PC2

That too and because you've changed your avatar to the Toyota!

914und993

I vote for the distributor belt failure. That pellets in a can sound at WOT/high rpm was my clue the belt was broken in my old C4. I guess if one plug isn't firing, the old knock sensor induced retard can't do enough to prevent the detonation.

Chip

JasonAndreas

Unless you are running a MAF sensor I would put the old EPROM chip back in. The gas at the station you went to was probably just switched over to the winter blend. Around April/May you could put the new chip back in. When I had the exact same problem the culprit was bad gas. I had the car towed to a mechanic and they checked everything out to be okay so they replaced the fuel and the problem went away. I never bought gas from that particular station again.

Lorenfb

No more guessing! Let's get to work and pull those distributor caps.
Everyone is "dying" for the results.

Good Luck
Loren
'88 3.2

David K.

Check the sheet metal around the motor and exhaust. Over time it develops cracks and sounds like pinging. Tap on it with a ballpeen hammer.

Randall G.

Hey Jeff,

You must feel a little better, knowing that you're not the first to experience pinging in a 964 (or 993).

BTW, I didn't mention your chip in my earlier posts. Like yourself, I figured it should have pinged a long time ago, if it's the source. But, if everything else turns up okay, suppose it makes sense to try a swap (as you're already planning).

Davies

My 993 has the exact same symptoms and I've been through
everything (high octane gas, dist. belt, plugs, coils, new ecu..) and I still
can't figure out what's wrong. On my car, if I push hard enough,
I'll get a CEL. Diagnostic code reads a misfire on cylinder 5. I haven't checked
the knock sensors yet....I assumed that the diagnostic would pick that up.

I'll be curious to see what you come up with. (I hope it's just bad gas!!!)
Good luck!

David K.

I had a broke exhaust stub that also sounded like pinging on my old 911SC.

Jeff Curtis

Good one Peter, I wondered about that - but that little blue/silver thing is so damned cute...isn't it?

Randall, I do feel a little better knowing that others have had this issue.

I wouldn't think that it's rattling engine sheet metal or broken exhaust studs...but I have wondered if something is loose. Oh how I know pinging, after all I had a 340HP Supercharged SC that pinged so much the pistons BROKE!

But I'm open to the suggestions.

Wasn't able to get my 911 in the garage tonight as I had my Atlantic motor apart running tests...leakdown/compression, etc. and got it out of there, loaded it up in the trailer just in time for the bottom to drop out of the sky - damn, cats and dogs...no better way to describe it!

Anyway, will have to check it out tomorrow night...after I get my truck/trailer out of here, the neighbors just LOVE a 24ft. enclosed trailer parked out front.

SO, the saga will continue for another 24hrs...I know, it's killing me too!

Good news though, the Atlantic motor will last another 5hrs or so before it's next "checkup" - Lord knows how I have enough on my "to do" list without having to refresh that thing. 2% leakdown, across the board.

Bill Wagner

Jeff:

I'd be more than likely inclined to look at the distributor belt before doing anything else for the following reasons:

1. You have a '91, so unless the check engine light is not functioning (that happens with some after market chips) it should be logging any faults with your knock sensors.

2. I get the impression you've had your car mods in for some time and this, if I've read everything right, came on all of a sudden. That's also very typical of a distributor belt failure. If your mods were the cause, I would have thought you would have heard something long before now. A distributor belt failure will not be logged by the DME.

If it isn't the distributor, I'd be looking at the ignition system items that aren't under DME control or monitoring (coils, wires, etc. for example). If you check the distributor belt, make sure it hasn't jumped a tooth.

Jeff Curtis

Bill, plans are to check the dizzy belt first. I have seen what this does to a motor and it is frightening, to say the least.

Ask Adrian about the wonderful pics I took of my friend's engine...better yet, buy the book and you'll even have a pic of my ugly mug.

The usual procedure I use is to hookup a timing light to my pickup truck's battery (parked in the driveway, Porsche in garage) and with the P-Car running, put the sensor on at least two leads on the secondary distributor to see if the light pulses.

It was raining like crazy and my truck was attached to my trailer, out in the street...ready to deliver said trailer with my silver bullet back to the storage lot.

THEN I will have OODLES of room to changeout my front swaybar, do an alignment and figure out this damned PINGING mess! Dist. check 1st, then a general "look-see" over and under the car, check for broken head studs, etc.

If I haven't figured it out by then, I will pour the 5gal. of 110octane I will buy on the way home from work today and road test.

If it still acts up, BYE-BYE chip!

Adrian

Did I leave that picture in there? I know your hands show up a few times.
Ciao,
Adrian
964C4

Jeff Curtis

Okay, I'm somewhat appeased, I checked the distributor, all working okay.

SO, grabbed the girlyfriend and said, "we're going for a ride"...of course, she agreed.

Went up to the local Texaco that sells Unocal 76 110 octane racing fuel and bought 4 gallons...I had about 5 gallons of whatever the hell was in there left, so dumped the 4gal. of 110 in there and bought $5 worth of 93 - $20.

I neglected to remember that 110 Racing Gasoline is LEADED, so the pump has the BIG outlet that will NOT fit in our filler door. Good thing I had a pen in the glove box to hold the door open while I dribbled gas into the tank.

Imagine the looks THAT yielded from the station clerk.

Just for you worried folk out there...I don't have a catalytic converter anymore, so the leaded gas will not harm my beast.

Left the station and wiggled the car a bit (mixes the gas don't ya know), drove ~2miles to get to the highway. Mind you, I replicated the issue a few times enroute to the Texaco, so I had her confirm that she heard the pinging as well...problem still there, of course.

So we get to the highway and decide to nail it going down the ramp:

1) the car seemed to HAUL A__!

2) NO PINGING.

I tried several pounces on the throttle and shifted under FULL load a few times - NO PINGING...this my friend, was good.

Girlyfriend said, "MY GOD!! ...I didn't realize how fast this car was!"

I drove the rest of the way home with a SH__ eating grin. (read as gingival smile)

SO, dizzy belt good, higher octane eliminates the pinging...I'm voting for either:

A) I am a dumb-*** and put in the wrong grade of fuel while throwing a fit over the fact that my "giftcard" for said gas station kept shutting off in $7 increments.

-OR-

B) Amoco ("BP" now) had some BAD gas...and I don't mean from eating Mexican food either.

I'm kinda voting for "A" - I've been using that Amoco for awhile, no issues...but I guess it's possible??

Anyway, plans are to drive the car to work tomorrow and burn up some of the gas in there and go back to my normal routine of dumping 93octane in there...but will do it from ANOTHER station, just for a tank or two...then return back to Amoco to see if the trouble returns.

If the trouble returns while using the gas from ANOTHER station, bye-bye Mr. Chip.

PC2

Glad to hear that it's just BAD gas and nothing serious.

HSB

Hi Jeff,
I just came from your favorite repair shop after having some codes cleared. I saw your car there and just thougt I would drop you a line.
Later, Harpreet