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Old 09-06-2019, 08:14 PM   #1
endneu913
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Default FXT, All Cylinder Misfire-

Heyo-

So, 04 FXT with a Sti swap. Pretty straight forward, no mods, basically stock except this motor doesn't belong on this car. It has a Cobb cone intake. OEM tune etc. Fairly low miles on motor 70kish)

Symptoms:
Misfires in ALL holes ( CEL) - After clearing codes, it comes back randomly. Like 20 miles or 2 miles.
Runs like a dog below 3k, sputters, dies at idle
Slurped up an entire tank of gas in 70 miles (Rich like Dubai)
Didn't develop over time, just started out of nowhere (after sitting a few hours after 2 hour drive from sea level to 7k feet)
Runs BETTER with MAF unplugged
Compression "seems" if not normal, at least consistent ( audible consistency with fuel pump relay/fuse pulled)

Things I've done:
Replaced Fuel Pump and Filter
Replaced all the gas with fresh 91
Found and fixed 2 vacuum leaks ( obvi didnt help)
No other vac leaks exist ( smoke machine verified)
Random ( found the rear passenger coil pack unbolted at first inspection on day one)
EDITS**
NEW MAF
New AFR sensor



Im a shade tree mechanic, able to wrench anything, but just need some more experienced minds to wind me and set me in a direction, cause now i'm at a loss. I drove it around for 2 hours with a cobb 3 on it looking at metrics, but i don't know too much about stoich. The AVCs system wasn't giving consistent readings either.

Any help would be pretty rad! Thanks!
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Last edited by endneu913; 09-16-2019 at 04:14 PM.
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Old 09-06-2019, 09:35 PM   #2
Commander Keen
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How are the oxygen sensors set up?
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Old 09-06-2019, 10:41 PM   #3
GalaxyWide
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Sounds exactly like clogged AVCS oil screens, though I think those are usually accompanied by varies CELs.
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Old 09-07-2019, 12:14 AM   #4
scooby24
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If it runs better with the MAF unplugged then replace your MAF.
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Old 09-08-2019, 03:26 PM   #5
endneu913
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Quote:
Originally Posted by Commander Keen View Post
How are the oxygen sensors set up?
As far as i know, 02 sensors are totally normal- What would i be looking for?

We thought the same think on the ACVs, the builder says he always pulls them out. I checked the one closest to front passenger side and it was gone... so i would assume he did them all.

Yes, weird that there are no other codes right ? If the MAF was bad, would it not throw a code? I have yet to try to clean the MAF with the special cleaner, which i will asap
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Old 09-08-2019, 04:56 PM   #6
scooby24
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MAF can read inaccurately without throwing a code. If it runs better without the MAF plugged in either it's almost always either the MAF is bad or the wiring to the MAF is bad.

If I unplug my MAF that is good the car dies.
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Old 09-08-2019, 05:00 PM   #7
2slofouru
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Check and see if there is debris in the maf, it can affect flow readings.
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Old 09-08-2019, 06:30 PM   #8
endneu913
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Quote:
Originally Posted by scooby24 View Post
MAF can read inaccurately without throwing a code. If it runs better without the MAF plugged in either it's almost always either the MAF is bad or the wiring to the MAF is bad.

If I unplug my MAF that is good the car dies.
Ill def take a peek tonight! If i unplug it, it keeps running. If i plug it back in, it shuts off.
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Old 09-09-2019, 03:42 AM   #9
endneu913
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Quote:
Originally Posted by 2slofouru View Post
Check and see if there is debris in the maf, it can affect flow readings.
Negative on the debris and cleaned it out with MAF cleaner spray- Sadly no improvement.

Replace MAF now? # moneyPit-baru
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Old 09-09-2019, 09:40 AM   #10
scooby24
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Yes, Denso 197-6040.

My local auto parts store will match densoproducts.com price

https://www.densoproducts.com/product.aspx?zpid=20040
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Old 09-11-2019, 04:15 PM   #11
endneu913
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New MAF installed- At first the cold idle sounded cleaner, but after warming up and taking it around the block ( a few miles ) its actually running worse. Before this, idle to 3000 rpms, its jumpy and clearly misfiring, but above 3k it was cleaner feeling. Now its just running like crap all across the power band.

Could it be wrong part? or does that MAF cover most models of engine?

and...wha wha... i stupidly slammed the old MAF under the hood and pretty sure its busted. Cracked the case anyway.
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Old 09-11-2019, 04:30 PM   #12
scooby24
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Did you reset the ECU learning? You probably need to do that if the learning is all over the board after a bad MAF.

If that doesn't help, next step I'd be doing is replacing the AFR sensor (upstream)
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Old 09-11-2019, 06:11 PM   #13
endneu913
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Quote:
Originally Posted by scooby24 View Post
Did you reset the ECU learning? You probably need to do that if the learning is all over the board after a bad MAF.

If that doesn't help, next step I'd be doing is replacing the AFR sensor (upstream)
Oh please educate me on how to do that!

Side note- Now ( for the moment ) only getting #2 misfire. Previously it was all 4 all at the same time. If it stays that way, ill do the coil pack swap test.
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Old 09-11-2019, 06:29 PM   #14
scooby24
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If you have an OBDII adapter and torque pro, resetting codes also pushes a reset of learned values.

Otherwise just disconnect the battery's negative terminal and leave it disconnected 20 minutes or so, then reconnect.
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Old 09-11-2019, 06:55 PM   #15
endneu913
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Quote:
Originally Posted by scooby24 View Post
If you have an OBDII adapter and torque pro, resetting codes also pushes a reset of learned values.

Otherwise just disconnect the battery's negative terminal and leave it disconnected 20 minutes or so, then reconnect.
Thanks- OBD2 yes, no Toure Pro. Ill Disco the battery
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Old 09-11-2019, 10:15 PM   #16
endneu913
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Left it off for a while. Reconnected, same results-

Still ONLY Cyl #2 misfire ( was all 4)

Now falls on its face at 4500 repeatedly

Wondering if the MAF was bad all along and just uncovered masked something else.
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Old 09-12-2019, 07:16 AM   #17
scooby24
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Very likely. If anything changes with the MAF that points to a problem with it. I wouldn't rule out coil packs based on the symptoms. Especially number 2 which is front drivers side. That one is easy to get to also.
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Old 09-12-2019, 12:54 PM   #18
endneu913
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Quote:
Originally Posted by scooby24 View Post
Very likely. If anything changes with the MAF that points to a problem with it. I wouldn't rule out coil packs based on the symptoms. Especially number 2 which is front drivers side. That one is easy to get to also.
Thanks, ill swap them over tonight and see if the misfire follows.

Anyone got an used packs laying around for sale?

What is next after that? AFR or ACVs? LOL

Last edited by endneu913; 09-12-2019 at 01:49 PM.
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Old 09-12-2019, 03:07 PM   #19
scooby24
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Quote:
Originally Posted by endneu913 View Post
Thanks, ill swap them over tonight and see if the misfire follows.

Anyone got an used packs laying around for sale?

What is next after that? AFR or ACVs? LOL
I actually do have one. If do AFR next as fuel all over the place can hurt the sensor.
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Old 09-12-2019, 06:49 PM   #20
endneu913
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I found one at the autozone on my way home. Ill just return it if its not part of the issue.

Any idea on a part #for the AFR ?
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Old 09-12-2019, 08:25 PM   #21
scooby24
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Denso 2349120
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Old 09-12-2019, 11:03 PM   #22
endneu913
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Installed new from box Ign Coil in # Cyl. Same symptoms. ( but did not clear ECU ) So doing that now and will test again.

The clip on the harness on #2 is broken. Was hoping that maybe the clip had come undone. It looked seated, just not clipped tight. No change tho ( I zip tied the clip on )
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Old 09-12-2019, 11:12 PM   #23
endneu913
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Quote:
Originally Posted by scooby24 View Post
Denso 2349120
This is the guy ? https://www.amazon.com/Denso-234-912.../dp/B001F799X6

Where does he live?
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Old 09-12-2019, 11:19 PM   #24
scooby24
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In the header right before the uppipe. You can get to it without even having to get under the car really. Passenger wheel well and follow the wiring to the plug up behind the airbox. You'll want an o2 sensor socket. Harbor freight has em for cheap.
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Old 09-12-2019, 11:58 PM   #25
endneu913
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Quote:
Originally Posted by scooby24 View Post
In the header right before the uppipe. You can get to it without even having to get under the car really. Passenger wheel well and follow the wiring to the plug up behind the airbox. You'll want an o2 sensor socket. Harbor freight has em for cheap.
Oh gotcha- Yeah i know it- Blue wire covering- It actually looks fairly new.

OK, reset ECU, drove about 7 miles. Its crazy how 180 degrees the engine is acting ( bucking like crazy at 4500 )

Codes now: Misfire in 2 and 4 ( same side of motor) 1 is new, one is old.
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