Misfires while engine is cold

[2k05gt]

My Aeroforce Interceptor guage is showing about 25-30 misfires in 10 min before the engine warms up, then at idle to 1500 rpm I get a couple more,
I just got a Tune from American Muscle to reflect my 127300 cams. No Codes or CELS just shows up on the guage and I can feel the car miss.
The Tune I got from AM (Bama) is running 11.5-11.8 Air Fuel at WOT so it's running rich for a N/A Car... Any ideas?

 

[Kuro!]

You got a mailorder tune...

Is the CEL flashing at all and just not catching the code?

 

[2k05gt]

No flashing CEL, No Codes, just watching the Aeroforce guage and watch the mis-fire PID

 

[TexasBlownV8]

...spark plugs? when did you change them? what gap? which ones are you using?

 

[2k05gt]

...spark plugs? when did you change them? what gap? which ones are you using?

I replaced them last year, not sure of gap but they are motorcraft (stock type) not more than 10,000 miles

 

[demarcom]

Here is a thread I had with my tuner, Justin @ VMP last year.

My description: On a leasurely drive I am getting about a dozen in 20 miles of driving. Last week I was at the Carlislie Ford Nationals and on a 150 mile trip I got about 60, and got into boost several times.


I dont know if the misfire count is normal/irrelevant? or if it is a sign of a problem in the tune or spark plugs. The plugs are at a Whipple adjusted to .30 from the factory and I checked each one. I also put the recommended small amount of Nickel Anit seize on the plugs being very careful to stay away from the tip. What do you recommend? The car seems to run fine and I dont sense anything is wrong, but the misfire reading concerns me.

Justins Response:
Sounds normal, also misfire detection logic is not guaranteed

So taking his word for it, I have been driving the car for 1 year and no issues. I ignore the misfire count now. never had performance issues or any sign of misfire, no CEL, nothing. Had the car to JDM on the dyno and they didnt mention anything wrong either.

 

[b00stedgt]

I have a similar issues right now. I get a mis on cold starts

 

[porkipine]

i don't know if this can help or not, a dealership can pull up mode 6 with ids and i.d. the cylinder that is misfiring. coils can do this... just a thought

 

[porkipine]

intake gaskets could also cause this...just another thought

 

[2k05gt]

intake gaskets could also cause this...just another thought

You mean leaking? intake not torqued correctly?
I did have my intake off when I installed the cams, I ran the battery cable going to the alternator under the intake instead of along side it.

 

[Cone Sweeper]

I too had this issue and then looked further into it with a few different tuners down here. It's pretty common.. the ECU detects a number of misfires before throwing an actual CEL. I've heard from numerous tuners as well as ford tech's that number is more so over a 100 misfire counts before throwing an actual misfire CEL. <shrug> Hope this helps ease your thoughts of a big problem.

 

[Noclutch]

I feel them all the time after my 127200 install no codes and it has not hurt performance. I always wondered what the count would have to be to get a code.

 

[BruceH]

My Aeroforce Interceptor guage is showing about 25-30 misfires in 10 min before the engine warms up, then at idle to 1500 rpm I get a couple more,
I just got a Tune from American Muscle to reflect my 127300 cams. No Codes or CELS just shows up on the guage and I can feel the car miss.
The Tune I got from AM (Bama) is running 11.5-11.8 Air Fuel at WOT so it's running rich for a N/A Car... Any ideas?

I've noticed them with my new na motor. I have had 127300 cams for about 9 months and never had a problem with my old motor, same cams, and Whipple.

So far I've narrowed it down to clunk related to the dashpot function. One of the fixes for surging nuetral idle after a cam change is to lower the isc dashpot gain. However this parameter is also used in conjunction with dashpot preposition to control tip out related clunking which I've noticed occurs more during high load/low rpm situations like cruising along in 4th at 1500 or so rpms, barely on and barely off the gas.

I've been messing with these parameters and a few others to get rid of the clunk, surge, and misfire count. I can tell you that the misfires show up during the clunk.

Hopefully a real tuner will see this thread and chime in. All I have for reference is written material on engine management and experience through experimentation with prp (ie flying blind).