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Discussion Starter #1
Has anyone experienced what seems like frequent pinging and loss of power with just light to moderate throttle from having been at neutral throttle?

The sound also has a metallic-like, solenoid tripping quality. Basically, it sounds/feels like pinging, accompanied with the customary reduced power and this happens at least half the time when I apply light to moderate throttle from having been steady throttle for a while. I’ve noticed that 100 octane will not lessen the symptoms any more. This has been happening for a long time and seems to be more pronounced these days.

Every time this happens I instinctively back off the throttle and when I reapply the same amount of throttle within a second or so the symptoms largely disappear and more power is felt from the same rpm starting point - plus 100rpm perhaps.

Unbelievably, I have been on a number of test drives with technicians and have not been able to reproduce the problem to the point where they could detect it, except once but it was much less obvious and subsequent test drives by him didn’t reproduce the problem. I can detect the problem when it’s not as pronounced since I know what to expect. Usually, it’s pretty pronounced and I've come to expect it every time I apply light to moderate throttle. Heavy throttle will induce it but at the lower rpm’s I’ll downshift if I want that kind of pickup. The point is that it will happen without asking a lot from the engine at lower- mid rpm’s.

Examples: driving in traffic (2200-2500rpm) and then picking up a little bit of speed. Also will happen on freeway from neutral throttle at say 3300rpm, and then applying moderate throttle to pick up a little speed. Noticed it comming on to the freeway at around 3000 or so with heavy throttle.

When the engine is cold the car responds perfectly to light throttle input, but even before one or two rpm light bars turn off the symptoms begin to arise. I’m very gentle when it’s cold so I don't apply a moderate/heavy throttle at this time.

Isn’t noticeable from 3400-3500 and up. At 4000rpm for sure, power delivery does not feel like it's being reduced or backed off by what must be knock sensors retarding the system, but I suspect that fixing this issue will result in a power increase at these higher revs from what I'm experiencing now.

No fault codes with GT2 and BMW dealer checks, multiple times. New MAF’s, cam sensors, VANOS solenoids (one bank), and reset DME to normal parameters did not have any affect on this problem and no codes were seen. Plugs were fairly recent when I started noticing the problem.

Possible causes?

Doing a search under pinging or preignition pulled up a somewhat similar symptom involving pinging which was resolved by replacing the Tank Vent Valve (TVV).

All the VANOS posts I read didn’t raise pinging issues.

I wonder if one or more of the VANOS or timing chain tensioners are faulty given that they require oil pressure to work. Maybe not enough oil pressure at lower engine speeds?

Anyone with similar symptoms?

I’m quite frustrated and really concerned at the long term damage that this behavior will do to my engine. Low-end torque is a large part of the fun with the M5. I miss it.
 

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Could it be one faulty spark plug/coil upsetting the balance?
 

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Basil: My car does the same thing. However, a bit of 100 octane in the tank completely takes care of the problem. It is very subtle and you have to listen carefully for the pinging. And yes,t the knock sensors do work, but they do still allow some pinging.

You can blame 91 Octane in CA for the problem. Note that in Europe and moswt of the US 93 octane is available.
 

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KirklandM5 said:
Basil: My car does the same thing. However, a bit of 100 octane in the tank completely takes care of the problem. It is very subtle and you have to listen carefully for the pinging. And yes,t the knock sensors do work, but they do still allow some pinging.

You can blame 91 Octane in CA for the problem. Note that in Europe and moswt of the US 93 octane is available.
I had the same problem a few months ago with a tank of 91 I bought at an ARCO station. Barely noticeable preignition noise (when making rapid throttle movements at low rpm) and then could feel the knock sensors realing back the timing (delayed throttle responce and reduced low rpm acceleration).
After 2 days I added 2 gallons of 100+ and the problem went away immeadiatly.
Have not had any problems in the 6 tanks of Chevron 91 since then, so they must of had 89 or 87 in the premium tank at the ARCO. The car does seem to really like 93+ better than 91 but normally no observable knocking with 91 and Dinan S2 mods. Try putting in some 100 octane or tolulene and see if it goes away.
 

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Discussion Starter #5 (Edited)
It just so happens that the service light went on today. I made an appointment to bring it in.

Tin, I'll see what they say about the plugs and coils.

Jeff and Paul, 100 octane by itself doesn’t help much and the problem is usually more than slight. It never used to be this way.

Given the severity and time length of the problem I would not be surprised if the warning light was tripped by something else.

Thanks Guys. I'll post a follow-up for the search knowledge base if a remedy is found.

I don't know if I should be concerned or relieved that the light went on. :confused3
 

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Discussion Starter #7
It was the battery! To begin diagnosing the problem I was told to get a new battery since my original one was not charging well (black dot, not green). As soon as I started the car after installing a new battery I sensed smoother running. After extended freeway running I found that my problem was solved. I was very suprised. I guess the voltage output was too low. :M5thumbs:
 
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