StevoT2000

Hi all,

I just recently had an apexi power fc fitted and mapped with a few other upgrades,

Last night I was driving back from my mates and the knock meter went upto 36! (I will put a pic up to show what revs and boost it was doing). This was in 2nd gear and oil was upto temp also.
It did it earlier on in the day aswell, similar conditions as above but the knock was only showing 25 this time.

Is this a massive problem?
What could be causing this?

Obviously I will contact my mapper but dont wanna disturb his bank holiday weekend.

I wasnt planning on driving my car until this is sorted, would this be the right thing to do?

Thanks in advance



Also what is the airflow? how does that get read?

joz8968

iTrader: (13)

Contact your mapper on Tuesday - he'll tell you how he mapped it and what to expect for knock at WOT/max load, etc.

Did this reading happen in 4th or 5th at WOT/near max revs? Any CEL knock light flashing at the same time (if set to do so)?

FTR, IIRC JGM correctly:-

MY93-96 - max of 50
MY97/98 - max of 30
MY99/00 - max of 20

Obviously these are rough ballpark figures - each individual mapped engine is bespoke, of course (some are quieter/noisier then others of the same MY).


The A-Flw parameter is the MAF voltage. So long as it's around 4500+ mV when at WOT/near max revs, then that's the important thing...

joz8968

iTrader: (13)

Sorry, just studied your readings...


If that log shown is correct though, then that does seem "not right" i.e. to get a max knock reading of 36, whilst never going above -6mmHg / 2945mV / 3440rpm, is something to flag up for sure. After all, you've not placed any meaningful load/boost on the engine.

In the meantime I'd stay off boost and carefully monitor the Commander, until such time as you've had that conversation with the mapper...

Of course, it could be many erroneous things, such as momentary fuel starvation (going round a corner when low on fuel), stale fuel, inaudible misfire, etc., etc...

Is your cooling system in good order with normal running temps. Try swapping the "rpm" parameter for the "water temp" one to monitor temps. Or even better switch to "8-ch" mode and see all the parameters - can see "ign timing" and "inj duty" too. Monitor everything to see if something's not as expected...

StevoT2000

Thanks for your reply,

I should of added this to the first post... the mapper said he'd set it to trigger cel light if it went to 30, but this never came on when it went to 36 could this mean the commander is faulty?

He also said if it ever goes over 15 upto 20, then to call him. Which is what i will do as soon as bank holiday is over. I jus thought I'd try and seek advice on here in the meantime

I usually have it on water temp instead of airflow, I jus fancied a change for that journey

I wont be driving it at all until it gets sorted.

joz8968

iTrader: (13)

You prob 'mssed' the flashing - it can be extremely transient (I speak from personal experience). Plus you're naturallly not staring at the CEL - it just catches the corner of your eye.... sometimes! But if it defo didn't, then it prob wasn't knocking. Good.


Yes - totally the best thing to do!