Misfire vs. Transmission Slip

[A K]

As an update to my (what I thought were) transmission issues, my shop guy said that he pulled four misfires from the computer but could not tell in which cylinder the misfires occurred.



Before my last long drive, which preceded taking it to the shop, I pulled the negative battery cable for about an hour to reset the system. Assuming the memory cleared, then this could make some sense of my issue.



My questions then are:



Can a misfire cause transmission slipping-like symptoms? I'm pretty positive the transmission clunked when the increase in revs/power issues occurred, but then again, because it happened so quickly and randomly, I can't say the jolt wasn't caused by PA's terrible turnpike paving.



Or, are these two distinct issues, which means either I am in for a world of car pain soon (if it's not a cracked elbow) and I should trade it in before then?



As to the transmission, the fluid and filter were fine, no codes were on the system, and my guy hasn't been able to repeat the issue, despite using the ST for shop business these last few days (getting transmission parts, etc., which I'm fine with).

 

[Art Garcia]

Adam,



how much mileage is on your ST?

i had one of my cylinders misfire and it

did cause a jerk-like filling while driving.

almost as if the tranny was slipping.

 

[A K]

77,000 +/-.



However, the tranny before has been fine. Fluids flushed, changed filter (and checked old), etc.

 

[Art Garcia]

mine happened around 130k.

more than likely it will be the cylinder causing those symptoms

 

[scott degroot]

The way I describe a misfire feeling to a customer is to ask them if they have ever been fishing. If you are driving down the road and a misfire occurs it will feel lilke you are getting a fish bite, consecutive misfires could be mistaken for a trans issue and I get ALOT of people in the shop who think they have trans problems when in fact it is a misfire situation.



I'm confused as to how your shop guy "pulled 4 misfires from the computer". If indeed you are having a misfire situation and can't pinpoint the affected cylinder or cylinders if your guy has the right scanner he can access mode 6 data. Mode 6 data will list test results in hexidecimal form so you have to know what you are looking at to understand what is going on. On all Fords the mode 6 data for misfires is TID 53, this indicates what test and CID 01 in this particular instance would indicate which cylinder. The whole string on a scanner would look like TID53CID01, this indicates misfire monitor on cylinder #1, TID53CID02 would be misfire monitor on cylinder #2 and so forth. Any reading after that would be the number of misfires accumulated for that given cylinder, when the reading reaches a certain threshold it turns on the check engine light. Some Fords will allow thousands of misfires to occur before ever setting a code so this information is critical when diagnosing a suspected misfire where no code has set. This information is also available for all of the monitors on the car and if you know how to read it you can tell exactly how each system is operating.

 

[Jack Adams]

Adam,



Just curious if you did a spark plug change recently? On our old 01 we had a misfire issue shortly after, as I didn't replace the plug wires. For that she saw a flashing check engine light when it was misfiring. Not much fun changing plug wires in the rain at a motel parking lot. I think the plug change was recommended around 60K. Good luck.

 

[James Sniezek]

I had the something had today when driving home from someplace. My st start to jerking and when my st was doing it the check engine light was flashing then it was fine. I did have the radio on so I could not hear if it misfire. So is that a misfire or transmission slipping.

 

[A K]

Haven't changed the plugs or wires at all, actually. It was first on my list for this weekend's projects. But, I'm also hoping it solves this issue.



As I will be changing the plugs and wires, is it also worthwhile to change the coil while I'm in there? Or is that overkill?



I just hate to do it piecemeal until something solves the misfire.