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Discussion Starter #1
I was hoping that someone could give me some suggestions on what to do. I am the original owner and have never had problems until now. I just cleared 90k, and I have a rough idle and loss of power. About a year ago my idle was really rough and my check engine light came on. I got some code stating it was running to rich and it pointed to the oxygen sensor. Had that replaced and was back in business.
Just recently that same rough idle if not worst is back. The thing is that my check engine light is not on and we have checked for pending codes which yields nothing. Besides the rough idle the truck has lost major power and when I do step on it, the intake noise is loud, like its not getting enough air. I can get the truck to any speed I like, but it just takes a bit longer and I can hear the engine ping a bit too. Things I have done:

-Cleaned MAF sensor
-Replaced MAF with known good sensor -another 99 prerunner
-Replaced Fuel filter since it seemed a bit clogged
-New air filter just because the old one was dirty ( not a big deal)
-Cleaned throttle

I am at a loss on what to do, with no check engine light I kind of have my hands tied down. Any suggestions would be greatly appreciated. Thanks in advanced
 

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I am having the same problems. Over the past year of having that issue I have replaced the plug wires, mass airflow meter, throttle position sensor, fuel filter, idle air control valve, EGR diaphragm, and had the cylinder head rebuilt. Right now I'm leaning towards replacing all of the injectors.

For you I would start by figuring out if the problem is caused by lack of spark or lack of fuel. From there you can start narrowing down the suspects. A set of spark plugs and wires is cheap.
 

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Theres another thread goin on about a PCV valve. I cant explain but search for it and youll see.
 

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Check your fuel filters and have an injector service done as well.
 

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Discussion Starter #8 (Edited)
Thanks for all your replies. My father owns an Auto parts store so getting parts is no big deal, assuming their in stock or can be ordered for a reasonable price. I just switched out the fuel filter so I got that covered. Plugs are cheap so I will be trying that next. It just seems to me that whatever is wrong is going to be a bear to find.

Funny that someone mentions valve adjustments since I have had a little clicking in the drivers side head for a couple of years. Not much at times but enough for me to hear it from the inside of the cab.

As for the PCV valve, not sure what the problem is but I am running a FRAM one so not sure if the problem is specific to OEM parts.
 

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dont forget there's another filter in the tank on the fuel pump
 

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Discussion Starter #10
Yeah, the strainer. I'm not sure how much work it would take to drop the tank, but at this point it might be worth it.
 

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I had an issue that was similar to yours and it turned out to be a bad Ignition Coil. It was misfiring under acceleration bad- I could still accelerate but I had to be gentle on the throttle and cruising it was fine normally without load. As things progressed longer it was starting to miss at idle too. I went through everything too... wires, plugs, pcv, cleaned MAF, cleaned Throttle Body etc and didn't have any codes until the cylinder it was on misfired enough times to throw a code.
 

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My buddy had the same prob. tried all of these suggestions. Come to find out one of the coil packs was bad. it would fire only about half the time. It seemed to run fine just putsing around town but if he excelerated to get on highway or to go up a hill it would sputter, with lots of power loss. The mech. said he did not find the prob right away because it would work at an idle or light excel. it only miss fired under heavy excel. sometimes he would get a check engine light other times not.
 

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Mine looked like to was overcharging or something odd... it was arcing down the inside of the boot and shorting the plug. I have two plugs that had trace "burn" marks down them. You can also see a burn mark down the inside of the boot.
 

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Didn't see this mentioned, Throttle Positioning Sensor (TPS). Mine was doing the same thing for quite a while. As I was finally taking it in to get looked at, it sputtered, slowed and wouldn't go over 35 mph. A new TPS, and all's good.
 

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Edrod13 said:
I was hoping that someone could give me some suggestions on what to do. I am the original owner and have never had problems until now. I just cleared 90k, and I have a rough idle and loss of power. About a year ago my idle was really rough and my check engine light came on. I got some code stating it was running to rich and it pointed to the oxygen sensor. Had that replaced and was back in business.
Just recently that same rough idle if not worst is back. The thing is that my check engine light is not on and we have checked for pending codes which yields nothing. Besides the rough idle the truck has lost major power and when I do step on it, the intake noise is loud, like its not getting enough air. I can get the truck to any speed I like, but it just takes a bit longer and I can hear the engine ping a bit too. Things I have done:

-Cleaned MAF sensor
-Replaced MAF with known good sensor -another 99 prerunner
-Replaced Fuel filter since it seemed a bit clogged
-New air filter just because the old one was dirty ( not a big deal)
-Cleaned throttle

I am at a loss on what to do, with no check engine light I kind of have my hands tied down. Any suggestions would be greatly appreciated. Thanks in advanced
Have you changed your timing belt yet? I had some similiar issues that wouldnt go away, after timing belt swap I was all good?
 

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Discussion Starter #18
Have a friend that works for a local Toyota Stealership. I spoke to one of the techs, and he is going to look at my truck tomorrow at his house. He did mention though that regardless of what happens we should start by replacing the timing belt since I am at 90k miles. He said that he has seen similar symptoms on tacomas where a streched belt does what my truck has. I will post back with any news since you guys have put some time in helping me. Nothing worse than giving advice and then never hearing from a person to see if what you suggested worked or not. Thanks guys
 

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Discussion Starter #19
Well it looks as if a leaking water pump weakend the timing belt. The belt had 3 teeth that were pretty worn. Also, the leak was so small, that the water would crystalize and turn into small hard rocks which would eat at the belt when they fell from the pump. I never had any indications since my truck was never overheating, but just wanted to let you guys know what was the problem. I can tell you one thing though, it feels good to have full power back. Thanks
 

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I am having the same problems. Over the past year of having that issue I have replaced the plug wires, mass airflow meter, throttle position sensor, fuel filter, idle air control valve, EGR diaphragm, and had the cylinder head rebuilt. Right now I'm leaning towards replacing all of the injectors.

For you I would start by figuring out if the problem is caused by lack of spark or lack of fuel. From there you can start narrowing down the suspects. A set of spark plugs and wires is cheap.
Try this, get a plier and try pinching the fuel return hose. If it idles properly while pinching it then i know the solution. Try it first
 
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