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Knocking With Stage 2 Cobb?

maxzugkraft

By maxzugkraft,
in R35 GTR

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maxzugkraft Enthusiast

maxzugkraft

Posted
Posted

Hi Guys,

I got a Cobb and have been using Stage 2 & LC5 for my ADM2009 on the road since. Great burst of power and improved drivability.

(I'm on 98RON Shell vPower, HKS res midpipe, K&N air filter element)

I took it to Phillip Is (18 deg C) and Sandown yesterday (23 deg C).

I noticed flashing of the boost gauge - which I think means that there is "knocking". This usually happens after the 3rd or 4th lap, especially if I hit the rev limiter. Sometimes it occurs even at 5000rpm in 2nd gear and tends to linger for about 5 to 10 seconds. I feel the car is not as fast as it normally is.

How do I fix this?

Is this BAD for the engine?

Thanks in advance.

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https://www.sau.com.au/forums/topic/411598-knocking-with-stage-2-cobb/
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maxzugkraft Enthusiast

maxzugkraft

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  • Author
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Thing is, it doesn't do it when I drive on the road.

The Stage 2 is the Off-the-shelf map that came with the Cobb, which I thought was conservative.

What parameters should I log?

Thanks for the reply, Martin. I received your Trans Fluid 35TML last week and filled it up before Sandown. Goes nicely.

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

Sounds just like the tune is street conservative, but not track conservative (3-4 laps heat++ etc) - they are two totally different scenarios really.

Good news is it's not a major fix required, but certainly shouldn't keep trying to replicate it! Knock = bad.

So maybe after 2 laps have an easy 1 rather than going for 3-4 (until its fixed) :)

maxzugkraft Enthusiast

maxzugkraft

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  • Author
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Does that meant if I get a track-oriented tune, it would generate less power? Because it would have to dial down the timing or boost to cope with heat.

Would larger injectors to fix this?

Martin Donnon Mentor

Martin Donnon

Posted
Posted

No point in speculating about it, you need to generate a log of some third and fourth gear pulls and then let me have a look through it. Either that or get the right map for your car running Aussie 98 fuel - such as the tune we supplied for Duncan Forrests GTR that won the NSW Supersprint championship two years in a row. No knocking, plenty of power.

OTS Cobb maps are ok, but they tend to not be a bit sketchy when pushing the limits of our 98 fuel - as they simply dont calibrate on it in the US. Regardless of what you do, that flashing engine ligh it something to take note of, and try to avoid if the idea of rebuilding an engine scares you even just a little bit :)

Snowman Grand Master

Snowman

Posted
Posted

If you want someone local (Bayswater-Vic) the guys at Racepace can put it on the dyno for you and they have the Cobb tuning software.

9762 9421

But I've seen a few R35's knock at Sandown and PI as they have a lot of engine load at those tracks.

Martin Donnon Mentor

Martin Donnon

Posted
Posted

Ok maxzugkraft I have had a chance to have a look at a few of your looks. Looks like the tune is working really really nicely, the only time there was any indicated knock (false knock) was when you shifted on the rev limiter. The yellow line in the picture below is 'knock' and as you can see it stays on zero the whole length of the run...which is very nice :)

486666_10151212210434571_56066567_n.jpg

maxzugkraft Enthusiast

maxzugkraft

Posted
  • Author
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Thanks Martin.

I can't see your picture. There is a question mark instead.

Will this tune work for warmer weather? 25-28deg C?

Bear in mind the log was done at 15 deg C ambient temp.

Is it running too rich, as I'm getting a lot more black soot on back now.

maxzugkraft Enthusiast

maxzugkraft

Posted
  • Author
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Thanks Martin.

I can see your screenshot now.

Now I can use full power without holding back!

Can't wait to get back on the track!

Hope to see lap times plummet.

Good job. Cheers!

rehab2010 Proficient

rehab2010

Posted
Posted

If you want someone local (Bayswater-Vic) the guys at Racepace can put it on the dyno for you and they have the Cobb tuning software.

9762 9421

But I've seen a few R35's knock at Sandown and PI as they have a lot of engine load at those tracks.

Would you recommend some further intercooler upgrades on top of the custom dyno tune?

Pinging at 18degC or 23degC ambient temp is pretty bad.

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