Cannot stop the pinging...

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Falcon_LS

Falcon_LS

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on my '01 Grand Marquis (factory catalytic converter delete, no oxygen sensors). The conditions are:

- Light throttle
- Engine under load
- Cylinder head temperatures over 192 F

One of the first things that crossed my mind was a vacuum leak, so I thoroughly checked all the hoses. I have an inline oil separator, which I removed to see if that was the cause, and the conditions were still the same.

I then checked the EGR valve. With a hand vacuum pump connected and vacuum applied, the engine stalled. I replaced the EGR valve afterwards. The pinging did not stop.

Whilst driving yesterday, I decided I would pull over and disconnect the MAF. Pinging went away completely, although the transmission wasn't shifting very smoothly. So this morning I replaced it and reset the PCM - same result.

Installed a brand new set of injectors (old ones looked horrible) as well, along with a new fuel filter. The pinging is still there. Coolant was flushed recently as well.

Only things that cross my mind that are untouched are the DPFE, CPS and the TPS. Just wondering if anyone has any other ideas. Thanks!
 
What octane gasoline are you using, and does it ping when using gasoline from different companies and filling stations? Also, does the pinging occur all the time, only during the day [not at night], and does it get worse when the engine in under a load [accelerating]?
 
Did the pinging start at once or has it been getting worse over time? Carbon build up in the combustion chamber is one possibility. Have you tried a good fuel SYSTEM cleaner like Techron or RedLine?
 
Is it that lightweight sounding type pinging when you get on the throttle after the engine is good and hot? That`s what mine does,and I just suspect that today`s gasolines are just sub-par and the ethanol content probably has something to do with it too.
 
To be honest, the previous owner was running 95 RON (91 AKI) even though the manual clearly states 91 RON (87 AKI). They think high octane burns "cleaner" here.

When I got the car, I did some research and found 98 RON (93 AKI) had a better detergency pack (kind of like the Top Tier fuel in the States), so I switched to that. When they changed the supplier from their refinery in the Netherlands to Malaysia, the detergency pack became the same as the other two offerings. This was when I switched to the recommended 91 RON (87 AKI), as I saw no point in running higher octane than required.

I'm currently running 91 RON (87 AKI). When I noticed the pinging, I switched up to 95 RON (91 AKI) which is the mid grade. There's barely any difference in the price, so I won't mind running 95 RON, but I still experienced pinging. If I fuel up with 98 RON (93 AKI), the pinging disappears most of the time, but still doesn't go away completely.

Unfortunately, there's only one company supplying gasoline in the country. The pinging happens regardless of day or night, granted the average ambient temperature at night is 118 degrees.
 
Originally Posted By: Eddie
Did the pinging start at once or has it been getting worse over time? Carbon build up in the combustion chamber is one possibility. Have you tried a good fuel SYSTEM cleaner like Techron or RedLine?


I regularly run 200 ml of MMO at each fill up. I've also used a high PEA cleaner, namely Liqui-Moly's Valve Cleaner and Fuel Injector Cleaner. Oddly enough, if I add either to the tank, the pinging goes away. As soon as I refuel, the pinging comes back.

Originally Posted By: aquariuscsm
Is it that lightweight sounding type pinging when you get on the throttle after the engine is good and hot? That`s what mine does,and I just suspect that today`s gasolines are just sub-par and the ethanol content probably has something to do with it too.


Sorry, I should have mentioned our gas contains no ethanol. It sounds like marbles in a can, but lately there's a random, metallic pinging noise as well.
 
My old 96 Merc 4.6 had the same problem. I finally removed the air intake that the EGR valve is attached to and cleaned it. There was a lot of carbon buildup in the EGR ports. After cleaning all was well. Even though your EGR is still working there can still be build up. Also are you sure it was the MAF you replaced? Those things are very expensive. Thought maybe it was something else you changed. Anyway, cleaning the MAF in the air intake after the air filter is another problem area for pre- ignition.
 
Originally Posted By: 95busa
Carbon on the pistons? Maybe sea foam the upper engine?


I run MMO and fuel system cleaner regularly, and the car sees WOT quite often. Could that still be a possibility?

Originally Posted By: tig1
My old 96 Merc 4.6 had the same problem. I finally removed the air intake that the EGR valve is attached to and cleaned it. There was a lot of carbon buildup in the EGR ports. After cleaning all was well. Even though your EGR is still working there can still be build up. Also are you sure it was the MAF you replaced? Those things are very expensive. Thought maybe it was something else you changed. Anyway, cleaning the MAF in the air intake after the air filter is another problem area for pre- ignition.


Yes, definitely replaced the MAF.
thumbsup2.gif
We don't have core charges here, but it still wasn't too bad at $88 for a Genuine Motorcraft unit (re-manufactured).

When you say EGR ports, do you mean the tube that connects to the EGR valve with a 27 mm bolt on it?
 
Originally Posted By: Falcon_LS
Originally Posted By: 95busa
Carbon on the pistons? Maybe sea foam the upper engine?


I run MMO and fuel system cleaner regularly, and the car sees WOT quite often. Could that still be a possibility?

Originally Posted By: tig1
My old 96 Merc 4.6 had the same problem. I finally removed the air intake that the EGR valve is attached to and cleaned it. There was a lot of carbon buildup in the EGR ports. After cleaning all was well. Even though your EGR is still working there can still be build up. Also are you sure it was the MAF you replaced? Those things are very expensive. Thought maybe it was something else you changed. Anyway, cleaning the MAF in the air intake after the air filter is another problem area for pre- ignition.


I don't remember that tube as it has been several years, but there are openings inside the air intake that are in the area of the EGR that can carbon up.

Yes, definitely replaced the MAF.
thumbsup2.gif
We don't have core charges here, but it still wasn't too bad at $88 for a Genuine Motorcraft unit (re-manufactured).

When you say EGR ports, do you mean the tube that connects to the EGR valve with a 27 mm bolt on it?
 
Putting those additives in the tank probably reduces the volatility of the fuel, sort of like increasing octane. If that slight decrease in fuel volatility resolves the pinging problem, perhaps the fuels you are buying are not really up to the standards indicated.
 
Try a few tanks WITHOUT any MMO. Heavier hydrocarbons like motor oil or even light oil in gasoline tends to lower the effective octane rating, which is one reason why oil-burning engines ping much worse than those that burn no oil. It may be that the MMO is triggering detonation. I agree its not LIKELY in such diluted concentrations, but its something to try.

Also people have the wrong idea about ethanol- it RAISES octane significantly, which is why flex-fuel vehicles tend to make more power on E85 than on E10- on E85 the PCM can advance the timing all the way to the limit without detonation. The downside is that MPG goes in the toilet, and frankly I don't believe corn-produced E85 is an environmental winner... but it sure runs great in engines set up for it!
 
Check the DPFE sensor!

This is going to sound crazy, but the 6 years I drove my 01 Taurus it pinged like CRAZY all the time. We spent probably over $1000 trying to get it to stop pinging. Running premium fuel, had the FI system professionally cleaned, tried lower temp thermostat, verified that the car wasn't overheating, reflashed the computer a number of times.

Finally one day it threw a CEL, I replaced the DPFE and it was fine after that. Makes no sense that it was "bad" for 6 years ... just good enough to never throw a code.

Towards the "end" of the DPFE sensor, the car was misfiring a lot at part throttle cruise. I suspect it was "sticky" and causing the car to run real lean all the time.
 
You stated your engine does not use oxygen sensors, so how does the PCM determine A/F ratio???

Myself, I'd forget that additives(I never use them), swap to a 180* thermostat, use whatever grade fuel that mostly stops the pinging, & be happy...
 
When you say "factory catalytic converter delete, no oxygen sensors", assume you mean removed? Most upstream o2 sensors serve dual role. 1) Monitor exhaust gasses which the ECU uses to set Air/Fuel mix. 2) initial reading of exhaust gasses for catalyst efficiency. Wonder if your pinging because your ecu has the fuel trim set wrong because it does not have upstream o2 sensor?
 
I can say this- my '00 P71 pinged at WOT, especially at high RPM close to shifting. I dropped a 180 stat in it and it still pinged. Couldnt run high octane gas on it (govt wont buy it), but it pinged the whole abused, hot climate, multiple pursuit time I had it (i think two years) and she never missed a lick.
 
Originally Posted By: LeakySeals
When you say "factory catalytic converter delete, no oxygen sensors", assume you mean removed? Most upstream o2 sensors serve dual role. 1) Monitor exhaust gasses which the ECU uses to set Air/Fuel mix. 2) initial reading of exhaust gasses for catalyst efficiency. Wonder if your pinging because your ecu has the fuel trim set wrong because it does not have upstream o2 sensor?


It is a GCC spec(Middle East) vehicle, sensors & converters are factory delete... How it operates I don't have a clue, no doubt has special PCM programming...
 
Originally Posted By: TFB1
Originally Posted By: LeakySeals
When you say "factory catalytic converter delete, no oxygen sensors", assume you mean removed? Most upstream o2 sensors serve dual role. 1) Monitor exhaust gasses which the ECU uses to set Air/Fuel mix. 2) initial reading of exhaust gasses for catalyst efficiency. Wonder if your pinging because your ecu has the fuel trim set wrong because it does not have upstream o2 sensor?


It is a GCC spec(Middle East) vehicle, sensors & converters are factory delete... How it operates I don't have a clue, no doubt has special PCM programming...

33.gif
Lesson learned, check location.
 
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