5 (which were the 2 injectors I switched around).

If your mechanic friend is willing to help you, ask him to do the swap I suggested.... it's just a little insurance. If you swap in a new one, and it's not that... you've just paid for an injector you didn't need to replace.

Try swapping one of your other injectors for the Cylinder 4 one.... if the code follows to the other cylinder... you're on the right track!

Good luck man! I lost my mind trying to track down this issue with my truck this winter... I just wish I would have listened to someone who told me it was my injector... before I went and bought new plugs, wires, a coil.....

[/QUOTE]I'm not saying he should throw parts at it, but simply taking things apart, and swapping one injector with another one from a different location, will cost him nothing, and is a sure fire way to find the culprit. When I did so, it went from a Cylinder 1 misfire to I believe cylinder 5 (which were the 2 injectors I switched around).


Good luck man! I lost my mind trying to track down this issue with my truck this winter... I just wish I would have listened to someone who told me it was my injector... before I went and bought new plugs, wires, a coil..... [/QUOTE]


I'm a lady.... Lol. There's a guy a couple of towns over that tests injectors while off the vehicle. I'm going to take them to him to be sure it's the injector. That way I've only gotta take it apart once.

I'm not saying he should throw parts at it, but simply taking things apart, and swapping one injector with another one from a different location, will cost him nothing, and is a sure fire way to find the culprit. When I did so, it went from a Cylinder 1 misfire to I believe cylinder 5 (which were the 2 injectors I switched around).


Good luck man! I lost my mind trying to track down this issue with my truck this winter... I just wish I would have listened to someone who told me it was my injector... before I went and bought new plugs, wires, a coil..... [/QUOTE]


I'm a lady.... Lol. There's a guy a couple of towns over that tests injectors while off the vehicle. I'm going to take them to him to be sure it's the injector. That way I've only gotta take it apart once.[/QUOTE]

Well then, you should post a pic of yourself and your rig in the 3rd Gen Owners thread! ;) This would clear up any further issues with gender identity.... lol! JK!

http://www.toyota-4runner.org/3rd-ge...thread-18.html

Good thing you have someone to test yours for you! I didn't!

Lol. I guess so. How long did it take you to tear it down? I might be able to do it this weekend if I can get enough daylight after work. I'll work on the gender issue..

Don't feel too bad. I just picked up a '00 4Runner that had a mis in it, the hack mechanic the guy took it to put in:

TPS,
Cam Sensor
Plugs

Couldn't find the issue. (never tested the injectors or tried swapping them BTW) So he,

pulled the valve cover, told him the exhaust cam had come out of timing so he reset it. That didn't work so then he,

pulled the heads to check for burnt valves, there were none. So then he,

claims to have done a compression test (with the heads off it, good trick) and said it had low compression in Cylinder 3 & 5 so he concluded the piston rings are bad in those two cylinders.

After charging him $800 for the work he had already done, he told him $5000 (not a typo) to swap in a used engine.

So in closing, try the injector swap that Fightman suggested, it's a great way to test to see if it is indeed an injector issue. It could save you a ton of money and even save you from selling it to someone like me, for very, very little money...

Good points everyone!

And good luck lady