94 Explorer Pinging
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94 Explorer Pinging
I have a 94 Explorer 4X4, 6 cyl, automatic with Fuel Injection that is gradually showing its age (130K miles). Over the past 2 years almost every engine sensor has been replaced. For about the past year the engine has been pinging whenever I require more power, like climbing a hill (at 65 mph) or when I am pulling a load. My mechanic has not been able to solve the problem. I think it is running lean, but I am not sure. A few days ago I ran a short errand and it would not start (did not smell gas so I assumed the fuel pump had failed). My mechanic replaced the fuel pump, but the symptoms continue ... Pinging, hard start at times, check engine light at cold start (I live in Montana), minor surging in RPM when idleing, and now constant gearing up and gearing down at about 60mph, like I am climbing a hill -- even on the flats -- until the engine warms up. I need to get a handle on this. I can't afford to have my mechanic troubleshoot for ever.
Thanks.
Thanks.
New User
Joined: Dec 2003
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From: Colorado
I had my 94 "de-carbonzied". Basically a chemical clean job that reduced the carbon build up in the fuel rails/injectors, intake valve areas and combustion chamber. I'd say it knocked back the pining by about 80%. The rest has cleared up by using a higher octane fuel. I live in Colorado, so the mid blend of 87 octane seemed to do the job.
Post Fiend
Joined: Feb 2003
Posts: 6,940
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From: Eastern WA
Back in Feb 03 I posted the TSB which details how to decarbon the engine in the Ranger forum. About 2 weeks ago it resurfaced so you may want to do a search. If you implement the TSB, replace the spark plugs when done decarboning. As for the higher octane gas, it's worth noting that the TSB specifically advises against doing this; the reason is in the TSB.
Next, clean your MAF sensor. A dirty MAF sensor results in the computer seeing less than actual airflow and consequently leaning out the mixture. Lean mixtures burn hotter than rich mixtures, and thus you get pinging.
Next, clean your MAF sensor. A dirty MAF sensor results in the computer seeing less than actual airflow and consequently leaning out the mixture. Lean mixtures burn hotter than rich mixtures, and thus you get pinging.
Postmaster
Joined: Dec 2001
Posts: 3,742
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From: UT
Along with the dirty MAF causing a lean mixture, a vacuum leak or an air intake leak downstream of the MAF causes a lean mixture. so check for vacuum leaks. The first time I dealt with ping on my 4.0, I resolved it by tightening the lower intake manifold bolts. It's fairly common on this engine for them to come loose over time, you get a vacuum leak through the gasket, and the engine pings.
Pinging on the 4.0 is actually quite common, and now you've been introduced to most common reasons for it (carbon buildup, dirty MAF, leaking lower intake).
Pinging on the 4.0 is actually quite common, and now you've been introduced to most common reasons for it (carbon buildup, dirty MAF, leaking lower intake).
Posting Guru
Joined: Apr 2003
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From: West Chester PA
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Yes, the fuel filter was also replaced. The reason that the fuel pump was replaced is because the mechanic said that the pressure dropped after a few minutes of operation.
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Dec 15, 2009 04:51 PM