"Ping" is back!

[SA-AUII-MAX]

Hi, my name is Max and I’m a Falco(n)holic living in South Africa.
I own a Fairmont AUII 2002 model with nearly 200.000 kilos done. Having a problem with the car, I checked this web-site intensively to get more info regarding pre-ignition or pinging. Realising that there are many leads regarding this problem, none of them is putting my mind at ease. I smashed my catalyst converter not so long ago. As it is rather expensive to replace the cat-thing and the whole exhaust was due for replacement, I decided to leave the cat out, gain some horsepower, and installed a stainless free flow system. The CO (Hego) sensor is placed before the cat so no problems were expected. For a couple of days the Fairmont went really well but started to “ping” driving at light throttle (1500-2300 RPM). Was told that because the cat is gone, the speed of exhaust gasses increases and the temperature of the exhaust gasses decreases - trying to “confuse” the CO sensor. No engine warning light is coming on though.
To compensate I bought a K&N filter. This worked for a couple of days but the engine started pinging again. Installed a “mini-cat”, a 5 cm long piece of tubing installed where normally the CO sensor fits and fitted the sensor at the end of the tubing. Because the restriction from the cat was gone, I took the CO sensor out of the direct flow of exhaust gasses, to give it more time to “read” or “smell”. Helped for a couple of days, then... the “PING” was back! Next up a Unichip was installed, and yes I know some of you guys hate the thing, but I had to control the timing in some way. Got a dyno-tune, more horsepower under the bonnet and better fuel consumption. Great, but again after two-three days, “PING”! (read £**%)
Retarded the timing (6 to 8 degrees), made the fuel richer and tried again and again. Right now the timing is retarded so much that the power is flat, the car is using too much fuel and still “pings” sometimes - I’m starting to believe that it is not really a timing issue.
I use 95 fuel and when the car is under heavy load, towing ± 2.000 Kg, one would expect it to be worse but there is no difference in the problem. Checked the car with a proper code reader at the Ford garage and got a code 0325. Checked and cleaned connections to the Knock Sensor, tested the sensor itself and did the voltage test. All fine but “PING” is still remaining and I’m running out of options.

Is there somebody out there that had similar problems and got it fixed besides buying another car?

[nikos]

Are you sure its actually 'pinging'? If its under light load at 1500-2300rpm and doesn't increase under load (ie. trailer) I don't think it would be pinging. Does it do it under light load at high rpm?
Could just be a rattle in the engine bay somewhere. Are you sure the knock sensor is ok?

[BAGTP454]

do u have any of the pictures of your car in south africa? that would be cool.

[howesy]

The cat doesnt just provide a restriction. Inside a cat it is like ceramic honeycomb and gets red hot to burn off poison and carcenogenic gasses. Cats get so hot they have been known to start grass fires. I would be tring to adapt something from a wrecker somewhere. a cat is a cat.

[SA-AUII-MAX]

Thanks guys for your response. Yep I’m quite sure it’s pinging because during the dyno tune while setting up the engine it made similar noises. Each time we made corrections preventing it knocking, only to find out that it starts to “ping” later again. This pinging or knocking is sometimes present when I put the pedal to the metal from a standing start. Weather conditions apply though, the warmer and drier the heavier it’s starts to ping. Driving with the aircon on makes it worse too.
I tow a horsebox with the car, explaining the rather heavy load. That cat converters can start a fire in long dry grass I did know, one reason more to take the cat-thing off. And why the cat got smashed?, a big stone in long dry grass. LOL

[JC]

Have you checked the exhaust manifold bolts? If they are loose, the noise it can make sounds like pinging.

If no matter what you do, it's continually pinging, then it probably needs a tear down and rebuild, as it means the internals have been affected and the engine management system cannot compensate enough under tough driving conditions.

[EA2BA]

What AFR did you get from the dyno run?

[SA-AUII-MAX]

Two weeks ago I did check the exhaust manifold bolts, some bolts were slightly loose. From what I can see the engine is rather clean on the inside. Talking here about the inlet manifold and what I can see though the spark plug hole. There no excessive carbon build-up on top of the pistons, and also the engine is using only a little oil and top-up between services is not necessary.
Regarding the outcome of the dyno-tune I don't have any papers from that run. The only thing I can remember is that the engine is close to the rated power output, 157kW at about 4900 RPM and 1500 meter above sea level.

[mik]

are you sure of the fuel qaulity??

[SA-AUII-MAX]

No I'm not to sure about the fuel quality because most the fuel is coming from one or two refineries. Higher than 95 you can't get anyway high up here. At the coast one will get 98.
Just coming back on my last response, the 1500 meter above sea level got nothing to do with the rated power of course and onother thing before the cat-smash and exhaust replacement there wasn't a "pinging" issue.

[SA-AUII-MAX]

Just a quick update.
Yes the “ping” is no more.
Problem was the multi plug next/above the intake manifold where all engine sensors wires join together. Most properly caused by engine washes the plug got corroded inside, resulting in bad connections to the PMC.
So, before starting to change sensors, do your self a favour and check the connectors.
Thanks to all who responded to this tread.

[ronwest]

Originally Posted by SA-AUII-MAX

Just a quick update.

Thanks for that. It's always good to hear resolutions to problems.

Originally Posted by SA-AUII-MAX

So, before starting to change sensors, do your self a favour and check the connectors.

Yes, I once spent $2600 on an auto rebuild (different make of car) when the problem was in fact a corroded connector (also because of engine washing).

Oh, good luck to the 'Boks on the weekend.

[SA-AUII-MAX]

Thanx for that, I was also pi**ed off when you guys got send home, a tri-nations final would have been better.
Southern hemisphere rugby rules!