'01 4.0 misfire cylinder 1

colt933 · 03-05-2009, 02:26 PM

The symptoms are rough idle, sometimes hard to start (must press gas pedal), and occasionally it will throw the P0301 misfire on cylinder 1. Once it threw a Camshaft position sensor code (I forget which one) along with the P0301. I have some oil leaks on that side of the engine so I cleaned all of the connectors with contact cleaner and haven't seen that code again.

So sitting at a stoplight, I get lots of shaking and it will occasionally surge and die. But when I accelerate the problem seems to go away. The Jeep seems to have plenty of power for acceleration.

It seems to run a lot better after I reset the computer to clear the code (running on factory data tables). But then after 50 starts or so it gets bad again (computer builds new data tables).

I replaced the spark plugs with the OEM Champions - no difference.

I replaced the O2 sensors with Denso brand - no difference.

All 6 cylinders show about 150 lb of compression.

I have an appointment with the Stealer Friday morning to reprogram the PCM as I have read similar (but not identical) problems described in a couple of TSBs. I don't want to pay them to do anything other than the selective erase and re-program mods for the PCM that I can't do myself.

What next?

Fuel pressure/fuel pump? If it were a fuel related problem why would it seem to have plenty of power for acceleration?

#1 Fuel injector? Try swapping #1 and #2 and see if the code changes to cylinder #2?

Coil pack/coil rail? Can these things be intermittent or will it just stop working?

Crankshaft position sensor? Would the Jeep still run at all if this was bad?

Any ideas on where to go next?

ETA: compression was 150, not 180.

**tjwalker** · 03-05-2009, 06:14 PM

Quote:

Originally Posted by colt933

What next?

#1 Fuel injector? Try swapping #1 and #2 and see if the code changes to cylinder #2?

I would definitely try the swap and follow with the injector.

Would also be a good idea to clean your idle air control and throttle body and also to test your throttle position sensor and your fuel pressure as a matter of course.

You may have two separate issues here....

colt933 · 03-27-2009, 07:00 AM

Swapped fuel injector and misfire stayed on cylinder #1.

Compression test shows 85psi dry on cylinder #1 and 150 on all others. Wet test shows 125psi on cylinder #1.

This is not my daily driver and I haven't driven it in about 10 days. I've had the intermittent rough idle and cylinder #1 misfire for like a year. But normally the miss goes away when I touch the gas pedal. While trying to diagnose this over the last several days (swapping fuel injector, verifying spark at coil rail, changing spark plugs, cleaning IAC, cleaning throttle body, etc.), the motor is obviously missing at all rpm ranges, not just idle.

Might I just have a sticky ring now on top of the previous miss condition? Am I just dreaming that I don't need a new motor?

???

colt933 · 03-30-2009, 04:39 PM

So I sprayed a bunch of PB blaster in through the spark plug hole of cylinder #1 and let it sit for a couple of days.

Then I did the compression check again and #1 comes up at 150psi like the rest of them.

Now, at idle, if I pull the wire from then #1 fuel injector you definitely notice the idle get rougher. A few days ago, when I was only showing 80psi on cylinder #1, you couldn't notice a difference in the idle when pulling the wire from the #1 fuel injector, while you could DEFINITELY notice a difference if you pulled the wire from another injector.

So I think I'm running on all 6 again.

Just a stuck ring?

I guess it's time to flush the crank case. On my other cars, I have added a quart of ATF to the crank case, driven it for a day, then changed the oil and filter. I've never flushed the crank case on this jeep aside from adding 1/3 bottle of seafoam one time last year or maybe the year before.

Should I do something else since I had the stuck ring? Lucas, Rislone, etc.?

AZ Jeff · 03-30-2009, 08:38 PM

Quote:

Originally Posted by colt933

So I sprayed a bunch of PB blaster in through the spark plug hole of cylinder #1 and let it sit for a couple of days.

Then I did the compression check again and #1 comes up at 150psi like the rest of them.

Now, at idle, if I pull the wire from then #1 fuel injector you definitely notice the idle get rougher. A few days ago, when I was only showing 80psi on cylinder #1, you couldn't notice a difference in the idle when pulling the wire from the #1 fuel injector, while you could DEFINITELY notice a difference if you pulled the wire from another injector.

So I think I'm running on all 6 again.

Just a stuck ring?

I guess it's time to flush the crank case. On my other cars, I have added a quart of ATF to the crank case, driven it for a day, then changed the oil and filter. I've never flushed the crank case on this jeep aside from adding 1/3 bottle of seafoam one time last year or maybe the year before.

Should I do something else since I had the stuck ring? Lucas, Rislone, etc.?

Your plan sounds good. Maybe go with TWO quarts of ATF, and just drive gently. Or, you could spring for Marvel Mystery Oil, but I think ATF is just as good.

colt933 · 04-07-2009, 10:53 AM

Update:

Put 1 qt ATF in crank case on top of 500 mile old brown oil. Drove 150 miles, changed oil, oil was BLACK.

Put 1 bottle of Techron in gas tank. Halfway through this tank, it's running and idling much smoother.

No check engine lights yet!

Fingers crossed!

00blkxj · 04-20-2009, 11:29 AM

Colt how is your XJ running? I am about to try this. Did you put the ATF in on top of your Oil? Does it matter what kinda of ATF? Thanks.

colt933 · 04-20-2009, 03:04 PM

Quote:

Originally Posted by 00blkxj

Colt how is your XJ running? I am about to try this. Did you put the ATF in on top of your Oil? Does it matter what kinda of ATF? Thanks.

It still misses a little at idle but hasn't thrown a check-engine-light in a few weeks. I've run a couple of tanks of gas with techron as well.

I put the ATF on top of my oil. I think I had a quart of Castrol ATF.

Some say to let 1 quart of oil out before adding ATF, some say it doesn't matter.

I've done this before with other cars and it seem to work. I believe that the ATF is REALLY high in detergent but does not have the same load bearing properties as motor oil. So one quart of ATF in the crank case is like using a REALLLY high detergent motor oil.

I've also read that when you drain this mixture, after it's done draining, to pour a gallon of kerosene in through the oil filler cap and let this all drain into your receptacle. It's supposed to really flush out the crap that may still be in the residual oil. I've never done this part. It seems kind of scary.

00blkxj · 04-20-2009, 03:50 PM

Ok I have been running Marvel Mystery through my Gas tank for a few weeks now. And i will go get a quart of ATF. I have a lot of driving to do the next few days so I will change the oil after. And maybe a can or 2 of seafoam.

colt933 · 05-05-2010, 04:37 PM

Over a year later, this problem is still nagging at me from time to time.

To recap, here are the symptoms:

Occasionally it will throw P0301 - cylinder 1 misfire.

Sometimes, after going up a long hill under load, then coasting down the other side, CEL flashes and it goes into limp mode. Now it shows P0301 and P0300 - cylinder 1 and multiple cylinder misfire. Shutting the engine down and immediately starting it back up makes the flashing light and limp mode go away.

A few startups later and CEL is off.

This happens every few weeks.

What I have done/ruled out:

Tried both Champion and Autolite plugs as advised on this site - no
difference.

Fuel pressure good (around 50 as I recall).

Cylinder compression good (all around 150).

Techron every few fill-ups.

Bought OBDII to USB thingy and have monitored sensor output - MAP shows 12 - 20 inches of mercury so probably no vacuum leak.

Swapped fuel injectors around - misfire stays at cylinder 1 or multiple.

Replaced IAC, cleaned recess.

Since this is a 2001, I have not replaced the distributor cap/button/plug wires.

But since the fuel pressure, cylinder compression, and manifold pressure (vacuum) all check out - I'm leaning toward replacing the ignition coil rail.

Which one do you guys recommend - Autozone Duralast, Airtex from Advance, OEM, Echlin from Napa?

**filluptrk** · 05-05-2010, 09:40 PM

Rock Auto has pretty good prices on them. I got one on eBay for $40 off of an 02 Wrangler. Put my old one (still good) away as spare, new one works great.

robsjeepxj · 05-05-2010, 09:51 PM

If you have/had low compression (80 lbs) in the #1 cylinder then nothing but fixing that will help. Stop throwing away your money on outside stuff it sounds like your issue is internal. (bad valve/ valve spring/ cracked head/ head gasket/ bad rings/ badly worn cylinder etc)

colt933 · 05-06-2010, 06:35 AM

Quote:

Originally Posted by robsjeepxj

If you have/had low compression (80 lbs) in the #1 cylinder then nothing but fixing that will help. Stop throwing away your money on outside stuff it sounds like your issue is internal. (bad valve/ valve spring/ cracked head/ head gasket/ bad rings/ badly worn cylinder etc)

Cylinder #1 shows 150psi now like all others.