more knock after decat

[vxer]

Hi there,

Just took the car out for a spin to test the decat - feels nice, more responsive etc, however, i\'ve noticed i appear to be getting more knock on boost than i did before.

Two questions:

*) Is there anything i can easily change on the PFC to see if i can decrease the knock on boost?

*) Is there any way to get the PFC to display knock in numbers instead of a bar?

I realise that i need a remap, but i can\'t afford one right now, i just need a stop gap...

Cheers, Paul.

[nikp]

to get numbers for knock, the only way you can do that is to use the peak hold function - which shows the maximum that you get

[vxer]

to get numbers for knock, the only way you can do that is to use the peak hold function - which shows the maximum that you get

How do you enable that?

Cheers, Paul.

[vxer]

Could it be as simple as lowering the boost base duty to reduce knock?

Ta, Paul.

[gonzoninja]

To get the peak hold function you have to press the up or down button (sorry I forget which) and the numbers should appear in white with a black background.

I tend to run with only 4 things being monitored, so you can get the peak hold volumes next to the actual running values

[nikp]

Me too. I run with 4 displays, and peak hold on at the same time.

[vxer]

Me too. I run with 4 displays, and peak hold on at the same time.

Thanks guys!

I guess the trouble with peak hold on knock is its going to be difficult to measure knock on boost since you get a lot of "fake knock" when you lift...

Hmmm.

Cheers, Paul.

[Jonathan_F]

Hi vxer,

Pip gave me this tip. Use the PIM voltage page to add 3-5% fuel across the boost range you are having problems with. This will add fuel at all times however so can cause problems. I don\'t know whether rotarys suffer from bore wash (fuel removes protective oil coating on bore faces - high wear) but If I were you I\'d not drive it under load and get it mapped.

Jon

[vxer]

Hi vxer,

Pip gave me this tip. Use the PIM voltage page to add 3-5% fuel across the boost range you are having problems with. This will add fuel at all times however so can cause problems. I don\'t know whether rotarys suffer from bore wash (fuel removes protective oil coating on bore faces - high wear) but If I were you I\'d not drive it under load and get it mapped.

Jon

Thanks Jon!

I guess thats going to be similar in effect to lowering the boost...

I\'m tempted to try retarding the timing, except i don\'t know which way is retarded and which way is advanced on the PFC?! :eek

Cheers, Paul.

[Jonathan_F]

Well its knocking becoause its running lean, which is bad. Its running lean because its breathing better. I\'d give it a bit more fuel. Or not drive it under boost. Retarding the timing won\'t help that much. Will disguise the problem perhaps.
Jon

[Glenn Butcher]

Spot on Jon, vxer - there are quite a few posts on this subject.  One here: http://www.mazdarotaryclub.com/forums/showthread.php?t=14428&highlight=boost

[vxer]

Well its knocking becoause its running lean, which is bad. Its running lean because its breathing better. I\'d give it a bit more fuel. Or not drive it under boost. Retarding the timing won\'t help that much. Will disguise the problem perhaps.
Jon

Yes, you are correct, indeed. Just heard that the apexi\'s std map has some dubious advance in some places which might not be helping - but i really need to get it remapped.

I\'m getting knock values of 37 under hard boost on 2nd turbo...

Cheers, Paul.

[G@NDY]

I didnt think that knock readings in the 30\'s was anything to worry about. I was always led to believe that real knock is a reading over 60:confused: but then i do tend to just make stuff up, i often see high 20\'s low 30\'s:Typing

[vxer]

I didnt think that knock readings in the 30\'s was anything to worry about. I was always led to believe that real knock is a reading over 60:confused: but then i do tend to just make stuff up, i often see high 20\'s low 30\'s:Typing

Its just that i\'m sure it was lower before the decat :confused: , so i\'d like to get back down to that level again - IIRC tuners say they map to under 20.

I\'m pleased its not too much to worry about though! :wiggle

Cheers, Paul.