Rough Running

[dl117]

Hello, I have a 1990 regal that one day just out of the blue started running rough when it warms up, I have pulled plug wires to see if I am dropping a coil, so far to no aval.

What other ideas does anyone have to check next, I was thinking Converter overheating (creating to much back pressure) injectors, and fuel filter.

any help would be appreciated

Thanks Doug

[richtazz]

On these cars, rough running once warmed up is caused by one of three things.

1. Ignition component heat-sinking (ICM, crank position sensor, cam position sensor if equipped, ignition coil, etc...)
2. ECM failure (it's mounted under the hood)
3. EGR valve not opening, throwing off air/fuel ratio

[dl117]

Thanks, where are these located and is there a test I can perform on them.

I have had a similar condition in the past and replaced a coil, but that did not solve it so I put a ignition module in and that was it, so I have an extra good coil to use it that is it.

I just am not familiar with the ECM (and its location) and where the EGR valve is (1st time having to deal with one)