jhand

Hey guys,
I need help fast. To start off with I purchased a used 01 Cherokee Sport about a month ago. At the time of purchase, the guy that sold it said the the original 4.0 engine went out and he replaced it with a 4.0 from a 98 model. The engine itself only had 95xxx on it. The body showed 165xxx. The cel was not on and the jeep ran good at the time of purchase. Around 2 days after purchase I got a rough idle and threw a cel code that was P0301, which is a cylinder 1 misfire. I immediately ran seafoam in the fuel and put some in the intake and I put new plugs in it, (the old plugs looked fine, no oil or coolant) and then I cleared the codes and within half an hour of new plugs the code came back. So then I said screw it and put a new coil pack on it, that is when the real problems started. After the new coil pack the cel started flashing and the jeep was acting like it wasn't getting fuel. It would rev up normally in park but with a miss but as soon as I put it in drive it started acting like it wasn't getting fuel, it would struggle to reach high rpms, although it would catch at times and rev high with a horrible miss and sputter. If I was going down the road I would place in neutral, shut off and back on and it would run fine besides a miss when you stop. It only seems to do this when I'm cruising at 1500 rpms or lower. Then I was like screw it high mileage I will start replacing sensors. New TPS. New crankshaft positioning. New oxygen sensor, new cam shaft sensor and none of them helped. So I was like ok I'll put in new upgraded fuel injectors, the upgrades have 4 holes instead of the single hole. Still no good. I'm not losing coolant, my oil is staying up and good. I'm about to lose my mind. I'm going to try to get a compression test done however if it is the block i thought I would be losing coolant or the plugs would show something. I'm at a complete loss. There are times this this happens I do show a multi cylinder misfire. Any suggestions? I will check and make sure that the plug in the coil pack is good and tight. Also I don't know if this makes a difference but during the miss I unplugged #1 injector and no change. Could it be the rail that the injector plugs come from? Help is needed. I purchased this jeep as a go to work vehicle because my dodge trans went out. Please help!

rgr4475

Free bump for you but definitely do the compression test in that cylinder if all of those parts your threw at it didn't work.

In the future, I would do that first before throwing parts at it to rule low or no compression out.

Turbo X_J

Do the compression test now.
It's entirely possible to replace perfectly good parts with stuff that's junk right out of the box. A systemic approach is much better than the shotgun style, and don't forget to document any and all changes / observations you have made.

jhand

Thanks for the reply. I'll try the compression test ASAP and let you guys know. I'm not good with motors but if the compression tests fails what are the possibilities? am I just looking at a cracked head or could it be something as simple as a seal?

jhand

Sorry it's taking me so long to reply. I did a compression test and all cylinders are showing 120 psi with no loss. The map sensor is showing good when checked. I have new iinformation too, I replaced the crankshaft sensor a few weeks ago and after I replaced it I got a no cam or crankshaft sensor code. I figured it was because I took it off so I cleared it and it came back so I pulled it off and checked it with a volt meter and it read good. Put it back on and I have to clear the codes again but I can't figure out why it was reading no ceankshqtt sensor. Also it will only go into limp mode during prolong idling or the rpms are under 1500. Any suggestions?

md21722

It's possible the valves for #1 are intermittently getting stuck. Try to do the compression test when the problem occurs. There is a TSB about valves not rotating when the engine doesn't see over 3200rpm. Check it out.

Kalali

It sounds like with the exception of the misfire, the engine was running fine before you started throwing parts at it. Backtrack your steps particularly the coil pack installation. Make sure all the six spark plug tubes are fully seated.

cruiser54

Yes. And Seafoam won't cut the carbon deposits under the valves.

jhand

Ok I got a little more information, I'm throwing code p1391 which is intermittent loss of camshaft or crankshaft sensor. It only goes into limp during idle and the engine is getting hotter (while driving engine temp is 190 it goes into limp about 210 or more). Still no change in the compression test. I bought a cheap crankshaft sensor online, I'm going to the Chrysler garage and get the actual jeep part. Again when it goes into limp if I turn the jeep in neutral, off then on it straightens right out no problem. But it seems the hotter it gets, again past 190 the miss gets worse and that's when it goes into limp. Is there anything or way to clean cylinder 1 valve? Again the compression test is normal at all times.

md21722

I'm not sure what "compression test normal at all times" means. How many times have you done the compression test when the problem occurs? Compression test can be low for either rings or valves. Often valve work will cause an increase in compression. Factory spec is 120-150 so you're at the lower end of what's allowed. My 01 XJ had a problem just as you describe with multiple cylinder misfire when hot. In my case after a long highway drive, then get stuck in traffic, idling, it would start missing. Head came off, valve work done, and problem never came back. Also, you have an 01 with a 98 engine. What year is the head and manifold? Both the manifolds and head castings changed between those years. 2000-2001 heads were "0331" castings and 1998 should be "0630".