centuryhouse

My 2000 WJ (Limited, V8, automatic, 2WD) was running fine for the first 700 miles of the trip, then suddenly began to run very rough and then kept dying if I didn't keep the rpm way up.

I pulled over, flipped the key 3 times and got the following codes:

p0201, p0202, p0203, p0204, p0207, p0208 (Injector or wiring to injector on cylinders 1-4, 7 and 8);

p0303, p0307 (cylinders 3 and 7 misfiring)

p0121 (TPS / throttle position sensor)

p1685 (SKIM (Smart Key Immobilizer Module) invalid key)

What could possibly make this happen?

The only previous problem I'd experienced related to any of this, was an occasional p0307 that would pop up for a while, then go away again for a while, and an occasional slight surging of RPM when sitting in idle.

centuryhouse

Day 3 and no comments? Is my post confusing, or does no one have suggestions or experience in this?

Outlaw Star

Tell you what, later tonight I'll cross reference my manuals to see what I can come up with for ya. Sounds almost like a bad ground somewhere.

centuryhouse

Thanks, Outlaw Star.

This stuff is so tricky. Most of my car experience was with a '73 Ford pickup, and my 67 and 70 Ford Mustangs. Things were so simple to figure out. These two Jeeps are really a whole other magnitude of complication, with sensors, computers etc.

centuryhouse

Almost 3 months later, and my Grand Cherokee is still sitting in the parking lot undrivable. I don't have the money for a shop, so I'm stuck doing it myself or doing nothing.

I've replaced the TPS, cleaned the AIC, checked all of the wiring and connectors I can think of, cleaned the throttle body, and replaced the fuel filter.

The car seems to run a little better but is still chugging/bucking mainly when accelerating. Idle seems mostly smooth, idle RPM is no longer surging and is about where it should be now.

The codes all went away when I had the battery disconnected. I've driven it 15 miles or so, but no codes yet - however, the engine light came on and was flashing which I believe means 'imminent engine damage', so I've been afraid to drive it far enough to get the codes to come up.

Any thoughts? I'm pretty desperate but out of ideas and cash. To add to it, my XJ is having problems too now so I'm about to be out of transportation.

dave1123

Have you checked/changed the TPS? Sounds like the computer doesn't sense where the throttle position is. You can check it electrically. It should read 1 volt or less at idle and 5 volts at WOT and be changing smoothly in between.

jtodaro

I agree with Outlaw Star, and it really does sound like a ground issue. When you got all the original CEL codes, they weren't ALL related to each other, but were kinda all over the place. Seems very odd, and ground like. I'd refresh (check/clean/retighten) all your grounds in your engine compartment.

dave1123

Check the plug on the PCM. It could be loose or not making good contact.

centuryhouse

What are some of the ground points I should check?

Obviously start at the battery's negative terminal, but where else?

auto2

you should look for a moble tech that for 100 bucks or so will come to your truck and tell you want is wrong.

also see if your computer has an update sticker on /near it. my 2000 has had the ecm updated.like from a recall?

investinwaffles

This is actually good advice.

Look on CraigsList and find someone that can help diagnose. To me, it sounds like it is a bad electrical connection if it all of a sudden starts running rough.

Plugs are all fresh? Have you tried unplugging each cylinder while the engine is running to narrow down the area of the problem??

centuryhouse

An update:

I got the Jeep to a local Jeep shop. While I thought it illogical that 4 coils or injectors could go bad at once, apparently somehow they did. So the mechanic pulled a few extras he had lying around and replaced them one by one, and the engine improved with each.

Next, he found a vacuum leak. It was a split on a hose somewhere behind the engine (behind & below throttle body, slightly to the passenger side, and attached to the end of a longish tube). We fixed that.

The engine was running MUCH better, but there was still a problem though. The #7 still got a 0303 code, misfiring cylinder. I had been getting this code intermittently here and there long before this all happened.

He replaced the cool/plug/injector and we still had a problem. He then ran compression tests, and all cylinders looked good (150 or so) EXCEPT for #7, which was 35.

The heads were replaced (with new) about 6 months ago, right before I bought the car. This was the shop that replaced them, and that sold me the car. They said that it is unlikely to be the new heads (worn rings), and that if it is a problem deeper in the engine (valves, etc) they would need to rebuild the engine, and that since they had sold me the car they would cut the labor in half and do it for $1200.

Opinions? I don't know much about inner engine stuff.

auto2

My humble opinion being a mechanic for 40 years is to not let them rebuild the engine but to buy a rebuilt engine from a major engine rebuilder with a warentee and pay them half the Labour to install it.call a few local shops and get a labor price to judge from.