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Unread 03-23-2009, 08:45 AM   #1
drewguere
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Backfiring Through Intake

My cherokee is making a popping noise and backfiring through the intake. It used to do this periodically, but it is now doing it a lot more often.

I looked it up and it said it could be a problem with the timing, having a lean mixture, or a vacuum leak

Has anyone else had this problem? Anyone have a solution, or something to check?

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Unread 03-23-2009, 09:02 AM   #2
CJ7-Tim
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How about a specific and detailed description of when and how your Cherokee does this trick. All the time, sometimes, only when cold, only when warm, only after ........... ? What parts, sensors, or systems have you inspected, have you tested, or have you replaced ?

When was your last full tune-up ?
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Unread 03-23-2009, 10:05 AM   #3
drewguere
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It used to do it rarely, usually when taking off from a stoplight or something. Now it is doing it whenever I start the jeep.

You can hear it sucking air through the intake very hard, like you can hear it over the motor when the hood is open. It will sound like its going to die, then rev up a bit, then do it again and again.

It does it warm or cold.

The jeep hasnt been driven since september 07. So of course I need a tune up, and I will get to that this weekend, but this problem was happening even when I used to drive it daily and had new plugs/wires on it.

It has a brand new crank sensor on it, and relatively new O2 sensors.
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Unread 03-23-2009, 10:14 AM   #4
CJ7-Tim
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Quote:
Originally Posted by drewguere View Post
It will sound like its going to die, then rev up a bit, then do it again and again....It does it warm or cold....
Put a can of SeaFoam or Chevron Techron fuel injector cleaner into the next two gas tank fill-ups. Clean the Idle Air Controller (IAC) and throttle body. Tune up with Champion spark plugs, a new air filter, new wires, cap, and rotor.

If you get all the routine maintenance done and it still mis-behaves, test the Throttle Position Sensor and Coolant Temperature Sensor for smooth response and readings within specifications.

Cleaning the Idle Air Controller (IAC) :

Purchase sensor safe Throttle Body cleaner spray.

1. Remove the Throttle body from the intake manifold.
2. Remove the IAC with a TORX 15 driver (2 bolts)
3. Gently wiggle out the IAC from the throttle body
4. Clean the IAC with throttle body cleaner (not carburetor cleaner) Use cleaner, a rag and a toothbrush.
Be gentle; don’t twist or pull on the pintle as it is fragile and can be damaged easily
5. Also clean where the IAC seats in the throttle body with the same throttle body cleaner
6. Reinstall IAC, the Throttle body, and check idle quality.
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Unread 03-23-2009, 04:10 PM   #5
CheyenneK5
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also check your fuel pressure...a faulty fuel pump will cause this as it causes a lean condition
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Unread 03-23-2009, 08:37 PM   #6
swells
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my cherokee backfired through the intake when I would start it. the battery was toast and the alt was only producing 9 or 10 volts apreantly low voltage causes this and many other problems
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Unread 03-24-2009, 05:55 AM   #7
tjwalker
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I agree with CheyenneK5, fuel pressure would be one of the first tests to perform. Takes only a few minutes and a fuel pressure gauge installed on the schrader valve on the fuel rail. Compare to factory specs.
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Unread 03-25-2009, 08:46 AM   #8
drewguere
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Where would I get a fuel pressure guage?

Would auto zone or something like that have one?
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Unread 03-25-2009, 09:28 AM   #9
88XJSport
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Quote:
Originally Posted by CheyenneK5 View Post
also check your fuel pressure...a faulty fuel pump will cause this as it causes a lean condition
Bingo. Low fuel pressure will cause backfiring thru the intake.


FP gauges can be purchased at Autozone.
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Unread 04-08-2009, 11:52 AM   #10
Camo-5
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Any luck finding out what this was? I have the EXACT same problem. I could not describe it any better myself. Mine started last summer, went away for over 6,000 miles, then came back again a couple weeks ago. I've done the following trying to figure out what it is:
New TPS
New Idle air control
New throttle body (well, I wanted a 62mm anyway)
New MAP sensor
New plugs, cap, rotor, wires, coil, battery.
I just bought a new temp sensor today so I'll try that over the weekend (need to replace thermostat anyway).
If that doesn't work, I'm going to move onto the alternator. I just replaced the battery. Not sure if it was bad, but it was 6 years old. It wouldn't hold a charge very long. Maybe it was the alternator.

Anyway, please let me know if you find out what you problem was and I will do the same!

BTW, great site! I've been visiting for years, figured this would be a good time to join in!
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Unread 04-08-2009, 02:45 PM   #11
98CherokeeLTD
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mine has had the same issue ever since I got it. But mine only does it when its damp or i go baja thru a puddle. so i think mine may be a vacuum leak..it gets really annoying when your wheelin and it starts poppin and fartin and losin power
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Unread 08-25-2011, 07:29 AM   #12
chadtheman
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DId you end up fixing the problem. MIne is doing the same thing and is getting super annoying.
MIne started doing it while i was wheeling. SAme thing backing firing through the intake and when i jam the pedal down, it hesitiates real bad and acts like it is gonig to stall.
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Unread 08-25-2011, 11:55 AM   #13
Topgun514
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Chad, sounds like a TPS, follow CJ7-Tims examples first
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Unread 02-02-2014, 11:08 PM   #14
DallastheJeeper
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anything happen with this?
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