Chattering (pinging) under acceleration

[porschpow]

Yeah I'm baffled here as well. I know I can't be the only person that goes through this.

[Kodachrome Wolf]

Yeah I'm baffled here as well. I know I can't be the only person that goes through this.

You're not. My '97 has had issues with pinging for a while. 87 octane is not an option, or it pings under regular operation, 89 octane is fine when it's cold, but come summer, it pings under regular operation. 93 octane is great all around, I've can't get it to ping on that stuff, even on the hottest days with a heat soaked engine. On top of that, when I'm burning 93, the car feels like it's all "there" when accelerating and is considerably more responsive.

I've changed my plugs and wires recently. New plugs helped reduce the effects, but did not make the issue go away. Going based on actions taken by BigMerc96, his Town Car had also been experiencing significant pinging issues that could be lessened, but never would go away. His solution: Using a spark plug one heat range colder than stock. He says it alleviated all of the pinging issues. I'd give it a shot at this point. I'd recommend Autolite APP103 or an equivalent. Interestingly enough, RockAuto lists the APP103 for the Crown Victoria, just like the APP104, except it doesn't list it for the Grand Marquis or Town Car. If you do go the colder heat range route, it would appear that the APP103 and similar plugs use a closer gap (.044) than the APP104 plugs (.054), so make sure the gap is set correctly before installing.

[porschpow]

Will running a colder plug change the engine performance/economy

[Kodachrome Wolf]

Will running a colder plug change the engine performance/economy

I'm not sure. Obviously with the pinging issue, that indicates a pre-ignition situation which is not good for the engine. If running a colder plug solves the issue, you'll probably find engine performance to be a bit better since it'll be firing properly. MPGs on the other hand, I'm not sure if they'll be affected. I noticed when my car isn't pinging when running on 93 I'm pulling around 18 city versus 16 city when the engine is pinging like mad, but YMMV.

[sly]

May also need to check the incoming air temp sensor to make sure it's actually working (the one on the air filter box next to the MAF). The timing cannot be changed on 92+ without a tune as it's all sensor controlled. I had the same problem with the 93's original motor and had to use 89+ octane to keep it from pinging on anything other than FLAT land. The mileage on the 93 was always 19 city and 26-28 highway with the original engine and 2.73 open gears no matter what fuel we ran. I do believe that the stock tune on the 92-97 and maybe 98 cars was right on the edge of too lean so it would get the mileage. The 2000 vic doesn't have that problem. Runs great on 87 but won't get more than 24mpg on the highway and gets maybe 17 in the city.

[DerekTheGreat]

Whales are bit more unaerodynamic compared to aeros though, right? Looking at Kodachrome's sig shows a slippery looking car. While it's not a mod motor, Ashley just reported her best ever MPG (short of our trip to Virginia) of 18.03 mpg with her TC. That's probably 65% highway. This is after retarding the timing to a value that didn't produce pinging under acceleration. Before that, her car was pinging pretty badly under almost any acceleration condition and got the worst ever MPG average of 14.xx mpg, same situation as current.

[porschpow]

SO the incoming air temp sensor, is that the thing in the airbox, looks like a small light bulb (blue in color)? How do you check to make sure it works? How do you think it affects the pinging?

There's not too many places around that have 93 octane, so I guess ill have t settle with 91 octane.

Is there a compatible colder spark plug on the motorcraft side (not autolite)

[sly]

This is for the box sensor on the lower intake manifold, but the temperature curve should be close if not the same for the one on the airbox. Just pull the harness off and measure with an OHMmeter and see if it's right with the ambient temps. Check first thing in the morning and around 4pm and you should be able to tell if it's working. Should be getting a few hundred ohms difference at least.

http://www.grandmarq.net/oldfuelinjection/page29.html

[Kodachrome Wolf]

Is there a compatible colder spark plug on the motorcraft side (not autolite)

Yep: -Motorcraft AWSF22FM (Original Half Thread Design)
-Motorcraft SP-405 (Superseded Full Thread Design)

It doesn't matter if you get the half or full thread design since our cars only have a small amount of threads (something like 4 or 5 threads). Both will work fine, it's just up to you depending on what you purchase.

It's listed as the spark plug for the CNG cars, but shares cross reference with the Autolite APP103, which is the heat range colder than stock. It might be gapped at .044, but may need to be re-gapped to .054 which is factory plug gap for our cars.

[porschpow]

I should use a multimeter more often, I hardly use these things. How would I use it in this application?

This is for the box sensor on the lower intake manifold, but the temperature curve should be close if not the same for the one on the airbox. Just pull the harness off and measure with an OHMmeter and see if it's right with the ambient temps. Check first thing in the morning and around 4pm and you should be able to tell if it's working. Should be getting a few hundred ohms difference at least.

http://www.grandmarq.net/oldfuelinjection/page29.html

[porschpow]

I will try the plugs. I used the platinum motorcraft plugs that were called for these cars. But first, I want to run it with high test 93 and see what happens

Yep: Motorcraft AWSF22FM

It's listed as the spark plug for the CNG cars, but shares cross reference with the Autolite APP103, which is the heat range colder than stock. It might be gapped at .044, but may need to be re-gapped to .054 which is factory plug gap for our cars.

[sly]

I should use a multimeter more often, I hardly use these things. How would I use it in this application?

pull the harness off and put the leads, one to each pin. There's only 2 pins, and there's no polarity, so it doesn't matter which pin. The sensor is basically a variable resistor affected by temperature as far as this system is concerned.

[porschpow]

Gotcha, what magnitude setting for ohms should I set it to?

[sly]

check the page I linked for the chart at the bottom. It shows the ranges. 20K range should get most temps concerned, but you may need the 2K range.

[porschpow]

gotcha thank you so much for the help dude! Stay cool in Texas!