Hey guys,

Just changed out my spark plugs and put new ignition coils on. When I first started it up, it ran really rough for about 10 seconds. After hitting the throttle a couple of times, it runs smooth now and sits where it should at idle.

But, when I gun it hard in neutral (about 4,000 rpm), I hear a couple of small backfires from the exhaust.

I did take the computer off to get to the #4 plug. I assume I can just put it back on without a reset from the dealer, correct?

I'm also assuming it's possible I didn't get one of the boots on exactly right and that might be causing the backfire. If that's the case, is there any way to tell which boot, or do I just have to check them all? Seems like if one of the boots was not on right, it would still run rough or I'd throw a misfire code.

I suppose it's also possible that it is some residual PB Blaster that was in the spark plug wells, but I figure that would burn up in the first second or two (not to mention, I did blow out the chambers with compressed air, so any residual stuff would be minimal).

I haven't been able to do a proper test drive. Traffic is horrible right now, so that will wait until the a.m.

Thanks for any help.

 

what coils did you use?

 

After much research and lack of funds, I settled on the Araparts coils on Ebay.

I made the initial post several days ago. The day after I posted, I did a proper test drive and everything seems good. The stammer in the engine is gone now. It used to shake between 40 and 50 mph (classic coil problem). That is gone. I have more power now too.

I am thinking the initial rough engine was caused by either the computer re-setting or a little too much dialectic grease. It's humming nicely now.

The small backfire I noticed also seems to be gone. It might have been from the Redline fuel injector cleaner I put in before I did the plug change or the PB blaster.

I do notice that the idle still seems to be bouncing just a little. I thought that would disappear with the new plugs. Probably O2 sensors being old. I've got 110,000 miles on it.

 

Clean the IAC with throtle body cleaner and lube it with WD 40

 

No IAC, as far as I can tell with quick research. It's an electric throttle body. Good advice though. I'm going to remove and thoroughly clean the throttle body. Any advice on this would be helpful. I'm probably going to get to it Sunday.

 

With the computer having been disconnected, it has to relearn the fuel trim.

4.6L or 5.4L? If 4.6L, plugs gapped correctly?

PCV and vacuum lines intact and where they belong?

Check Engine light on or flashing?

Clean the PCV valve with carb cleaner.

Generally speaking, I'd wait until you drive it for the final verdict.

 

I think there is a How To in the Articles and How To section. Check the index. Clean the MAF if you haven't.