I hear pinging
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Senior User
Joined: Jan 2002
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From: Minnesota
I hear pinging
90 F150 4.9L 3.08 rear, M50D
It started pinging a while ago and seems to be getting worse. I have tried using 89 octane and it helped for a while and now doesn't. Highway driving is tough since it won't hold speed (65) even on the small hills unless I punch it hard and when I put the pedal down it pings real bad. It doesn't do it all the time either. It is worst on a hot day when it is warmed up. I don't drive it much anymore and it gets short trips. I took it on a 200 mile round trip today to try and run the carbon out of it and it ran fine this morning with minor ping, but in the afternoon, it ran bad. I have changed plugs, wires and rotor and checked the timing. I am starting to wonder if my cats are getting plugged, but don't want to go changing them since they are expensive. Doesn't look like they are an easy item to cut out and put a strait pipe in. If I could fine a y pipe that fits the manifold and oxygen sensor I would put that in since my muffler and tail pipe are rusted out anyway.
Anyone think the cats are a probable cause, or should I look elswhere?
It started pinging a while ago and seems to be getting worse. I have tried using 89 octane and it helped for a while and now doesn't. Highway driving is tough since it won't hold speed (65) even on the small hills unless I punch it hard and when I put the pedal down it pings real bad. It doesn't do it all the time either. It is worst on a hot day when it is warmed up. I don't drive it much anymore and it gets short trips. I took it on a 200 mile round trip today to try and run the carbon out of it and it ran fine this morning with minor ping, but in the afternoon, it ran bad. I have changed plugs, wires and rotor and checked the timing. I am starting to wonder if my cats are getting plugged, but don't want to go changing them since they are expensive. Doesn't look like they are an easy item to cut out and put a strait pipe in. If I could fine a y pipe that fits the manifold and oxygen sensor I would put that in since my muffler and tail pipe are rusted out anyway.
Anyone think the cats are a probable cause, or should I look elswhere?
Senior User
Joined: Sep 2003
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From: Houston TX
I doubt it's the cats. That can be checked using a
vacuum gauge. I'd be looking for a lean burn scenario,
if the timing is ok, including the advance circuit.
Probably carbon clogged injectors, and intake valves.
EFI engines are bad about carbon buildup. Will cause
lean burning due to injector restriction, and also the
carbon itself can soak up fuel/vapor. If it gets real bad
the intake valves get clogged. In a worst case, the carbon
heats up when hot, expands, and keeps the valves from
closing. No run...This is *real* common on JA cars like toyotas,
etc, but I imagine any can have this problem. Thats the
first thing I would be looking at. MK
vacuum gauge. I'd be looking for a lean burn scenario,
if the timing is ok, including the advance circuit.
Probably carbon clogged injectors, and intake valves.
EFI engines are bad about carbon buildup. Will cause
lean burning due to injector restriction, and also the
carbon itself can soak up fuel/vapor. If it gets real bad
the intake valves get clogged. In a worst case, the carbon
heats up when hot, expands, and keeps the valves from
closing. No run...This is *real* common on JA cars like toyotas,
etc, but I imagine any can have this problem. Thats the
first thing I would be looking at. MK
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Joined: Apr 2003
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From: Heart of Dixie
I had the same problem with my '94. I replace the lower intake gasket and that fixed the problem. I had replaced the intake split-line, TB, IAC, and EGR gasket about a year ago. I also ran 2 cans of combustion chamber cleaner plus some water sprayed in. The intake valves have just a little carbon around the outer edge. I don't know what they looked like before, so I can't really say how well the CC cleaner worked. Check all your vacuum lines for cracks or loose connectors, check your fuel pressure, replace your fuel filter, etc.
Senior User
Joined: Jan 2005
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From: Augusta, Maine
A couple things you mentioned were heat related. Maybe your running a little hot. Running hot can increase spark knock. Maybe time for a new thermostat and/or radiator flushing. Not positive about this, but worth a try!
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Senior User
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From: Minnesota
Thanks for the replies. I am not running hot and the thermostat and radiator are relatively new. I know that at 90k the previous owner had the valves 'ground'. Presumably to fix this problem. I will look for vacuum leaks first. I have used fuel injector cleaner and marvel mystery oil with no help. Maybe I could try the water or sea foam in the intake. Might just have to pull the head if those things don't work.
