'97 Expedition knocking
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New User
Joined: Jul 2003
Posts: 18
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From: Kingman, AZ.
'97 Expedition knocking
I've had this vehicle for about 3 yrs. now, bought it used with 60k miles, it now has 82k. I've had to run mid grade gas or above from the start because of knocking, I just lived with it.
I had a 3" Flowmaster catback installed and put in an AirRaid air intake, alot more fun to drive. I also bought a Power Programmer. Now trouble, I can't use it. I get to much knocking. Used premium with an octane booster(suggested by Hypertech) and ended up fouling 3 sets of plugs trying different brands of booster. Changed the fuel filter, didn't help.
Could the problem be low fuel press., bad knock sensor...?
Bought a boat and even with the programmer not installed, running premium in November, still having some knocking. What's it gonna do come summer when it gets hot?
Any help on this knocking problem would be appreciated.
I had a 3" Flowmaster catback installed and put in an AirRaid air intake, alot more fun to drive. I also bought a Power Programmer. Now trouble, I can't use it. I get to much knocking. Used premium with an octane booster(suggested by Hypertech) and ended up fouling 3 sets of plugs trying different brands of booster. Changed the fuel filter, didn't help.
Could the problem be low fuel press., bad knock sensor...?
Bought a boat and even with the programmer not installed, running premium in November, still having some knocking. What's it gonna do come summer when it gets hot?
Any help on this knocking problem would be appreciated.
Post Fiend
Joined: Jan 1997
Posts: 23,165
Likes: 18
From: Enjoying the real world.
If it was knocking with 87 octane prior to using the Hypertech then there's a problem with the system. Put a code reader on it and see if you can pull any codes. That will pin-point anything obvious first. Autozone will pull codes for free.
Thread Starter
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New User
Joined: Jul 2003
Posts: 18
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From: Kingman, AZ.
I had it in to two different dealers when I went through the fiasco of fouling plugs and specificaly mentioned the problem of knocking. They never came up with anything.
However, over the weekend I replaced the PCV valve and hosed down the MAF with contact cleaner. One of the two made a difference, probably the MAF. I was able to use the Programmer on a trip back from Phoenix and the only time it would knock was wide open throttle after 4k an the tach. Doubt this would be an issue if I could get 93 octane.
Speaking of, any ideas on octane booster. I Would use it if I hadn't already had so much trouble fouling plugs.
Thanks for your input.
However, over the weekend I replaced the PCV valve and hosed down the MAF with contact cleaner. One of the two made a difference, probably the MAF. I was able to use the Programmer on a trip back from Phoenix and the only time it would knock was wide open throttle after 4k an the tach. Doubt this would be an issue if I could get 93 octane.
Speaking of, any ideas on octane booster. I Would use it if I hadn't already had so much trouble fouling plugs.
Thanks for your input.
Post Fiend
Joined: Jan 1997
Posts: 23,165
Likes: 18
From: Enjoying the real world.
It was probably the MAF sensor. If its dirty you'll get a faulty reading and the engine will run lean. Octane booster will help with minor knocking (such as yours) with premium fuel. It will not work to boost 87 octane up to 93 octane. When the can says "5 octane points" they mean ".5", not "5.0". Go with the highest boost rating in order to get as close to one true point of increase.
