2001 Grand Cherokee 4.0

[Ryan Emig]

I have a 2001 WJ Grand Cherokee 4.0. I bought it yesterday with it missing bad, I ran the codes today and it was a random misfire code, misfire #1,2,3,4,5 and a bank one rich code. Any idea what this could be? It stumbles and misses at idle and even worse under load.

 

[JPNinPA]

Being you just bought it and don't have the history. Check the fuel pressure. Check the spark plugs. Post up the make and part number of the plugs. Check the gap. Do a compression test. Verify you have spark. Check the plug boots to see they are not cracked or damaged.

Also check for vacuum or intake leaks.

 

[Ryan Emig]

I have new plugs, coil pack, and a fuel pressure guage on there way. I'm doing a compression and a combustion leak test tomorrow. Just wanted to see if someone knew something I didn't but as much as I searched, couldn't find much. Thanks for the reply JP

 

[98Chero]

Also check for leaks in your cooling system. could be a blown head gasket. Hopefuly not but if the cooling water runs low your head gasket will take a beating for sure.
I hope this helps

 

[Ryan Emig]

I just did the combustion leak test, the blue liquid in clear tube, stuck in the radiator cap opening. It turned light green after about 4-5 minutes. So I'm guessing it's the head, since they're known to be crap. Then to top it off, when I was going to shut it off the oil pressure visage was at 0. I'm thinking I might as well get a used engine from Craigslist. This is just a vehicle I'm fixing to sell, trying to do it as fast and cheap as possible. Any input is appreciated.

 

[JPNinPA]

No oil pressure could just be the sending unit.

 

[98Chero]

Ya I had a sending unit that just needed to be cleaned. if you dont know how they work its a cheap replacement for a new one. If it is the head gasket it could cost 1.700.00 to replace it. Thats with a new water pump and cooling fan and igintion coil with a RnR on your radiator. I just payed that much on my 2000 Grand ! sould have run it across the scales because it has a leak in the heater core !

 

[Ryan Emig]

I just bought a reman head for $300. The oil pressure visage started working again after I let it sit and started it again. I'm going to start with the head and go from there. I'll part this out before I put over $1000 into it. No way I'd pay $2000