Misfire, lose of power, wont rev past 3,000

[brucebotti]

Start simple.. Clear the codes...

New plugs, costs about $25 for plugs and some dielectric grease and antiseize.

Drive and see if the problem comes back.

If the problem comes back.. Clear the codes... Swap one of the cylinders that are reporting a misfire with one that isn't, for example take the coil pack from #1 and put it on #2. Drive until it acts up again and then get the codes again and see if #1 had a misfire now but #2 is ok. If thats the case then you have a bad coil pack. If neither 1 or 2 have a misfire then swap them back and take #1 and swap with #3 or #4 and again clear codes and try again. The goal here is to troubleshoot if its bad coil packs without spending any money.

If you can eliminate a misfire on one of the cylinders by swapping then go buy a new coil pack and replace that one. And again drive for a while and see if the other two still act up. And continue that until they are all swapped.

They aren't too bad of a price though, like $20 a piece at Advance Auto Parts the last time i looked, so if you wanted you could buy three new ones, or heck six new ones, just depends on how much money you want to spend.

Hey kbOnly,
You are like the Dear Abby of Jeep Maintenance and Repair. You always seem to know exactly what to do, or at the very least least the right course of action to take to get to the root of the problem. Thanks for all the level-headed advice that you give us!
Bruce

 

[tjkj2002]

I'd stay away from advance auto(and the like) coil packs,you can get OEM coil packs for $26.

http://www.moparpartsamerica.com/pa...erty&year=2005&catalogid=2&displayCatalogid=0

 

[moparman]

See it all the time on the Nissan 3.0/3.5 V6,common issue for them and can happen to others also.

Oh, did I say unlikely? I meant unlucky! I was speaking hypothetically without experience to call on. I did not know that about Nissans. Thanks for the info. I just realized that it's been about 16 years since I last turned wrenches for a paycheck. Time flies.

 

[moparman]

Can the coil be checked with an ohmeter? (as I look for my Haynes manual) Answer is yes but the trick would be trying to catch an intermittent failure.

 

[tjkj2002]

Could also be cracked porcelain on the spark plugs,usually does not show up until fully warmed up if it's a hairline crack.

 

[belvedere]

Worst possible thing you can do since it now gives aother path for the spark to travel causing a misfire.Just a small amount on the end of the plug where the coil sits is all that is needed,a very small amount so it does not get on the coil boot.

You've got it bass-ackwards. The boot/porcelin is where the di-electric grease goes. No "other spark path" occurs, since di-electric grease is non-conductive.

The benefits are keeping moisture out (thus preventing corrosion) and making sure the boot doesn't stick to the plug.

 

[tjkj2002]

You've got it bass-ackwards. The boot/porcelin is where the di-electric grease goes. No "other spark path" occurs, since di-electric grease is non-conductive.

The benefits are keeping moisture out (thus preventing corrosion) and making sure the boot doesn't stick to the plug.

Not always,had a 5.4 in Ford F150 that had a bad misfire(all 8 cylinders) from that junk,cleaned it all off and no more misfire.

 

[kb0nly]

Hey kbOnly,
You are like the Dear Abby of Jeep Maintenance and Repair. You always seem to know exactly what to do, or at the very least least the right course of action to take to get to the root of the problem. Thanks for all the level-headed advice that you give us!
Bruce

No problem... Im cheap if you havent already notice, do the cheap things first!!!

I was raised by old school wrench turners.

 

[kb0nly]

I'd stay away from advance auto(and the like) coil packs,you can get OEM coil packs for $26.

http://www.moparpartsamerica.com/pa...erty&year=2005&catalogid=2&displayCatalogid=0

True... And i will agree if they give the same warranty on the coil pack, any idea on that? Not sure what Mopar parts does for stuff like that as i usually end up going to the local parts store instead, not always for price but sometimes its a combo of price and better warranty replacement.

The other problem i have been having is Chrysler dealers around here are really low on parts. I mean like super low "we don't have it but can in a week" low. I know one local dealership using parts from Advance Auto to do maintenance and repairs because everything is on backorder when they need it.

I don't know if its a Chrysler problem or the suppliers that make the parts for them?? Speaking of which, the coil packs in the KJ are made by another company and just branded for Mopar, same company makes coils for places like Napa and Advance with their name on it. Just saying......

 

[belvedere]

Not always,had a 5.4 in Ford F150 that had a bad misfire(all 8 cylinders) from that junk,cleaned it all off and no more misfire.

I would guess that there was too much grease, and it may have been built up between the contacts, preventing a good spark. The word "dielectric", by definition, means insulation.

 

[punkguy]

Replaced all the coils and plugs last weekend and she's running like a dream again. Those plugs in there were still stock I'm thinking.......they were toasted.

 

[ridenby]

Replaced all the coils and plugs last weekend and she's running like a dream again. Those plugs in there were still stock I'm thinking.......they were toasted.

Good Deal!!!!

 

[Giggity]

New to the forum and found this thread as I started having the same problem yesterday with my '03. It would start cutting out at 2000 RPM after warming up.
Today I replaced the plugs (old ones looked to be original as the electrodes were worn down to almost nothing) but not coil packs and took it for a ride. After it warmed up it died on me and I was stranded along road. Let it sit for about 10 minutes and got it started again. I made it back into the subdivision and it died again before I made it back to the house. Fault codes are P0320, P0340, P0700. Do I need to now replace all 6 coils?