Performance chip and detonation

[Brett619310]

I installed the EAT chip last night for my '93 525i (Vanos). I went through the procedure of letting the car run for a minute or two after installation to reset the computer. On the first drive things were fine for a few minutes, then when accelerating past 4k rpm I heard detonation in the engine for about 5-10 seconds. I slowed down and stopped and a stoplight, and did not hear anything after that.

The peformance seems a little bit improved, but its really hard to tell. This may be due more to the fact that I'm driving around city streets in LA and stopping and starting a lot. What I'm wondering is whether or not the anti-knock sensors may have detected the problem, and corrected it. If so, could this mean that my performance is being degraded as a trade-off, negating the effect of the chip? Keep in mind I am stuck with 91 octane here in LA.

[bahnstormer]

mark'll chime in i'm sure
but i have never heard of his before....
are u sure it was detonation?

[Brett619310]

mark'll chime in i'm sure
but i have never heard of his before....
are u sure it was detonation?

It was the telltale "marbles" in the engine on acceleration. I'm pretty sure. My main question relates to how the M50 engine handles detonation in regards to the knock sensors. I'm wondering if it retards the power in order to reduce the knocks, and how for how long it does this.

[everest]

I have a 93 525iA with VANOS. I have a noise that occurs from roughly 1700-2500 RPM. I can't tell whether it is VANOS rattle or pinging/detonation, but I'll even hear the noise right after a shift. Have you checked out the VANOS rattle thread?

[Brett619310]

I have a 93 525iA with VANOS. I have a noise that occurs from roughly 1700-2500 RPM. I can't tell whether it is VANOS rattle or pinging/detonation, but I'll even hear the noise right after a shift. Have you checked out the VANOS rattle thread?

No I haven't... I've only heard it that once and it was around 4000 RPM. I'm just going to wait and see right now.

[bjl4776]

At 2500rpm there is no way it is detonation. I had a turbo on a non vanos M50 and I got detonation at 4400rpm with 10psi of boost and stock injectors, so I have a hard time believing a chip could make you detonate. Luckily the pinging went away with new injectors and a tad lower boost

[Brett619310]

At 2500rpm there is no way it is detonation. I had a turbo on a non vanos M50 and I got detonation at 4400rpm with 10psi of boost and stock injectors, so I have a hard time believing a chip could make you detonate. Luckily the pinging went away with new injectors and a tad lower boost

Ok... but I had it at 4k rpm, not 2.5k.