I have a 01 Caravan with 159,000 miles on it. I decided to give it a tune up and put in new spark plugs and wires. the plugs I took out were pretty bad. Guessing it never was done before I owned it. Anyway after I did all this I have now got a misfire at an idle sometimes and on acceleration. I checked all my connections with the new wires and they seem fine. I then decided to run some seafoam thorough induction and now it has gotten worse and it now backfires on heavy acceleration. No check engine light is on yet. It was running fine before the tune up. It had a slight rough idle but no miss. I am at a loss here. Any ideas anyone???? Need Help!!!!

 

Put all the old parts back in? Maybe you have a cracked spark plug, cross threaded one and it's not sealing?

 

I will try that...I dont have the old parts put will try with different plugs. It also seems like it does it more when the engine gets warm. And it doesn't miss or backfire when I'm at cruising speed.

 

When an engine is cold, it's running richer and higher idle which often hides misfire conditions.

 

The coil pack are numbered to the cylinders, front head 2,4,6 rear 1,3,5. If you look at the coil, the rear firing order is 3,1,5 and the firing order 2,4,6. One other thing you should always do, is gap the new spark plugs.

 

Another thing I noticed last night was when I hit a puddle the miss was there almost instantly and then after about 30 seconds went away on cruising speed. When I am at a constant speed then give it gas to accelerate it misses and sometimes backfires in the engine, a "pop" noise. Ill check the gap on the new plugs. I admit I didn't do that.

 

Any word on what the outcome was here?
I just tried to help gramps tune up his 2001 almost the letter on what happened here.
plugs, wires, seafoam,.... missing and backfiring with no codes.
(Changed rear shocks to but seriously doubt that is culprit
DOH!
Thank you.

 

Yes...Sorry forgot to post the solution...It was a cracked spark plug. replaced it and everything was fine. Hope this helps you!!

 

Thanks for posting the fix and glad to hear it was a comparatively easy one for this problem.

BTW - Born and raised in Michigan City. Hey neighbor.