Last post on Oct 24, 2003 at 8:47 PM
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Ford Explorer, Ford Ranger, Ford Explorer Sport Trac, Engine
Oct 20, 2003 (11:42 pm)
I have a 91 explorer with the same problem, 150,000 and have had it at the dealer for decarbing at least 2 times a year, very persistant problem, until i started using 89 octane gas from chevron, havent been back to the dealer since then, its been about 2 years now. I have a 86 ranger 2.9 v6 216,000, and have never had problems like his, why the 4.0?
Oct 21, 2003 (9:19 pm)
from the chicago tribune auto q&a, i think the columnist said that higher octane gas has more cleaning additives than the 87 octane. given that premium is about 20 cents a gallon more, would a 99 cent bottle of gas additive/fuel injector cleaner do the same thing?
Oct 22, 2003 (7:21 am)
Nah, that stuff is harmless as a cleaner. There are good additives around but not that cheap stuff, which I think is just kerosene and a few other mild useless chemicals.
Besides, if he has this noise at idle, octane is not his problem. There is no load on the engine at idle, so pre-ignition really can't happen.
Perhaps his highway speed noises are octane related but not his idle noises. He has to look at injectors, noisy lifters, things like that. I can't recall if this engine is chain driven or not, but that would be another good bet.
#15 of 20 PRE-IGNITION at highway speed
Oct 22, 2003 (8:08 pm)
I have been told that the heavy pinging at freeway speed that i experience, is pre-ignition from the glowing hot carbon deposits in the combustion chamber and on top of the piston heads.
And yes this engine is chain driven
Oct 23, 2003 (8:13 am)
No, I don't think your pinging is from that. Hot carbon deposits mostly cause POST ignition, not as likely to cause pre-ignition. Post Ignition is engine "run-on" --that is, when you shut the ignition off and the engine keeps on going.
If you have some clatter at idle, you should definitely put an ear to your timing chain, and if you DON'T have post-ignition (engine run on) I would rather doubt you have excessive carbon build up.
If you are pinging loudly at freeway speeds, I think you have an engine management problem, with some sensor that controls engine timing; also, pinging and a loose timing chain have a relationship worth exploring.
So far, I think this car is being mis-diagnosed. If there were more data I might change my opinion, but given what's on the board, that's what I think right now.
#17 of 20 a little more info
Oct 23, 2003 (8:18 pm)
The first time I noticed this noise was shortly after I bought it. I was sitting in a parking lot waiting for someone and I had the engine idling (30,000 Miles). I took it to the dealer figuring that something was loose and rattling. There diagnosis then was that something was loose in the catalytic converter. (they replaced that under warranty). Shortly after leaving I still could notice the noise and told the dealer that there was still a rattling noise and they needed to investigate further. At this time I was also starting to notice a pinging while driving on the freeway. The dealer came up with a TSB from ford stating that this motor was prone to excessive carbon buildup and instructed them to check the MAF sensor and if everything was O.K. they were to decarbon the motor and leave it at that. After they do this decarboning the motor is quiet for a short while (a couple months). The TSB also stated that the motor needed to be run over 3000 RPM every day to keep the motor clean. On a couple trips I've made to the beach or over the mountain on long steep grades I will lock the transmission down in second gear and drive up the hill running the motor around 4500 RPM for a sustained period and this seems to help. The noise will be less noticeable for a couple weeks. Right now at 65,000 miles the car runs good except for this noise wich I am afraid could be damaging my motor, and currently the noise is the worst at around 70-75 MPH. On startup there is a little rattle but I assume that is probably just a dry motor rattling. I have always been very good with maintenance and always run good quality gas, Premium does not seem to make a difference except on my wallet.
#18 of 20 pshaw, why not just write motor has to run over 12,000 RPM daily
Oct 23, 2003 (11:17 pm)
awfully hard to get an exploder up to 3k with the transmission shift points in it. I'm suspicious. have another mechanic evaluate this.
Oct 24, 2003 (8:47 am)
Me, too. If you are actually pinging loudly at 75 mph this is really not a good thing.
That "pinging" by the way, is actually the internal parts of your engine rattling around like a chicken grabbed by a terrier. In extreme cases, the actual cylinder walls of the block will flex. Typical damage from severe pinging is a hole through the top of the piston.
Heavy and sustained pinging is very dangerous...a light and brief ping now and then is not.
#20 of 20 jcasper:4.0 Pinger
Oct 24, 2003 (8:47 pm)
From the sound of things, no one has even been able to isolate the source of your noises. The catalytic converter is a long way from the top half of the engine. You need to take it to get a second and maybe third opinion to locate your noises. It's entirely possible you have two separate sounds, like an exhaust heat shield rattle at idle and a motor knock at speed. Let us know when you've isolated the noises. Until then it's just a million guesses.