Engine Code

[DriverJC]

On the way home from the trail last weekend my Jeep threw a code. I got home and checked it and found it was a 43. Cylinder Misfire. I went to kragen got the parts for a tune up and installed them.

Well today on my way to the smog station the jeep throws another code. get to a parking lot and find it to be the same code. DAMN.

Took it into the mechanic this afternoon and find out that it's a bad Injector.

Gota love computer controlled vehicles.

I really need to get me one of those scanners.

Joel

[DriverJC]

So I went in today to get the injector changed, took about 20 minutes then as I was driving away it threw a code again. stop on the side of the road and checked the code on the Odometer. Same damn thing.

Went back into the mechanic and told them the problem.

They did a compression test and found that the $3 Cylinder is only registering 60psi vide the 120 it should have.

So it's either a Blown Head gasket, Stuck/burned Valve, Cracked Piston Ring, or cracked block.

I'm waiting for some help to show up so I can force air into the cylinder to see if we can determine where the leak is.

Needless to say all upgrades are now on hold.

See ya
Joel

[Matt2001TJ]

So I went in today to get the injector changed, took about 20 minutes then as I was driving away it threw a code again. stop on the side of the road and checked the code on the Odometer. Same damn thing.Went back into the mechanic and told them the problem.They did a compression test and found that the $3 Cylinder is only registering 60psi vide the 120 it should have.So it's either a Blown Head gasket, Stuck/burned Valve, Cracked Piston Ring, or cracked block.

That sucks, I think I would find another mechanic though. Anyone can do trial and error parts swaps at your expense. Also, I bought my code reader at Harbor freight for 40 bucks. Autozone will let you use there reader on site for free...MATT

[DriverJC]

Unfortunately, I got to see what their 10K code reader said.

P0304: Misfire #4 Cylinder.

According to the literature that code is thrown if the coil is week (although that would get a random cylinder not just #4), Plug, Wire, Cap and/or Rotor is bad (just changed them all two days ago), Injector is bad (replaced that today), or the Cylinder isn't firing/or is firing week.

They did a Compression test on three cylinders of the engine, 1,6, and 4, they got 120psi on cyl 1 and 6, and 60 on #4.

The good thing is that we should be able to troubleshoot it down a little farther once I get some help tomorrow. We will be forcing air into the cyl in order to see where the leak is. If it's intake or exhaust then it's a valve or cracked head, crankcase it's a ring or cracked block.

One reason that I'm leaning on trusting this mechanic is that they are crediting me with the 189.00 that I paid for the injector replacment. Basically they did the work today for free. Granted they are not giving me the money back, but if I need something else done, and I will, the first 189 is on them.

I'm leaning towards a Valve or Head gasket. The reason for this is that Last March it over heated when the water pump went. When I got home from deployment in late november I replaced that and the Radiator. Then drove it on two trail runs with no problems. After the second trail run I got a code after the run was over and I started driving at speeds on the street back to the tow rig.

Just need to fix it so it can pass smog then I'm good to go.
Joel

[miguelitojeep97]

what motor/vehicle is this on?

[DriverJC]

97 Jeep Wrangler 4.0L Inline 6 Cyl with a Manual Trans.

Thanks
Joel

[Matt2001TJ]

Unfortunately, I got to see what their 10K code reader said.

P0304: Misfire #4 Cylinder.

According to the literature that code is thrown if the coil is week (although that would get a random cylinder not just #4), Plug, Wire, Cap and/or Rotor is bad (just changed them all two days ago), Injector is bad (replaced that today), or the Cylinder isn't firing/or is firing week.

They did a Compression test on three cylinders of the engine, 1,6, and 4, they got 120psi on cyl 1 and 6, and 60 on #4.

The good thing is that we should be able to troubleshoot it down a little farther once I get some help tomorrow. We will be forcing air into the cyl in order to see where the leak is. If it's intake or exhaust then it's a valve or cracked head, crankcase it's a ring or cracked block.

One reason that I'm leaning on trusting this mechanic is that they are crediting me with the 189.00 that I paid for the injector replacment. Basically they did the work today for free. Granted they are not giving me the money back, but if I need something else done, and I will, the first 189 is on them.

I'm leaning towards a Valve or Head gasket. The reason for this is that Last March it over heated when the water pump went. When I got home from deployment in late november I replaced that and the Radiator. Then drove it on two trail runs with no problems. After the second trail run I got a code after the run was over and I started driving at speeds on the street back to the tow rig.

Just need to fix it so it can pass smog then I'm good to go.
Joel

I can see the point about the mechanic. Ah the wonderful P0300 through 306 codes. I have seen that many times on my code reader as well. Well here is a reality to that regardless of the compression test. The TJ and cherokee 97 on up have the fuel pump inside the tank thanks to the great fuel injection which goes right through smog of course. The fuel pump has a built in regulator which if that starts to malfunction then it will not regulate the fuel properly and then the fuel injection system which is super sensative will not perform up to par also. I know this by first hand experience trust me. Also, the crank shaft sensor is your next thing to wonder and worry about. I carry both items in my rig just in case because I know better....MATT

[DriverJC]

My Fuel Pump was replaced in March of 2007 because it went bad. The crank sensor has not been replaced. Is there a way to troubleshot that specific sensor?

I will check the Fuel Pump to see if it is putting out the required PSI when we troubleshot it tomorrow. although I would think that if it was the Fuel Pump going bad it would give me a random cylinder. This one comes up at #4 every time it has come on.

I will be looking more into it tomorrow.

Thanks for the advice
Joel

[Matt2001TJ]

My Fuel Pump was replaced in March of 2007 because it went bad. The crank sensor has not been replaced. Is there a way to troubleshot that specific sensor?

I will check the Fuel Pump to see if it is putting out the required PSI when we troubleshot it tomorrow. although I would think that if it was the Fuel Pump going bad it would give me a random cylinder. This one comes up at #4 every time it has come on.

I will be looking more into it tomorrow.

Thanks for the advice
Joel

your crank sensor will let you know when its bad because your jeep will just shut off and after about 15 to 30 minutes it will start again (after it decides to de-magnetize itself) and run for a few more minutes and then same thing. It is just a part you buy and keep in your toolbox for when it does happen because if it happens on a trail your screwed. Pep Boys 68 bucks.

[DriverJC]

I completed a Compression check of all cylinders on the engine.
Cyl #1: 120psi peek; 110psi first crank
Cyl #2: 120psi peek; 110psi first crank
Cyl #3: 120psi peek; 105psi first crank
Cyl #4: 90psi peek; 90psi first crank (every crank after the first the psi went down until stabilizing at 60psi)
Cyl #5: 120psi peek; 110 first crank
Cyl #6: 120psi peek; 110psi First crank

After resetting the engine to TDC on Cyl #4 we blew air into the #4 Cylinder to check where it was leaking.
Rule of Thumb is if you hear air from the intake it's a bad intake valve; Exhaust; is a bad exhaust valve; radiator; is a cracked head; Valve Cover; it's a bad ring, bad piston, or cracked block.

We found lots of air escaping from the exhaust valve. we did this ten times resetting the engine all the time and both myself and my father listened at all the points for air escaping. we got the same readings.

The exhaust valve is bad on the #4 Cylinde.

Now the last Valve Job we had done was something like 10 years ago (not on this vehicle, lol) and it ran 250-300 dollars. Anyone know what the going rate is now?

I found at Wranglerbarn a complete Cylinder Head for 199.00 w/free shipping so I'm thinking of get that one. I have emailed the website and asked if the head has been checked and if all the valves are in good working order. hopefully they will respond today and I will be able to purchase it.

Thanks
Joel

[DriverJC]

Well I have an update to this.

We took the head off today and found no burned valves. however once we turned the head on its side we sprayed WD40 into the Intake valves and found that after spraying the fluid into the #4 Intake Valve that it would leek out the #4 Exhaust valve. After clearing out all the oil and drying the head again we sprayed the oil into the exhaust valves. This time the fluid leaked out the exhaust valve.

So it looks like the problem is a cracked head. well I bolted up the newer head today and will finish buttoning it up tomorrow.

Lets hope this fixes it.

joel

[Materdaddy]

Joel, Thanks for keeping us updated. The information in this thread may prove useful to somebody else.

Matt, Do you have the part number for the CPS? I've been meaning to pick up a CPS and TPS to keep in the tool bag, but want to make sure the guy at the parts counter doesn't give me the wrong one. I wouldn't find out until I needed it, and having the wrong one would piss me off more than not having one at all!

[DriverJC]

After bolting up the head and getting everything buttoned up I found I have a MAJOR Vacuum leak. Apperently the Intake Manifold is not sealing.

Will definately be re-doing that this week. I need to get it going for the sledge hammer rum next weekend.

Joel

[DriverJC]

Here is the final outcome. We took the intake manifold off again and and found that it was not alligned with the centering pins on the head. it was actually resting on top of the pins.

After re-seating the intake manifold we re-Torqued te bols and it fired right up and purrrrred like a kitten.

after idling for 20 minutes we found no engine codes in the system other then the 12 (Battery Disconnect) and 55 (End of codes).

Good news.

So When I get home from work today I will be driving it all over in order to ensure that the codes do not comes back.

Thanks for all the help.
Joel