hey guys got a Q my roller rockers went a couple months ago summit brand i think. well i had my computer programed for the 1.6 rockers and when i took them out i put on new stock rockers and push rods been trying to figure out motor shake and the spark advance on the scanner runs about 23 to 25 bouncing back and forth i think i read for an a4 it should be under 20 at idle. could the pcm prog be the issue cause of the 1.6 prog if so let me know thanks

 

Generally, you don't need a PCM tune just for roller rockers. The stock tune is good enough to handle the increased lift.

 

Not likely that the swap back to the stock rockers upset the PCM tune. Sounds more like the valves are not adjusted correctly, and the resulting instability of manifold absolute pressure (MAP) is causing the PCM to hunt through the spark advance tables. The tables set timing based on RPM and MAP.

 

now the map sensor reads 27.39 since i v had the scanner for 4 months never changes. and the way iv done the valve adjustments was by the book, then iv done them by shbox, and iv done them by setting each cylinder at tdc in the fireing order just like i do my roller in my drag truck. on the camaro iv set the preload to 1/2 to 3/4 and 1 turn and i mark the nuts to get each one the same. and i check the threads to make sure there the same or close. now i did notice on #5 exhaust valve was one thread more. would that point at the lifter being bad or is there anouther way to do these cams

 

27.39 as in 27.39 "Hg, or 27.39kPa?

If your MAP sensor reads a steady value its not working. It should show close to 100kPa without the engine running (depending on your elevation above sea level). That's how the PCM determines the barometric pressure.

 

its 27.39 hg checked the volts got 5.1 engine off and with engine on i got on the scanner 1.25 ish at idle and rev it jumps up but drops all the way to .30... with load it goes up and stays if i hold the rmp. now when u said i must of adjusted the valves wrong i was going by the arrow pointing at 12 oclock and this time i did it again with a pen in 1 cylinder it didnt stop till one o clock postintion for tdc (arrow on balancer) and i checked it three times just to make sure and shur enough same. would that lead me to my timing chain being streched... because of all the issues im having with timing, sputtering, and every now and then miss. and i do hear it but its not slapping around or nothing. and i guess she not going to boston i dont dare to drive that far even thou i know she make it, guess i got to take the titan man thats gunna be alot. let me know on that map and timing stuff on what u think, thanks