O K guy's, I'm a newbie to Lexus, but an experienced tuner, anyway I changed my water pump and timming belt on my newly acquired '98 GS 400, I used the yellow "T" timing marks on the cams and set-up the crank on TDC, ( used the lexus belt with the marks on it)after re-assy there is a rough idle when the engine gets to temp and clears out until a point where the engine seems to stumble, the right cam makes a funny noise, everything sounds wierd for a couple of seconds then back to smooth. Did I use the wrong alignment marks or what? I feel like an idiot PLEASE HELP.

 

Is the check engine light come on? Everything putting back the same way? You have to be very carefull with these vvt-i engine. Miss three teeth and you will bend the valves.
JPI

 

the check engine light is not on, and all the alignment marks line up after rotating the engine several times by hand, Is there any alignment for the VVTI actuator? If a valve were bent the engine would run like --it. It runs and sounds smooth and quiet until after it gets warm, then it idles smoothly except for this stumble.

 

Check all your vaccum hose. Did you take the throttle body out by any chance? If your valves are bend, the bend will very bad all the time. Check all your hoses and run a compression test really quick.
JPi

 

Thanks for your help, I found my "F" up.. It turns out that the yellow T marks were not the correct place to set the cams. FYI If the crank is TDC the cams yellow mark lines up on the hash mark and not the yellow T mark. Seems kind of tricky, but my car runs perfect now...THANKS AGAIN,,, Mark

 

I'm so glad you didn't do any damage to the engine. I've seen rookies bend valves on Sc430 .
JPI