I picked up a 2005 MCS last year and couldn't have been happier, ive had to replace quite a few things however lately the car has been throwing a code 1489 for the vacuum leak after the supercharger i think? by all means correct me if i'm wrong. the last couple months ive noticed that under heavy load the engine soudns like its breaking up and misfiring, i've replaced the plugs and wires but not the coilpack however i've spoken to a few people about this and from what i understand the coilpack rarely goes bad. Is this true? are there any other things i should look for? The car is basically stock, one ball mod and coilovers but it was breaking up before all that. Could the occasional 1489 code be causing the sound i hear under load. Could the sound be something completely different? Any suggestions are very welcome. Thanks in advance.

edit: the code typically dissapears overnight and it never goes into limp mode or anything.

 

What happens with the OEM coil pack is that the terminals corrode. Pull off each spark plug wire and look closely at the coil terminal and inside the spark plug boot for corrosion. Every older MCS I have looked at has had some corrosion on the coil terminals. You can clean off (sand) the corrosion on the terminal and reinstall with di-electric grease.

After cleaning my coil terminals a couple times, I installed a screaming demon coil to eliminate the corrosion issue.

 

yea there was corrosion on the #3 but i sanded it down and used di-electric grease but still the issue continues. could it be a timing chain issue? or an intake issue?