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Discussion Starter #1
I have a '16 JK truck project. It ran perfectly when I took it to a body shop in March and when I picked it up last week (early July) it has a miss.

Things I know.

1. TJ fuel tank swap and it had 7 gal of gas back in March (gauge isn't reading correctly, but it hasn't ran much) I need to dump some fresh stuff in.

2. Battery went dead while at body shop, it was jumped a few times and battery replaced.

3. EVAP emissions system is still unhooked.

Could it have a stuck injector from sitting?
Engine misses at idle and while driving.

I have a Bluetooth obd2 adapter with torque pro and alphaobd. first Tim I check I had a u0103 network code (lost communication with gear shifter) after clearing the initial code neither app show anything, I unhooked the battery for 24hr and no improvement. Tried an injector kill test (narrow down what cylinder) with alphaobd and killing any injector would kill the motor.

Anyone have any thoughts or suggestions???
 

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It seem like your scan tool can access the fuel injector test. However you did not perform the test properly. The test is not meant to kill the motor, but rather to perform a such called "injector balance test". It needs to be performed with the engine NOT running and the fuel pump primed. The idea is to monitor, note and compare the pressure drop among the injectors by using the scan tool to pulse each injector separately.

Regardless, I doubt you have a sticky injector. I think the unconnected EVAP could very well cause issues.

Very nice build by the way. Incidentally I just today stumbled upon your thread.
 

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Discussion Starter #3
It seem like your scan tool can access the fuel injector test. However you did not perform the test properly. The test is not meant to kill the motor, but rather to perform a such called "injector balance test". It needs to be performed with the engine NOT running and the fuel pump primed. The idea is to monitor, note and compare the pressure drop among the injectors by using the scan tool to pulse each injector separately.

Regardless, I doubt you have a sticky injector. I think the unconnected EVAP could very well cause issues.

Very nice build by the way. Incidentally I just today stumbled upon your thread.
Iran a kill test. I was expecting it to shut off an injectior so I can listen if the misfire got worse or same helping to narrow down what cylinder isnt working.

I'll keep poking around in alfaOBD to see what else is available. it is an impressive phone app, but still short or a real professional scanner.

I'll try plugging the leak detection pump back in and hooking up the purge line. I don't think it has tried to run a cycle because the fuel level is below 1/4 tank and I don't have any EVAP related codes.

Thanks for your help
 

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Using a scan tool, check your fuel trim numbers. What are the Short term and long term for both bank 1 and 2?

That can usually give some direction. Also unplug the purge valve for the evap. (after checking fuel trim). Wondering if by chance your evap purge solenoid is opening up and pulling in extra air (instead of fuel vapor).
 

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Discussion Starter #5
Using a scan tool, check your fuel trim numbers. What are the Short term and long term for both bank 1 and 2?

That can usually give some direction. Also unplug the purge valve for the evap. (after checking fuel trim). Wondering if by chance your evap purge solenoid is opening up and pulling in extra air (instead of fuel vapor).
I unplugged the purge valve and it shows up as a pending fault, also stuck a bolt in the line to plug it off.

Trims are
L/T bank 1 -5 something
L/T bank 2 +5 something
S/T bank 1 reads just over 0
S/T bank 2 reads about 0

Here is a graph of the fuel trims.
Looks like bank 1 is doing the weirdness.
 

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The fuel trims look normal. Usually you want the fuel trim total for a bank to be +- 10.

Does jscan have a misfire counter screen? I have it but haven't played with it.

When you ran the injector kill test, could you find a cylinder that did not change when you killed the injector?
 

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Discussion Starter #8
The fuel trims look normal. Usually you want the fuel trim total for a bank to be +- 10.

Does jscan have a misfire counter screen? I have it but haven't played with it.

When you ran the injector kill test, could you find a cylinder that did not change when you killed the injector?
Not sure about jscan, but I haven't found a misfire counter in torque pro or alfaOBD. (But I swear I saw one in torque when plugged into my LS powered YJ.

The injectior kill test just killed the engine, didn't matter what cylinder I turned off, she just died.

Sitting in it with the engine running and a/c blowing cold. Engine load is 46% right now, ltft1 is -3.1% and ltft2 is 10.2%

I have a buddy coming by with a real scanner sometimes, hope to learn something.
 

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You need to connect all systems to be able to get a good picture. A scanner is just what it's name says a scanner. The actual diagnosis is done on board by the vehicle. Having certain systems disconnected may have implication for other sytems, hell your engine management may not even ever enter closed loop.

Regardless what kind of scanner your friend brings over, count on having to have ALL systems properly buttoned up first.

Then if you are still having issues, then you will need get methodical and notably you need access to "description and operation" of systems and components. Otherwise you will be hunting in the dark and need to be lucky. I'm talking from experience.

Also, you have mentioned having had no issues prior to the body shop and having had issues post body shop. Brainstorm what steps may have been taken by the body shop, what has been needed to be disconnected/connected and how those steps may have contributed to the issue that you are experiencing.

What has the body shop done anyway? Reading your build thread, I thought most of the body work was performed by you? No?
 

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Discussion Starter #10
Tried some old fashioned stuff today.

Unplug fuel pump and cranked it over, spins evenly. More than likely it doesn't have a weak cylinder or damaged valve

Pulled a spark plug. #1 smelled of old gas so I grabbed a set and changed them all. #2 was black on the tip, all others were tan. Reassembled and started up, sounded the same. Noted a small mouse nest on top of #6 coil, mostly shop rag, no visible damage to the harness in the area.

Went for a short drive (no rear lights) and got a flashing MIL going uphill. Cylinder#2 misfire

Plugged into snap on thingie, tried the injector kill test and the engine died the same as it did with the alfaOBD phone app. Clicked on the box for "what cylinder is misfiring" and it showed primarily #2 with an occasional #4

and #6.
 

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Discussion Starter #11
You need to connect all systems to be able to get a good picture. A scanner is just what it's name says a scanner. The actual diagnosis is done on board by the vehicle. Having certain systems disconnected may have implication for other sytems, hell your engine management may not even ever enter closed loop.

Regardless what kind of scanner your friend brings over, count on having to have ALL systems properly buttoned up first.

Then if you are still having issues, then you will need get methodical and notably you need access to "description and operation" of systems and components. Otherwise you will be hunting in the dark and need to be lucky. I'm talking from experience.

Also, you have mentioned having had no issues prior to the body shop and having had issues post body shop. Brainstorm what steps may have been taken by the body shop, what has been needed to be disconnected/connected and how those steps may have contributed to the issue that you are experiencing.

What has the body shop done anyway? Reading your build thread, I thought most of the body work was performed by you? No?

They made my work look respectable and added lower cab corners, extended the rockers, made some interior cab corners, attached the belt rail and removed the hood, fenders, windshield, cowl for paint.

They did quite a bit of welding, jump-started it a few times before replacing the battery. Lots of start it up and move around (very short trips)

The Jeep probably hasn't been in closed loop since the body was first removed almost 11 months ago.

I found a short video of it running on my phone from November 30, 2018, and I'm almost positive that was the gas that was in the tank unil drained and refilled it on July 9, 2019.

The best way to describe the misfire is, it sounds like a bad valve, but it doesn't go away at high rpm like a valve usually does. Definitely short on power
 

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Where EVAP is unhooked? Check all vacuum hoses are tight.
EVAP needs to be closed at the manifold.
Check also PCM hose at the valve and intake side and brake booster hose for vacuum leaks.

Ethanol blends are good for 60 days only.
 

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Discussion Starter #13
Where EVAP is unhooked? Check all vacuum hoses are tight.
EVAP needs to be closed at the manifold.
Check also PCM hose at the valve and intake side and brake booster hose for vacuum leaks.

Ethanol blends are good for 60 days only.
Purge valve is plugged in and hooked up, purge line to the back has a bolt stuffed in it, tank pressure sensor is plugged in and covered with a rubber glove, leak detection pump is unplugged.

Hopefully I'll get a chance to pull the intake tomorrow and swap the coil pack to a different hole.

I wonder if the injectors can get hung like the ones in a LS do after they sit a while?
 

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Purge valve is plugged in and hooked up, purge line to the back has a bolt stuffed in it, tank pressure sensor is plugged in and covered with a rubber glove, leak detection pump is unplugged.

Hopefully I'll get a chance to pull the intake tomorrow and swap the coil pack to a different hole.

I wonder if the injectors can get hung like the ones in a LS do after they sit a while?
Without removing and testing its difficult to say.
Vacuum could leak through injector O-ring also. rare but possible.
 

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Discussion Starter #15
Update.

Changed plugs (#2 was definitely blacker than the rest)

Drove and got a misfire#2

Pulled valve covers and rolled engine around for a leakdown test. Well under 10% on 2/4/6.

Pulled fuel rail/injectors. 2 was full of stuff, 4 and 6 weren't as bad. 135 were clean. Little black chunks, possibly from the braided AN fuel line from the tank to frame. I blowed it out after assembly, must not have been enough.

Hopefully get a chance to reassemble in the next few days
 

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you said there was a mouse nest?... I am wondering if he chewed a wire causing your issues!!!
 

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Update.

Changed plugs (#2 was definitely blacker than the rest)

Drove and got a misfire#2

Pulled valve covers and rolled engine around for a leakdown test. Well under 10% on 2/4/6.

Pulled fuel rail/injectors. 2 was full of stuff, 4 and 6 weren't as bad. 135 were clean. Little black chunks, possibly from the braided AN fuel line from the tank to frame. I blowed it out after assembly, must not have been enough.

Hopefully get a chance to reassemble in the next few days
Advice: replace injector o rings, assemble with oil.
 
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