Low RPM Hard Acceleration - Pre-detonation

[SoCalRPM]

I removed my tune yesterday and cleared the adaptations (thanks for the help chocstraw) and the pinging/rattling went away instantly. I'm not saying this is the end all, be all solution. But it's a good variable to eliminate for further investigation.

I'll try the winter blend tune soon to see how that goes. Crappy CA 91 gas...

[eriktufa]

This is very interesting how you all have the same tune and believe that the low rpm timing is way too high/advance.

Have you all discussed this with Alex and get a better understanding what this is happening?

I'll go back to stock tune tomorrow and reassess my option. I have been hearing the same thing and I thought it's just exhaust or engine noise as the car makes all sort of metallic noise during cold start (for my car anyway).

[eriktufa]

Update:

I discussed this with Alex (he has been super helpful) to compare stage 1 tune vs stock tune vs stage 1 tune without Vanos adjustment.

Magic!!! The rattling/metallic/knocking noise is gone when I switched to the tune without Vanos adjustment!! This might be something you guys can try?

Alex said the car won't have optimal power but I rather have a peace of mind.

[SoCalRPM]

Originally Posted by eriktufa

Update:

I discussed this with Alex (he has been super helpful) to compare stage 1 tune vs stock tune vs stage 1 tune without Vanos adjustment.

Magic!!! The rattling/metallic/knocking noise is gone when I switched to the tune without Vanos adjustment!! This might be something you guys can try?

Alex said the car won't have optimal power but I rather have a peace of mind.

Good to know - Yeah, I've been chatting with him, too, and as always he's been very responsive.

A friend with similar issues here wasn't convinced that his revised tune fixed the knocking issue but I cannot confirm that he got the sans-vanos option.

I'm assuming "won't have optimal power" means not an optimal Stage 1 tune, but still better than OEM, yeah?

[eriktufa]

Originally Posted by SoCalRPM

Good to know - Yeah, I've been chatting with him, too, and as always he's been very responsive.

A friend with similar issues here wasn't convinced that his revised tune fixed the knocking issue but I cannot confirm that he got the sans-vanos option.

I'm assuming "won't have optimal power" means not an optimal Stage 1 tune, but still better than OEM, yeah?

I might have reclarified my comparisons and findings to help everyone here.

I compared Stage 1 Tune vs Stock Tune vs Stage 1 Tune "Winter Blend" vs Stage 1 Tune without Vanos Adjustment.

Both Stage 1 Tune and Stage 1 Tune "Winter Blend" tune make knocking/metallic/rattling noise under certain RPM and throttle load.

I'm 99% certain that the Vanos Adjustment causes the noise.

The car is now noise free now and I can't be happier.

SoCalRPM you are spot on, not an optimal Stage 1 tune however it is still better than stock tune and still more responsive I can't say how much hp I am losing but I don't think it's relevant for my situation.

[Scharbag]

Yeah, I have been running Shell 91 again to try and while the winter tune is better, there is still noise at full throttle when in a high gear on the highway (passing in 6th gear).

I am not convinced that this is purely a fuel quality thing. Perhaps it is VANOS noise that sounds like knock. Grrr

As others have said, and as always, Alex has been super helpful. This would be easier had the car thrown at least 1 damn code at some point...

This has been a journey...

[Scharbag]

Revised my first post.

This has been a fun journey... But Alex was helpful and I think we have this licked. Not timing or pre-det. Pretty sure it was VANOS noises.

I will keep you all updated after a few more spirited drives.

Cheers,

[buldogge]

^^^If this really is the case...then the real question is, what are the consequences (short term and/or long term) of this VANOS noise, if any?

Sometimes a noise is just a noise...Sometimes a noise is a warning siren for parts and $$$ soon to be flying from your motor/car.

So, which is it?

Lastly...Still doesn't explain why increased octane solves the issue.

-Mark in St. Louis

[Alex@Alpine]

Originally Posted by buldogge

^^^If this really is the case...then the real question is, what are the consequences (short term and/or long term) of this VANOS noise, if any?

Sometimes a noise is just a noise...Sometimes a noise is a warning siren for parts and $$$ soon to be flying from your motor/car.

So, which is it?

Lastly...Still doesn't explain why increased octane solves the issue.

-Mark in St. Louis

Could be many things, sludge build up, oil pressure solenoids, seals, vanos gears are going bad, and so on.

As these vehicles get older more problems arise. You use to only see threads on throttle actuators & prevention maintenance like rods, now you see various different problems arising.

High compression motors like such run better on higher octane (slower burning) fuels overall. Could also be a placebo effect.

Regardless of the problem I am here to help if I can. Please keep in mind it has been years many members have ran tuned without any major failures including the OP himself. I wouldn't put anyone's vehicle in harms way.

[pbonsalb]

However, others with what appears to be the same symptoms have found that higher octane has makes the noise that sounds like predetonation pinging go away.

Maybe there is more and more bad gas out there or bad winter formulation gas? Maybe altering the vanos timing affects cylinder pressure in a way that makes detonation more likely? The circumstances when people hear this pinging sound are classic detonation circumstances — lower rpm higher load.

[Scharbag]

Originally Posted by pbonsalb

However, others with what appears to be the same symptoms have found that higher octane has makes the noise that sounds like predetonation pinging go away.

Maybe there is more and more bad gas out there or bad winter formulation gas? Maybe altering the vanos timing affects cylinder pressure in a way that makes detonation more likely? The circumstances when people hear this pinging sound are classic detonation circumstances — lower rpm higher load.

I tried my Dinan tune again and I get the same low rpm clatter with it too.

I am not sure what the root cause is but fingers crossed, the VANOS changes that Alex provided will help long term.

Out fuel quality on the island is bad. Our winter blend is terrible from what I have been told. BC gas is a the shits in general.

This has been a strange issue. If I discover anything else, I will let you all know.

Cheers,

[Scharbag]

Here is cylinder 2 from my car. Cheap borescope.

60,000KM on it. What do you guys think? SYT_Shadow Piston edge looks pretty sharp.

Also plugs from 1 and 2. 8,000KM on the plugs.

Cheers,

[eriktufa]

Originally Posted by Scharbag

Here is cylinder 2 from my car. Cheap borescope.

60,000KM on it. What do you guys think? SYT_Shadow Piston edge looks pretty sharp.

Also plugs from 1 and 2. 8,000KM on the plugs.

Cheers,

I still have my concern as well mate, I'm starting to listen to some noises. The easiest way to identify the noise is driving through a lane or tunnel when the noise muffles.

[SYT_Shadow]

Originally Posted by Scharbag

Here is cylinder 2 from my car. Cheap borescope.

60,000KM on it. What do you guys think? SYT_Shadow Piston edge looks pretty sharp.

Also plugs from 1 and 2. 8,000KM on the plugs.

Cheers,

Why are those plugs orange? Have you used octane booster?

The pistons don't look like mine, but mine are probably an extreme example anyway.

What happens when you go to the stock tune?

[Scharbag]

Originally Posted by SYT_Shadow

Why are those plugs orange? Have you used octane booster?

The pistons don't look like mine, but mine are probably an extreme example anyway.

What happens when you go to the stock tune?

Yeah, I used some booster to help with the noise for a bit.

It seems to be a lot better since the VANOS programming changes. We will see. I cannot really run stock for long due to the primary cats being gone. But when I do run stock 241E the noose is gone.

Cheers,

[SYT_Shadow]

Originally Posted by Scharbag

Yeah, I used some booster to help with the noise for a bit.

It seems to be a lot better since the VANOS programming changes. We will see. I cannot really run stock for long due to the primary cats being gone. But when I do run stock 241E the noose is gone.

Cheers,

Have you tried a couple 'spark plug defoulers'? They should allow you to run catless with the oem software for a while

[jvictormp]

Originally Posted by SYT_Shadow

Have you tried a couple 'spark plug defoulers'? They should allow you to run catless with the oem software for a while

Why for a while? Doesn't last long?

[SYT_Shadow]

Originally Posted by jvictormp

Why for a while? Doesn't last long?

I'm not clear whether you will eventually get a CEL or not

[wyatth]

Between this thread and SYT's, I'm certainly rethinking any tune despite not exhibiting any of these symptoms.

[buldogge]

I've read the entire thread, and I certainly understand (and appreciate) what Alex said...but...I continue to have no issues while using a 3gal intermix of E85 and 93 (...in my case Mobil).

-Mark in St. Louis

[eriktufa]

Originally Posted by SoCalRPM

Thanks OP for all the time (and aggravation!) in helping to sort through this. I've had a very similar sound and missed this thread before. I'm still diagnosing but will report back soon!

I posted a video in a separate thread that you can seee here:https://www.m3post.com/forums/showthread.php?t=1659505

But also I'll link the video below for anyone with similar issues!

Did you ever sort this issue out with winter tune / non-vanos tune?

[SoCalRPM]

Originally Posted by eriktufa

Did you ever sort this issue out with winter tune / non-vanos tune?

I reverted to stock for the time being. Alex sent me the alternate tune files but haven't had time to upload and give the car a test run. Will update when I can!