Hi guys,

Recently had my car tuned with catback , intake , UICP and FMIC , putting down a solid 203kw/275whp on a mainline dyno.

All went well and had a track event just the other day , with a few knockCELs and everything running smoothly.

A few days after the track event , I begin noticing more knockCELs when I go partial throttle, maybe like 60%. I have a MR and it knocks during shift ups aswell. I thought it was just bad fuel so decided to go easy on the car until the next refill.

Problem is now , even after two tanks , the car seem to knock quite a fair bit at boost , not even at WOT. Everything is still the same as before when it got tuned so I'm not sure what actually went wrong that causes the knocks which didn't really exist before this.

Only big difference I noticed would be the change in temperature. When I got it tuned , it's about 17-20C degrees and now its usually about 10-14C degrees. Would this be a big factor ? My understanding would be that the MAF sensor would scale as the temperatures drop/rises. I will be meeting up with my tuner soon to have this sorted out but thought I'd drop a thread here to see what's everyone's thoughts on it

 

pull your spark plugs and give them a look. it's a quick and easy indicator.

oh but first check the vacuum hose from the FPR to the intake manifold. also do you have have the upgraded fuel pump relay?

 

yeap , already have the upgraded fuel pump relay and zip tied the vacuum hoses.

what indications should I look for in the spark plug if it was faulty

 

mostly just comparing the plugs to see if anything stands out as abnormal, possibly signs of oil on plug or detonation.

just make sure the engine is cold if you decide to pull the plugs. a spark plug socket is good for removing the plug, a magnet helps with positioning the plugs for reinstall. a tiny bit of anti-seize on the threads is a good idea since the head is aluminum. boot protector for the other side.

this chart is for traditional/copper plugs but it might help: http://www.aa1car.com/library/reading_spark_plugs.jpg

another thing to consider, have you noticed any new drive train noise or rattle? the knock sensor might be picking up something other than knock.

 

To be specific about the Anti Seize - I don't like it because I torque my plugs and it changes the torque spec, but it will prevent corrosion if it is going to happen. If you do use it DO NOT use copper - use a nickel base or your head will become sacrificial to the copper and become (slightly) more brittle / weak.

Even if you zip tied it double check the FPR hose and check for any other air leaks. It just warmed up here in the states and I split a hose that had been fine for 3 years on a long drive (which is probably easier on things than a track day)

 

all sorted now , sat down with tuner yesterday night and went for a few runs.

The problem was at part throttle/cruise speed , the timing was too aggressive so each time when I go onto WOT in 5th gear , about 3k rpm ~ , the sudden change in boost must've spiked from cruising to WOT.

Reduced the timing slightly and the car is running beautifully now

 

do you know what your timing was set when you had knock and your new timing ?

 

Colder air runs leaner as more can fit into the engine as it is denser.

Track days and dyno sessions are two different scenarios requiring two different TUNES