Hey guys, thanks for all the help with this and my other posts! This is a 01 LS V8 that has been a pain in my A$@! Secondary tensioner was broke, replaced that and started right up, still runs rough and cylinder 7 misfire is still coming up when i scan it. I am thinking its out of time or I have a nicked valve? To time these cars do any of you have instructions on that? Will i need to take the front cover off? I am going to do a leak down test tomorrow on #7. I am however leaning towards a timing issue. Any imput would be great!
**Broken 2nd Spring Tensioner Replaced, Still Rough Idle?**
- Thread starter Eleanor88
- Start date
fbird18
Dedicated LVC Member
Did you check the timing when you took the cam off? There is a flat spot on the front end of the cam. As you rotate the crankshaft with a breaker bar, the flat spots on the two cams should face straight up together. You should be able to set a flat bar across the two flats. If you can, they should be in time. Someone with more experience will probably chime in and correct me if I'm wrong. Also its possible the coil is bad also.
I did replace the coils, and I did check the cams and they were Not perfectly flat. I did however scribe the sprocket and chain before i changed the tensioner. But i guess it is possible that it jumped the chain when the tensioner broke.
De-marko
Dedicated LVC Member
Like Fbird said, did you rotate the engine to where the "flats" of the cams are straight up to make sure the cams are in the correct relationship? I just want to make sure I understand you right. If the cam did indeed jump a tooth the scribe you made would be in the wrong place when you re-assembled the engine by that scribe. I'm sure you have seen this pic.
Ideally, when doing the timing chains there are two special tools that lock the cams and crank in place before the sprockets and chains are put back on to assure the cams are in the precise location. I know some guys have had success without these tools, but I like that peace of mind.
Ideally, when doing the timing chains there are two special tools that lock the cams and crank in place before the sprockets and chains are put back on to assure the cams are in the precise location. I know some guys have had success without these tools, but I like that peace of mind.
Before i removed the broken tensioner i scribed the cam sprockets and the chains. I then pulled the exhaust cam caps to remove the secondary tensioner. It is also important to note that before i scribed the cams i did notice that the flats on the cam were not perfectly aligned. I thought, never doing this before that once the new tensioner was installed it would be aligned. However once i torqued the tensioner and the cam the scribes were aligned but the cams were still not flat. Is there a thread on how involved it is to time this?
De-marko
Dedicated LVC Member
Ok, if they are off that can be the problem. Do your remember how far off they are? I know some of the guys here have a link on how to do this, but I can't remember who.
To make sure the engine is in time is not hard at all.
You have to take off the valve covers, rotate the engine to TDC and then an additional 45 degrees. On the Torque converter cover there is a small plastic plug that you have to remove along with the crank trigger sensor. Inside you will see a crank trigger ring that has some square holes. One of those holes is a special shape and that crank tool fits in where the sensor was into that special hole in the ring. That tool holds the crank in the right spot.
The flats of the cam should all be facing up. You would then use the 2nd special tool to lock the cams in place after the sprockets and chains are off. This puts the engine in precise mechanical relationship. With the 2nd tool still bolted down, you would then put on the chains and sprockets on and torque everything down. After that you would remove the tools and re-assemble everything.
This is just a quick rundown to give you an idea but that is the correct way, but like I said there are some members on here that have done things different with positive results.
To make sure the engine is in time is not hard at all.
You have to take off the valve covers, rotate the engine to TDC and then an additional 45 degrees. On the Torque converter cover there is a small plastic plug that you have to remove along with the crank trigger sensor. Inside you will see a crank trigger ring that has some square holes. One of those holes is a special shape and that crank tool fits in where the sensor was into that special hole in the ring. That tool holds the crank in the right spot.
The flats of the cam should all be facing up. You would then use the 2nd special tool to lock the cams in place after the sprockets and chains are off. This puts the engine in precise mechanical relationship. With the 2nd tool still bolted down, you would then put on the chains and sprockets on and torque everything down. After that you would remove the tools and re-assemble everything.
This is just a quick rundown to give you an idea but that is the correct way, but like I said there are some members on here that have done things different with positive results.