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Idle erratic, Pinging on accdeleration
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msrouter
User
Nov 15, 2010, 1:21 PM
Post #1 of 7
(2746 views)
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Idle erratic, Pinging on accdeleration
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1993 Lincoln town car with 4.6L engine. 170000 miles.
When the engine is first started it idles normal. Within about a minute the rpm will decrease and idle is rough. It will also do this at times when I stop at a light or stop sign. Additionally, there is pinging with moderate acceleration such as accelerating from a stop light. When I let up on the accelerator the ping stops. So, I have to accelerate very slowly to avoid the pinging.
Here is what I have tried: I put Octane booster and injector cleaner in the fuel with no improvement.
I found that when the car is stationary and at idle and running rough if I remove the electrical connector from the MAF sensor the engine will smooth out and the rpm increases.
Question, Would a defective MAF sensor cause both erratic idle and pinging on acceleration? I considered replacing it to find out. I backed off that when I found out the cost of a new MAF sensor.
Recommendations ????
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Sidom
Veteran
/ Moderator
Nov 15, 2010, 2:02 PM
Post #2 of 7
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Re: Idle erratic, Pinging on accdeleration
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Get a can of MAF cleaner and clean the sensing wire to see if this makes a difference, it's the wire in the camber in the sensor. If this makes a big difference, replace the sensor.
Even if cleaning it makes it run better, I have yet to see cleaning them bring them all the way back into fuel control.
So in a nutshell what this means, over a long period of time you could be damaging your cat plus not getting as good of gas mileage as you could even though is "seems" to be running good.
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msrouter
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Nov 16, 2010, 10:04 AM
Post #3 of 7
(2730 views)
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Re: Idle erratic, Pinging on accdeleration
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Thanks Sidom. Is it ok to remove the sensor from the duct it is mounted on to clean the sensor. I assume the wire extends into the small tube inside the duct and would come out with the sensor.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Nov 16, 2010, 12:18 PM
Post #4 of 7
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Re: Idle erratic, Pinging on accdeleration
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I've had several with the plug wires at the plug end go bad but that doesn't account for pinging? When they jumped inside that long hole it just missed on that cylinder - sometimes erratic. Don't have one in the stable right now but I recall you could see them arc if bad. Certainly do what Sidom suggested as it can't hurt,
T
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Sidom
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/ Moderator
Nov 16, 2010, 9:41 PM
Post #5 of 7
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Re: Idle erratic, Pinging on accdeleration
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Yea there should be a couple of tamper proof torx screws that bolt the sensor in the housing. You can remove the house but don't touch the sensing wire with anything, just spray cleaner on it............
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msrouter
User
Dec 6, 2010, 3:10 PM
Post #6 of 7
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Re: Idle erratic, Pinging on accdeleration
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I used the MAF cleaner on the sensor. I still have the problem with the engine idling down and then run rough. Regarding pinging, it seems to be intermittent. I upgraded the grade of gas and so far it runs ok. Maybe I had some LOW octane fuel although I got the fuel at the same place that I always get it. The weather has turned colder too. Maybe that has an impact. When I get time I think I will change plugs and check the plug wires at the same time.
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Sidom
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Dec 6, 2010, 8:51 PM
Post #7 of 7
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Re: Idle erratic, Pinging on accdeleration
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Taking care of basic maintenance items is always a good idea and sometimes solves problems.....
Since it's idling low I would suggest cleaning the throttle body if it looks real dirty around the throttle plate....
On this car here is the catch 22.......
You will probably see a sticker on the throttle body saying "DO NOT CLEAN, THIS WILL CAUSE DAMAGE". Fords have a "plastic" coating in their throttle bodies. Carburetor clean will definitely take that coating off. Ford does not want you cleaning those, they want you to replace it. They make throttle body cleaner that works good on those and todate I have had no problems cleaning them. Personally I can't in good conscience charge someone close to $500 (throttle body only) for something I can do for $100 (that includes the injectors & intake)
It's your call but if it's dirty, something has to be done......
Actually if this car has never had a fuel service done, that wouldn't be a bad idea. The throttle body is something you could clean with a little brush or rag and the correct cleaner. The intake manifold & injectors takes special equipment....
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