Gotta grand cherokee for the wife and its got low power runs and drives but misfires code says secondary circuit malfunction...I'm stumped...bad coil pack rail, pcm?...not a bad cat just replaced that still didn't work help

 

I would say it's the coil pack, but I have no idea if you have the coil pack because you did'nt say what year your rig is.

 

Sorry it is a 99 4.0

 

Also is there a way I can test pack without taking it to a mechanic? I run on distributors lol don't know about coil packs yet...gonna learn a little here tho !

 

An easy way? not really without a scan tool that can do function tests. I would just replace the coil rail, they're not as expensive as you would think. www.rockauto.com will have it.

 

well i just checked rock auto (i use them for everything) but for some reason i cant seem to find coil pack rails in their inventory.....could u elaborate on the scan tool that can do function tests?....if its something i might need more than once im sure its something i would be interested in buying....sorry im pretty brand new to mechanics but im determined to figure this out without going to a mechanic lol....call it pride...or call it i told the wife i could fix it and i will :-)

 

You can find the old Snap-on scanners on ebay for around a hundred bucks, just have to make sure all of the cartridges are with it.

 

replaced coil rail, alternator, new terminals, spark plugs, ground strap contacts cleaned, contact points to new alternator clean......still P0353, P0352,P0351, aaaaand P1931...still irregular engine running, also unplugged battery & 3 pcm plugs for about 30 min




99 WJ 4.0 I6 220K wifes new to her first jeep
98 XJ 4.0 I6 145K my work in progress :°}

 

Busted.....coming up empty, I need u buddy lol

 

It may be a mechanical problem, start with a compression test and a leak down test if you can.

 

Been a while but after the spark plugs, injectors, wiring harness check, alt replace, new battery, cleaned ground straps, new coil packs....and 3 cpu,s...i bought a brandy new cpu...works great lol...figures