spark knock
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Elder User
Joined: Jul 2003
Posts: 599
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From: VB. Virginia
spark knock
I need some advice on eliminating my spark knock. I have a 94 with a 302. It has headers, high flow converter, 56mm. throttle body, 73mm mas air, K&n filter pack, 180 degree thermostat, timing is at 10 degrees btdc. I'm using mid grade gas. And it will spark knock just cruising in overdrive. If I get on it at a stop light it rarely spark knocks. Do you think I've leaned the mixture out and need 24lb. injectors or its something else.
Thanks for your help.
Thanks for your help.
Senior User
Joined: Jun 2004
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its probly carbon build up, i have the exact problem u do. and have knock and dont have it in the same conditions. and all i got is a k&n. and open exaust. mines an 88 302. but i know some of the sounds are the valve train bein lose (which sounds like knockin also). cause the valves havent been re tourqed in atleast 50k miles, at 50k ur supposed to check them. im puttin a new motor in so i dont care. u on the other hand might wanna check. depending on miles, also check out seafoam, cause u probly have carbon and that'll cause knock. seafoam will get rid of pretty much all carbon in ur motor and itll run lika champ
~~WoZ~~
~~WoZ~~
Senior User
Joined: Apr 2004
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Also, double check your timing. If the band around the damper has shifted then you're getting an incorrect degree reading. You could also check the distributor gear to make sure it's not worn out and is sloppy on the timing. And make sure you check timing with the SPOUT connector dis-connected. That's all I can think of. Others will have more I'm sure.
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Elder User
Joined: Jul 2003
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From: VB. Virginia
I put a can of seafoam in when I filled up. It doesn't seem to have helped. It seems to spark knock worse when it's colder outside. It was rattling away tonight when it was 48 degrees outside.
Lead Driver
Joined: Sep 2002
Posts: 9,182
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From: Gateway to the West
Um... silly question, have you checked the knock sensor to make sure its functioning properly? If its failed the PCM has no idea that its knocking and won't make andjustments to compensate.
Elder User
Joined: Dec 2002
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From: South Carolina
I have another idea - I had a truck with a loose spark plug once, and it made a very aggravating racket. I didn't find it until I checked with a socket and ratchet - it snugged up considerably, and the noise was gone.
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Elder User
Joined: Jul 2003
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From: VB. Virginia
I put a new set of spark plugs in last week, so I know all the plugs are tight. I replaced the knock sensor a few months back. I'm not showing any codes as of last week. It acts like a sensor it will run fine one time and spark knock the next time I drive it.
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Elder User
Joined: Dec 2002
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From: South Carolina
I think wozxxx86 means the Seafoam can also be used "intraveinously." Use a narrow diameter section of vaccuum hose that can be discarded, and connect it to the metal vaccuum tree on the intake. Insert the other end in the Seafoam while the truck is running - warn the neigbors, because it's going to smoke *quite a bit* but that's good. It will remove carbon. Also, that cold thermostat's probably doing you no favors in the carbon and deposit build up department. If your pcm has not been reprogrammed for the larger mass air meter, I've heard that can cause pinging as well. I'd call the company that supplied the mass air unit and pick their brains - they'll know what you need to match the components of your FI system. 
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Elder User
Joined: Jul 2003
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From: VB. Virginia
Spark knock finally fixed. I was able to catch up with my brother in law that works in the service department at a local Ford dealership. He brought home a Ford diagnostic computer that he hooked into the EEC test harness. It showed everthing going on with the engine then we took the Bronco on the interstate with the computer hooked up and found out it was running lean which was caused by the mass air sensor. We changed out the sensor and the air / fuel mixture went back to within spec.
Thanks guys all your help.
Thanks guys all your help.
Last edited by 94 XLT White/ Silver 302; Dec 4, 2004 at 03:51 PM.
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