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Misfire at idle... no codes

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Location
Los Angeles
#1
I have a very slight misfire at idle... most people wouldn't notice it.

No misfire during driving... no check engine lights.

My old supras and rx7 use to do this also... sometimes plugs would help.

Anyone else experience this?

Bone stock besides a drop in air filter...

Problem did start after I changed the air filter... hmmm
 


Messages
429
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64
Location
Dearborn
#2
I have a very slight misfire at idle... most people wouldn't notice it.

No misfire during driving... no check engine lights.

My old supras and rx7 use to do this also... sometimes plugs would help.

Anyone else experience this?

Bone stock besides a drop in air filter...

Problem did start after I changed the air filter... hmmm
If you're considering heading to your dealer on this, please keep me in the loop so I can look into some options.

Meagan
 


me32

1000 Post Club
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fairfield
#3
Are you sure its a miss fire an not just the sound the car makes? Being new am stock I don't really see it miss firing. Have you logged it? Did you try putting stock filter back in?
 


OP
Teezlr
Messages
242
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Location
Los Angeles
Thread Starter #4
Are you sure its a miss fire an not just the sound the car makes? Being new am stock I don't really see it miss firing. Have you logged it? Did you try putting stock filter back in?
No and no, it's more like a pop/studder..... Sounds like a misfire

I'll try stock air cleaner soon
 


D1JL

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Staff Member
Premium Account
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#5
A misfire is a very bad thing and can destroy a CAT.
Even if you don't get a hard code with CEL on.
You should get a Pending Code.



Dave
 


Messages
299
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66
Location
Tupelo
#6
Ford constantly searches for timing at idle. You could pull the entire spark plug out of the block at idle and it wouldn't throw a code. The variable cam timing won't recognize a misfire until the engine is under load. This is common on all fords.

Carry on.
 


Messages
173
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26
Location
LA
#8
Bumping this older thread for more thoughts.

At 18k miles my engine has developed a rough idle. Every few seconds (no real pattern, though), if you stand by the exhaust, you can hear an occasional poor detonation (can't rally think of another way to describe it), almost like an occasional single cyl. misfire. No codes and no CEL. A/F ratio meter bounces around a bit when it does produce the symptom. The only mod I have is the Mountune 215 kit. Could it be carbon? This early? I checked the PCV hose that exits the valve cover and connects to the front of the intake and it was dripping with oil before I installed a Mishimoto compact catch can about 1k miles ago.
 


Messages
173
Likes
26
Location
LA
#9
Embarrassed to admit it, but it was a bad tank of gas. I think the station where I live had the wrong octane in the wrong tank or something is messed up with that pump. New tank of premium solved the issue immediately. Put some new plugs in just in case and all seems to be well. Hope there are no long term repercussions.
 


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54
Location
Morton Grove
#10
I'm bringing this back to life because I'm getting a misfire under load and I'm running 1 step colder gapped to .025.
 


CanadianGuy

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Southern Ontario
#11
I'm bringing this back to life because I'm getting a misfire under load and I'm running 1 step colder gapped to .025.
Do you have a code? Previous fault was bad gas. Did you just fill up? NOt saying this is your issue but I had similar misfire under load on my Ford Edge. It turned out to be a bad coil pack. Replaced it and it was fine. Could also be a bad spark but without a code it is hard to say.
 


Messages
280
Likes
54
Location
Morton Grove
#12
Do you have a code? Previous fault was bad gas. Did you just fill up? NOt saying this is your issue but I had similar misfire under load on my Ford Edge. It turned out to be a bad coil pack. Replaced it and it was fine. Could also be a bad spark but without a code it is hard to say.
I've got half a tank and it ran fine when full. I always use she'll since we have them everywhere here. Plugs aren't even more than 1k old, and the only thing out of the ordinary for the car was an auto x event. The car ran fine after the event too. I'll start checking all these things 1 by 1 this weekend. I still have the original plugs too.

Edit: still have no code, but I definitely feel hesitation as the car accelerates. Is there anything I can look for in a data log?
 


Last edited:

CanadianGuy

4000 Post Club
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Location
Southern Ontario
#13
I've got half a tank and it ran fine when full. I always use she'll since we have them everywhere here. Plugs aren't even more than 1k old, and the only thing out of the ordinary for the car was an auto x event. The car ran fine after the event too. I'll start checking all these things 1 by 1 this weekend. I still have the original plugs too.

Edit: still have no code, but I definitely feel hesitation as the car accelerates. Is there anything I can look for in a data log?
Boost leak?
 


WaterMore

New Member
Messages
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2
Location
Waterford, Ireland
#15
Can I comment on this, in the hope someone might know something, just posted this as a thread:

Hi all,

I searched and searched for answers to this and couldn't find anything. So thought I might post it to see does anyone have the same issue.

I have a 2015 registered (Oct 2014 built) Fiesta ST-3.

I bought the car second hand April 2019. The car since day one ish, has had a very noticeable misfire and this misfire happens at idle, driving off boost and in boost, meaning it is constant. But at idle the misfire only happens when the car reaches full temp, and not the temp on the dial as that goes full at around 62°, but on my torque pro app I monitor it and it doesn't start till the car is over 92°.

It is only at idle in the above conditions that it will knock in to limp mode. This was always really annoying as I am in traffic on the way home from work and the only way for me to combat it is to rev the car from its idle 780 ish rpms to 1k rpms.

The 4 fault codes that I have listed below are the ones that I could find that I wrote down, but some have appeared more than once. They are (I will give a full description below):
P006A:64-6C - MAP
P0106:64-2F - Barometric Pressure
P1060:64-2E - MAP
P00CF:62-6C - MAP

I have brought the car to Ford dealership when one of the times the code P0106:64-2F - Barometric Pressure put the car in limp mode, and the only real information that I got back from them was the boost reading was different from one sensor to another and when it happens again they will look at it.

What I have done in the hope of sorting it:
New spark plugs
X2 new MAP sensors, first was not OEM, the second was.
New boost pressure sensor, under warranty the re-seller changed this but was not OEM as they are not a Ford garage
I have since tightened all the boost clamps, which were in fairness pretty lose, this was the information that Ford had give me, and I started looking at the boost, I was only boosting 16psi instead of 21psi (1.1 bar instead of 1.44). The cars is only boosting 19.2 at the moment, but there is one pipe I can't get at till my 7mm spanner I ordered online arrives, these are hard to find locally for where I live.
I also did the ground wire with file and dielectric grease in the hope it was just an electrical mishap.
I got it serviced hoping it was something stupid

The current modifications on the car are:
Mountune boost pipes
Mountune coolant pipes
Mountune intercooler
Mountune short shifter
COBB engine rear mount
Eibach Pro strings
Vudu Symposer Delete
K&N filter - only, no Mountune box

From what I can make out from my OBD and live data the car does not have a software tune, the power at the wheels is exactly what the manufacture states, though it took me some time to find this as Ford advertise the power at the crank.

I am eager to get this resolved as I am waiting until it is to purchase ITG intake and Peron Stage 1+, and I'll stop after I have that.

Any help at all would be appreciated at all.
 




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