My car is missing at idle; a lot. On light throttle too. Adding a load of injector cleaner stuff clears it, but it comes back. I had all the injectors taken out and professionally cleaned - that lasted for two weeks.
New injectors are bloody expensive.
How about this:
I work on the front bank, buy one new injector, replace one, try it for a day, if not that one, try the next.
Then if I try all three in front and no difference, swop the three front for the three rear and start again.
What do you think? I don't have much spare cash, three would cost too much; six, I'd scrap the car I think.
oh, BTW, there are no codes.

 

Here's something you can try without spending any money.

You unplug the wire harness connector from one coil pack at a time and see if the miss gets worse or stays the same. If the miss gets worse, that means that the cylinder you unplugged is working fine. If the miss doesn't change, then you have found the problem cylinder.

 

Cool. I'll try that. Thanks!

 

Snake oil, there's no fix-it-in-a-bottle.
Obviously the injectors aren't your problem.

I'd be looking at the oh so famous 4th gen coil pack failure.
A weak coil pack will show itself from time to time. Cooler spark gets blown out under a load and as the coil pack gets hot, it sometimes gets worse.
They don't necessarily throw a code either as the side that fails is usually the high voltage side which the ECU doesn't see. Could be a spark plug too.

If your injectors were professionally cleaned, then they're flowing. If they were failing electrically, the ECU should see that. You can also test them with a test light or ohm meter, which I'm sure the place the professionally cleaned them already did. You would also be throwing lean codes if your injectors were failing.

Look elsewhere for your misfire.

HINT: Ignition.

 

But if it were a coil pack, wouldn't it misfire more under load? WOT there is no problem; in fact, as it comes past 4000 taking off, it squeals the tyres; loads of power and no misfire.
Back in the days when I had the TR6 I used to check the injectors by pulling them out one at a time while the motor was running, and watching to see if it had a good spray pattern or had started to dribble. That was a straight 6 though and rather easy to work on, and no computer, either....

 

A misfire caused by a failing injector not spitting enough gas will be less noticable at a higher RPM.

Another problem it could be is a loose spark plug. Several years ago I didn't tighten one of the spark plugs enough. As the spark plug fired more it slightly enlarged due to the heat. With the plug enlarged it sealed off the chamber better making the misfire less noticable.

I advise you to check all 6 spark plugs.

 

If you have an ohm meter, unplug each injector and check the current across each. The correct spec is 10 to 14 ohms. You might find one out and there's your culprit.

Do this electric check with the engine off!

 

FIXED.

 

If you really think it is your injectors, you can pull the plugs off each injector individually instead of each coil. It should show the same thing...if it gets worse, that isn't your problem...if nothing changes, you found it. I was running on 5 cylinders a while back and thankfully it was the front left coil, so i didn't have the intake manifold in the way. If you do end up finding a bad injector i have a few i could send you for like $10 or so. I bought 4 or 5 when I was fixing my car and haven't needed any others since. Hope you figure it out! Troubleshooting can be pretty frustrating sometimes.

P.S. Forgot to mention...are you positive you are buying good gas? It would have to be pretty awful to foul up injectors in two weeks, but you never know. That was what caused the problem for me.

 

93 octane Chevron fuel and big bottle of chevron injector cleaner cleared my 95's up for good!

i got put in jail for a week and my car sat in my Garage the entire time i got out and it had a horrible miss fire on two cylnders i ruled out the coilpacks and knew it was the injectors. took it to a penzoil oil change station they said to save money try that trick with Chevron so i did and about 38 miles after putting 30 bux in gas and that bottle of chevron injector cleaner it ran smooth as can be and never came back.


before i did this trick i ran a bottle of lucas injector cleaner through a quarter tank and let me tell you DONT BUY LUCAS it sucks it doesnt do **** except MAYBE lube the fuel system up.


Good luck.

 

Oh yeah thanks! I forgot to mention, the gas here is not as clean as in the US. Nowhere near. What I suspect is that one has got a worn spot at the point on the actuator where it hovers on idle, and every now and again it sticks there for a moment, causing a misfire, which causes the motor to wobble on its mounts, which unsticks the injector - something like that. If I add some top oil to a quarter tank, the problem gets less after a little while. I can tell it's just one cylinder; it runs, mmmmmmmmmtickmmmmtickmmtickmmmmmmmmmmmmmmtick.... and so on. Fortunately I cleaned all the intake side and EGR and auto idle valve about 6 weeks ago, so it's not stalling, but it is very annoying. It makes me want to drive everywhere WOT!

Great idea re unplugging; I'll either get 5 cylinders with the ticks, or one that just goes 5 cylinders. Thanks. I do have a multimeter, too, I'll check the resistance. Or even, I could try listening with a stethoscope

 

had the same problem. coil pack boots were the problem. id get new ones, they're only $50 for all 6