Lets talk tests

brillo_76 said:
New good wires on it?
New plugs in it?

If the above are good I would use my spark plug info thread and check the coils corresponding to your cylinders 1,2 and 6

As you either have an ignition issue or a fuel injector issue by the looks of your codes with 3 cylinders.


Also possible engine ground issues causing the cylinders or injectors to misfire as well.

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Spark plugs good. Coming up on about 8 months old and about 3000 miles. When I did the valve covers a few weeks ago still looked good.
New wires as of 2 weeks ago.
I chased grounds in engine compartment the other day if I have them all they are good and tight.
 
I will track down a compression tester and check that as well hopefully tomorrow.

I have a set of injectors pulled from junkyard that I ohmed out to test good. I can send them out to be cleaned next week.
I have all of the new injector o rings already.
I can buy a FPR but haven't done any tests on it I figured that would be evident if to was the issue.

I have not tested fuel pressure at rail which I probably should.

Anything else?
 
It's either ignition or fuel causing the cylinders not to fire. :)

So use the spark plug information on my info thread to verify your coils.:)

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Doubt its low compression unless your loosing antifreeze and oil.

If the spark plugs are wet they are not firing. If they are clean and dry injectors may not be firing.

Fuel pressure at the rail would be a good idea. :)

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It’s still worth knowing what the compression is with your milage.

Stalls at idle on the old CJ were two cylinders running 90psi hot.

Also ohm our your coils and anyone near the upper limit resistance wise replace.

Sadly none of your missfire codes have a ignition coil in common.

What is your MAF and Load reading at idle?


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Last edited:
19963.4lsr5 said:
It’s still worth knowing what the compression is with your milage.

Stalls at idle on the old CJ were two cylinders running 90psi hot.

Also ohm our your coils and anyone near the upper limit resistance wise replace.

Sadly none of your missfire codes have a ignition coil in common.

What is your MAF and Load reading at idle?


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I am going to run it tomorrow and wait till it stalls and pull the plugs to see what is what. In a stall it always smells of fuel which now leads me back to unburnt fuel.

Tunnel vision sometimes gets hard to get away from.

I have ohm tested the coils before but always cold. I will check them out when hot as well. Ill look for the values for both. Ill check the wires again as I changed them due to arcing on one of the coils.

All a matter of process with limited tools.

Fuel pressure and compression will be on the list.
 
sweet88gt said:
I am going to run it tomorrow and wait till it stalls and pull the plugs to see what is what. In a stall it always smells of fuel which now leads me back to unburnt fuel.

Tunnel vision sometimes gets hard to get away from.

I have ohm tested the coils before but always cold. I will check them out when hot as well. Ill look for the values for both. Ill check the wires again as I changed them due to arcing on one of the coils.

All a matter of process with limited tools.

Fuel pressure and compression will be on the list.
Click to expand...


Fuel pressure will be the most difficult because it will require buying a new banjo bolt with a test port in it and they you will have to adapt it to a pressure sensor.


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19963.4lsr5 said:
Fuel pressure will be the most difficult because it will require buying a new banjo bolt with a test port in it and they you will have to adapt it to a pressure sensor.


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Agreed
Thought about if and when to permanently mount a gauge and be done with it.
 
19963.4lsr5 said:
It’s still worth knowing what the compression is with your milage.

Stalls at idle on the old CJ were two cylinders running 90psi hot.

Also ohm our your coils and anyone near the upper limit resistance wise replace.

Sadly none of your missfire codes have a ignition coil in common.

What is your MAF and Load reading at idle?


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Your MAF, fuel trim, and load may give you a hint as to what is causing the issue.
 
Today I decided to check the coils and wires again.
Coils are on the high side of the primary ohm readings. I checked the wires that are a few weeks old and all should be good there.

I did however change the not that old plugs with new. Properly gapped them and checked over vac hoses.
So I ran it for 30 minutes with long idle up and down hill short burst of throttle 4x4 operation.
Shut it off and restarted with no stall

Restarted it after competed cool down with no stall.

Next is to drive it around.
I had cleared the codes and have rechecked them with nothing stored.

I can see the fuel trims trying to stay near 0

Im not sure I understand what Im looking at but I still think the coil or coils could be an issue.

Noticed I have 2 with small Denso stickers and 1 with a large Denso sticker. All of them ohm on the high side of the value when warm. Ill test them completely cold on another day.

I am going to test compression and fuel but will have to wait a few days for sure.
 
Im not sure where I bought them but they both were NGK with the same part number.

I just did a 45 min drive/idle test. It did stall once when I was messing with the a/c speeds. It fired right up after.

Waiting about 20 mins and going back to drive it around a bit more.
 
Am I missing something? The correct plug should be correctly gapped. The -11 on the NGK part number defines the gap and I’ve really seen no plugs that were not factory gapped properly unless the box was damaged.


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19963.4lsr5 said:
Am I missing something? The correct plug should be correctly gapped. The -11 on the NGK part number defines the gap and I’ve really seen no plugs that were not factory gapped properly unless the box was damaged.


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You would be correct as far as hoping they are all the same.
At least 2 of them needed slight adjustment. It just takes out the fact I didn't do it it the first time.
 
So I pulled the coils off once again to check resistance.
1.1
1.2
1.2
Are the results of the primary on all 3 here in Florida at 80 degrees.

So because Im not sure about the readings I decided to put them in the refrigerator for 20 mins and retest. No change.
Because at this point I dont much care I put them in the freezer just to see what would happen. Same readings.
I now am more intrigued so I have a heat gun and warmed them up to take the same test and the results changed slightly to
1.2
1.2
1.2

What are the chances and my luck that all 3 coils are just on the outskirt of out of range of the values?
 
Resistance values that low are notoriously hard to test accurately. If they are *just* out of range high, you are probably fine. The meter is also measuring probe and contact resistance, which adds to the reading (0.2-0.5 ohms, generally).

-Charlie
 
phattyduck said:
Resistance values that low are notoriously hard to test accurately. If they are *just* out of range high, you are probably fine. The meter is also measuring probe and contact resistance, which adds to the reading (0.2-0.5 ohms, generally).

-Charlie
Click to expand...

Agreed as the meter I would trust is no longer working and these are cheap units.

But...I need to rule out items concerning my issue.
 
The secondary side is more important and what has always failed for me.

Those primary numbers look good if it was my “fluke” measuring it.

Read between the two spark plug connections. There should be a speck for the secondary also and it will be in K ohms.


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