hshawn31

my 97 jeep country, 4x4 inline 6 cylinder, has a misfire...new plugs, wires, distributor checked, new map sensor, new tps, new ignition coil and starter. Theres no coolant loss. While idling it sounds like it is coming from drivers side somewhere. I cleaned the ccv valve and still no luck. Theres no vaccuum leaks, i have checked like 6 times and followed each line. It has been doing this for 3 weeks now...

PLs HELP!!!!!

hshawn31

nobody? i am thinking maybe the Crankshaft Position Sensor?....i took off the IAC and cleaned it, still has a slight miss but CEl doesnt come on right away anymore.

VTJeep

Ya, the the things I didn't see where new TPS, IAC, and both o2's. That's pretty much in order of $$$, the TPS and IAC are pretty much the same. Just go legit OEM parts, not like autopartswarehouse.com type stuff. Not to pick on them, it's nothing personal. But there's a lot less hassle going right thru an OEM source.

Edit- didn't they stop using the CPS in 94?

hshawn31

no, my 97 still has it. It in my haynes manual and all the things that could act up due to the sensor being faulty are what im experiencing. As for the o2 sensors, i dont have and codes for the o2 sensors being faulty, just the generice misfire in one or more cylinders.
i tried taking it to autozone and their reader wouldnt connect to the computer...

hshawn31

and it does have a new TPS, the IAC is about a year old and i can tell the downstream O2 sensor is about a year old....the upstream one is very dirty and oily...

tjwalker

Always post the EXACT code number here for the most accurate replies. There are lots of codes that have a description close to another.

If it is is a P0300, start with verifying fuel pressure. For a 97, you should have 49 psi, plus or minus 5 psi.

Also perform a comprehensive search for a vacuum leak.

hshawn31

sorry, it was a code 43, misfire in one or more cylinders. I just changed the upstream o2 sensor since i believe it was the original. ( Jeep has 263,000 miles) We will see tomorrow....

tjwalker

A number of possibilities. I would start with getting a new distributor cap and rotor on there though to finish your tuneup. Don't want to chase your tail for $20 worth of parts. The ignition coil is another possibility here and certainly should be tested or replaced to eliminate that as a possibility.

I remember a weird valve spring issue on your vintage that can cause a code 43. Think it was caused by a bad batch of valve springs that got into a very limited quantity of 4.0 engines.

Here is a link to some threads on it (GOOGLE code 43 + Jeep)

http://www.wranglerforum.com/f5/chec...3-a-37718.html

http://www.wranglerforum.com/f5/chec...3-a-61955.html

http://www.playcircuit.com/help-96-c...ode-16117.html

Something to keep in mind if you can't find root cause with the usual suspects.

Flash1034

Following this closely as my 97 is doing the same thing right now. Seems to come and go on a bi weekly basis...weird...I know.

Flash

Flash1034

Changed my plugs today to stock Champions...No difference. Guess Ill replace the coil next....Im running out of ideas?

Flash

Flash1034

Anybody else have any ideas?

Flash

hshawn31

my coil is a week old and it didnt help. This is what i have replace so far: TPS, IAC, PLUGS, CAP, IGNITION COIL, UPSTREAM O2 SENSOR, MAP SENSOR, oil pressure sending is about a year old, new alternator, and sprayed half a can of carb cleaner into her. All vacuum lines are checked and triple checked, all fine. No coolant or oil loss. I put a bottle of that compression loss stuff (dont rmbr name) but didnt help....


As for the valve thing. I read that was mainly on Wranglers. They have totally differant valves and springs than these. And if not, wouldnt mine have failed by now? Its been like this for 3 weeks now. i just want it back to normal

ball buster

heat soak is an issue.. alot of folks dont think about the heat affecting the injectors but it does. my injectors were getting heat soaked after sitting for less than 5 min after shutdown and giving me missfire codes and i dont even have plug wires,cap&rotor. since i insulated my injectors I have not had a missfire code yet (knock on wood) im still in the testing stage. running all oe components with 107k mi except plugs. I changed them last week

Boost Happy

Sounds like you have a valve seat issue. This is very common issue for the trusty 4.0 on the exhaust side. The seats tend to warp. I recommend a cylinder leak down test, you should notice your leakage around 30-50%, Anything more than 20% is bad. This issue can be resolved with a simple reseating of the valves by a machine should, but in more extreme cases it may need machining of the seat or simply replacing the head with a reman. remans are $500 from napa btw

Boost Happy

That was an issue for the 99-00 4.0l's There is actually a TSB on that. It is due to the cast manifold with conjunction of late style injectors