misfire, need assistance!!!
02-04-2011, 04:28 PM
#1
misfire, need assistance!!!
Cliffs: 24lb injectors, misfire on 1 and 4, replace cops on 1 and 4 and all 8 plugs, still doing it, alternator died right before this started, no tune still but didnt do this before, what should i do?
Long story:
Ok guys, I've never posted in this section before but I need some help! I am no noob but I have no clue whats going on with my car right now.
I have 24lb injectors off a 01 cobra on my car and have had them on for a couple months now. But for the last 3 wks or so my car has had a bad misfire on startup for a couple mins then goes away and sometimes even comes back as I'm driving and sometimes just stays from start til I get to work 10 mins later, it varys.
My check engine light is on and I checked the codes and they were for a misfire on 1 and 4 so naturally I replaced both those cops and now I have also replaced all of the spark plugs but it still doing it.
I havent had a chance yet to check what codes are popping up now but I am at a total loss what the problem could be now. I know its not good that I also dont have a tune yet on the car but I dont see that being the problem as I drove with the injectors on the car for a couple months with no problems until now, however I am currently working on getting an email tune to see if it fixes it.
Also not sure if this couldve done something like fried a wire or injector or something somehow but my alternator went out right before this started happening?? Also the first couple months they were installed I was running 92 octane and now for the past couple winter months I went back to 87 for the mpg's, doubt thats the problem but just a thought.
Any and all help is veryyyyy appreciated as I am at a total loss right now, even my buddy that works for ford isnt sure what it is, he just thinks I need the tune, but I figured I would ask on here since many of you guys know a LOT more than a 21 yr old ford tech and myself would know.
Thanks.
Long story:
Ok guys, I've never posted in this section before but I need some help! I am no noob but I have no clue whats going on with my car right now.
I have 24lb injectors off a 01 cobra on my car and have had them on for a couple months now. But for the last 3 wks or so my car has had a bad misfire on startup for a couple mins then goes away and sometimes even comes back as I'm driving and sometimes just stays from start til I get to work 10 mins later, it varys.
My check engine light is on and I checked the codes and they were for a misfire on 1 and 4 so naturally I replaced both those cops and now I have also replaced all of the spark plugs but it still doing it.
I havent had a chance yet to check what codes are popping up now but I am at a total loss what the problem could be now. I know its not good that I also dont have a tune yet on the car but I dont see that being the problem as I drove with the injectors on the car for a couple months with no problems until now, however I am currently working on getting an email tune to see if it fixes it.
Also not sure if this couldve done something like fried a wire or injector or something somehow but my alternator went out right before this started happening?? Also the first couple months they were installed I was running 92 octane and now for the past couple winter months I went back to 87 for the mpg's, doubt thats the problem but just a thought.
Any and all help is veryyyyy appreciated as I am at a total loss right now, even my buddy that works for ford isnt sure what it is, he just thinks I need the tune, but I figured I would ask on here since many of you guys know a LOT more than a 21 yr old ford tech and myself would know.
Thanks.
02-04-2011, 11:51 PM
#3
I was thinking this but I decided to tuck that wayyyyy back in my head cause that sucks, I dont wanna have to replace 5 month old injectors(they were literally brand new when i bought them) : / guess imma clean them first and see what happens, then replace if it persists, thanks for the suggestion bramas
02-05-2011, 10:36 AM
#5
Join Date: Jan 2011
Location: NC
Posts: 47
Get a new Ignition coil pack. Id bet a pretty penny thats your problem. I just test drove an 02 and it was misfiring like crazy he said it was probably the coil pack so they replaced it and BAM good as new. Car doesnt misfire at all. Also, it could be your MAF or your IAC. But most likely its the coil pack... ive heard they arent the best on our years. Their not expensive so its not a big fix at all. Hope this helps 
Best of luck
Best of luck
02-05-2011, 11:59 AM
#6
yea like I said I am working on getting an email tune asap so that everything gets set up properly such as the maf being recalibrated and what not for all the stuff I have on it
but also a good point whitefoxgt, i guess in my total annoyance with this problem I havent been thinking of all these things to check and see what is wrong, but i do appreciate all the help thus far guys
also to fordracer, our cars actually dont have iat's it is built into the maf sensor on the late 01's to 04's, and I have also already replaced 2 of the coil packs, and if it isnt an injector then my next step will be to replace the rest of the coil packs
but also a good point whitefoxgt, i guess in my total annoyance with this problem I havent been thinking of all these things to check and see what is wrong, but i do appreciate all the help thus far guys
also to fordracer, our cars actually dont have iat's it is built into the maf sensor on the late 01's to 04's, and I have also already replaced 2 of the coil packs, and if it isnt an injector then my next step will be to replace the rest of the coil packs
02-05-2011, 12:18 PM
#7
TECH SAVANT
Join Date: Dec 2006
Location: Saint Augustine, FL
Posts: 10,938
From the shop manual (emphasis added):
Degraded performance and or failure of the CKP is not uncommon, and will cause the sort of actual intermittent misfiring you report.
The Misfire Detection Monitor is an on-board strategy designed to monitor engine misfire and identify the specific cylinder in which the misfire has occurred. Misfire is defined as lack of combustion in a cylinder due to absence of spark, poor fuel metering, poor compression, or any other cause. The Misfire Detection Monitor will be enabled only when certain base engine conditions are first satisfied. Input from the ECT or CHT, MAF and CKP sensors is required to enable the monitor. The Misfire Detection Monitor is also performed during on demand self-test.
The input signal [from the CKP] to the PCM is then used to calculate the time between CKP edges and also crankshaft rotational velocity and acceleration. By comparing the accelerations of each cylinder event, the power loss of each cylinder is determined. When the power loss of a particular cylinder is sufficiently less than a calibrated value and other criteria is met, then the suspect cylinder is determined to have misfired.
The input signal [from the CKP] to the PCM is then used to calculate the time between CKP edges and also crankshaft rotational velocity and acceleration. By comparing the accelerations of each cylinder event, the power loss of each cylinder is determined. When the power loss of a particular cylinder is sufficiently less than a calibrated value and other criteria is met, then the suspect cylinder is determined to have misfired.
02-05-2011, 01:47 PM
#8
so replace ckp and see if it fixes, check
thanks cliff, i was actually waiting for you to respond at some point or another cause i used to be on here before but got deactivated and i remember that you had helped me out before on something
thanks cliff, i was actually waiting for you to respond at some point or another cause i used to be on here before but got deactivated and i remember that you had helped me out before on something
Last edited by 03stiffiGT; 02-05-2011 at 01:52 PM.
