possible misfire? no codes

[tsoko24]

hello, I have a 2007 Mercury Mountaineer AWD V8. 73,000 miles. a couple months ago I had misfire that only happened when the truck was in 6th gear under a load. like going up a slight incline and giving it a little gas. or when it was above 4k getting on the highway. one day the check engine like flashed and we were able to pull a code saying there was a cylinder #4 misfire. replaced the coil and the spark plug. everything was fine for a while until it started doing the same thing a couple weeks ago. No codes. So I had a mechanic friend use his snapon tool while I drove it and recreate the misfire. According to the snapon tool, all the cylinders are firing like they are supposed to. No hiccups. even tho we both can feel it. So he said we should check the torque converter. well according to the tool the torque converter is performing as it should. he said he doesnt really know what it is, and Id just be playing the guessing game with replacing stuff.
really hope to get this fixed before it leaves me stranded somewhere

Has anyone had this problem?

any help would be much appreciated

 

[Bobmbx]

What was the Snap-On tool measuring? Spark voltage on the wire or that the cylinder was firing?

It sounds like you're starving for fuel at high flow rates. Run a can of Gum Out (fuel injector cleaner) through it. Thats would be the cheapest step. Next guess would be the fuel filter needs to be changed. If that's not it, then check your fuel pressure and flow rates.

 

[willied]

I've got a similar problem with no codes. I have had problems with it in the past, but it only happened at around 45-50 MPH and a trans fluid change fixed that. But this time it happens at higher speeds. I haven't changed the fuel filter in mine as long as I've had the car, so it might be that. I did buy one to replace the old one, but I haven't gotten around to installing it yet. I'll try to get it done tomorrow and see if it helps.

 

[Henders]

Sounds like your spark plugs might just be starting to go. If you haven't replaced them yet, I'd do that first. Had the same issue with my 06. It didn't throw a code until 115K miles. The only thing I did notice was wasn't getting as good MPG (Highway) as before (dropped from about 22 to 17-18 MPG). After I had the plugs replaced, my MPG's are back up to 22 MPG.
PS: I currently have about 121K miles on it with the original Fuel Filter and the Ex is running Great!

 

[tsoko24]

Okay thank you for the input, I think I'm gonna keep driving it until it throws a code! Hopefully it's soon!

 

[willied]

I got the fuel filter changed out on mine. The old one was pretty dirty. However, it didn't solve the issue I'm having. I had my spark plugs changed out around 40,000 miles ago. I think I'm going to try some fuel system cleaner.

 

[Henders]

May also want to check the ignition coils. There's a few threads out there that talk about some of them going bad causing problems (noticeable during uphill climbs...)

 

[makuloco2000]

hello, I have a 2007 Mercury Mountaineer AWD V8. 73,000 miles. a couple months ago I had misfire that only happened when the truck was in 6th gear under a load. like going up a slight incline and giving it a little gas. or when it was above 4k getting on the highway. one day the check engine like flashed and we were able to pull a code saying there was a cylinder #4 misfire. replaced the coil and the spark plug. everything was fine for a while until it started doing the same thing a couple weeks ago. No codes. So I had a mechanic friend use his snapon tool while I drove it and recreate the misfire. According to the snapon tool, all the cylinders are firing like they are supposed to. No hiccups. even tho we both can feel it. So he said we should check the torque converter. well according to the tool the torque converter is performing as it should. he said he doesnt really know what it is, and Id just be playing the guessing game with replacing stuff.
really hope to get this fixed before it leaves me stranded somewhere

Has anyone had this problem?

any help would be much appreciated

I don't want to come off as a jerk but your mechanic friend should know what a secondary miss feels like. I can tell from your description alone that it is a secondary miss. It happens more just past 45mph when torque convertor come on then slight press on the gas to load it up and it jerks right?