runs great when cold, bad when up to temp
 

Ok, here are the specifics.

1995 Jeep Grand Cherokee 5.2L V8, unknown history with 146,000 miles on it.


When the engine temp is old, it runs fine. However as soon as the coolant temp gauge goes above the 1/4 mark, it starts to have a really bad miss (but it's more of a random miss, not a rythmic miss) that is worse when overdrive kicks in. At full throttle the miss is still there, it actually gets bad enough at full throttle that it feels like you lift your foot partially up on the throttle and then slam it back down.

I don't know what the gas mileage is supposed to be on these but according to the overhead console mine is averaging about 14 mpg and I've been taking it really easy on it.

There currently is no CEL.


Any ideas guys? I've already tried doing a back yard shade tree mechanic top end cleaning that cleans the combustion chambers and the exhaust valves, but it had no effect.

Got a chance today to work on it. As with all my cars that I've ever owned, I like to do a tune up on them shortly after I buy them. So, today I went out and bought plugs, wires, cap, rotor, fuel filter, new 195 degree thermostat, thermostat gasket, intake manifold gasket set, and a light that was blown in the back.


Well, I only changed the fuel filter, plugs, wires, cap, and rotor. Come to find out, the plugs and wires were pretty new, but the cap and rotor were in bad shape. The cap showed signs of severe arching inside from one terminal to the adjoining ones!! Now after changing it I know why it wasn't changed in the past!! I broke 4 vacuum lines just trying to get the dat gum thing out!! :icon_eek: It's a tight fit between the firewall and fuel line!

So after changing all these, I took it out for a test drive. It runs soo good now!! I could probably turn around and sell it for a nice profit since I only paid $1700 for it!

I'm gonna put the intake manifold gasket set in my garage and just sit on it cause I imagine I'll have to change it out one day. As far as the thermostat, I'll probably change it next weekend since according to the stock gauge, the engine is only running at 170 degrees after the stat opens.

whats your gas mileage like now? I am averaging 14.5/15 mpg taking it real easy. It is all stock with 235/75/15s right now.

Before the tune up it was showing 14 mpg on the overhead console. I haven't even ran a tank of gas through it to see how accurate it is. Since I only drive 20 miles a day, it will probably be another almost 2 weeks before I find out what this tank of gas averaged.