Mechanics

F150 ENGINE RUNS ROUGH AND PINGS UNDER LOAD

1997 Ford F-150

Engine Performance problem
1997 Ford F150 V8 Four Wheel Drive Automatic 175000 miles

I have a '97 F150 with 4.6 V8, automatic transmission, 4x4. The truck was not used for approximately 1 year prior to me purchasing it. When I first purchased the truck it had a slight spark knock during acceleration, slight miss that seamed to clear up and would die when you came to a stop after driving when it was at operating temperature, unless the AC was on. But it was drivable.

Then it would sometimes exhibit a no start condition until it was cranked for several minutes. When it did start it would run really rough, like it had a miss fire or vacuum leak, but would clear up and run okay.

Now it runs rough anytime you start it up, seams like a bad misfire. It can be driven, however you can not accelerate fast or it sounds like it has major spark knock. I have replaced the sparkplugs with autolite platinums, new plug wires, removed the throttle body and spacer and cleaned the carbon deposits from them. Also cleaned the IAC. Also during the whole ordeal there has been no check engine light.

I have read many threads that point at a large range of possibilities but all of the threads have noted a CEL was on. As I have pointed out, I have no CEL on. This could be due to the truck not being driven for very many miles. Trying to avoid the high cost of taking to the dealer, but I am at my wits end for what the cause could be. Any help would be greatly appreciated.
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Omarii
January 29, 2009.



Try taking the vehicle to a good autoparts store (autozone etc.) Have them check for codes. Most do this for free. With the faults you are describing codes should be showing. Let me know !
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Dave H
Jan 29, 2009.
Thanks. I will take it and see if there are any codes.

Tiny
Omarii
Jan 30, 2009.
I am having he exact same problem as you are however mine started happening after I got a batch of stale fuel the other day. Starts pinging when under load however when I rev the engine in park there is no ping. Could you Let me know what you found out?

Tiny
Zombie hunter
Jul 20, 2012.
MIGHT WANNA GET THOSE CODES CHECKED. YOURS MAY BE DIFFERENT THAN HIS, HE DID NOT POST HIS.

ARE YOU "ALL CAUGHT UP ON" SCHEDULED MAINTENANCE?

DID YOU RUN A FUEL SYSTEM CLEANER THRU, SUCH AS SEAFOAM?

GET THE EXACT CODE NUMBERS. YOU CAN LISTEN TO THE FELLER CHECKING YOURS. THEY CAN BE INTERPRETED IN DIFFERENT WAYS

IT'S SORT HARD TO "OBJECTIVELY INTERPRET": "THE MAN SAYS IT'S THE EGR". WHEN THE MACHINE (SCANNER) ACTUALLY SAID (EXAMPLE) "P0442"

RETURN WITH YOUR INFO, SOMEONE HERE SURLY WILL ASSIST YOU!

THE MEDIC

Tiny
CJ MEDEVAC
Jul 21, 2012.

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