P0300, P0315, P0335 codes - misfire issue - JeepForum.com
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post #1 of 19 Old 10-14-2019, 11:04 PM Thread Starter
99sajeep
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P0300, P0315, P0335 codes - misfire issue

Here's what happened:
Accelerating to get on the highway and pass a slow driver, at about 65-70 mph, I get a big "thump" thru the drive train (like the trans shifted hard), MIL starts flashing, "Ding" goes off, and the traction control light on the dash comes on. Engine is still running, I can accelerate, downshift gears, etc., but I pull over to get my code reader out.

I get the following codes:
P0300 - Random misfire
P0315 - Crankshaft Position Sensor not learned
P0335 - Crankshaft Position Sensor Circuit

I clear the codes and start it back up to see if it's a fluke issue. The P0300 came back shortly after I started driving again.

So, I'm in Austin 75 miles away from my office and I have a meeting in 3 hrs back in San Antonio. It's running, but the MIL is still flashing and everything else seems to be working fine. So I drive.

Engine runs good, trans is shifting fine, MIL is still flashing, but then I notice that there is what appears to be a "shudder" thru the drive train while accelerating. It goes away while coasting or with light, constant throttle. But as I give it more gas to go up an incline/hill, there is a shudder.

It didn't appear to burning excessive fuel as my mileage was going up (according to the dash) since I was keeping my speed at 65 and under. It got up to 18.5 mpg by the time I got back to my office.

MIL stayed flashing the entire drive, but the "ding" from the dash would only happen every 5-10 minutes.

By the time I got to the office, there was a noticeable mis at idle and the engine was running a little rough.

I checked codes again:
P0300 - Random Misfire
P3402 - Cyl 1 Deactivation Control Performance
P3426 - Cyl 4 Deactivation Control Performance
P3442 - Cyl 6 Deactivation Control Performance
P1417 - Cyl 7 Reactivation Control Performance

The misfire is still there (obviously by the rough idle) but now the MDS is involved? I cleared the codes, and it ran smooth again. Figure I'd let it sit for the afternoon before I tried to drive the final 15 miles home.

After work, got going and things were smooth for the first 1/2 mile, then the shudder under acceleration came back. MIL still flashing.

Get home and the only code is the P0300.

I still have no idea what caused the initial "thump" but it never happened again. My scanner has read trans codes before and none are showing up now. The shudder under acceleration is RPM dependent. I can manually downshift the trans while accelerating and the frequency of the shudder will increase with RPM's, even though my speed remains the same.

So to me, it's totally engine related, but I'm not sure if it's mechanical or electrical. I'm tempted to look into the Crankshaft Position Sensor, but those codes only appeared the very first time and not again.

Any ideas or suggestions? I didn't have time to dig into it tonight, but will start checking anything I can tomorrow.


'99 WJ 4x4 Ltd 4.7L (sold)
'05 WK 4x4 Ltd 5.7L (mine) 200k+ club
'01 WJ 4x4 Laredo 4.7L (daughter)
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post #2 of 19 Old 10-15-2019, 08:11 AM
jtec
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guessing here - this is a STOCK 05 with a 5.7L?
Any recent repair or maintenance history ?

With scanner Did you look in history - and then freeze frame MIGHT be something pops out -
Next the only code right now is p0300?

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #3 of 19 Old 10-15-2019, 08:43 AM
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IMO, anytime you get a Crank or cam position sensor DTC, its best just to head to mopar, get a new one and replace it ASAP.

5 and counting :05 WK 5.7 HEMI
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post #4 of 19 Old 10-15-2019, 09:21 AM
Avs
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I wouldn’t drive around the car with flashing cel. Pull the plugs out and check the condition. Put some dielectric grease between the plug and the wires making sure you have good conductivity.
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post #5 of 19 Old 10-15-2019, 03:41 PM
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All of your symptoms are consistent with a bad crankshaft sensor. It acts as an input shaft speed sensor for the trans. If it suddenly loses communication, it will look for a lower gear in limp mode which is probably the source of your "thump". The RPM based vibration is also consistent with a misfire. When it regains communication, all may seem normal, but problems like that always get worse until complete failure.

Your scanner presented with crankshaft sensor codes. Is there a reason you want to look at something else? You're lucky you even got the code. The crank and cam sensors will often go bad and never show a code. It's an easy fix and easy to reach. One harness and one bolt. Just make sure you go with Mopar for that sensor. Had two defective Auto Zone crank sensors in a row. Thinking there's little chance of getting two bad ones, I wasted a lot of time and money looking for other issues.
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post #6 of 19 Old 10-15-2019, 05:41 PM Thread Starter
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@jtec
Yes, stock 5.7 with only mod being the addition of a catch can. Most recent maintenance was replacing two rear most exhaust manifold bolts on passenger side (2 days before). Only other thing beyond that was oil change about almost 2 months ago.
My scanner can read most of the codes, but doesn't keep history after being disconnected. I looked thru the live data while running it, and most everything looked within range. Fuel trims didn't appear abnormal, but RPM's at idle (with engine loping because of misfire) were jumping around a lot. Figures.

Yes, currently the only code showing up (last 2 times I checked it) is the P0300.

@Avs
I'm not driving it again until I can get this figured out. I'll be checking a lot of things once I get some time. I have a spare vehicle to drive, but I've been swamped with contract negotiations for a construction project these last two days. Part of the reason I had to drive it yesterday. I just didn't have the time to wait on a tow...

@YouStupidBunny
At first I thought the trans was in Limp Mode, but it wasn't. I could manually shift thru all the gears and it was running in 5th on the highway. But the misfire in the engine was very noticeable under load/acceleration. I don't think there is anything trans related, at the moment. Further driving and there could be. Another reason why I'm not driving it.

I was wondering about anything else beyond the Crankshaft sensor only because it's not showing the code as it did before. In my mind, that's the first place I need to start.

Oh, for what it's worth, the engine has over 219k miles on it. I'd be willing to bet that sensor hasn't been replaced before.

'99 WJ 4x4 Ltd 4.7L (sold)
'05 WK 4x4 Ltd 5.7L (mine) 200k+ club
'01 WJ 4x4 Laredo 4.7L (daughter)
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post #7 of 19 Old 10-15-2019, 05:57 PM
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I would do basics - spark, fuel, air, compression. If you have a scanner that can read misfires by cylinder, that may narrow down the issue and save you some time. Do not throw parts at the car, even Mopar parts.
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post #8 of 19 Old 10-15-2019, 06:35 PM
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Quote:
Originally Posted by 99sajeep View Post
At first I thought the trans was in Limp Mode, but it wasn't.
When the crank sensor loses communication, even for a moment, it triggers a limp mode scenario. It may instantly correct itself or correct after restart, but at that moment, it gave the PCM incorrect information or lost communication.

In many instances, a bad crank or cam sensor won't throw a code, but since you were able to view it once, you can be sure there was a problem when it triggered and is likely the cause of your "thump" and misfire. Replace it and since it's high mileage, might as well replace the camshaft sensor.
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post #9 of 19 Old 10-19-2019, 05:04 PM Thread Starter
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Well, it's been a rough week for me at work. Long contract negotiations all week, but I never had time to start looking at the WK before it got dark.

I'm finally looking at things this weekend. I got a crank sensor on order this week anyway and it arrived this Saturday afternoon.

Still, the only code showing up is P0300.

A couple things first:

- engine was low on oil. Apparently due to a leaking rear main seal that has just started showings signs. That might explain the MDS "activation" codes I got. I put the extra 1 qt and a half I had here in, but it still needs about 1 qt more. (Currently has about 5k miles since last oil change, but the seal issue wasn't there when I changed the oil.)

- I replaced the crank sensor. Sensor is a Mopar part. Was pretty easy. Went for a drive and the P0300 code came back. So no change.

- I'm checking plugs now and they are worn more than I would have expected. First two so far are reading a gap of .058" on the main firing one, and .050" on the secondary "wasted spark" plug. Current plugs have 52k miles and they are just over 2 yrs old. I'll plan for a new set. Wires also.

So my scanner does not have the ability to read which cylinder is misfiring. What next? Driving a short distance after replacing the crank sensor, the engine gets a definite misfire and runs a little rough. Stop and start it back up again and it's smoother, then will pick up the miss again shortly.

What else to look at?

'99 WJ 4x4 Ltd 4.7L (sold)
'05 WK 4x4 Ltd 5.7L (mine) 200k+ club
'01 WJ 4x4 Laredo 4.7L (daughter)
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post #10 of 19 Old 10-20-2019, 08:54 AM
Avs
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Quote:
Originally Posted by 99sajeep View Post
Well, it's been a rough week for me at work. Long contract negotiations all week, but I never had time to start looking at the WK before it got dark.

I'm finally looking at things this weekend. I got a crank sensor on order this week anyway and it arrived this Saturday afternoon.

Still, the only code showing up is P0300.

A couple things first:

- engine was low on oil. Apparently due to a leaking rear main seal that has just started showings signs. That might explain the MDS "activation" codes I got. I put the extra 1 qt and a half I had here in, but it still needs about 1 qt more. (Currently has about 5k miles since last oil change, but the seal issue wasn't there when I changed the oil.)

- I replaced the crank sensor. Sensor is a Mopar part. Was pretty easy. Went for a drive and the P0300 code came back. So no change.

- I'm checking plugs now and they are worn more than I would have expected. First two so far are reading a gap of .058" on the main firing one, and .050" on the secondary "wasted spark" plug. Current plugs have 52k miles and they are just over 2 yrs old. I'll plan for a new set. Wires also.

So my scanner does not have the ability to read which cylinder is misfiring. What next? Driving a short distance after replacing the crank sensor, the engine gets a definite misfire and runs a little rough. Stop and start it back up again and it's smoother, then will pick up the miss again shortly.

What else to look at?
It's kind of hard diagnose the misfire when you don't have a scanner that can pin point which cylinder(s) is causing the misfire. After you replaced all the spark plugs and wires and if there is still misfire. The next step you can look at is replacing all the coil(s). Not cheap @ 20+/coil or you can swap the coil (ie..cylinder 7 with cylinder 8). If misfire is moving from cylinder 7 to 8 then the original cylinder 7 coil is bad. Make sure you put some dielectric grease between the plug and the wire rubber boot doesn't get stuck or torn off next time you remove it.

Have you done any intake valve carbon clean? This can help with misfire issue at idle due to carbon build up on the back of the intake valves.

Last edited by Avs; 10-20-2019 at 09:10 AM.
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post #11 of 19 Old 10-21-2019, 07:46 AM Thread Starter
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Quote:
Originally Posted by Avs View Post
Have you done any intake valve carbon clean? This can help with misfire issue at idle due to carbon build up on the back of the intake valves.
I cleaned the back side of the throttle plate, sprayed as much as I could of the inside of the intake, and installed a catch-can to help that situation. That was 6 months and over 13k miles ago.

'99 WJ 4x4 Ltd 4.7L (sold)
'05 WK 4x4 Ltd 5.7L (mine) 200k+ club
'01 WJ 4x4 Laredo 4.7L (daughter)
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post #12 of 19 Old 10-21-2019, 08:05 AM
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Spark plugs only last 30,000 miles or 2 years in this vehicle. Make sure you replace them with the correct OEM plugs.

You need to find out which cylinder(s) is misfiring. I do not have your engine. In my 4.7L I would pull each plug wire one at a time while the engine is running to see if the engine idle changes to try and identify the cylinders. You could also use a spark tester on each cylinder. This assumes that spark is the issue.

Fuel could be the issue (fuel pump or injector). It is less likely but possible. For this you need to check fuel pressure first. If that is okay then you can try an injector leak down test.

Given that this is becoming more diagnostically challenging, you may want to find a great local mechanic and have the mechanic do these diagnostic tests for you. It will probably save you time and money in the long run.
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post #13 of 19 Old 10-21-2019, 08:28 AM Thread Starter
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I'm looking into the Torque app to try and maybe narrow things down a bit, but I don't know much about that app (and I'm an iOS person...). I have an old racing buddy that swears by it.

It looks like the Torque Pro app can be downloaded onto a PC, but I want to get some info from others about the extent of functions thru the app. Can it read individual cylinders in a misfire situation? I mean GPS, accelerometers, custom gauges, etc. are all nice, but if it doesn't get me further into my Jeep's computer, then it's a waste of money for right now.

'99 WJ 4x4 Ltd 4.7L (sold)
'05 WK 4x4 Ltd 5.7L (mine) 200k+ club
'01 WJ 4x4 Laredo 4.7L (daughter)
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post #14 of 19 Old 10-21-2019, 10:24 AM
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I use autoenginuity software downloaded onto my laptop and it provides misfires by cylinder for my 4.7L. The cost is approximately $600 for one brand/make vehicle.
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post #15 of 19 Old 10-21-2019, 11:47 AM
Avs
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If I’m not mistaken, after you replaced the crankshaft position sensor you may have to run a relearn process using the scanner. I doubt you can do with the basic one way scanner.
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