Suddenly I'm pinging...

[myk]

Hey folks,

I'm the original owner of my '98 GT and just noticed the other day that anything over 5K RPM I'm getting the rattling/pinging from the engine. I don't know how long I've had this problem because, as my daily driver over the last 21 years, this car never sees anything more than 3K RPM during my commutes. The car starts up easy, idles great, has excellent throttle response, pulls well, and does everything like it did back in 1998 except for the rattling/pinging above 5K. I never would've noticed if it hadn't been for the pushy Range Rover in the other lane.

In any case, the car's only mods are a K&N air filter element and a PI intake. After searching around the 'net and this forum I tried moving from 87 to 89 octane, cleaned the MAF sensor, ran a half can of seafoam in the gas tank and changed the fuel filter, and it is still pinging. There are no engine codes and the spark plugs (gapped to factory specs) and wires were changed to Motocraft brand pieces just under 20K miles ago; the car currently has 128K miles on it. I replaced the fuel pump back in 2006, and my fuel pressure gauge reads 30lbs at idle, and holds that pressure for at least a half an hour. I have always used synthetic oil but only change it when it gets to 7500 miles, which is only once a year and a half or so; I don't drive very far at all in this car.

I've read about seafoaming, top-end cleaner, and trying 91 octane, the highest octane available to me, but I'd rather not do that because as we all know the car should run fine on 87 and I'd like to genuinely fix the problem, not just band-aid it. Any suggestions or ideas are greatly appreciated, thanks in advance..

 

[01yellercobra]

My first thoughts are fuel pressure and inlet temps. Holding pressure at idle isn't the same as keeping up at WOT. You'll need to log fuel pressure some how for that.

Another possibility is the air temp sensor going bad and giving the wrong temp to the ECU causing it to give too much timing.

 

[Silver95bird]

96-98 cars ran two ECT sensors, one for the dash and one for the EEC. I had one go bad and it ran like garbage, but the dash one read fine so i had no idea. Things can go bad without being obvious. did it have any codes?

did it make noise more/less if you ran 87/89/91, just to be sure it was pinging and not another noise that sounds similar?

Sent from my moto z3 using Tapatalk

 

[myk]

My first thoughts are fuel pressure and inlet temps. Holding pressure at idle isn't the same as keeping up at WOT. You'll need to log fuel pressure some how for that.

Another possibility is the air temp sensor going bad and giving the wrong temp to the ECU causing it to give too much timing.

I guess I could tape my fuel pressure gauge to the windshield and do a run, right? I'll try that as soon as I can. Also, are you referring to the IAT? I will try to test it or swap it out if it's inexpensive enough.

96-98 cars ran two ECT sensors, one for the dash and one for the EEC. I had one go bad and it ran like garbage, but the dash one read fine so i had no idea. Things can go bad without being obvious. did it have any codes?

did it make noise more/less if you ran 87/89/91, just to be sure it was pinging and not another noise that sounds similar?

Sent from my moto z3 using Tapatalk

No codes showing or pending. I did read somewhere that a guy swapped out his IAT and ECT and all of his pinging disappeared, so I'll look into those two things. As for fuel, I just put in 89 octane and it's still pinging. How long does it take for the "new" fuel to take effect? If the pinging continues I will try 91. Personally, I've never heard pinging before so I wasn't sure what it was, but I'm certain that it's pinging-sort of like marbles or rocks shaking around in a can, right?

In any case, thanks guys, I'll look into the IAT, ECT and fuel pressure under throttle and report back...

 

[myk]

Update:

I swapped in a new IAT, and then made about four runs to 5K RPM or more and there wasn't one sign of pinging. Now, i was pretty ecstatic, but then I thought about the 89 octane I put in the car last night and can't help but wonder if the new gas was the fix instead of the IAT.

on a nearly empty tank, how long would it have taken for the 89 octane to make a difference to the engine? I would think it would be immediate right?

In any case, I put 87 octane back into the car tonight and I will wait and see if the pinging returns, telling me whether it was the IAT or not for sure. Thanks again guys...

 

[ttocs]

it just needs more cow bell and you will not notice.

 

[D3VST8R96GT]

Consuming oil? How much oil is in the intake track?

Crank case fumes/oil can lead to pinging. If there isn't much blowby launching oil into the intake.... compression test.

Slightly intoxicated hope it makes sense.

 

[myk]

Consuming oil? How much oil is in the intake track?

Crank case fumes/oil can lead to pinging. If there isn't much blowby launching oil into the intake.... compression test.

Slightly intoxicated hope it makes sense.

Oops never saw your response. I'm not sure about the blowby and I'll definitely look into that, but the problem was the IAT sensor. Car pulls all the way to redline again with no problems. If anyone else has a problem with pinging I hope they see this as a possible solution. Thanks everyone...

 

[Fast Lane]

Any chance it might be the tensioners for the timing chains starting to go? Maybe its not ping at all.

I would also try dumping a whole can of Sea Foam in with 91, and drive it hard.

 

[01yellercobra]

Any chance it might be the tensioners for the timing chains starting to go? Maybe its not ping at all.

I would also try dumping a whole can of Sea Foam in with 91, and drive it hard.

He said in the post above yours it was the IAT sensor.