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Discussion Starter #1
I changed my timing belt on my 2000 Tundra over the weekend. 4.7, V8. All the marks lined up right and stayed lined up right after turning it over twice like the Haynes manual says. Put it all back together, start it up and it seems like it's running fine timing-wise, but with a little miss. Barely noticeable at idle and even less noticeable revving about 2500. Took it out for a test run and it's missing bad under load and the check engine light flashes.... I know this is bad. Took it to Auto Zone and they came up with random cylinder misfire (p0300) cylinder 5 misfire (p0305) and cylinder 7 misfire (p307) Am I off on the timing? Or is this just a weird coincidence? I have done other timing belts in the past and anytime they were off--even a notch--the engine ran really bad and sputtered, backfired, etc. If I'm off on the timing how do I get it right when the marks are lined up? Any help would be GREATLY appreciated!! :)
 

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Check the following:

cam harness connector - connected securely ? no bent pins ?
coolant level in rad - full up and bled of air ?
air intake hose to throttlebody - clamp tight?
belt tensioner - did you compress and pin it, then remove pin after install ?

How is idle RPM ? o.k. , too high, too low
 

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Idle RMP is good. Everything else a yes except the belt tensioner install. Wasn't able to compress it, put it back on extended and tightened it down to torque specs. Will try in the morning to find a big enough vise. Was afraid that might be the problem. Any other suggestions if that doesn't work? :) Thanks!!!
 

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My question about the tensioner was to find out how you did it. I have also put them in without compressing and what you have to careful of is alignment onto the tensioner arm. My concern is that the belt tension may not have remained tight after the engine was started. See if you can confirm the belt is tight and is still aligned after the initial startup.

One other thing to check, and you may want to do this first, is the timing belt guide/crankshaft angle sensor plate. This is the toothed wheel that came off when you pulled the crank pulley. Pull the pulley and plastic cover and make sure you see it located on the outside of the belt. There will also be a polished side from the belt wear, it should face the belt. At this time also make sure the key is still in the crank so everything is aligned. Did the crank sensor get damaged or unplugged ?
 

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I have never changed a timing belt on a Toyota and do not know what I am talking about except to say I remember someone talking about a couple of the manuals having the #1 cylinder shown as being on the passenger side when it is actually on the drivers side on the V8. Forgive me if this is not of importance or is something you already knew, but I would rather say it just in case.
 

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I have never changed a timing belt on a Toyota and do not know what I am talking about except to say I remember someone talking about a couple of the manuals having the #1 cylinder shown as being on the passenger side when it is actually on the drivers side on the V8. Forgive me if this is not of importance or is something you already knew, but I would rather say it just in case.
In this case it would not be an issue as the belt aligns to marks on the cam pulleys and crank.

In reference to what you are mentioning, some V8's are reversed from others, and some manuals need to be read carefully as diagrams can be confusing. The most common mistake is the reference of right and left. The convention is the perspective from the driver's seat, looking forward. Therefore driver's side is left and passenger side is right. Now if you are leaning over the radiator working on the engine, your perspective is reverse and diagrams can look backwards. :)
 

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Discussion Starter #7
My question about the tensioner was to find out how you did it. I have also put them in without compressing and what you have to careful of is alignment onto the tensioner arm. My concern is that the belt tension may not have remained tight after the engine was started. See if you can confirm the belt is tight and is still aligned after the initial startup.

One other thing to check, and you may want to do this first, is the timing belt guide/crankshaft angle sensor plate. This is the toothed wheel that came off when you pulled the crank pulley. Pull the pulley and plastic cover and make sure you see it located on the outside of the belt. There will also be a polished side from the belt wear, it should face the belt. At this time also make sure the key is still in the crank so everything is aligned. Did the crank sensor get damaged or unplugged ?
I was concerned about the tensioner alignment--the first time I installed it and the second time I re-installed it.. I think the crank stuff is all good, but I will double check. Of course, I am second guessing everything at the moment! The crank sensor is sill plugged up, not sure if it may be damaged--didn't come up on the code scan, so I assume it's okay...?
 

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A total failure would code, however a sporatic signal may cause running issues and cause the misfire code, while not necessarily setting a crank sensor code. Perhaps go with the tensioner first.
 

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I discovered today that when I remove the pin with the tensioner on the truck, it just sits there. I was actually able to re-insert the pin. SO, think that might just be the problem! haha. Ordered a new one--supposed to be in at 9AM. We'll see if that's the only problem!
 

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The new tensioner didn't pop out either. Replaced the tensioner pulley and still nothing. Having it towed to the dealer in the morning. :-( Thanks for the help though!!
 

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did you remove the spark plugs when you changed the timing belt. if so the connectors for the coils might not be seated fully. this could cause the misfiring. as for the tensioner, if you don't have a vise try an arbor press or c-clamp. let us know what you find out.
 

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Thanks for all the advice. I had the truck towed to the Toyota dealer. Turns out a coil just happened to go out while I was doing the other work. Totally unrelated to the work I did--which figures with my luck! Replaced the faulty coil and everything is fine now.
 

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Thanks for all the advice. I had the truck towed to the Toyota dealer. Turns out a coil just happened to go out while I was doing the other work. Totally unrelated to the work I did--which figures with my luck! Replaced the faulty coil and everything is fine now.
Was it more than just one bad coil, because you had codes for random misfires and for two cylinders? Not that I don't believe you it's just that this is a little puzzling.


Paul
 

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It was just one coil bad. I was puzzled too about the random misfires and two specific cylinder misfires. What's even more puzzling is that the number 3 coil was the bad one and the cylinder-specific misfires were on 5 and 7. Maybe the bad one was throwing the others off--computer trying to compensate for the bad one or something? I dunno. But it runs good now, so I just accept it and drive on! :D
 

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My question about the tensioner was to find out how you did it. I have also put them in without compressing and what you have to careful of is alignment onto the tensioner arm. My concern is that the belt tension may not have remained tight after the engine was started. See if you can confirm the belt is tight and is still aligned after the initial startup.

One other thing to check, and you may want to do this first, is the timing belt guide/crankshaft angle sensor plate. This is the toothed wheel that came off when you pulled the crank pulley. Pull the pulley and plastic cover and make sure you see it located on the outside of the belt. There will also be a polished side from the belt wear, it should face the belt. At this time also make sure the key is still in the crank so everything is aligned. Did the crank sensor get damaged or unplugged ?
so i installed a timing belt kit a couple weeks ago and it didnt come with a tensioner so it didnt really occur to me to change it but after watching videos everybody compresses it, i installed mine by just using the mounting bolts without compressing it. im not having any issues or symptoms but im worried i might have messed up or something because i cant find anywhere that says you can do it except in this conversation. if it didnt seat right or was bad would it be immediately obvious or is this something i need to address right away.
 

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I changed my timing belt on my 2000 Tundra over the weekend. 4.7, V8. All the marks lined up right and stayed lined up right after turning it over twice like the Haynes manual says. Put it all back together, start it up and it seems like it's running fine timing-wise, but with a little miss. Barely noticeable at idle and even less noticeable revving about 2500. Took it out for a test run and it's missing bad under load and the check engine light flashes.... I know this is bad. Took it to Auto Zone and they came up with random cylinder misfire (p0300) cylinder 5 misfire (p0305) and cylinder 7 misfire (p307) Am I off on the timing? Or is this just a weird coincidence? I have done other timing belts in the past and anytime they were off--even a notch--the engine ran really bad and sputtered, backfired, etc. If I'm off on the timing how do I get it right when the marks are lined up? Any help would be GREATLY appreciated!! :)
recheck the marks
set to topdead center and make sure all marks line up perfect
 
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