So this is new, I get back from vacation and i go to start the truck and it idles really rough, light shaking and sputtering, until it levels out. Lasts for maybe 10-15 seconds and then its fine, idles back down fine, still runs great.. Why would this happen all of a sudden after sitting for 3 or 4 days? ive ran new gas in it since then, no difference. Thoughts?

 

Leaking injector?

 

Brain I saw you thread and noticed you had a very similar problem, did you ever get it figured out? This isn't something that's Been happening, it literally just started happening when I got back. I'm going to run some fuel cleaner through it today and see if that helps at all. Maybe gunk got ran through the lines and fouled up an injector

 

I did finally figure it out (after banging my head against the wall for over a year). It was a real PITA to diagnose too. One thing I'll say is that Toyotas don't break down like a Ford or Chevy, they just run like crap forever!

I had them run the truck with a tranducer hooked up and the wave on the computer screen showed that some of my valves were sticking or not fully opening/closing. Once I goosed the throttle a few times, the wave pattern would even out and it would start to look close to normal. When I let the truck cool down all the way (with the diagnostic tools still hooked up) and then started it back up, it would have a screwy wave again, I'd goose it and it would even out. So long story short, my valves are either dirty or worn or both (which would also explain my horrible fuel economy - 10 mpgs).

I found a place that would rebuild the whole engine and warranty P&L for 3 yrs/36K and for not much more than what a valve job would cost, so I'm probably going that route. The shop that ran the diagnostics said they can shim the valves or whatever for about $650, but they couldn't guarantee it would fix the problem 100% or my bad mpgs, so I don't like the sound of that plan.

I'm making one "last ditch" effort tomorrow to clean the engine with a machine that hooks up to the fuel rail (and bypasses my gas tank). I'm told they run concentrated cleaner through, then another chemical mixed with gas, and they run the truck on and off for about an hour, switching chemicals. I don't know much about it, but they say it will clean my valves, injectors, piston heads, etc.. and will make a big difference in performance. I figure it's worth the $200 or so to have this done in hopes of avoiding a costly rebuild. At the very least, I'm hoping it will restore some mpgs and buy me some time.

 

oil sludge monster attack!

definitely well worth $200 for cleaning

 

go through your fuel system. start with a new filter, and if funds allow, new fuel injectors *if cleaning helps, go ahead and put in new ones, will be better of in the long run. another issue to inspect would be the air hoses, check if there are any air leaks. air leaks are minor and a simple fix, but do cause problems with idle. pull the valve covers and see if there are build ups of sludge like cal01 said.
BG cleaner does do wonders, they dont put it inline with the fuel, they pull the intake hose, put the spray nozzle in before the throttle body, and let the engine run while spraying different chemicals at different pressures for certain amounts of time to clean out the throttle body, intake manifold, valves, and part of the combustion chamber.
just a few thoughts, good luck, hope that makes sense.

 

interesting diagnosis brian. hope its something more simple on my end.. ill start with the basics and see if anything gives..

 

Thanks for the input, glad to hear the cleaner "does do wonders". I trust this mechanic too and he said he's done the cleaning on about 100 cars and he told me no one has ever come back and said it didn't help, so I'm feeling a little better about spending 2 bills on this (especially when I could put the $$ towards a rebuild). I'll just keep my fingers crossed and hope it does the trick. I'll post the results when I get it back.

Cwaters, I agree - start simple. My gremlin has been stirring up trouble for a long time and I have ruled out everything else. Yours could be just a dirty IAC or something. In addition to my valves, it's possible that an injector may be dirty and the others are over-compensating and running rich, yet another possible cause for my bad mpgs. Since the cleaning will help both the valves and injectors, I figure it's worth a try. I've decided if I end up rebuilding, I'll have all the injectors cleaned while out of the engine and flow tested before they put them back in.

 

Here's a little update on my problem...
https://www.yotatech.com/forums/f2/s.../#post51390562

 

Thanks for the update brian, that sounds promising. I was going to have a BG fuel system service done. Its probably not as extensive but hopefully ill have similar results.

side note Id like to try and change the fuel filter, but it definitely looks like a PITA, is through the wheel well the best way to try and tackle it for the 2.7? I know its supposed to be a "lifetime" product but i dunno about that. Also, can the IAC be cleaning without taking off the TB?

 

so i havent had a chance to get any service done to it yet, but im thinking in worst case scenarios, I have been loosing coolant, not alot but its going somewhere thats not visible. I order a new cap cause i did notice some spill out stains on the top of the rad, but could this be as bad as a head gasket? I would think that would be more presistant problem. Whats a 100% way to eliminate that as the problem? i dont notice any white smoke on startup, or coolant in the oil.

 

Do a compression test to see if a HG is the problem. You could start it up and kill it while it's idling funky and pull the spark plugs and see if there is any coolant on them (or fuel if it's a leaky injector). I would also do a cooling system pressure test to see if you can spot the leak and I would get an extendable mirror too and look at the bottom of your water pump and thermo and see if there are any coolant stains anywhere under there.

 

i changed the plugs last week and didnt notice any fuel or coolant on top of any of the pistons. Do the coolant lines go through the intake manafold? could one of those gaskets be leaking?

 

You wouldn't see any coolant on the plugs after you run 15 seconds and burn it all off once it starts idling better. You need to kill the engine while the engine is doing it and before the idle levels out. If you kill it in the middle of it happening, that is the only way you are going to see coolant on the plugs - that is, if the coolant is even leaking thru the HG. If it's a leaky injector, you should see unburnt fuel on the plug.

I've never heard of any intake mani gaskets leaking coolant so I'm going to say that isn't possible.

 

clean the IAC .. worked for me..

 

you mind giving me brief instructions on how to? do i need to take off the throttle body?

 

all ya needed to do was search but here you go:

clean throttle body
https://www.yotatech.com/forums/f2/t...w-pics-194300/

and cleaning iac
https://www.yotatech.com/forums/f123...ac-pics-92286/

 

Thanks me and search button dont like each other very much..

 

I recommend going and getting a new gasket from toyota. you old ones most likely will rip when you remove them. there are 2 screws on the back of the tb that hold the rod in place, mark the point with a scratch so you can realign it.
after that it is streight forward.
I did mine and my rough idle and stalling /not ideling when it was hot out and the engine was cold stopped..
the procedure will take about 1 hour or less to do.

 

I took mine more appart then the pictures that 99runner4me did in his first pic what he is holding in his hand is the aic the plate on the back is what I removed. it is a strong magnet so i was nervous about pulling it out. though I may of taken it appart more then what would be required to clean it.. the rod in the middle should move very free mine barely moved. when I was done with it it was efforless.