'94 5.8L PINGING UNDER ACCELERATION

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Blk94BroncoXLT

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Hello, new guy here, 1st post...

I recently purchased a 94 Bronco XLT with the 5.8L, auto, 33 gal tank and manual hubs. It has 58k original miles and is like new. Since purchase 5 months ago, ALL fluids, hoses, belt, plugs (platinum in same heat range), PCV valve, air filters, wires, rotor and cap have been flushed/changed. Everything looked well actually, but I did it more for reassurance. The only mod is a Flowmaster muffler.

Since purchase, I've gotten 16mpg on the highway and about 10mpg around town. She starts, runs and idles perfectly. Not a leak, squeak, rattle or noise. Original AC is ice cold. Start idle is about 1100 rpm's & drops down to between 600 & 700 rpm's in a minute or so and stays perfectly level. My oil pressure remains constant between the "M" & "A" and Water Temp between "N" & "O" once warmed up. No CEL's since I've had her.

My ONLY issue so far is that once the engine is warmed up, it pings occassionally (sometimes soft, sometimes loud)during either slight acceleration from a dead stop or when accelerating slightly in OD when the truck doesn't downshift to 3rd automatically. When this pinging occurs, I get a slight puff of greyish smoke from the exhaust which otherwise is crystal clear.

The pinging goes away if I give it less (granny accelerate) or more (aggressive accelerate) gas. The loudness of the ping does decrease a bit if I shift to all 93. If I use a full tank of 93 Octane and 2 bottles of STP Octane boost, the pinging goes away completely. I've been up and down the east coast and have filled up in almost every state from CT to GA, no difference. The original plugs looked awesome when I removed them and the oil always looks great.

I realize my truck may be tuned from the factory to run lean and maximize MPG's, so I was curious if it is normal for this engine to ping under slight acceleration (like the owner's manual says)? If not, what else should I be looking for?

Thanks for the help!

 

89purple horse

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i have a 89 with the 351 as well and i run the 83 octane and i dont have a problem unless i buy gas from one certain station then it will ping but have no problems anywhere else. it sounds to me its gas thats causing yours as well if its happier with 93 then i would suggest staying with that

 

miesk5

96 Bronco 5.0
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yo

Welcome!

I agree w/89PH

Plus;

A cruddy combustion chamber from deposits can actually make the chamber smaller and thus increasing the compression ratio and those deposits heat up and ignite, causing the pre-ignition or ping.

Sometimes the engine timing is off.

Adjustment in Ford EFI Engines

Source: by Ryan M (Fireguy50) at http://fordfuelinjection.com/index.php?p=71

Also check this out; Misfiring/Pinging due to Improper Spark Plug Wire Routing for 5.8

94-96 5.0 ** - INCLUDES 5.8 - engine miss, spark knock, buck/***** surge and other driveability concerns

Source: by Tank92 (Tank) at http://www.supermotors.net/clubs/superford/vehicles/registry/media/299011

Back to da gas...

TOP TIER Gasoline Retailers; Gasoline retailers must meet the high TOP TIER standards with all grades of gasoline to be approved by the automakers as providing TOP TIER Detergent Gasoline. Source: by toptiergas.com

"...Why TOP TIER

The intention of the TOP TIER Detergent Gasoline standards is to create a winning situation for gasoline retailers, auto manufacturers and drivers. Currently, many gasoline retailers provide fuels with lower-quality additive packages that can build up deposits on fuel injectors and on intake valves. Others can build up deposits in combustion chambers and may lead to intake valve sticking. These lower levels of additives can have negative impacts on engine performance and vehicle responsiveness..."

TOP TIER Detergent Gasoline Retailers

Gasoline retailers must meet the high TOP TIER standards with all grades of gasoline to be approved by the automakers as providing TOP TIER Detergent Gasoline.

In addition, all gasoline outlets carrying the brand of the approved retailer must meet the TOP TIER standards.

Additional gasoline retailers are added to the TOP TIER list as they meet the standards. The retailers known to be on the TOP TIER list are shown below.

TOP TIER Gasoline Retailers:

QuikTrip

Chevron

Texaco

MFA Oil Co.

Conoco

Phillips 66

76

Entec Stations

Shell

The Somerset Refinery, Inc.

Kwik Trip / Kwik Star

Aloha Petroleum

Tri-Par Oil Co.

Turkey Hill Minit Markets

Mileage Stations

Road Ranger

CountryMark

Chevron Canada

Shell Canada

Petro-Canada

Sunoco Canada

btw, I used a local food chain's gas for about 6 months; had to stop because I had thus *** pinging in my ears. Went to my Doc; Doc said, Change your gas (supplier) and stop eating hot wings.

 
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Blk94BroncoXLT

Blk94BroncoXLT

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Thanks 89ph & m5. Will give the timing adjustment a try and checking the wiring. Will also run 93 for a while from the top tier guys and see how that works.

 

2percent

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I only use Marathon Gas and have never had this problem. My wife had this problem in her Monte Carlo so I Sea Foamed the engine and fuel system and ran some 93 through it. Ran quiet till we sold it. I don't know if it was the gas or not but it definitely went away when it was cleaned out.

 

Seabronc

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The engine is designed to run properly on 83 octane gas. If going to a higher octane gas works it is only covering up a developing problem. A likely candidate is the EGR system, in particular the EGR Valve. The EFI engine uses the cylinder cooling effect of the EGR system to prevent preignition during acceleration or any time the engine is put under a load.

Octane rating is a relative number which represents resistance to ignition. The higher the compression ratio of an engine, the higher octane it requires to prevent pinging or (preignition).

Good luck,

:)>-

 

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