Serious Pinging

[Peterlech]

For years, my '95 has run fine on 89 octane fuel, with only occasional pinging in very hot weather.. Recently it stared pinging excessively, so I switched to 91 fuel. It still pings, so I ran a double dose of Techron thru the latest tank, but no real improvement.

The pinging seems to happen between 2000 and 2500 rpm, under medium load, and are somewhat ambient temperature sensitive. Freeway rpms are 3K, so no issues there.

I didn't think this car had knock sensors because of the hot weather pinging, but after a search, I read that it does. Also read that they rarely fail.

Has anyone experienced this, and what did you find to be the cause?

TIA

Pete
1995 E-34 124K miles
1997 Carrera S

[xspeedy]

I have a 94 525i and I have a similar problem. I took the car to my local indy and he ran some bg44k to clean up the injectors and combustion chamber. It was fed directly into the fuel rail.

It helped some, but there is still some ping. Not sure if there is a real solution to completely get rid of the problem. If you want something more DIY, you could try Seafoam. Just search for it.

[whiskychaser]

You guys might want to have a look at this:
http://www.bimmernut.com/forum/showthread.php?p=282878

[Tiger]

Fuel pressure regulator is a good probability. I would also think of MAF too.

[Peterlech]

For years, my '95 has run fine on 89 octane fuel, with only occasional pinging in very hot weather.. Recently it stared pinging excessively, so I switched to 91 fuel. It still pings, so I ran a double dose of Techron thru the latest tank, but no real improvement.

The pinging seems to happen between 2000 and 2500 rpm, under medium load, and are somewhat ambient temperature sensitive. Freeway rpms are 3K, so no issues there.

I didn't think this car had knock sensors because of the hot weather pinging, but after a search, I read that it does. Also read that they rarely fail.

Has anyone experienced this, and what did you find to be the cause?

TIA

Pete
1995 E-34 124K miles
1997 Carrera S

Thought others could benefit from my find: It was a partially malfunctioning Oxygen Sensor. Usually when they fail, the system goes to full rich and the Check engine light comes on. In this case, unplugging the sensor stopped the pinging, so it was replaced. All is well. FYI, the original sensor went over 120K miles before acting up.

[Russell]

could be a knock sensor. I have one that isupposedly failed. However no knocking. FYI, my ox sensor has 115,000 miles. It will be replaced next week. Also my car is E.A.T. chipped and I use 93 octane fuel.

[russiankid]

I've been having this same issue for quite some time now. I've replaced all ICV hoses and vacuum lines, new oil filler cap, MAF cleaned, Bosch spark plugs, new fuel lines, fuel filter, and checked the fuel tank inside to make sure everything was nice and clean.

I am leaning towards a vacuum leak somewhere, MAF, or Vanos.

[Peterlech]

New information; the Oxygen sensor replacement helped the problem, but did not eliminate it. The shop spent several days and has determined that the VANOS unit is not connected to the camshaft it is supposed to affect. Once they get it off, they will determine if it has to be replaced or can be reinstalled. Maybe there was an installation problem when the head was rebuilt after a radiator failure warped it, but I doubt it, as that was 40K miles ago. The pinging problem developed all of a sudden a month ago.

Sounds like serious money here.

Update: the shop said it is not the VANOS unit. They have given up, returned the car after a week with N/C. Said they ran it on the road with the diagnostic laptop connected, saw where the knock detectors are retarding as they should, engine is clean inside the bores. As the new Oxy sensor took out 80% of the pinging, guess I will just run it on premium and put up with it.

[Luftpost]

I have been having the same pinging problems lately as the first post above. Was considering what all could be wrong with the car. Did some research on the board and bought some "Sea Foam" at Wally World for $8.XX. Filled the gas tank halfway with premium, poured in the entire bottle of Sea Foam and then started on a cross country from St. Louis to PA for a family getaway.

I kept the car in 3rd on the highway for the first 20 minutes. RPMs around 4-5000, with occasional quick bursts a little higher. Then went back into "Drive", and ALL PINGING IS GONE!!!!!

Unbelievable stuff!!! Hope it lasts.

L.

[Russell]

I have been having the same pinging problems lately as the first post above. Was considering what all could be wrong with the car. Did some research on the board and bought some "Sea Foam" at Wally World for $8.XX. Filled the gas tank halfway with premium, poured in the entire bottle of Sea Foam and then started on a cross country from St. Louis to PA for a family getaway.

I kept the car in 3rd on the highway for the first 20 minutes. RPMs around 4-5000, with occasional quick bursts a little higher. Then went back into "Drive", and ALL PINGING IS GONE!!!!!

Unbelievable stuff!!! Hope it lasts.

L.

"Chevron Techron" and "Regane (forgot who makes it)" work very well to help clean your fuel system of deposits. I use it several times a year along with mostly 93 chevron gasoline.