New symptom to old problem

ridg3runner

ridg3runner

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Over the last year, I've had an issue with spark knock (pre-ignition), mostly when I pull a long grade or take off from a stoplight. I've done everything short of taking it to a dealership to find out why it is happening. I am using the superchip flashpack and have tried all the different settings with the same results with each. It doesnt get driven for a month at a time while I'm at work so I usually put Stabil in the fuel tank. After coming home this time, I have a new symptom. It stalled twice yesterday and both times it started right up but had "that smell" of dieseling, which I know from past vehicles is a sign of the timing being off. It has never thrown codes for this issue either. I have replaced the following trying to find the cause: plugs and wires, coil pack, knock sensor, MAP sensor, O2 sensors, and even tried firmware update on the flashpack. Does not matter where or what grade of gas I buy, still does it. Is it even remotely possible the ECM is dieing without throwing the codes, OR , perhaps the timing belt has stretched enough to throw it out of time without jumping or breaking? The thing has just under 40k miles on it and has done this since the day I brought it home with 30k on it.

We are Jeep..Resistance is futile..
 
Last edited:
wayoflife

wayoflife

Administrator
Staff member
I know you don't want to do it but, your dealership would be able to get a lot more data by hooking up their scan tool to your Jeep. Being that you aren't seeing any codes, I would have them give things a look.
 
Canvas JK

Canvas JK

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Try running an additive in it like Berryman's B-12 to clean the fuel system. You may have put too much Staybil in the fuel causing the octane to be lowered. In older motors the pinging comes from the octane being too low. I had a super beetle I had to run an octane boost in to keep it from pinging.

Have you tried changing the brand of gas? Some cars are designed to run in 10% or less ethanol. Depending on which brand of gas may be higher than others. Then again you are in CA and that may be all you can get.

Hope this helps some.

R/
Will
 
ridg3runner

ridg3runner

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Have tried all brands, and staying away from anything starting with an "A". But now that is has started with the dieseling, I'm wanting to lean more towards timing. When I am home I run 3-4 tanks of plain gas, thereby cleaning the Stabil out of the system.
Two things I forgot to mention. First, this is a 3.8 w/ 6speed, and, before anyone suggests it, the '07 3.8 does not have a Mass Airflow Sensor.

We are Jeep..Resistance is futile..
 
SDG

SDG

Caught the Bug
I don't know if there is anything you can really do about it, but when ethanol is the oxegenating agent used in the gas it increases the rate at which the gas picks up water out of the atmosphere. I am not sure if this is something that stabil attempts to prevent, but a good way to help a little bit if you aren't already doing, is to store the jeep with a full tank of gas, that way the amount of headspace exposed to air is greatly diminished.

This may or may not have anything to do with it, just popped into my head since you said the vehicle sits for a month or more at a time.
 
jeeeep

jeeeep

Hooked
make sure you're getting E10 and not E15 or higher.

Also take a look at Screamin Demon coils and Live Wires by Performance Distributors makes a difference over stock coils and wires
 
J

JoshuaC999

New member
You might try using a intake cleaner like sea foam or BG induction service. If you have carbon build up on you pistons, and/or in the combustion chamber you could have, 1: increased the compression ratio causing the pre-ignition problem or 2: have a "hot spot" that ignites the extra fuel when under a load or acceleration.
 
J

JoshuaC999

New member
Also If you have a scan tool or access to one. Check you intake temp and coolant temp readings. If the computer is reading improper readings from one or both it could be altering the fuel ratio incorrectly.
 
ridg3runner

ridg3runner

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JoshuaC999 said:
Also If you have a scan tool or access to one. Check you intake temp and coolant temp readings. If the computer is reading improper readings from one or both it could be altering the fuel ratio incorrectly.
Click to expand...

But is this going to cause it to diesel as if it is out of time? The odor I'm smelling is the same as if the timing is off, not to be confused with the odor of an engine that is running too rich.

We are Jeep..Resistance is futile..
 
J

JoshuaC999

New member
Usually if I've had a vehicle dieseling it's due to the fact that it is running a little hot and when shut off there is enough heat remaining in the cylinder to ignite the remaining fuel without a spark, which is why it is called dieseling. Usually a problem more seen on carberated vehicles due to the fact that all you need is air flow to pull more fuel into the engine. If your jeep is dieseling you may have a leaking injector, cause fuel to enter the cylinder after shut down. Which could also be causing a rich miss-fire, and cause a smelly exhaust.
 
JeepinLife

JeepinLife

Caught the Bug
ridg3runner said:
But is this going to cause it to diesel as if it is out of time? The odor I'm smelling is the same as if the timing is off, not to be confused with the odor of an engine that is running too rich.

We are Jeep..Resistance is futile..
Click to expand...

Do you notice the dieseling on shutdown?? I believe thats the only time something "diesels" but correct me if I'm wrong on that. Have you looked at the crank sensor? Id go with timing like you said, looks like you covered most other probable causes. Mine starts to make similar noises when i get low in the rpms... such as needing to downshift.
 
ridg3runner

ridg3runner

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JeepinLife said:
Do you notice the dieseling on shutdown?? I believe thats the only time something "diesels" but correct me if I'm wrong on that. Have you looked at the crank sensor? Id go with timing like you said, looks like you covered most other probable causes. Mine starts to make similar noises when i get low in the rpms... such as needing to downshift.
Click to expand...

It stalled on me twice the other day ( like it flooded out)but fired right up both times. That's when I smelled it. I came home from town today and smelled it when I shut it off but at no time has it ( for lack of better terms) tried to run backwards.

We are Jeep..Resistance is futile..
 
JeepinLife

JeepinLife

Caught the Bug
ridg3runner said:
It stalled on me twice the other day ( like it flooded out)but fired right up both times. That's when I smelled it. I came home from town today and smelled it when I shut it off but at no time has it ( for lack of better terms) tried to run backwards.

We are Jeep..Resistance is futile..
Click to expand...

Grab that timing light and check it out I guess. I've been thinking about this all day
 
jeeeep

jeeeep

Hooked
ridg3runner said:
Over the last year, I've had an issue with spark knock (pre-ignition), mostly when I pull a long grade or take off from a stoplight. I've done everything short of taking it to a dealership to find out why it is happening. I am using the superchip flashpack and have tried all the different settings with the same results with each. It doesnt get driven for a month at a time while I'm at work so I usually put Stabil in the fuel tank. After coming home this time, I have a new symptom. It stalled twice yesterday and both times it started right up but had "that smell" of dieseling, which I know from past vehicles is a sign of the timing being off. It has never thrown codes for this issue either. I have replaced the following trying to find the cause: plugs and wires, coil pack, knock sensor, MAP sensor, O2 sensors, and even tried firmware update on the flashpack. Does not matter where or what grade of gas I buy, still does it. Is it even remotely possible the ECM is dieing without throwing the codes, OR , perhaps the timing belt has stretched enough to throw it out of time without jumping or breaking? The thing has just under 40k miles on it and has done this since the day I brought it home with 30k on it.

We are Jeep..Resistance is futile..
Click to expand...

do you run the tank empty several times before having to park it and adding more Stabil?

What plugs did you replace the stock ones with?

you bought it with 30k miles on it, did you check the throttle body to make sure it's an original stock unit? my buddy told me to mention this, he tried to install the viper TB on his JK and he told me it caused issues that you are describing
 
ridg3runner

ridg3runner

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jeeeep said:
do you run the tank empty several times before having to park it and adding more Stabil?

What plugs did you replace the stock ones with?

you bought it with 30k miles on it, did you check the throttle body to make sure it's an original stock unit? my buddy told me to mention this, he tried to install the viper TB on his JK and he told me it caused issues that you are describing
Click to expand...

while I am home, I usually go thru 4-5 tanks of gas. I want to say they are Champion plugs, I've tried the aftermarket crap and thats just what they are- crap. I have replaced the throttle body myself and I know for sure that it is an OEM unit.

We are Jeep..Resistance is futile..
 
ridg3runner

ridg3runner

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Mumbo Jumbo (fitting nickname at this point) is going to the stealership on the 30th, hopefully they can figure it out for less than the cost of a new ride.

We Are Jeep..Resistance Is Futile..
 
jeeeep

jeeeep

Hooked
ridg3runner said:
A while back I had someone ask me to provide a video of what I meant by "slow return to idle", so here is what I recorded today. Disregard the gas cap and check engine codes as they are unrelated to the engine issue.

https://www.youtube.com/watch?v=5kb0_RH6zKU&feature=youtube_gdata_player
Sent from my DROID4 using WAYALIFE mobile app
Click to expand...

:thinking: hmmmm my 2010 has done that since day 1 - but don't have any issues with it. If I recall my GC with Hemi did the same thing.
 
ridg3runner

ridg3runner

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Maybe it's just me but it seems slow as if there's a vacuum leak but yet it idles smooth as silk.

Sent from my DROID4 using WAYALIFE mobile app
 
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