Misfire on #1, low RPM?

Only 240,000 miles.............

Are you sure it's missing on #1? Did you replace with Denso or NGK plugs?

Have you tried cleaning the throttle body or MAF sensor?

 

you've already done all the logical stuff. The throttle body can cause all kinds of problems if there's too much carbon buildup.....especially low rpm

has the car ever overheated?

 

yup. clean intake manifold first, EGR pipe 2nd, and EGR valve when the above fails.

 

clean intake manifold too

 

Instead of going to the expensive route of replacing spark plugs, coils and fuel injectors, you could've swap them out with the one's that are working and see if its the part or the cylinder itself...

On another note. Since you replaced all 3 and still doesn't work. I would check if the engine wire harness is open or short for cylinder 1. Then check for connector connection, vacuum hose connections, ignition system, fuel injector assembly, fuel pressure, MAF assembly, ECT sensor, compression pressure, PCV hose connections, intake system, EGR valve assembly and last if none of those works, then it's possibly a bad ECM/ECU. I hope that list helps you on trying to diagnose your problem.

 

Well, you'r not making it a very short list.........before giving up.

 

What's your suggestions?

 

Well, you had made a plethora of them and cover all angles. Really, I'm short of them

 

I'm not sure if you're being sarcastic or being sincere. I'm not here to argue, I'm here to help, if you're looking for an argument, I will just ignore and go away. Have a good day.

 

Not sarcasm at all and there are not negative arguments from my part.

 

to be fair, that's a lot of work while the OP probably needs just some intake cleaning.

 

I'm not saying he should do all of those, I'm saying he should inspect those area for the misfire and diagnose each area to make sure its in working order. If he found the problem then he can omit the rest.

 

that changes everything. sounds like HG and engine is toast. at least you got 240,000 miles, not too bad.

 

Only 240K ... My corporate insurance will not cover anything past 250K. 240K is a good run ... anything could be wrong at the milage.

Sounds like you found your problem .......... If the engine was performing properly prior to the HG failure and you fix it quickly there is no reason to assume that the engine would not perform.

 

I had a similar thing happen at ~195k, turned out to be a blown HG around the #1 cylinder. Verified with a borescope showing a tiny leak, couple of drops a minute. Did the same thing as you...replaced coilpack, plugs, cleaned EGR pipe.

 

I have had the same exact problem for over a year. Mostly when its warm out and when just touching the accelerator. It started at about 120,000 miles and about a month after I had my first set of spark plugs replaced. Then Toyota replaced the EGR valve, the factory rep came in and said they still couldn't find the problem. Then after sitting for a couple of weeks it misfired bad on startup and I took it to a different Toyota dealer and they tightened up the spark plugs and said it may be bad spark plugs and said I should have them replaced again. I had them replaced again with stock Toyota plugs a few days ago. Still has issues. I believe that a port of somewhere is plugged that restricts O2 or fuel. I have also heard that the EGR system can't withstand higher speeds. I believe that is why I use oil when I drive at 75 or more for long periods. Maybe the two are connacted.