2.4L dual cam

timing-belts
valves

#1

I did a valve job on a 2.4L dual overhead cam and the timing is not right. Its backfiring and when it runs it will not go over 2000 rpm. What are my options?


#2

Although you don’t say, I assume the car did not have these symptoms before the valve job. Are you sure you got the clearances right? I’d start by re-checking your work on the valve job.

I also have no idea what motor you’re working on, but if for whatever reason you removed the distributor, you may have altered the timing when you put it back on. It may need to be rotated.


#3

It does not have a distributor. Its a 96 grand am GT. And all I did was clean up the valves and put it back together. The valves and the valve seats.


#4

It does have a timing chain, check your valve timing. If that is ok, then check your crank angle sensor and its wiring.


#5

[b]If you’re sure you got all the secondary igniton system connected correctly, then the problem has to be valve timing. Or the timing chain isn’t installed correctly.

The ignition system in your vehicle is called a Wasted Spark Igntion system. You’ll notice that you have two coils, and each has two towers. When a coil fires, it fires two sparkplugs at once. Only when this happens, the cylinder that has the proper air/fuel ratio is the one that fires. At the same time, another cylinder fires but it’s at a postion in valve timing where no air/fuel is in the cylinder. So nothing happens. Hence the name Wasted Spark Ignition.

If you get the valve timing off with this type of ignition system, air/fuel can end up in a cylinder where a wasted spark should occur. And this can cause backfire and lack of power on these engines.

Check that timing chain again.

Tester[/b]