Hi all,

I'm a new owner of a used 2007 V8V with 7800 miles. It was running great, but had the squeaky belt. I'm taking it in for that Wednesday.

I noticed over the past few days a very slight surging feeling. It's subtle, but feels like I'm jiggling the throttle very slightly and very quick. I notice it when there's a slight engine load...pulling away from a light, or going up a hill. Not when I'm on it hard. I don't feel it when coasting. I doesn't happen all the time, but it seems to be getting worse. The car sometimes sounds a bit rough at idle, but not always.

Sure enough, the check engine light came on today on my drive to work. The message said to check the emissions. Again, I bring it in on Wednesday, but I was hoping someone might give me an idea of what it is. Thanks!
Ken

 

Any chance it's a fuel quality issue? Our cars are incredibly finicky when it comes to the gas we use, and it's getting close to that time of year when the crappy winter blends start making there way into the pump.

 

That's too early to be an ASM car so its not creep mode
Could be a dirty throttle butterfly
I found on all mine clean that up gives a much more stable idle.

 

As Mikey said, throttle body is a suspect but could be a couple of things. Can you plug into a scan tool and check the DTC codes?

 

I neglected to say that I did clean the throttle body. It is a stick,too. It could be gas! I'm down to 1/4 tank, thinking it could be the gas tank vent thing, but I don't think that's it. I'll fill it up today. I usually use diamond shamrock, but I used conoco last time I filled up. I'll let you know! Does anyone use an additive every time you fill? I used to use BG something (the orange bottle) on an old porsche and it worked wonders.

Thanks!

 

I got new gas and it seems better. It still surges abit, but not as often or as much. I also remembered that I used Shell, not Conoco. I've read here that Shell has been problematic for others.

As mentioned, I'll be taking it in tomorrow for other fixes. I'll update this thread when I get it back!

 

I got the diagnosis. It's the ignition coil for cylinder 1. It's shorting out and will get worse over time and will eventually fail. Unfortunately, the coil is not in the US. It has to be ordered from the UK, so I'll be without my car again for a few days.

Thanks again for the help!
Ken

 

A bad ignition coil after only 7800 miles?!

 

If you can, please post a photo or two of the coil so perhaps we can figure out what Ford/Mazda/Jaguar part will work, at a lower cost and better availability.
Thanks!