Buddy Edwards

I have a weird problem that happens periodically on my 2006 GT stock Mustang. When I have been driving it for a little while and slow down from highway speeds to a stop it sometimes makes a knock sound like its starved for fuel and shakes a little. If I put it into neutral and give it a little gas it clears up and is fine for a while, sometimes weeks. I run 91 octane in it, I have cleaned the throttle body, maf sensor, replaced the fuel filter, alternator and battery and while all of it helped with performance and making it run better this ocassionally happens. Its driving me nuts. When this was happening intially it would throw a CAM sensor error I had that replaced by a ford dealership... didn't do any good and they were trying to tell me that if it happened again I would need either the CAMs replaced or a total rebuild. I would think that if it was something like that it would happen more often. I was hoping someone on here would have some ideas. The car has about 80K miles on it, I bought it used a few months ago and this started happening about a month after I got it. I was thinking about replacing the throttle body, I have spark plugs coming as well but my guess is that the spark plugs aren't going to do much. Any ideas would be appreciated, thanks!

BigDinTexas

I would start with a compression test to see if there might be a problem. Also, does the CEL come on with this happens?

Don

Buddy Edwards

I was told by a local mechanic that it had good compression when he tested it. I have taken it in to shops before I started troubleshooting it myself. The problem is that its so intermittent that it works fine when its there only to start acting up for a couple minutes every couple weeks. It seems to not have the problem when I'm running injector cleaner in it either, I just don't want to have put a bottle of sea foam in every time I fuel up. The CEL has only come on a few times and was resolved when I replaced the alternator. It came up with codes for the CAM sensor which led me to replace it when I had Ford check the codes.... I don't think that was the issue.

ziperhead

Did you put on a new or repaired alternator?

Buddy Edwards

It was a rebuilt one from advance auto parts.

BigDinTexas

Throwing this against the wall, so pardon me if it's not possible, just sorta thinking out loud...

Your compression is good, the fuel delivery from the tank to the fuel rail is likely good (you replaced the filter), and you've cleaned the MAF and TB... Could one or more of your injectors be sticking closed intermittently, being made more obvious when you take your foot off the gas? What about a COP going out? Not sure if either is feasible, but just somethings that are sticking out in my mind.

Don