Help please!! Misfiring no codes - coils look fine -???

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Happysacks00

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Hey all,

Ive been having this problem for quite some time now, and i have no clue where to start looking.

Ive used the search feature for this but found little direction to go in....I have a 2002 ls v8 sport. Had a misfire for about 6 months when at idle, climbing hills, and when the tranny goes into OD at approx 1500-1800 rpm. If i shift into D4 the misfire will rarely occur but still there sometimes.

I have had no check engine lights come on, and when i feel it misfire i have slammed on the gas to throw a code out and nothing. Its very frustrating and i literally have no idea where to start. I have replaced all 8 coils/plugs and valve cover gaskets. I have checked all coils / plugs about a month ago and there was no oil on them, nor did the coils appear to be damaged or have carbon deposits on them.

Any other suggestions???
 
Is it:

1. You had the problem. Then you changed the coils and plugs and the problem remained?

or

2. You had a problem. You changed all coils and plugs and it fixed it. Now months later the same problem is back or a new problem is here? If it's that, then probably one or more of your new coils is failing. A stress test will find it for sure. A good Ford scan tool that can get to the pending misfire counts would probably find it or them. If you put cheap coils in, it might be more productive to buy a full set of new rev Motorcraft coils and new plugs.
 
I had many problems with misfires and coils failing. Id scan it, find the cylinder, replace coil/plug (with generic ones from carquest-not OEM).

Everytime i ever had a coil problem id slam the gas and it would throw a code. This is not the case. The misfire routinely happens when at idle, climbing up hills between 40-60 mph at 1500-2000 RPM, and when driving at highway speeds only when its shifting into OD.
 
joegr said:
Is it:

1. You had the problem. Then you changed the coils and plugs and the problem remained?

or

2. You had a problem. You changed all coils and plugs and it fixed it. Now months later the same problem is back or a new problem is here? If it's that, then probably one or more of your new coils is failing. A stress test will find it for sure. A good Ford scan tool that can get to the pending misfire counts would probably find it or them. If you put cheap coils in, it might be more productive to buy a full set of new rev Motorcraft coils and new plugs.
Click to expand...


1- Ive had issues with coils blowing - first one i did back in 2009 i noticed oil in the spark plug wells - i replaced failed coils and valve cover gaskets. Every coil after that had failed i replaced plug/coil one at a time as they came.

2- New problem - it almost seems like a coil that has gone bad, but slamming on the gas pedal does not throw a code, nor does it seem to weaken the "would be" bad coil if it was a coil. and where can i get a ford stress test done?? would i have to go the dealer, or can i buy the scan tool. I have an old scanner that was my uncles (he is a mechanic - and i cannot even get him to look at it). I dont know the name of the scanner tool but i know that i have to use key K2-A for it to read the lincoln.
 
Happysacks00 said:
1- Ive had issues with coils blowing - first one i did back in 2009 i noticed oil in the spark plug wells - i replaced failed coils and valve cover gaskets. Every coil after that had failed i replaced plug/coil one at a time as they came.

2- New problem - it almost seems like a coil that has gone bad, but slamming on the gas pedal does not throw a code, nor does it seem to weaken the "would be" bad coil if it was a coil. and where can i get a ford stress test done?? would i have to go the dealer, or can i buy the scan tool. I have an old scanner that was my uncles (he is a mechanic - and i cannot even get him to look at it). I dont know the name of the scanner tool but i know that i have to use key K2-A for it to read the lincoln.
Click to expand...

The tools to do the stress testing cost in the thousands. You'd have to go to a dealer and pay the diagnostic charge.
 
Happysacks00 said:
2- New problem - it almost seems like a coil that has gone bad, but slamming on the gas pedal does not throw a code, nor does it seem to weaken the "would be" bad coil if it was a coil. and where can i get a ford stress test done?? would i have to go the dealer, or can i buy the scan tool. I have an old scanner that was my uncles (he is a mechanic - and i cannot even get him to look at it). I dont know the name of the scanner tool but i know that i have to use key K2-A for it to read the lincoln.
Click to expand...

I'm going through the same thing. No codes were coming up even though I could feel the misfires so I asked my mechanic to scan the OBD with his tool. His result was a clean scan.
Also this is affecting the transmission I think. It feels like the trans can't decide which gear it want's to be in. It happens as Happy said between 40 to 60 under a load. Like going up an incline or trying to accelerate on an onramp to highway speed. Curious thing I find is, I try to watch the tach when I think this is going to happen, and it's always steady. I would think it would change RPM if trying to go between gears. Even at idle when I feel a misfire I see no drop in RPM.
 
ah i was just about to buy new cops as the same thing is happening to me as well,
 
Ace, the production tach isn't sensitive enough to show the condition as you describe it. If you replace ALL the coils, at once, along with the plugs, and ascertain that the plug silos are all dry, and examine the wiring to the coils to be sure you have no damage or other difficulty there, you'll likely find that your miss is gone. Based on my experience. (I installed Accel coils almost 50K miles ago.)

KS
 
Ah mine is doing the same thing as i was reading i was kinda iffy about getting new cops after hearing this, i got new plugs and a whole engine rebuild so im assuming that should be fine, there and more then likely the cops. My misfire is very obvious and sometimes you can slightly see it on the tach.
 
Wicked Ace said:
I'm going through the same thing. No codes were coming up even though I could feel the misfires so I asked my mechanic to scan the OBD with his tool. His result was a clean scan.
Also this is affecting the transmission I think. It feels like the trans can't decide which gear it want's to be in. It happens as Happy said between 40 to 60 under a load. Like going up an incline or trying to accelerate on an onramp to highway speed. Curious thing I find is, I try to watch the tach when I think this is going to happen, and it's always steady. I would think it would change RPM if trying to go between gears. Even at idle when I feel a misfire I see no drop in RPM.
Click to expand...
Mine did the exact same thing as well. I replaced all of the coils and plugs and the miss is gone but the transmittion still seems confused. It only does it when I ease of the gas to the point that I am slowly decelerating. Probably could use a re-flash but it is barely noticable since the miss is gone.
 
This really sucks and it's been goin on for quite some time. I can't afford to put in 8 coils all at once. I was kinda hoping that there could be some sort of scan that can monitor which cylinder is missing. I'll have to take it apart again and examine all coils/plugs and wires. I also read in another thread this misfire was happening bc of a timing chain & tensioner issue
 
I would bet COPs. I had the same problem but after time it will get worse and start bucking when you mash the gas. I had NO codes. I bought aftermarket COPs on Ebay from alanisdeals. I also changed the plugs since the COPs would be off already. Almost a year later and you have to look at the tach. to see if the car is running because it is so smooth.
 
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