I have a rough idle problem that came on out of nowhere (feels like the engine is running on 3 cylinders), one minute I was driving stopped and got some coffee and when I pulled out and the engine is missing. I limped back home which was a couple blocks at most and haven't been driving since. I just changed the plugs (gaped at .032), cap & rotor about 3000miles ago. So I checked all of it and turns out the #3 cylinder plug was fouled up. I'm not to sure what type of fouling exactly but its pretty burnt and dirty looking but dry. So I changed the plug and also changed the wires and no improvement still missing. I'm not sure where to look next, I'm a novice mechanic at best. Any ideas what could cause this type of problem that fast.

 

If the plug was black then most likely it's oil or carbon fouled. If it was a white/gray color, that's usually caused by the additives they put in fuel.
If you pull that spark plug wire off are you getting spark from it?

 

An injector going out would do that. Since the problem seems to be isolated to the one cylinder and you already know the plug and wire on that cylinder are good, the injector is the only other culprit. Well, aside from the cap. But, you said you'd replaced it and they don't usually just take a dive like that. Wouldn't hurt to check it, though. Hopefully, it's that simple for you.

As for the injector, it's not the fun job, but you'll have to inspect it.
http://personal.utulsa.edu/~nathan-b...31injector.pdf

There are a couple of options here. Test the injector and if you find it's bad, you can send them off to have them rebuilt. I'd have all of them rebuilt at once.

OR....you could buy a rebuilt or new injector to have on hand in the event you find it to be bad and go ahead and replace it. This would save on down time, but the other injectors may be close to the same condition. Later down the road....same problem. One (or more) dead cylinder.

I'd had my injectors rebuilt when I was rebuilding the entire engine. It's a very good thing. Ask anyone who's done it. You can't go wrong, there. And, it's not very expensive compared to the cost of a new or one single rebuilt injector.

Run a search on injector rebuild for sources. I used Mr. Injector on ebay. Very satisfied.

 

abecedarian
I have not checked to see if I am getting spark, just assumed it was good. I'll definitely check it out.

 

thook's got a good point that a sudden loss of a cylinder, particularly when you're not driving it, usually only has a couple of causes. You took care of most of the easy stuff- plugs, wires, etc. leaving the injector or possibly its wiring as the most likely cause (but not the only possible one).

 

I had a similar thing happen on my '85 22rec. Pretty good on theory here, but not a great mechanic. Not sure why I suspected a broken valve spring...its been several years since this happened.

I think my reasoning at the time, was... I had spark, and fuel on the other cylinders... and I'm not much of a fan of injector problems... never had an injector fail.. not sure why... maybe the fuel I use and its additives. That left valves.

Since the 22re's are so easy to work on... I pulled the valve cover... and saw the broken valve spring on #2.

I searched this forum and found several ideas of how to fix it without pulling the cam drive chain. I was then able to take my FSM and the idea on how to fix it, to a trusted mechanic. He didn't want to do it at first, but called me back and said he thought he could do it. The trick is in getting the valve to lift up without doing damage.

Anyway... the total cost was $200 bucks in parts and labor.. as opposed to a quote from my otherwise excellent Toyota dealer of $1100.

No problems with the engine since... runs like new.

I also note that #2, and #3 run hotter because of their position (I've measured it) so are more prone to heat related problems... such as spring failure. I would expect a failure of this sort to occur on one of them first.

So its an easy check to make... and easy to fix if you can find a good mechanic, or you are a pretty good mechanic yourself.

 

its usually, sparks and wires with yotas, at the worst it might be a coil.

 

Wow...that's one I wouldn't have thought of...lol! Not that a broken valve spring is really a laughing matter. And, I didn't know that about #2 and #3 cylinders. Something to keep in mind.

What is it about their positions that make them runner hotter, anyway? Is it the exhaust design?

 

True......injectors don't fail very often. I've had it happen to my V6, though. (Long story....I'll spare the details). But, were it the coil it wouldn't be isolated to one cylinder and would have definite running problems on the whole.....like not running hardly at all, if at all.

 

Thanks everyone for the great input, I think the only thing now is to do some more investigating and see if I have a injector problem or a valve problem.

 

I would think a compression test on the #3 cyl. would tell if it's the valve spring. Or, just pull the valve cover. That's simple and you don't need any special tools. You might check that first since it is easier than the injector deal.

 

A coil that is close to failing can cause fouled plugs to misfire more easily.

 

Oh, I see. Weak voltage/spark.

Wouldn't there be evidence on the other plugs, though?

 

if the other plugs are not as fouled they won't misfire as easily

 

Okay. I suppose a weak coil would also cause them to foul? Not burning as hot as they should?

 

over time, possibly. but like they say the weakest link breaking first, so one plug with too much build up will most likely be the first one to cause problems and since the coil may already be weak, it will accelerate the build up on that plug...
it's a vicious cycle!

 

Well, I'm only asking because when I tore my motor down I found the #3 plug to be the most fouled. (This was a constant even before the rebuild). And, when I'd sent my injectors off to be rebuilt the #3 was also the weakest.....the least flow and worst spray pattern.(#4 was pretty bad, too) Fortunately, though, with "new" injectors and plugs, cap, rotor, etc. it's running with no missing.....just a faltering idle (related to other things, as you know). So, I guess I can breath a sigh of relief knowing my coil (w/ 220k) is just fine....lol.

Anyway, just tryin' to put pieces together. Thanks, Abe.

 

I think the reason for the higher temps on 2 and 3 is because both of them have a cylnder on both sides of them, whereas 1 and 4 don't.

 

Probably so. Seems plausible to me!