Author Topic: 94 GT pinging  (Read 9825 times)

nmponygirl

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94 GT pinging
« on: July 01, 2008, 09:16:10 PM »
Hey experts out there,
Got a 94 5.0 that sounds great but today she started pinging when I pushed hard on the gas.  Have been using premium gas, the timing has recently been adjusted (just had a full tuneup done) and mechanic (friend) assured timing was set for optimum HP.  Live in hot New Mexico and the temp was slightly high.  Any ideas?
-T

Soaring

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Re: 94 GT pinging
« Reply #1 on: July 05, 2008, 04:06:49 PM »
Retard that timing about 1 or two degrees and get yourself a K&N air filter.  You are experiencing pre detonation, which causes the ping which sounds like your engine is grinding marbles.  Your piston is not at the top of its' stroke before it fires, causing the pre detonation and therefore the ping.  Your mechanic has obviously set your timing by the book, and us old timers know that what the book says is for an initial setting.  From there, we tune by ear.  If you are in Colorado way up above sea level, your timing will be set at a different setting than a guy living in Galveston, Texas. 
The K&N air filter just breathes a hellava lot better than the cheap paper ones do.  More cold air, better performance. 

nmponygirl

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Re: 94 GT pinging
« Reply #2 on: July 13, 2008, 10:36:06 AM »
Ok, got our mechanic over with his timing light.  He had set it to 10 (book) so he set it at 8.  I took it out for a while and after about 1/2 hour of driving she started pinging again.  He set it down to 5 (where it was when I first got it) and he took it out and said there was no more pinging.  I haven't been able to drive it since then since it's been raining nonstop here.  Hopefully that will do it.  The timing seems low, and he thought it should have been accelerated rather than retarded (for better performance), but we'll see.  I live in ABQ New Mexico and it's pretty high; 5300 above sea level. I guess I'll get better gas mileage now but will suffer on the performance.  It's better than taking her out and hearing pinging!  P.S. Already got a K&N on it. 

rmodel65

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Re: 94 GT pinging
« Reply #3 on: July 14, 2008, 12:21:05 AM »
im gonna say the harmonic balancer outer ring has slipped(very common with age look at it and see if you see any rubber sticking out or if it is dry rotted) or you tps sensor is out of range. the balancer will give a false reading with it set at 10degs with 87 oct you really should have any pinging. i have mine set in my 91 somewhere in between 12-14 cant remember exactly

nmponygirl

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Re: 94 GT pinging
« Reply #4 on: July 14, 2008, 09:06:03 AM »
Wow!  You have yours set pretty high.  That's what he was saying, though, that he thought it should be high.  It was set at 5, though, when I first got it and he looked at it, so that's where he finally reset it.  I'll take her out today (hopefully) and we'll see what happens.  How do you know if you should retard or accelerate?  "Soaring" said to retard it, you've got yours accelerated.  Does it vary that much in cars?  I'm confused.  The harmonic balancer was one of the first things he changed.  How do you know if the tps sensor is out of range?

rmodel65

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Re: 94 GT pinging
« Reply #5 on: July 14, 2008, 04:23:09 PM »
the stock 10 degs should be no problem at all on regular gas.

when you advance the timing you normally have to run mid or premium fuel. but advancing makes the car run smoother reduces engine temps, increase low to mid range power(you lose a few mph on the top end) and best of all an increase in fuel economy :)



what kind of codes are you getting when they scan?? i looked around seems the 94-95 tps is non adjustable so if you have a tps out of range code it is bad

Soaring

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Re: 94 GT pinging
« Reply #6 on: July 14, 2008, 04:27:59 PM »
Pre-detonation is caused by the intake valve opening and the initial detonation of the fuel before the piston reaches the top of its' stroke.  If you retard the timing, you are allowing the initial detonation to wait longer before firing.  Therefore, my recommendation to rertard the timing which is what you did and you achieved results.  All engines are different in some ways, depending on what performance parts you have added or not.  Again, the initial setting is for getting it running after replacing the Distributor, etc. but not necessarily the final setting.  There are a lot of factors involved.  Just keep using premium gas and keep your foot out of the pedal until the price of gas comes down. 

rmodel65

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Re: 94 GT pinging
« Reply #7 on: July 15, 2008, 01:05:26 AM »
i meant to ask by did the mechanic remember to unplug the spout connector when setting the base timing? if not that may be why your having the problems?

nmponygirl

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Re: 94 GT pinging
« Reply #8 on: July 15, 2008, 09:03:49 AM »
Yes (that's the little gray connector, right?).  When the pinging first started, he actually had me unconnect it and put it in the glovebox.  The pinging stopped.  I started using premium gas, then plugged it back in.  Same thing.  If I drove it around for about 1/2 hour, the pinging would start up if I was going up a hill or pushing her a little.  So that's when we messed with the timing again and, ultimately, setting it back down to 5.  I'm still a little confused about retarding vs. accelerating and high vs. low sea level and better mpg vs. performance.  All I really want is for her to run good and not ping.


You guys are all great, though.  I've gotten so much advice and learned so much on this forum.  I've been having fun working on my car.  Hey!  I changed out the back center brake light all by myself!  ha ha!  At least that's working good for me.

Oh, and thanks Soaring for the info.  And I'll try to keep the pedal off the floor too!  :)

rmodel65

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Re: 94 GT pinging
« Reply #9 on: July 15, 2008, 09:10:37 PM »
some occasional pinging under heavy loads up hill or in the wrong gear isnt necessarily all bad did you find out what if any codes might have been pulled?

Soaring

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Re: 94 GT pinging
« Reply #10 on: July 15, 2008, 09:24:35 PM »
some occasional pinging under heavy loads up hill or in the wrong gear isnt necessarily all bad did you find out what if any codes might have been pulled?
I certainly hope you are not pulling a trailer behind your Mustang with a load on it going uphill at a 12 % angle.   ;D  If you have an automatic transmission, that takes all the guesswork out of what gear to be in under load.  Your engine should never ping under any circumstance unless you have a manual transmission and you are too dumb to change to a lower gear while going up a hill at a slow speed.  I don't see that to be the case here, so let's get back to timing and octane of your gas you are using. 

nmponygirl

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Re: 94 GT pinging
« Reply #11 on: July 15, 2008, 11:24:25 PM »
Heavy load?  I don't weigh that much!  ha ha!  No, I haven't been pulling anything.  Not sure what you mean by pulling the codes, either.  sorry.

Took it out today.  Remember, I'm at 5300 ft above sea level and it got to 90 degrees & humid.  It is STILL pinging, and seems to be running very sluggish, even at setting the timing at 5.  It is soooo frustrating.  I've been putting in (at least) 90 octane gas.  Tomorrow I'm pulling the gray plug again to see if that helps.  Then I'll call the mechanic again and we'll mess with the timing.  It's only costing me beers!

rmodel65

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Re: 94 GT pinging
« Reply #12 on: July 16, 2008, 01:04:05 AM »
hmm go by autozone and ask them to scan the computer. and with your timing at 5degs it is gonna act sluggish. if you pull the spout then it will probably be even more sluggish


try this for me unplug your maf sensor it is in between the  air cleaner and the throttle body it has three wires going into it maybe a greyish color and sorta oval in shape. if it runs a lot better let me know.

nmponygirl

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Re: 94 GT pinging
« Reply #13 on: July 16, 2008, 11:23:57 AM »
Is the plug inside the housing unit the air filter & maf unit share? 

(yeah, when the spout was pulled before, and then when I plugged it back in, I could tell the difference...better!)

Soaring

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Re: 94 GT pinging
« Reply #14 on: July 16, 2008, 05:46:46 PM »
The MAF (Massive Air Flow) is located between your air filter and your EFI throttle body.  (See pic of mine )  I think Steve is asking you to unplug that wiring.  It's possible that the MAF is dirty and just needs a good cleaning.  If the engine runs better with it unplugged, then that may be the case.  You will need to take it out and use a cotton swab (Q-Tip) with special cleaner to get the oils ,etc off of it inside.

 

rmodel65

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Re: 94 GT pinging
« Reply #15 on: July 16, 2008, 11:01:49 PM »
yeah unplugg that sensor it will put the car into a "limp" mode and will run off a fuel table that will protect the engine from damage. if it runs a lot better(take a test drive and see) then try cleaning it they sell an actual MAF sensor cleaner at the auto parts store. you will need a set of anti tamper torx bit to unscrew the 2 screws that hold it down. you spray the to wires that you will see once you unbolt it then carefully wipe them with a qtip then reinstall as removed.

if it runs alot better with the maf unplugged then it is either dirty or bad. the cleaning will eliminate the choice if it is just dirty. if runs worse when plugged in and it has been cleaned buy a new maf sensor

Soaring

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Re: 94 GT pinging
« Reply #16 on: July 17, 2008, 04:42:44 PM »
The tamper torx bit is different from a regular torx bit in that it has a hole in the middle of the bit to match up with the little needle coming from the middle of the screw, so a regular torx won't work.  Most auto supply places have those.  The size is T20.

 

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