Your repair advice, please?

[AlexG]

I have a '99 Toyota 4Runner SR5, 2WD, with ~250,000 miles on it. The engine is a 5VZ-FE, 3.4 L, V-6, automatic transmission.

Lately I'm having intermittent problems with rough idle, usually while waiting at a stoplight, sometimes also while getting up to speed on surface streets (I'm avoiding freeways). When the rough idle happens, the check engine light sometimes flashes, otherwise it just stays on. But yesterday, for example, the car drove fine all day - no rough idle, no flashing CEL. I suspect maybe weather has something to do with it - it seems to have problems on warmer days but runs fine on cooler days?

I took it to a shop that I trust, and they pulled codes
P0171
P300
P303
P306

First they replaced a coil, but that made no difference at all. They were kind enough to put my old coil back in and refund my money.

After further testing, they now recommend replacing the #3 injector, plenum gasket, and mass air flow meter.

Question: Does this sound about right? (Plugs, wires and 02 Sensor were replaced 3 years ago...)

Problem is, I really can't afford it. If I can wait 4 months, I *think* my state will help with the repairs through its clean air program to get the vehicle to pass emissions inspection. (Does anyone have experience with Air Check Texas? Would these repairs likely qualify?)

Also: How long can I put off these repairs? What's the worse that can happen if I continue to drive it ~1,500 miles over the next 4 months? (I only drive on road, and gently at that...)

 

[fourwd1]

More than likely you have a vacuum leak somewhere creating the lean condition which causes the random misfires. Could be a hose or hardline, or maybe an intake gasket.

 

[AlexG]

Thanks for the reply. What would be involved in finding and fixing a vacuum leak? I mean, how many hours of labor would be reasonable, and what parts might typically need replacement? Or can you just patch the leaks somehow?

(I'm guessing that this is pretty involved and difficult, and that mechanics would rather replace some more easily replaceable part to see if that fixes the problem first?)

 

[Ducmonsta]

The redneck way to check for intake leak is with carb cleaner. Spray around the suspected area and listen for a change in idle. I DO NOT condone this unless you have some common sense and experience. Carb cleaner is extremely flammable.

All the codes you've reported are lean code 171, misfire cylinder 3 and 6 303 306 and random misfire 300. Your vehicle should have the air/fuel ratio sensor, not necessarily an o2 sensor. If I recall, you have 3 sensors maybe 4. The front 2 are air/fuel ratio sensors which are common to fail at that mileage.

Unfortunately, you either need to come up with the money to pay a knowledgeable repair facility and get it done right. Or come up with the money to start throwing parts at it.

Depending on your location, you may want to check local 4x4 clubs and see if you can befriend someone there. But be aware, you still may end up just throwing parts at it if that person isn't repair savvy.

 

[supmike]

yes. i'd really like to know how to check for this leak.

i've changed my wires and plugs less than 10k miles when i got a P303 error. I had a wire that was bad when i changed it last. I'm getting the P303 check engine light again. i've tried swapping the wires, plugs and coil positions to see if the error would move to another cylinder but it doesn't. I changed all of my fuel injectors 2 years ago (less than 20K miles). I believe i had an error for a clogged injector.

Could it be an air leak?

 

[KaiLoRunner]

If your running lean, and having issues with rough idle and acceleration it really sounds like you have a bad injector, especially if the electrical part(spark,wires, etc) are not having issues. And what was the "further" testing they did? They should be able to test if the injector is sticking or if there is too much resistance on the injector. This would be my first guess just from what your saying.

I can tell you from personal experience, that I had similar symptoms like this and running lean on cylinder 4 on a ford fusion. I replaced the ignition coil on plug and didn't help. Ran a resistance test on the injector and was not within spec, replaced it and ran fine after.