rcbrown23

So out of nowhere my 2000 4runner (3.4L) started missing badly. It happened for like 30 seconds a month ago, turned it off then back on and all was well. As of last week, if I start it cold, it's good to go, but if I shut it off and try and restart while the engine is still warm, it misfires. Code threw up a cylinder 4 misfire.

I changed the plugs and wires, and also the fuel filter, but it's still doing it. I did swap the coil pack, and when the check engine light comes on again, I'll check and see if the misfire has moved from cylinder 4 to another. I've been reading online and a lot of people are pointing to the fuel injector, but I wanted to check here before I buy new fuel injectors (or should I send mine in for a refurb? Whitchhunter refurbished service is mentioned a lot on the various forums).

Any advice? I'm leaving for a two week vacation in 5 days, really need to get this sorted so I have a running vehicle when I return.

aowRS

Nikki Seidel

been having the same problems. Changed plugs/wires a year ago. Now this problem so changed the coils. Fixed for a day them worse then ever.

75w90mantraN

Well each case is typically similar, rarely the same.

So same code or?

Replaced with correct type? I mean it happens right. Or better, installed correctly?

Mileage? More details?

Could be a few things...ignition related, injectors, wiring, sensors, timing...the more specific and factual your case, the narrower the suspect list.

My misfires were ignition related. But others were different, though similar codes.

Nikki Seidel

I get no code.
exact problem. Fine cold start. Starts fine always. If I drive, shut off, restart shortly after, I have a rough idle. And rough acceleration under 2.5 rpms. Over 2.5 is fine. Check engine light blinks at high rpm stays on at low. Goes off eventually even while problem persists.
the plugs and wires were changed a year ago. Figured had to be a coil. Changed all 3. Fine for a few hours. Drive stop start shut off restart. Same problem not as bad when it came back. Never left for a whole day. And now as bad as ever. Cant even drive long without it starting. Never happenes on cold start.
it's a 99 runner limited. V6 185000 miles.
I'm the 2nd owner.
I also have a 4wd issue.

75w90mantraN

OP has a misfire code. You confirm that you dont, but give 2 scenarios with check engine light flashes and stays on...?
Not exact issue. Plus you posted 4wd problems in a separate post. What OP has going could differ from what you got going on. Not worth debating.

Like old87 said to your previous thread, a good scan tool would help you, as pending codes can be seen AND live data streams can tell whats going on in this largely unknown engine state with nothing on history. Unless you are the original owner.

From what's going on, as a new owner to a used auto, have to start from scratch. Said you did coils and plugs/wires. Can only assume you wired them back in correctly, but that does happen for some, so I throw it out there in case.

With a good scan tool, I would check data streams on things like fuel trims, misfiring cylinders, oxygen sensor 1 readings (air/fuel sensor), engine coolant temp, MAF...to name a few. I spent a couple hundred on an Innova, but it saved me hundreds in parts throwing over the years and can be used across multiple makes and models after '96. Do a cross-reference on the sensors' specs and then go from there.

My hunch is to check the sensors...before jumping to a suspected component. But then again, maintenance and tuneup from scratch, I would at least look at replacing sensors like a/f and oxygen sensors. Maybe the a/f sensor isnt going into closed loop or something. I slowly got around to replacing that after I bought my used 3.4

The check engine light blinks at high rpm to warn about actual driving conditions that are damaging the catalytic converter, a necessary emission/evil in the battle for clean air. An expensive thing to replace. And if emissions testing is required where you live, well then, good luck.

I hesitate to advise on possible suspects from others experience to discourage parts throwing. We can start a possible list, once a code(s) is known.

Invest in a good scan tool. Best advice!

75w90mantraN

For the OP,

Injector threads are common, so its up to you, whether cleaning or replacing, new or refurbished, oem or not. Lot of opinions on, but its your engine. Can go from least expensive perspective or from most reliable perspective or somewhere in between like a blend.

A sure way to tell, apart from trial and error, is to check the live data. DIY or professionals both can and do use scan tools and it can save both money and time.

Unfortunately, limits do exist on how far something like injectors can be flow checked. Usually done professionally. Maybe pay for the inspection and go from there depending on results. Can check fuel trims on a scan tool. Or try the simple approach of listening to the cyl head by each injector for the tap tap noise (lack of to verify, or suspect, dead inj). Quick use of a long metal tool like a long screwdriver or rod (careful of listening from the front) while subjective, is a neat trick that seasoned pros still use.

Of course, if the problem is electrical, then injec replacement is futile without first checking wiring integrity. So while cheaper to own, a multimeter does require some knowledge on how to use.